Laminated core and method for manufacturing laminated core

Abstract

In each of the at least one pair of pellet-facing end surfaces (e.g., a pair of pellet-facing end surfaces (111a, 111i)), 1lt is satisfied; ra (D) / Ra (S) < = 12. Here, Ra (D) is the surface roughness in the stacking direction of the facing end surfaces of the pellets. Ra (S) is the surface roughness in the main magnetic flux direction (or the rolling direction) of the plate surface of the steel plate having an end surface constituting a part of the facing end surfaces of the core blocks.

Description

Technical Field

[0001] The present invention relates to a laminated core and a method for manufacturing a laminated core. This application claims priority based on Japanese Patent Application No. 2022-159532 filed in Japan on October 3, 2022, the entire contents of which are cited herein. Background Art

[0002] In a laminated core (laminated core) formed by stacking a plurality of steel plates, each of the stacked steel plates vibrates when excited. Due to the vibration of each steel plate, noise may be generated from the laminated core. Therefore, a technology for suppressing the vibration of such steel plates is required. As such a technology, there are technologies described in Patent Documents 1 to 4.

[0003] Patent Document 1 discloses a technique in which a vibration-damping steel plate is partially sandwiched between a plurality of stacked electromagnetic steel plates.

[0004] Patent Document 2 discloses a technique for stacking a plurality of electromagnetic steel sheets so that the surfaces without the processed grooves do not overlap each other after processing grooves are processed on the surface of each electromagnetic steel sheet. Patent Document 2 also discloses a technique for applying an adhesive resin to the end surfaces of the stacked plurality of electromagnetic steel sheets.

[0005] Patent Document 3 discloses a technique in which a stress member that is compressively deformed in the longitudinal direction of a plane constituting the outer periphery of an iron core is provided on the plane.

[0006] Patent Document 4 discloses a technique for laminating a plurality of electromagnetic steel sheets, each of which has an insulating coating containing 4.9% to 7.1% Si and having a surface roughness Rmax of 3.5 μm or more. Patent Document 4 also discloses inserting an impregnating agent having an adhesive function between the laminated plurality of electromagnetic steel sheets.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Publication No. 2006-14555

[0010] Patent Document 2: Japanese Patent Application Publication No. 2003-77747

[0011] Patent Document 3: Japanese Patent Application Publication No. 2000-114064

[0012] Patent Document 4: Japanese Patent Application Laid-Open No. 4-361508 Summary of the invention

[0013] Problems to be solved by the invention

[0014] However, in the techniques described in Patent Documents 1 to 4, a material different from the steel plate is required to suppress vibration of the laminated core.

[0015] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a laminated core capable of suppressing vibration without using a material different from a steel plate.

[0016] Means used to solve problems

[0017] The laminated iron core of the present invention is characterized in that it comprises a plurality of core blocks, each of which has a plurality of stacked steel plates, and the plurality of core blocks have core block opposing end faces, the core block opposing end faces are end faces of the core blocks that are located at positions opposite to other core blocks, and in each of at least one pair of the core block opposing end faces, the following formula (A) is satisfied, and the pair of core block opposing end faces are two core block opposing end faces arranged at positions opposite to each other.

[0018] 1 <Ra(D) / Ra(S)≤12…(A)

[0019] Here, Ra(D) is the surface roughness Ra of the opposing end faces of the core block in the stacking direction of the steel plate, and the unit is μm. Ra(S) is the surface roughness Ra of the plate surface of the steel plate having an end face constituting a part of the opposing end faces of the core block in the direction of the main magnetic flux flowing in the steel plate or the rolling direction of the steel plate, and the unit is μm.

[0020] The manufacturing method of the laminated iron core of the present invention is a manufacturing method of a laminated iron core having a plurality of core blocks, wherein each of the plurality of core blocks has a plurality of steel plates laminated thereon. The manufacturing method is characterized by comprising: a cutting process of cutting the steel plates; a first roughness measurement process of measuring the surface roughness Ra(S) of the plate surface of the steel plates cut in the cutting process, with the unit being μm; a second roughness measurement process of measuring the surface roughness Ra(D) of the opposing end faces of the core blocks, with the unit being μm, where the core blocks have the steel plates that are the measurement objects of the surface roughness Ra(S); and a roughness adjustment process of adjusting the surface roughness of the opposing end faces of the core blocks when the ratio Ra(D) / Ra(S) of the surface roughness Ra(D) measured by the second roughness measurement process to the Ra(S) measured by the first roughness measurement process does not satisfy 1 < Ra(D) / Ra(S) ≤ 12. The surface roughness Ra(S) is the surface roughness Ra in the direction of the main magnetic flux flowing through the steel plates when the laminated iron core is excited, or the surface roughness Ra in the rolling direction of the steel plates, with the unit being μm. The surface roughness Ra(D) is the surface roughness Ra in the lamination direction of the steel plates, with the unit being μm. The opposing end faces of the core blocks are the end faces of the core blocks that are located at positions opposing other core blocks in the laminated iron core. In the roughness adjustment process, the surface roughness of at least one of each pair of the opposing end faces of the core blocks is adjusted to satisfy 1 < Ra(D) / Ra(S) ≤ 12, and the pair of opposing end faces of the core blocks are two opposing end faces of the core blocks arranged at opposing positions. Description of the Drawings

[0021] Figure 1 FIG. is an example showing a laminated iron core.

[0022] Figure 2A FIG. is a first example illustrating the measurement position of the surface roughness in the lamination direction.

[0023] Figure 2B FIG. is a second example illustrating the measurement position of the surface roughness in the lamination direction.

[0024] Figure 2C FIG. is a third example illustrating the measurement position of the surface roughness in the lamination direction.

[0025] Figure 2D FIG. is a fourth example illustrating the measurement position of the surface roughness in the lamination direction.

[0026] Figure 2E FIG. is a fifth example illustrating the measurement position of the surface roughness in the lamination direction.

[0027] Figure 3AIt is a diagram for explaining a first example of the measurement position of the surface roughness in the in-plane direction.

[0028] Figure 3B It is a diagram for explaining a second example of the measurement position of the surface roughness in the in-plane direction.

[0029] Figure 3C It is a diagram for explaining the third example of the measurement position of the surface roughness in the in-plane direction.

[0030] Figure 3D It is a diagram for explaining the fourth example of the measurement position of the surface roughness in the in-plane direction.

[0031] Figure 3E It is a diagram for explaining the fifth example of the measurement position of the surface roughness in the in-plane direction.

[0032] Figure 4A This is a diagram for explaining a first example of the number of crystal grains on the opposing end surfaces of the steel plates and the length of the opposing end surfaces of the steel plates.

[0033] Figure 4B It is a diagram for explaining a second example of the number of crystal grains on the facing end surfaces of the steel plates and the length of the facing end surfaces of the steel plates.

[0034] Figure 4C It is a diagram for explaining the third example of the number of crystal grains on the facing end surfaces of the steel plates and the length of the facing end surfaces of the steel plates.

[0035] Figure 4D This is a diagram for explaining the fourth example of the number of crystal grains on the facing end surfaces of the steel plates and the length of the facing end surfaces of the steel plates.

[0036] Figure 4E It is a diagram for explaining the fifth example of the number of crystal grains on the facing end surfaces of the steel plates and the length of the facing end surfaces of the steel plates.

[0037] Figure 5 This is a flowchart showing an example of a method for manufacturing a laminated core. DETAILED DESCRIPTION

[0038] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

[0039] Furthermore, when the comparison objects such as length, position, size, and interval are the same, in addition to being strictly the same, they also include differences within the scope that does not depart from the gist of the invention (for example, differences within the scope of tolerance set at the time of design).

[0040] Figure 1 1 is a diagram showing an example of a laminated core 100. Figure 1 The x-y-z coordinates shown are indicated for the convenience of explaining the orientation of each part. Figure 1The laminated core 100 shown is, for example, a laminated core wound with a coil for flowing a three-phase alternating current (so-called a three-phase laminated core). In addition, the current flowing into the coil wound on the laminated core 100 is not limited to a three-phase alternating current. For example, the current flowing into the coil wound on the laminated core 100 may also be a single-phase alternating current. In addition, the laminated core 100 is used as an iron core provided in various devices. The laminated core 100 may also be an iron core provided in a transformer, a converter, a rotating electric machine, and a reactor, for example.

[0041] exist Figure 1 In the embodiment, the laminated core 100 includes a plurality of core blocks 110a to 110e. Each of the plurality of core blocks 110a to 110e includes a plurality of steel plates stacked so that the plate surfaces face each other.

[0042] exist Figure 1 In the figure, the double-arrowed lines shown in the core blocks 110a to 110e indicate the direction of the main magnetic flux flowing in the steel sheet when the core blocks 110a to 110e are excited or the rolling direction. In the following description, the direction of the main magnetic flux flowing in the steel sheet when the core blocks 110a to 110e are excited is referred to as the main magnetic flux direction as needed.

[0043] In addition, the main magnetic flux direction is the magnetic flux direction set excluding the main magnetic flux in the area where the direction changes due to the outflow and inflow with other core blocks among the main magnetic flux flowing in each core block (that is, the main magnetic flux direction is the direction in which the main magnetic flux moves in a straight line). In the case where the steel plate is a unidirectional electromagnetic steel plate, it is preferred that the main magnetic flux direction is as close to the rolling direction as possible, and it is more preferred that the two are consistent. In addition, in the case where the steel plate is a unidirectional electromagnetic steel plate, it is preferred that the rolling direction is as close to the easy magnetization direction (direction parallel to the easy magnetization axis) as possible, and it is more preferred that the two are consistent.

[0044] In the following description, when the steel plates are stacked in a manner that the direction of the double-arrowed lines shown in the plurality of core blocks 110a to 110e is approximately parallel to the rolling direction of the steel plates (preferably parallel), it means that the main magnetic flux direction (or rolling direction) can be either the main magnetic flux direction or the rolling direction. On the other hand, when the steel plates are not stacked in a manner that the direction of the double-arrowed lines shown in the plurality of core blocks 110a to 110e is approximately parallel to the rolling direction of the steel plates (preferably parallel), it means that the main magnetic flux direction (or rolling direction) is the main magnetic flux direction. Since the rolling direction can be determined by simply observing the plate surface of the steel plate, it is easy to determine the rolling direction.

[0045] In the present embodiment, the laminated core 100 is configured to have a quadratic symmetry relationship with its center line CL as the rotational symmetry axis. The center line CL is an imaginary straight line that passes through the center of gravity of the laminated core 100 and extends in the stacking direction (z-axis direction) of the steel plates constituting the laminated core 100. In the following description, the stacking direction of the steel plates constituting the laminated core 100 will be referred to as the stacking direction as needed.

[0046] In addition, in the present embodiment, a case where a plurality of core blocks 110a to 110e are formed by stacking a plurality of unidirectional electromagnetic steel sheets of the same steel type and plate thickness is exemplified. However, the steel sheet is not limited to the unidirectional electromagnetic steel sheet. The steel sheet may be, for example, a bidirectional electromagnetic steel sheet. In addition, the steel sheet may be a non-directional electromagnetic steel sheet. In addition, at least one of the steel type and plate thickness of the steel sheets constituting at least two of the plurality of core blocks may be different. In addition, at least one of the steel type and plate thickness of the plurality of steel sheets constituting one core block may be different. In addition, in the present embodiment, a case where the thickness (the length in the stacking direction (z-axis direction)) of the plurality of core blocks 110a to 110e is the same is exemplified. In addition, in the present embodiment, a case where the core blocks 110a to 110b are constructed and arranged in a quadratic symmetric relationship with the center line CL as the rotational symmetry axis is exemplified. Similarly, a case where the core blocks 110c to 110d are also constructed and arranged in a quadratic symmetric relationship with the center line CL as the rotational symmetry axis is exemplified.

[0047] The number, shape, size, and arrangement of the core blocks are determined by the specifications of the equipment equipped with the laminated core. Figure 1 The illustrated form.

[0048] The end faces of the plurality of core blocks 110a to 110e include core block facing end faces 111a to 111p. The core block facing end faces 111a to 111p of the core blocks 110a to 110e are end faces of the core blocks 110a to 110e that are located at positions facing other core blocks. Figure 1 In the example shown, the end surface of the core block 110a includes core block opposing end surfaces 111a to 111d. In addition, the end surface of the core block 110b includes core block opposing end surfaces 111e to 111h. In addition, the end surface of the core block 110c includes core block opposing end surfaces 111i to 111j. In addition, the end surface of the core block 110d includes core block opposing end surfaces 111k to 111l. In addition, the end surface of the core block 110e includes core block opposing end surfaces 111o to 111p.

[0049] Two core block facing end faces arranged at mutually opposing positions are referred to as a pair of core block facing end faces. For example, the core block facing end face 111a of the core block 110a and the core block facing end face 111i of the core block 110c are arranged at mutually opposing positions. Therefore, these core block facing end faces 111a and 111i are a pair of core block facing end faces 111a and 111i. Figure 1 In the illustrated laminated core 100, there are eight pairs of core block facing end faces 111a and 111i, 111b and 111l, 111c and 111m, 111d and 111n, 111e and 111k, 111f and 111j, 111g and 111o, 111h and 111p. Here, a pair of core block facing end faces (for example, core block facing end faces 111a and 111i) is a so-called butt joint. Therefore, a part or the whole area of ​​a pair of core block facing end faces (two core block facing end faces) is in contact with each other.

[0050] exist Figure 1 In the embodiment, the core block facing end faces 111a to 111p are divided at the inflection points that appear when a line representing the core block facing end faces 111a to 111p that can be seen when the laminated core 100 is viewed from the stacking direction (z-axis direction) is approximated by a straight line (see Figure 1 The core blocks shown are facing end faces 111c and 111d, 111g and 111h, 111m and 111n, 111o and 111p).

[0051] In addition, when a curve approximation (for example, approximation using a quadratic function) of a line representing the opposing end faces 111a to 111p of the core blocks that can be seen when observing the laminated core 100 from the stacking direction (z-axis direction) can approximate the line with higher accuracy than a straight line approximation, the opposing end faces of the core blocks may be divided at the position of the extreme value when the curve approximation is performed.

[0052] Hereinafter, the laminated core 100 of the present embodiment will be described together with the knowledge and findings found by the inventors of the present application. Figure 1 The reference numerals shown here are used to illustrate the knowledge and insights found by the inventors of the present application. However, the knowledge and insights found by the inventors of the present application are not limited to Figure 1 Detailed description of the laminated core 100 shown.

[0053] The vibration at the butt joints of the core blocks 110a to 110e (the core block facing end faces 111a to 111p) has a significant influence on the noise of the laminated core 100. The inventors of the present application focused on the shape of the steel plate in order to suppress the vibration at the butt joints of the core blocks 110a to 110e without using a material different from the steel plate. In addition, the inventors of the present application found that by making the roughness of the core block facing end faces 111a to 111p moderate, the vibration at the butt joints of the core blocks 110a to 110e (the core block facing end faces 111a to 111p) can be suppressed, thereby suppressing the noise of the laminated core 100.

[0054] Specifically, the inventors of the present application have discovered that by satisfying the following formula (1) in at least one pair of core block opposing end faces (two core block opposing end faces) among a plurality of pairs of core block opposing end faces 111a and 111i, 111b and 111l, 111c and 111m, 111d and 111n, 111e and 111k, 111f and 111j, 111g and 111o, 111h and 111p, the vibration of the butt joint (core block opposing end faces) can be suppressed.

[0055] 1 <Ra(D) / Ra(S)≤12…(1)

[0056] Here, Ra(D) is the surface roughness Ra(μm) in the stacking direction (z-axis direction) of one of the pair of core block opposing end faces (two core block opposing end faces) that are the objects of calculation of formula (1). In the following description, the surface roughness determined in this way for each core block opposing end face is referred to as the stacking direction surface roughness as needed. In addition, Ra(S) is the surface roughness Ra(μm) of the plate surface of the steel plate in the main magnetic flux direction (or the rolling direction of the steel plate), and the above-mentioned steel plate has an end face that constitutes a part of the core block opposing end face. In the following description, the surface roughness determined in this way is referred to as the in-plane direction surface roughness as needed. Let the surface roughness Ra (the stacking direction surface roughness Ra(D) and the in-plane direction surface roughness Ra(S)) be the average height Rc of the roughness curve element determined by JIS B 0601:2013. In addition, the core block opposing end faces are composed of the end faces of a plurality of stacked steel plates. The end surface formed by a part of the opposing end surface of the core block is the end surface of one of the plurality of steel plates. In addition, Ra (μm) means that the unit of surface roughness Ra is micrometer (the unit is expressed in the same way for other variables n, L, and n / L). The surface roughness Ra (S) in the in-plane direction is, for example, not less than 0.10 μm and not more than 3.00 μm.

[0057] For example, it is assumed that the pair of core block facing end faces (two core block facing end faces) to be calculated by equation (1) is a pair of core block facing end faces 111a and 111i. In this case, as long as equation (1) is satisfied for each of the core block facing end faces 111a and 111i, equation (1) is satisfied for each of the pair of core block facing end faces 111a and 111i. Similarly, it is determined whether equation (1) is satisfied for the other pairs of core block facing end faces 111b and 111l, 111c and 111m, 111d and 111n, 111e and 111k, 111f and 111j, 111g and 111o, and 111h and 111p.

[0058] Figure 2A to Figure 2E It is a diagram for explaining an example of the measurement position of the surface roughness Ra (D) in the lamination direction. Figure 2A and Figure 2D The y-z coordinates shown correspond to Figure 1 The y-coordinate and z-coordinate of the x-y-z coordinate shown. Figure 2B , Figure 2C and Figure 2E The x-z coordinates shown correspond to Figure 1 The x-coordinate and z-coordinate of the x-y-z coordinate shown. As mentioned above, Figure 2A The core block 110a and Figure 2D The core block 110b shown is constructed and arranged in a quadratic symmetric relationship with the center line CL of the laminated core 100 as the rotational symmetry axis. Figure 2B The core block 110c and Figure 2D The core blocks 110 d shown are also constructed and arranged in a two-fold symmetric relationship with the center line CL of the laminated core 100 as the axis of rotational symmetry.

[0059] Figure 2A and Figure 2D The figure shows an example of the measurement position of the surface roughness Ra (D) in the lamination direction of the core block opposing end faces 111 a to 111 d and 111 e to 111 h of the core blocks 110 a and 110 b . Figure 2B and Figure 2E The figure shows an example of the measurement position of the surface roughness Ra (D) in the lamination direction of the core block opposing end faces 111i to 111j and 111k to 111l of the core blocks 110c and 110d. Figure 2C This is a diagram showing an example of the measurement position of the stacking direction surface roughness Ra (D) of the core block opposing end faces 111m to 111p included in the core block 110e.

[0060] The stacking direction surface roughness Ra (D) is measured on an imaginary straight line passing through the centers of both ends of a pair of core block opposing end faces in a pair of core block opposing end faces that are the objects of calculation of formula (1) when the core block opposing end faces are observed in the stacking direction of a steel plate having an end face that constitutes a part of the core block opposing end faces.

[0061] exist Figure 1 In the example shown, the stacking direction of the steel plates having the end faces formed by part of the core block facing end faces 111a to 111p is the z-axis direction. Figure 1 In the embodiment, when the core block facing end faces 111a and 111i, 111b and 111l, 111c and 111m, 111d and 111n, 111e and 111k, 111f and 111j, 111g and 111o, 111h and 111p are viewed from the z-axis direction, both ends 113a and 113b, 113c and 113d, The positions of the centers of 113e and 113f, 113f and 113g, 113h and 113i, 113j and 113k, 113e and 113f, 113f and 113g, 113l and 113m, 113m and 113n are respectively 112a, 112b, 112c, 112d, 112e, 112f, 112g, 112h. The positions of the centers of the two ends of the core block facing each other can be obtained on each end face in the stacking direction (z-axis direction). If we proceed along the positions of the centers of the two ends of the core block facing each other, as shown in FIG. Figure 2A to Figure 2E As shown in FIG. 2 , imaginary straight lines 201 a to 201 p are obtained.

[0062] Therefore, when the pair of core block facing end faces to be calculated in equation (1) are the pair of core block facing end faces 111a and 111i, Figure 2A and Figure 2B As shown in FIG. 1 , the stacking direction surface roughness Ra (D) of the core block opposing end faces 111a and 111i is measured on the imaginary straight lines 201a and 201e, respectively. In addition, when the pair of core block opposing end faces to be calculated by equation (1) are the pair of core block opposing end faces 111b and 111l, as shown in FIG. Figure 2A and Figure 2E As shown in FIG. 1 , the roughness curves used to calculate the stacking direction surface roughness Ra (D) of the core block opposing end faces 111b and 111l are measured on the imaginary straight lines 201b and 201p, respectively. In addition, when the pair of core block opposing end faces to be calculated by equation (1) are the pair of core block opposing end faces 111c and 111m, as shown in FIG. Figure 2A and Figure 2CAs shown in FIG. 1 , the roughness curves used to calculate the stacking direction surface roughness Ra (D) of the core block opposing end faces 111c and 111m are measured on the imaginary straight lines 201c and 201g, respectively. In addition, when the pair of core block opposing end faces to be calculated by equation (1) are the pair of core block opposing end faces 111d and 111n, as shown in FIG. Figure 2A and Figure 2C As shown, the roughness curves for calculating the surface roughness Ra (D) in the stacking direction of the core block opposing end faces 111d and 111n are measured on the imaginary straight lines 201d and 201h, respectively.

[0063] The same is true for other pairs of core block opposing end faces 111e and 111k, 111f and 111j, 111g and 111o, 111h and 111p. The roughness curves used to calculate the surface roughness Ra (D) in the stacking direction are measured on the imaginary straight lines 201k and 201o, 201l and 201f, 201m and 201i, and 201n and 201j, respectively.

[0064] In the following description, the position on the imaginary straight line 201a to 201p where the roughness curve (roughness curve element) is measured is referred to as the stacking direction measurement position as needed. The above roughness curve is used to calculate the stacking direction surface roughness Ra (D). Figure 1 In the illustrated laminated core 100, the stacking direction measurement position is as follows: Figure 2A to Figure 2E Shown is the location of the chamfer.

[0065] The plurality of steel plates of the core block opposing end faces of one of the pair of core block opposing end faces constituting the calculation object of formula (1) are extracted piece by piece, and the stacking direction surface roughness Ra (D) is measured at the stacking direction measurement position of the extracted steel plates. Instead of the above method, the stacking direction surface roughness Ra (D) can be measured at the stacking direction measurement position of the steel plate before stacking used to constitute the core block having the core block opposing end faces on the one side. Such measurement is performed for all the steel plates constituting the core block opposing end faces on the one side. For example, when the number of stacked sheets is 200 sheets, 200 stacking direction surface roughness Ra (D) is measured for one core block opposing end face. The representative value of the plurality of stacking direction surface roughness Ra (D) measured as above (200 in the above example) is set as the stacking direction surface roughness Ra (D) of the core block opposing end faces on the one side. The representative value is, for example, the arithmetic mean. The median or the like can also be used instead of the arithmetic mean. The stacking direction surface roughness Ra(D) of the other of the pair of core block facing end faces to be calculated by equation (1) is calculated in the same manner as the stacking direction surface roughness Ra(D) of one of the core block facing end faces.

[0066] For the core block opposing end faces 111a and 111i, 111b and 111l, 111c and 111m, 111d and 111n, 111e and 111k, 111f and 111j, 111g and 111o, 111h and 111p, the stacking direction surface roughness Ra (D) of one and the other of a pair of core block opposing end faces is calculated as described above.

[0067] Figure 3A to Figure 3E This is a diagram for explaining an example of the measurement position of the roughness curve for calculating the in-plane surface roughness Ra(S). Figure 3A to Figure 3E The x-y coordinates shown correspond to Figure 1 The x-coordinate and y-coordinate of the x-y-z coordinate shown.

[0068] Figure 3A , Figure 3D The figure shows an example of the measurement position of the roughness curve used to calculate the in-plane surface roughness Ra(S) of a steel plate having an end surface constituting a part of the core block opposing end surfaces 111a to 111d and 111e to 111h of the core blocks 110a and 110b. Figure 3B , Figure 3E The figure shows an example of the measurement position of the roughness curve used to calculate the in-plane surface roughness Ra(S) of a steel plate having an end surface constituting a part of the core block opposing end surfaces 111i to 111j and 111k to 111l possessed by the core blocks 110c and 110d. Figure 3C The figure shows an example of the measurement position of the roughness curve for calculating the in-plane surface roughness Ra(S) of the steel plate having the end surface constituting a part of the core block opposing end surfaces 111m to 111p of the core block 110e.

[0069] Here, the direction perpendicular to the main magnetic flux direction (or rolling direction) and the stacking direction of the steel plate is referred to as the width direction as needed. The roughness curve used to calculate the in-plane surface roughness Ra (S) is measured on an imaginary straight line passing through the center of the width direction of the steel plate and extending along the main magnetic flux direction (or rolling direction) of the steel plate in the plate surface having an end face of a part of the opposing end faces of a pair of core blocks constituting the calculation object of formula (1).

[0070] exist Figure 1 In the example shown, the stacking direction of the steel plates having the end faces constituting a part of the core block facing end faces 111a to 111p is the z-axis direction. In addition, the main magnetic flux direction (or rolling direction) of the steel plates constituting a part of the core block facing end faces 111a to 111d and 111e to 111h is the y-axis direction ( Figure 1In addition, the width direction of the steel plate constituting a part of the core block facing end faces 111a to 111d, 111e to 111h is the x-axis direction. The main magnetic flux direction (or rolling direction) of the steel plate constituting a part of the core block facing end faces 111i to 111j, 111k to 111l, 111m to 111p is the x-axis direction ( Figure 1 In addition, the width direction of the steel plate constituting a part of the core block facing end faces 111i to 111j, 111k to 111l, and 111m to 111p is the y-axis direction.

[0071] In this case, Figure 3A In the example, the imaginary straight line 301a passes through the center of the width direction (x-axis direction) of the steel plate having the end surface constituting a part of the core block opposing end surfaces 111a to 111d and extends along the main magnetic flux direction (or rolling direction, y-axis direction) of the steel plate. Figure 3D In the figure, the imaginary straight line passing through the center position in the width direction (x-axis direction) of the steel plate having an end face constituting a part of the core block opposing end faces 111e~111h and extending along the main magnetic flux direction (or rolling direction, y-axis direction) of the steel plate is the imaginary straight line 301d.

[0072] In addition, Figure 3B In the example, the imaginary straight line 301b is a line passing through the center of the width direction (y-axis direction) of the steel plate having the end surface constituting a part of the core block opposing end surfaces 111i to 111j and extending along the main magnetic flux direction (or rolling direction, x-axis direction) of the steel plate. Figure 3E In the figure, the imaginary straight line passing through the center position in the width direction (y-axis direction) of the steel plate having an end face constituting a part of the core block opposing end faces 111k~111l and extending along the main magnetic flux direction (or rolling direction, x-axis direction) of the steel plate is the imaginary straight line 301e.

[0073] In addition, Figure 3C In the figure, the imaginary straight line passing through the center position in the width direction (y-axis direction) of the steel plate having an end face constituting a part of the core block opposing end faces 111m~111p and extending along the main magnetic flux direction (or rolling direction, x-axis direction) of the steel plate is the imaginary straight line 301c.

[0074] Therefore, if Figure 3A , Figure 3D As shown in FIG. 1 , the roughness curve for calculating the surface roughness Ra (S) in the in-plane direction of the steel plate having the end surface constituting a part of the core block opposing end surfaces 111a to 111d and 111e to 111h is measured on the imaginary straight lines 301a and 301d, respectively. Figure 3B , Figure 3E As shown in FIG. 1 , the roughness curve for calculating the surface roughness Ra (S) in the in-plane direction of the steel plate having the end surface constituting a part of the core block opposing end surfaces 111i to 111j and 111k to 111l is measured on the imaginary straight lines 301b and 301e, respectively. Figure 3C As shown, a roughness curve for calculating the in-plane surface roughness Ra(S) of a steel plate having an end surface constituting a part of the core block opposing end surfaces 111m to 111p is measured on a virtual straight line 301c.

[0075] In addition, when the measurement position (virtual straight line) of the roughness curve for calculating the surface roughness Ra (S) in the in-plane direction is set as described above, the virtual straight line may be separated into multiple ones depending on the shape of the steel plate. In this case, the roughness curve is measured on one of the multiple separated virtual straight lines. In addition, it is also possible to set the multiple virtual straight lines not to be separated (that is, set the interval between the multiple virtual straight lines to 0 (zero)), and measure the roughness curve on the multiple virtual straight lines.

[0076] In the following description, positions where imaginary straight lines 301 a to 301 e for measuring a roughness curve (roughness curve element) for calculating the in-plane direction surface roughness Ra(S) are measured are referred to as in-plane direction measurement positions as necessary.

[0077] The plurality of steel plates constituting one of the core block opposing end faces of a pair of core block opposing end faces constituting the calculation object of formula (1) are extracted one by one, and the surface roughness Ra(S) in the in-plane direction is measured at the in-plane direction measurement position of the extracted steel plates. Instead of the above method, the surface roughness Ra(S) in the in-plane direction is measured at the in-plane direction measurement position of the steel plates before stacking used to constitute the core block having the core block opposing end faces on the one side. Such measurement is performed for all the steel plates constituting the core block opposing end faces on the one side. For example, when the number of stacked sheets is 200 sheets, 200 in-plane direction surface roughness Ra(S) are measured for one core block opposing end face. The representative value of the plurality of (200 in the above example) in-plane direction surface roughness Ra(S) measured as above is set as the in-plane direction surface roughness Ra(S) of the core block opposing end faces on the one side. The representative value is, for example, the arithmetic mean. The median or the like may also be used instead of the arithmetic mean. The in-plane surface roughness Ra(S) of the other of the pair of core block facing end faces to be calculated by equation (1) is calculated in the same manner as the in-plane surface roughness Ra(S) of one of the core block facing end faces.

[0078] For a pair of core block opposing end faces 111a and 111i, 111b and 111l, 111c and 111m, 111d and 111n, 111e and 111k, 111f and 111j, 111g and 111o, 111h and 111p, the in-plane surface roughness Ra (S) of one and the other core block opposing end faces of a pair of core block opposing end faces is calculated as described above.

[0079] As described above, in order to calculate the surface roughness Ra (D) in the stacking direction and the surface roughness Ra (S) in the in-plane direction, for example, a roughness curve (roughness curve element) is measured. For example, the roughness curve (roughness curve element) is measured for each of the plurality of steel plates constituting the opposing end faces of one core block. In addition, the roughness curve (roughness curve element) is measured at the stacking direction measurement position and the in-plane direction measurement position.

[0080] For example, when the number of stacked sheets is 200, for one core block facing end face, 200 roughness curves (roughness curve elements) are measured as roughness curves (roughness curve elements) for calculating the surface roughness Ra (D) in the stacking direction. The representative values ​​of the plurality of (200 in the above example) roughness curves measured as above are set as the roughness curves for calculating the surface roughness Ra (D) in the stacking direction of the one core block facing end face. In addition, the representative values ​​of the plurality of (200 in the above example) roughness curves are calculated by calculating the representative values ​​of the values ​​at the same point in the thickness direction in each of the plurality of roughness curves. The representative value is, for example, the arithmetic mean. The median or the like may also be used instead of the arithmetic mean. In addition, in the case where the thickness of the plurality of steel plates is different, for example, the roughness curve connecting the plurality of (200 in the above example) roughness curves may be set as the roughness curve (roughness curve element) for calculating the surface roughness Ra (D) in the stacking direction.

[0081] The roughness curve used to calculate the surface roughness Ra (S) in the in-plane direction is measured, for example, for all steel plates having end faces that constitute a part of the opposing end faces of a core block. For example, when the number of stacked sheets is 200, 200 roughness curves are measured for the opposing end faces of a core block as the roughness curve used to calculate the surface roughness Ra (S) in the in-plane direction. The representative value of the plurality of (200 in the above example) roughness curves measured as above is set as the roughness curve used to calculate the surface roughness Ra (S) in the in-plane direction of the steel plate having the end faces that constitute a part of the opposing end faces of the core block. The representative value of the plurality of roughness curves can be obtained, for example, by calculating the average value of the values ​​at the same position (x coordinate and y coordinate) in the direction of the plate surface. The representative value is, for example, the arithmetic mean. The median or the like can also be used instead of the arithmetic mean.

[0082] In the measurement of the roughness curve (roughness curve element), for example, the One-Shot 3D profile measuring instrument (model: VR-6000) manufactured by Keyence Corporation can also be used. Regarding the measurement field of view, for example, the measurement magnification is set to 200 times so that, for example, the size of one field of view is 500μm×500μm. When measuring the average height of the roughness curve element with a digital microscope, the vibration of the steel plate during measurement can also be corrected by setting the cutoff value λs=0μm and the cutoff value λc=0mm. The measurement magnification is preferably 100 times or more, and more preferably 500 times to 700 times.

[0083] Using the surface roughness Ra(S) in the in-plane direction and the surface roughness Ra(D) in the stacking direction calculated for the facing end faces of the same core block, Ra(D) / Ra(S) is calculated. Then, it is confirmed whether the calculated Ra(D) / Ra(S) satisfies the formula (1).

[0084] The method for satisfying the formula (1) may be any method as long as the roughness of the end surface of the steel plate can be adjusted. The roughness of the end surface of the steel plate is adjusted by, for example, grinding, cutting, or polishing.

[0085] For example, in order to obtain the planar shape ( Figure 1 When the steel plates are cut into the shape of the x-y plane shown in the figure, the roughness of the end faces of the steel plates one by one can also be adjusted. In addition, the roughness of the end faces of the steel plates cut into the planar shape of the core blocks 110a~110e can also be adjusted. For example, when the steel plates are cut one by one, the roughness of the end faces of the steel plates one by one can also be adjusted by controlling the gap between the upper and lower blades of the shearing machine. In addition, after stacking a plurality of steel plates, the roughness of the end faces corresponding to the end faces 111a~111p opposite to the core blocks can be adjusted. In addition, two or more of these methods can also be combined.

[0086] Furthermore, after stacking the plurality of steel plates, it is also possible to confirm whether the end faces corresponding to the end faces 111a to 111p facing the core block satisfy equation (1). Furthermore, if equation (1) is not satisfied, the roughness of the end faces may be adjusted. Furthermore, it is also possible to adjust the roughness of the end faces of the steel plates one by one after disassembling the plurality of stacked steel plates. Furthermore, it is also possible not to adjust the roughness of the end faces of the steel plates before stacking the plurality of steel plates, but to confirm whether the end faces corresponding to the end faces 111a to 111p facing the core block satisfy equation (1) after stacking the plurality of steel plates. Furthermore, if equation (1) is not satisfied, the roughness of the end faces may be adjusted to satisfy equation (1).

[0087] It is conceivable that by satisfying equation (1), when the laminated core 100 is excited, the steel plates adjacent in the stacking direction (z-axis direction) can apply a bonding force that acts on the core block opposing end faces 111a to 111p in a mutually attractive manner to the butt joints (core block opposing end faces 111a to 111p) of the core blocks 110a to 110e and the areas in the vicinity thereof. In equation (1), if Ra(D) / Ra(S) is lower than 1 (Ra(D) / Ra(S)<1), the roughness of the core block opposing end faces 111a to 111p becomes too small (close to a flat state). Therefore, it is conceivable that the above-mentioned bonding force cannot be applied to the butt joints (core block opposing end faces 111a to 111p) of the core blocks 110a to 110e and the areas in the vicinity thereof. On the other hand, if Ra(D) / Ra(S) is higher than 12 (Ra(D) / Ra(S)>12), the above-mentioned bonding force becomes too strong, so excessive compressive stress is introduced into the steel plate. It can be imagined that due to this compressive stress, the butt joints of the core blocks 110a~110e (the opposing end faces 111a~111p of the core blocks) vibrate.

[0088] Furthermore, the inventors of the present application have found that it is more preferable to use the following formula (2) instead of formula (1) from the viewpoint of more reliably improving the noise suppression effect of the laminated core 100 .

[0089] 6≤Ra(D) / Ra(S)≤8…(2)

[0090] As described above, it is sufficient that at least one pair of the core block facing end faces 111a and 111i, 111b and 111l, 111c and 111m, 111d and 111n, 111e and 111k, 111f and 111j, 111g and 111o, 111h and 111p satisfies the formula (1) (preferably, the formula (2) is also satisfied). However, it is preferred that at least two pairs of the core block facing end faces satisfy the formula (1) (preferably, the formula (2) is also satisfied). Furthermore, it is more preferred that the total number of the core block facing end faces (in Figure 1 In the example shown, the formula (1) is satisfied (preferably, the formula (2) is also satisfied) in each of a pair of core block opposing end faces that is 1 / 2 times or more of 8). In addition, it is more preferred that the formula (1) is satisfied (preferably, the formula (2) is also satisfied) in each of all pairs of core block opposing end faces.

[0091] In addition, the inventors of the present application focused on the grains of the steel plate in order to suppress the vibration at the butt joint (core block opposing end faces) of the core blocks 110a to 110e without using a material different from the steel plate. Here, as required, the end face of the steel plate having an end face constituting a part of the core block opposing end faces 111a to 111p is referred to as the steel plate opposing end face. In addition, as required, among the grains existing in the steel plate having the steel plate opposing end faces, the number of grains containing the steel plate opposing end faces as a boundary is referred to as the number of grains on the steel plate opposing end faces. In addition, as required, the value obtained by dividing the number of grains on the steel plate opposing end faces by the length of the steel plate opposing end faces is referred to as the number of grains per unit length on the steel plate opposing end faces. Here, the number of grains on the steel plate opposing end faces is n (pieces). In addition, the length of the steel plate opposing end faces is L (mm). Then, the number of crystal grains per unit length on the facing end surfaces of the steel plate is n / L (pieces / mm).

[0092] The inventors of the present application investigated the relationship between the number n / L of crystal grains per unit length on the steel plate facing end faces and the noise level of the laminated core 100. At this time, the number n / L of crystal grains per unit length on the steel plate facing end faces was calculated as follows. First, the number n / L of crystal grains per unit length on the steel plate facing end faces was calculated for all steel plates having end faces that constitute a part of the core block facing end faces of one of a pair of core block facing end faces 111a and 111i, 111b and 111l, 111c and 111m, 111d and 111n, 111e and 111k, 111f and 111j, 111g and 111o, and 111h and 111p. Then, the arithmetic mean of the calculated number of grains per unit length n / L on the steel plate facing end faces is calculated as the number of grains per unit length n / L on the steel plate facing end faces of the core block on the one side. As a result of calculating the number of grains per unit length n / L on the steel plate facing end faces in this way, the inventors of the present application obtained the following knowledge: the noise level of the laminated core 100 changes significantly due to the vibration of the butt joints (core block facing end faces 111a to 111p) of the core blocks 110a to 110e, when the number of grains per unit length n / L on the steel plate facing end faces is 0.5 (pieces / mm). It can be considered that if the number of grains per unit length on the opposing end surfaces of the steel plate n / L is higher than 0.5 (pieces / mm), then in the opposing end surfaces of the steel plate, since multiple grains vibrate separately, the vibration of the docking portion of the core blocks 110a~110e (the opposing end surfaces of the core blocks 111a~111p) cannot be fully reduced.

[0093] Therefore, the inventors of the present application have obtained the following knowledge and insights: by satisfying the following equation (3) in at least one of a pair of core block opposing end faces 111a and 111i, 111b and 111l, 111c and 111m, 111d and 111n, 111e and 111k, 111f and 111j, 111g and 111o, 111h and 111p (preferably two core block opposing end faces), the vibration of the laminated core 100 can be suppressed.

[0094] n / L≤0.5…(3)

[0095] Figure 4A to Figure 4D It is a diagram for explaining an example of the number n of crystal grains on the facing end surfaces of the steel plate and the length L of the facing end surfaces of the steel plate.

[0096] Figure 4A , Figure 4D The diagram is a diagram for explaining the number n of crystal grains on the steel sheet opposing end surfaces constituting a part of the core block opposing end surfaces 111 a to 111 d and 111 e to 111 h of the core blocks 110 a and 110 b and the length L of the steel sheet opposing end surfaces. Figure 4B , Figure 4E It is a diagram for explaining the number n of crystal grains on the steel plate opposing end surface constituting a part of the core block opposing end surfaces 111i to 111j and 111k to 111l of the core blocks 110c and 110d and the length L of the steel plate opposing end surface. Figure 4C It is a diagram for explaining the number n of crystal grains on the steel plate opposing end surface constituting a part of the core block opposing end surfaces 111m to 111p of the core block 110e and the length L of the steel plate opposing end surface.

[0097] exist Figure 4A In FIG. 1 , as a crystal grain having a steel plate opposing end surface as a boundary, a crystal grain group 401a consisting of five crystal grains is exemplified, and the crystal grains are present in one of the steel plates having the steel plate opposing end surface constituting a part of the core block opposing end surface 111a. In this case, the number n of crystal grains on the steel plate opposing end surface constituting a part of the core block opposing end surface 111a is 5. Figure 1 and Figure 2A As shown, there are a plurality of steel plates having steel plate opposing end surfaces constituting a portion of the core block opposing end surfaces 111a in the stacking direction (z-axis direction). Therefore, the number n of crystal grains on the steel plate opposing end surfaces constituting a portion of the core block opposing end surfaces 111a is counted for each of these plurality of steel plates. For example, when the core block 110a has 100 steel plates, and the number n of crystal grains on the steel plate opposing end surfaces of the 100 steel plates constituting a portion of the core block opposing end surfaces 111a is all 5, the total number n of crystal grains on the steel plate opposing end surfaces constituting a portion of the core block opposing end surfaces 111a is 500 (=100×5).

[0098] The number n of crystal grains on the steel plate facing end surface constituting a part of the core block facing end surfaces 111b to 111p other than the core block facing end surface 111a is counted in the same manner. Figure 4A to Figure 4E In the figure, as a grain group including the opposing end faces of the steel plate as the boundary in the grains, grain groups 401b, 401c, 401d, 401e, 401f, 401g, 401h, 401i, 401j, 401k, 401l, 401m, 401n, 401o, and 401p are respectively represented, and the above-mentioned grains exist in a piece of steel plate having the above-mentioned opposing end faces of the steel plate which constitute a part of the core block opposing end faces 111b, 111c, 111d, 111i, 111j, 111m, 111n, 111o, 111p, 111e, 111f, 111g, 111h, 111k, and 111l.

[0099] As for the method of counting the number n of crystal grains on the opposing end faces of the steel plate, any method that can measure the number of crystal grains may be used. For example, the number n of crystal grains on the opposing end faces of the steel plate may be counted by observing with the aid of an electron microscope or an optical microscope as follows. First, after the opposing end faces (cut surfaces) of the steel plate are corroded in a 5% nitric acid alcohol etching solution for 100 seconds to 300 seconds, the grain boundaries are observed with an optical microscope. As an optical microscope, for example, an industrial microscope BX53M manufactured by Olympus Corporation may be used. When the opposing end faces (cut surfaces) of the steel plate are observed across the entire length of the longitudinal direction of the opposing end faces of the steel plate, the curves or straight lines extending from the plate surface on one side to the plate surface on the other side (for example, in the plate thickness direction) are uniformly defined as grain boundaries. In a steel plate opposing end face (cut surface), when the number of grain boundaries defined in this way is q, q+1 is the number n of crystal grains on the opposing end faces of the steel plate (n=q+1) (q is a non-negative integer). For example, in the case where the number of grain boundaries defined in this way is 3 in one steel plate facing end surface (cut surface), the number n of crystal grains on the steel plate facing end surface is 4. If the number of grain boundaries in one steel plate facing end surface is 0 (zero), the number n of crystal grains on the steel plate facing end surface becomes 1 (=0+1).

[0100] In addition, Figure 4A to Figure 4E In the embodiment, the length L of the opposite end faces of the steel plate is the length L of the opposite end faces of the steel plate in the direction perpendicular to the plate surface of the steel plate (in the direction perpendicular to the plate surface of the steel plate). Figure 4A to Figure 4E The length of the opposite end faces of the steel plate that can be seen when observing the steel plate having the opposite end faces of the steel plate in the direction perpendicular to the paper surface. Figure 4AIn FIG. 1 , the length L of the steel plate facing end surface constituting a part of the core block facing end surface 111a is shown as length L1. Figure 1 and Figure 2A As shown, there are a plurality of steel plates having a steel plate opposing end surface constituting a portion of the core block opposing end surface 111a in the stacking direction (z-axis direction). Therefore, the length L of the steel plate opposing end surface constituting a portion of the core block opposing end surface 111a is measured for each of these plurality of steel plates.

[0101] The length L of the steel plate facing end surface constituting a part of the core block facing end surfaces 111b to 111p other than the core block facing end surface 111a is measured in the same manner. Figure 4A to Figure 4E In the figure, the lengths L of the opposing end surfaces of the steel plates which constitute a part of the opposing end surfaces 111b, 111c, 111d, 111i, 111j, 111m, 111n, 111o, 111p, 111e, 111f, 111g, 111h, 111k and 111l of the core blocks are shown as L2, L3, L4, L5, L6, L7, L8, L9, L10, L11, L12, L13, L14, L15 and L16 respectively.

[0102] The method for measuring the length L of the opposing end faces of the steel plate can be any method as long as it can measure the length of the end face of the steel plate. For example, the length L of the opposing end faces of the steel plate can be measured by direct measurement using a vernier caliper or the like. In addition, the length L of the opposing end faces of the steel plate can also be measured by indirect measurement using image analysis or the like.

[0103] In addition, for example, by using a representative value (e.g., arithmetic mean) of the number of crystal grains n on the steel plate opposing end surface constituting a portion of the core block opposing end surface and a representative value (e.g., arithmetic mean) of the length L of the steel plate opposing end surface constituting a portion of the core block opposing end surface as n and L of formula (3), it can be confirmed whether formula (3) is satisfied. In addition, whether formula (3) is satisfied can also be confirmed for each steel plate opposing end surface.

[0104] In order to satisfy the formula (3), it is necessary to control the grain size of the steel sheet during the manufacture of the steel sheet. For example, the grain size of the steel sheet can be controlled to satisfy the formula (3) by controlling at least one of the nitriding amount during the nitriding annealing for precipitate control and microstructure control, and the annealing temperature and holding time (the relationship between the annealing temperature and time) during the final annealing for secondary recrystallization. Specifically, the grain size of the steel sheet can be controlled to satisfy the formula (3) by adjusting at least one of the flow rate of ammonia supplied to the gas atmosphere during the nitriding annealing, adjusting (extending) the soaking time during the final annealing, setting a holding time before reaching the soaking temperature during the final annealing and adjusting the holding time.

[0105] By satisfying equations (1) (or (2)) and (3), vibrations at the butt joints (core block opposing end surfaces 111a to 111p) of the core blocks 110a to 110e can be suppressed. Thus, it is preferable to satisfy both equations (1) (or (2)) and (3). However, in order to satisfy equation (3), the material of the steel plate must be selected. In addition, the workload of confirming whether equation (3) is satisfied is greater than the workload of confirming whether equation (1) (or (2)) is satisfied. In addition, if equation (3) is not satisfied, remanufacturing of the steel plate is required. Therefore, from the perspective of simply suppressing vibrations at the butt joints (core block opposing end surfaces 111a to 111p) of the core blocks 110a to 110e, it is also possible to satisfy only equation (1) (or (2)).

[0106] Figure 5 This is a flowchart showing an example of a method for manufacturing the laminated core 100 according to the present embodiment.

[0107] First, in step S501, a steel plate manufacturing process is performed. In the steel plate manufacturing process, steel plates constituting the laminated core 100 are manufactured. As a method for manufacturing the steel plate, a known method may also be used. However, in the present embodiment, the grain size of the steel plate is controlled to satisfy equation (3). As described above, the grain size of the steel plate may also be controlled by controlling the annealing conditions. In addition, from the viewpoint of simply suppressing the vibration of the butt joints of the core blocks 110a to 110e (the opposing end faces 111a to 111p of the core blocks), the grain size of the steel plate may not be controlled to satisfy equation (3) without determining whether equation (3) is satisfied.

[0108] Next, in step S502, a cutting process is performed. In the cutting process, the steel plate manufactured in step S501 is cut. In the present embodiment, the steel plate manufactured in step S501 is cut so that the shape of the plate surface of the cut steel plate becomes the planar shape of the core blocks 110a to 110e ( Figure 1 The shape of the x-y plane shown). As a method for cutting the steel plate, a known method may be used. For example, the steel plate may be cut by punching. In addition, the steel plate may be cut by laser processing. In addition, the number of steel plates cut at one time in the cutting process is not limited. The steel plates may be cut one by one. A plurality of steel plates may be cut at one time.

[0109] Next, in step S503, a grain measurement process is performed. In the grain measurement process, the following steps are performed: calculating (measuring) the number n / L of grains per unit length on the opposing end surfaces of the steel plate; and confirming whether formula (3) is satisfied. In the present embodiment, first, the number n of grains on the opposing end surfaces of the steel plate cut in step S502 and the length L of the opposing end surfaces of the steel plate are measured. Next, the number n / L of grains per unit length on the opposing end surfaces of the steel plate is calculated. Next, it is determined whether the number n / L of grains per unit length on the opposing end surfaces of the steel plate satisfies formula (3). For example, when the number n / L of grains per unit length on the opposing end surfaces of the steel plate is calculated for each of the core block opposing end surfaces 111a to 111p, it is determined whether formula (3) is satisfied for each of the core block opposing end surfaces 111a to 111p. In this case, a representative value (e.g., arithmetic mean) of the number n of grains on the opposing end surfaces of a steel plate constituting a portion of the opposing end surfaces of a core block and a representative value (e.g., arithmetic mean) of the length L of the opposing end surfaces of the steel plate constituting a portion of the opposing end surfaces of the core block are used as n and L in formula (3), respectively.

[0110] At least one of the calculation of the number n / L of grains per unit length on the opposing end surfaces of the steel plate and the determination of whether the number n / L of grains per unit length on the opposing end surfaces of the steel plate satisfies the formula (3) may be performed by a computer. In this case, for example, information including the number n of grains on the opposing end surfaces of the steel plate and the length L of the opposing end surfaces of the steel plate may be input into the computer. In addition, at least one of the calculation of the number n / L of grains per unit length on the opposing end surfaces of the steel plate and the determination of whether the number n / L of grains per unit length on the opposing end surfaces of the steel plate satisfies the formula (3) may be performed manually.

[0111] When the number n / L of crystal grains per unit length on the facing end surfaces of the steel sheet does not satisfy the formula (3), for example, step S501 is performed again. In this case, only steel sheets that do not satisfy the formula (3) are manufactured in step S501.

[0112] When the number n / L of grains per unit length on the opposing end faces of the steel plate in all the core block opposing end faces 111a to 111p satisfies the formula (3), the first roughness measurement process is performed in step S504. In the first roughness measurement process, the surface roughness Ra(S) in the in-plane direction of the steel plate cut in step S502 is calculated (measured). In the present embodiment, first, the roughness curve of the steel plate cut in step S502 is measured at the in-plane direction measurement position (the position of the imaginary straight lines 301a to 301e). Next, the in-plane direction surface roughness Ra(S) is calculated based on the roughness curve at the in-plane direction measurement position. The calculation of the in-plane direction surface roughness Ra(S) is performed, for example, in all the steel plates constituting the core blocks 110a to 110e. The calculation of the in-plane direction surface roughness Ra(S) can also be performed by a computer. In addition, the calculation of the in-plane direction surface roughness Ra(S) can also be performed manually.

[0113] Next, in step S505, the second roughness measurement process is performed. In the second roughness measurement process, the stacking direction surface roughness Ra (D) of the core block opposing end faces of the core block of the steel plate of the measurement object having the in-plane direction surface roughness Ra (S) is calculated (measured). In the present embodiment, first, all the steel plates constituting a certain core block are taken out from the steel plate cut in step S502. Next, the roughness curve of the steel plate constituting the core block is measured at the stacking direction measurement position (position on the imaginary straight lines 201a to 201p). Next, based on the roughness curve at the stacking direction measurement position, the stacking direction surface roughness Ra (D) is calculated. The calculation of the stacking direction surface roughness Ra (D) is performed, for example, on all the core block opposing end faces 111a to 111p of all the core blocks 110a to 110e constituting the laminated core 100. The calculation of the stacking direction surface roughness Ra (D) can also be performed by a computer. In addition, the calculation of the stacking direction surface roughness Ra (D) can also be performed manually.

[0114] Next, in step S506, a roughness adjustment process is performed. In the roughness adjustment process, the following steps are performed on each of the pair of opposing end faces of the core blocks: determining whether the formula (1) is satisfied (preferably, the formula (2) is further satisfied); and adjusting the surface roughness of the opposing end faces of the core blocks that do not satisfy the formula (1) (preferably, the formula (2) is further satisfied).

[0115] In the present embodiment, first, using the in-plane surface roughness Ra(S) and the stacking-direction surface roughness Ra(D) calculated (measured) for a pair of opposed end faces of the core blocks (for example, a pair of opposed end faces 111a and 111i), it is determined whether the condition of formula (1) (preferably, further the condition of formula (2)) is satisfied in each of the pair of opposed end faces of the core blocks. This determination is made, for example, for all of the opposed end faces 111a to 111p of the core blocks 110a to 110e. In addition, this determination may be made by a computer. In addition, this determination may also be made manually.

[0116] Next, the roughness of the opposed end faces of the steel plates that do not satisfy formula (1) (preferably, further do not satisfy formula (2)) is adjusted. The adjustment of the roughness of the end faces of the steel plates is performed, for example, for all of the opposed end faces of the core blocks that do not satisfy formula (1) (preferably, further do not satisfy formula (2)) among all of the opposed end faces 111a to 111p of the core blocks 110a to 110e.

[0117] Next, for the opposed end faces of the core blocks whose roughness has been adjusted as described above, it is determined again whether the condition of formula (1) (preferably, further the condition of formula (2)) is satisfied. The determination of whether the condition of formula (1) (preferably, further the condition of formula (2)) is satisfied and the adjustment of the roughness of the end faces of the steel plates are repeated until there are no longer any opposed end faces of the core blocks that do not satisfy formula (1) (preferably, further do not satisfy formula (2)).

[0118] As described above, in the present embodiment, in each of at least a pair of opposed end faces of the core blocks (for example, a pair of opposed end faces 111a and 111i), 1 < Ra(D) / Ra(S) ≤ 12 is satisfied. Thus, it is possible to provide a laminated core that can suppress vibration even without using a material different from that of the steel plate. In addition, if 1 < Ra(D) / Ra(S) ≤ 12 is set to 6 ≤ Ra(D) / Ra(S) ≤ 8, the effect of suppressing the noise of the laminated core 100 can be more reliably improved.

[0119] In addition, in the present embodiment, in at least one of at least a pair of opposed end faces of the core blocks (for example, the opposed end faces 111a and 111i) of the steel plate, the number of crystal grains per unit length n / L on the opposed end face of the steel plate is 0.5 or less. Thus, the vibration of the laminated core can be further suppressed.

[0120] In addition, the embodiments of the present invention described above are merely specific examples when implementing the present invention, and the technical scope of the present invention should not be construed as being limited thereto. That is, the present invention can be implemented in various forms without departing from its technical idea or its main features.

[0121] Examples

[0122] The following describes an embodiment of the present invention. In addition, the present invention is not limited to this embodiment. That is, the various conditions shown in this embodiment are condition examples adopted in order to confirm the feasibility and effect of the present invention. Therefore, the present invention is not limited to the condition examples shown in this embodiment. In addition, the present invention can adopt various conditions as long as it achieves the purpose of the present invention without departing from the main purpose of the present invention.

[0123] (Direct oriented electrical steel sheet)

[0124] Grain-oriented electrical steel sheets were produced using slabs of steel grades A to E having chemical compositions shown in Table 1. The unit of the values ​​shown in Table 1 is mass %, and the remainder of each slab (chemical components other than those shown in Table 1) is Fe.

[0125] Table 1

[0126]

[0127] Grain-oriented electrical steel sheets were produced under the production process and production conditions shown in Table 2 using slabs of steel types A to E.

[0128] Table 2

[0129]

[0130] As shown in Table 2, the hot rolling process, the hot rolled sheet annealing process, the cold rolling process, the decarburization annealing process, the nitriding treatment (nitriding annealing) process, and the final annealing process were sequentially performed under the manufacturing conditions shown in Table 2.

[0131] In this embodiment, a nitriding treatment (nitriding annealing) is performed on the cold-rolled steel sheet after decarburization annealing in a mixed gas environment of hydrogen-nitrogen-ammonia. The flow rate of ammonia is adjusted according to ammonia nitriding, thereby adjusting the nitriding amount. Furthermore, an annealing separator with magnesium oxide or aluminum oxide as the main component is applied to the cold-rolled steel sheet, and a final annealing is performed. As an annealing separator, a plurality of annealing separators with different mixing ratios of components containing the main component are used. In addition, the annealing temperature during the final annealing and the holding time at the annealing temperature are adjusted. In this embodiment, the grain size of the steel sheet after the final annealing is controlled according to the nitriding amount in the nitriding treatment and the annealing temperature and holding time during the final annealing.

[0132] An insulating coating solution is applied on the primary coating formed on the surface of the steel sheet after the final annealing. As the insulating coating solution, a solution containing phosphate and colloidal silica as main components and containing chromium is used. The insulating coating is formed by heat treating the steel sheet coated with the insulating coating solution. In this embodiment, unidirectional electromagnetic steel sheets are manufactured from slabs of steel types A to E as described above. In the following description, the unidirectional electromagnetic steel sheets manufactured from slabs of steel types A to E are referred to as steel sheets of steel types A to E as needed.

[0133] (Laminated core)

[0134] Using steel plate of steel grade A as raw material, we produce Figure 1 The laminated core 100 of the shape shown. The inventors of the present application have obtained the knowledge that there is a proportional relationship between Ra(D) / Ra(S) shown in formula (1) and the gap. In the present embodiment, based on this knowledge, when the steel plate of steel type A is cut to obtain the planar shape of the core blocks 110a to 110e, the gap between the upper and lower blades of the shearing machine is controlled to adjust the roughness of the end surface of the steel plate of steel type A. The steel plates of steel type A having the planar shape of the core blocks 110a to 110e are stacked to produce each core block 110a to 110e. At this time, as a group of core blocks 110a to 110e, a plurality of groups of core blocks 110a to 110e having mutually different roughnesses of the opposing end surfaces 111a to 111p of the core blocks are produced. Similarly, a plurality of groups of core blocks 110a to 110e are produced for the steel plates of steel types B to E.

[0135] In the following description, the core blocks manufactured from the steel plates of the steel types A to E are referred to as core blocks of the steel types A to E as needed. In addition, in the following description, the core blocks 110a, 110b, 110c, 110d, and 110e are referred to as upper core blocks 110a, lower core blocks 110b, left core blocks 110c, center core blocks 110d, and right core blocks 110e as needed.

[0136] The laminated core 100 is manufactured by combining the core blocks 110a to 110e manufactured from the steel plates of the same steel type. In the following description, the laminated core 100 manufactured in this way is referred to as the laminated core 100 of steel types A to E as needed. In addition, the left core block 110c, the central core block 110d, and the right core block 110e and the upper core block 110a and the lower core block 110b are set as core blocks manufactured from steel plates of different steel types, and the core blocks 110a to 110e are combined to manufacture the laminated core 100. Specifically, the laminated core 100 of steel types A and B, the laminated core 100 of steel types A and D, the laminated core 100 of steel types B and C, and the laminated core 100 of steel types B and E are manufactured. The laminated core 100 of steel types A and B is a laminated core in which the left core block 110c, the central core block 110d, and the right core block 110e are steel type A, and the upper core block 110a and the lower core block 110b are steel type B. The laminated core 100 of steel types A and D is a laminated core in which the left core block 110c, the central core block 110d, and the right core block 110e are steel type A, and the upper core block 110a and the lower core block 110b are steel type D. The laminated core 100 of steel types B and C is a laminated core in which the left core block 110c, the central core block 110d, and the right core block 110e are steel type B, and the upper core block 110a and the lower core block 110b are steel type C. The laminated core 100 of steel types B and E is a laminated core in which the left core block 110 c , the central core block 110 d , and the right core block 110 e are made of steel type E, and the upper core block 110 a and the lower core block 110 b are made of steel type B.

[0137] The width (length in the y-axis direction), height (length in the x-axis direction), and thickness (length in the z-axis direction) of the laminated core 100 are 750 mm, 750 mm, and approximately 41 mm, respectively. In addition, the width (length in the x-axis direction) of the upper core block 110a and the lower core block 110b and the width (length in the y-axis direction) of the left core block 110c, the central core block 110d, and the right core block 110e are 150 mm.

[0138] (Evaluation method)

[0139] The length L (L1 to L15) of the opposing end faces of the steel plates of steel types A to E having the planar shape of the core blocks 110a to 110e was measured with a vernier caliper. In addition, the opposing end faces (shear faces) of the steel plates were etched with a 5% nitric acid alcohol etching solution for 100 seconds to 300 seconds. Then, the opposing end faces of the steel plates were observed using an industrial microscope BX53M manufactured by Olympus Corporation, thereby counting the number of grain boundaries existing on the opposing end faces of the steel plates. And, by adding 1 to the counted number, the number n of grains on the opposing end faces of the steel plates was calculated. Based on the length L of the opposing end faces of the steel plates and the number n of grains on the opposing end faces of the steel plates obtained from the same steel plates, the number n / L of grains per unit length on the opposing end faces of the steel plates was calculated. For all the steel plates constituting the core blocks 110a to 110e, the number n / L of grains per unit length on the opposing end faces of the steel plates was calculated. Furthermore, the arithmetic mean of the number n / L of crystal grains per unit length on the steel plate opposing end faces is calculated for each of the core block opposing end faces 111a to 111p. The arithmetic mean of the number n / L of crystal grains per unit length on the steel plate opposing end faces calculated in one core block opposing end face is set as the number n / L of crystal grains per unit length on the steel plate opposing end faces in the core block opposing end face.

[0140] In addition, for each laminated core 100 manufactured as described above (laminated core 100 of steel types A to E, laminated core 100 of steel types A and B, laminated core 100 of steel types A and D, laminated core 100 of steel types B and C, laminated core of steel types B and E), the surface roughness Ra (D) in the lamination direction and the surface roughness Ra (S) in the in-plane direction are calculated in accordance with JIS B 0601:2013.

[0141] For each core block facing end face 111a to 111p of each laminated core 100, a plurality of steel plates constituting the core block facing end face are extracted one by one, and the stacking direction surface roughness Ra (D) is measured at the stacking direction measurement position (position on the imaginary straight lines 201a to 201p) of the extracted steel plates using a One-Shot 3D profile measuring instrument (model: VR-6000) manufactured by Keyence Corporation. Next, the arithmetic mean of the stacking direction surface roughness Ra (D) of the core block facing end face calculated from the plurality of steel plates constituting the same core block facing end face is calculated as the stacking direction surface roughness Ra (D) of the core block facing end face.

[0142] In addition, for each core block facing end face 111a to 111p of each laminated core 100, a plurality of steel plates constituting the core block facing end face are extracted one by one, and the in-plane direction surface roughness Ra (S) is measured at the in-plane direction measurement position (position on the imaginary straight lines 301a to 301e) of the extracted steel plates using a One-Shot 3D profilometer (model: VR-6000) manufactured by Keyence Corporation. And, the arithmetic mean of the in-plane direction surface roughness Ra (S) of the core block facing end face calculated from the plurality of steel plates constituting the same core block facing end face is calculated as the in-plane direction surface roughness Ra (S) of the core block facing end face.

[0143] Furthermore, Ra(D) / Ra(S) of the opposing end faces of the same core block is calculated based on the surface roughness Ra(D) in the stacking direction and the surface roughness Ra(S) in the in-plane direction of the opposing end faces of the core block. Such calculation of Ra(D) / Ra(S) is performed for all the opposing end faces 111a to 111p of all the laminated cores 100 manufactured as described above.

[0144] The noise of each laminated core 100 (laminated core 100 of steel types A to E, laminated core 100 of steel types A and B, laminated core 100 of steel types A and D, laminated core 100 of steel types B and C, laminated core of steel types B and E) was measured. Specifically, in a soundproof room with a background noise of 16 dBA, a noise meter was set at a position 0.3 m away from the surface of the laminated core 100. The noise of the laminated core 100 was measured by the noise meter using the A characteristic as an auditory correction. At this time, the laminated core 100 was excited under the excitation conditions of an excitation frequency of 50 Hz and a magnetic flux density in the laminated core 100 of 1.7 T. The values ​​of n / L, Ra(D) / Ra(S), and noise of each laminated core 100 obtained in this way are shown in Tables 3 and 4. In Table 1, it is shown that 111a to 111p are Figure 1 , Figure 2A to Figure 2E , Figure 3A to Figure 3E and Figure 4A to Figure 4E The core blocks shown in FIG. 1 are facing end faces 111 a to 111 p.

[0145]

[0146]

[0147] As shown in Table 3 and Table 4, in the laminated core 100 of the same steel type, for a pair of opposed end faces 111a and 111i, 111b and 111l, 111c and 111m, 111d and 111n, 111e and 111k, 111f and 111j, 111g and 111o, 111h and 111p that satisfy 1 < Ra(D) / Ra(S) ≤ 12, when the number of such pairs is 1 or more compared to the case where the number is 0 (zero), the noise decreases. That is, for steel type A, compared with numbers 1, 14 to 15, the noise decreases for numbers 2 to 13, 16 to 20. For steel type B, compared with number 21, the noise decreases for numbers 25, 29, 33, 37, 41. For steel type C, compared with number 22, the noise decreases for numbers 26, 30, 34, 38, 42. For steel type D, compared with number 23, the noise decreases for numbers 27, 31, 35, 39, 43. For steel type E, compared with number 24, the noise decreases for numbers 28, 32, 36, 40, 44.

[0148] Furthermore, in the laminated core 100 of the same steel type, if the number of pairs of opposed end faces of the core blocks that satisfy 1 < Ra(D) / Ra(S) ≤ 12 is more than 1 / 2 times the total number of pairs of opposed end faces of the core blocks (in this embodiment, it is 8 (16 in the "Ra(D) / Ra(S)" column of Table 3 and Table 4)), the noise reduction effect becomes greater. That is, for steel type A, compared with numbers 2, 3, 5, 7, 16, 17, 19, the noise decreases for numbers 4, 6, 8 to 13, 18, 19 to 20. For steel type B, compared with numbers 37, 41, the noise decreases for numbers 25, 29, 33. For steel type C, compared with numbers 38, 42, the noise decreases for numbers 26, 30, 34. For steel type D, compared with numbers 39, 43, the noise decreases for numbers 27, 31, 35. For steel type E, compared with numbers 40, 44, the noise decreases for numbers 28, 32, 36.

[0149] In addition, in the laminated core 100 of the same steel type, if there is a part where a pair of core block opposing end faces satisfies 6 ≤ Ra(D) / Ra(S) ≤ 8, the noise further decreases. If the number thereof is more than 1 / 2 times the total number of pairs of core block opposing end faces (in this embodiment, it is 8 (in the "Ra(D) / Ra(S)" column of Tables 3 and 4, the number is 16)), the noise reduction effect becomes greater. That is, regarding steel type A, compared with Nos. 2 to 7, 10, 13, 16 to 18, the noise of Nos. 8, 9, 11, 12, 19, 20 has decreased. Compared with Nos. 19, 20, the noise of Nos. 8, 9, 11, 12 has decreased. Regarding steel type B, compared with Nos. 25, 33, 37, 41, the noise of No. 29 has decreased. Regarding steel type C, compared with Nos. 26, 34, 38, 42, the noise of No. 30 has decreased. Regarding steel type D, compared with Nos. 27, 35, 39, 43, the noise of No. 31 has decreased. Regarding steel type E, compared with Nos. 28, 36, 40, 44, the noise of No. 32 has decreased.

[0150] In addition, if the conditions of Ra(D) / Ra(S) are the same, the noise of steel types B to E with the number of grains per unit length n / L on the opposing end faces of the steel plates being 0.5 or less has decreased compared with steel type A with more than 0.5. That is, compared with No. 4 (steel type A), the noise of Nos. 25 to 28 (steel types B to E) has decreased. In addition, compared with No. 12 (steel type A), the noise of Nos. 29 to 32 (steel types B to E) has decreased. In addition, compared with No. 13 (steel type A), the noise of Nos. 33 to 36 (steel types B to E) has decreased.

[0151] In addition, by selecting combinations of different steel types, it is possible to increase the number of core block opposing end faces that satisfy 1 < Ra(D) / Ra(S) ≤ 12, and to increase the number of core block opposing end faces with the number of grains per unit length n / L on the opposing end faces of the steel plates being 0.5 or less. Thus, a noise reduction effect can be obtained. That is, compared with No. 2 (steel type A), the noise of Nos. 45, 46 (steel types A, B) has decreased. Compared with No. 21 (steel type B), No. 22 (steel type C), the noise of No. 47 (No. B, C) has decreased. Compared with No. 21 (steel type B), No. 26 (steel type E), the noise of No. 48 (No. B, E) has decreased.

[0152] Industrial Applicability

[0153] The present invention can be used, for example, in equipment having a core.

Claims

1. A laminated iron core, characterized in that it includes a plurality of core blocks, and each of the plurality of core blocks has a plurality of steel plates laminated thereon, the above-mentioned plurality of core blocks have core block opposing end faces, the above-mentioned core block opposing end faces are the end faces among the end faces of the above-mentioned core blocks that are located at positions opposing other above-mentioned core blocks, in each of at least one pair of the above-mentioned core block opposing end faces, the following formula (A) is satisfied, the above-mentioned pair of core block opposing end faces are two above-mentioned core block opposing end faces arranged at opposing positions, 1 < Ra(D) / Ra(S) ≤ 12…(A) Here, Ra(D) is the surface roughness Ra of the above-mentioned core block opposing end face in the lamination direction of the above-mentioned steel plates, with the unit of μm; Ra(S) is the surface roughness Ra of the plate surface of the above-mentioned steel plate that constitutes a part of the above-mentioned core block opposing end face, in the direction of the main magnetic flux flowing through the above-mentioned steel plate or in the rolling direction of the above-mentioned steel plate, with the unit of μm.

2. The laminated iron core according to claim 1, characterized in that in each of the above-mentioned at least one pair of core block opposing end faces, the following formula (B) is satisfied, 6 ≤ Ra(D) / Ra(S) ≤ 8…(B).

3. The laminated iron core according to claim 1 or 2, characterized in that in at least one of the above-mentioned at least one pair of core block opposing end faces, the following formula (C) is satisfied, n / L ≤ 0.5…(C) Here, n is the number of grains among the grains existing in the above-mentioned steel plate that constitutes a part of the above-mentioned core block opposing end face and includes the above-mentioned end face as a boundary, with the unit of piece, and L is the length of the above-mentioned end face, with the unit of mm.

4. A method for manufacturing a laminated iron core, the laminated iron core includes a plurality of core blocks, and each of the plurality of core blocks has a plurality of steel plates laminated thereon. The method for manufacturing the laminated iron core is characterized in that it includes: a cutting process for cutting the steel plate; a first roughness measurement process for measuring the surface roughness Ra(S) of the plate surface of the steel plate cut in the above-mentioned cutting process, with the unit of μm; a second roughness measurement process for measuring the surface roughness Ra(D) of the core block opposing end face of the above-mentioned core block of the above-mentioned steel plate serving as the measurement object having the above-mentioned surface roughness Ra(S), with the unit of μm; and a roughness adjustment process for adjusting the surface roughness of the above-mentioned core block opposing end face when the ratio Ra(D) / Ra(S) of the surface roughness Ra(D) measured by the above-mentioned second roughness measurement process to the Ra(S) measured by the above-mentioned first roughness measurement process does not satisfy 1 < Ra(D) / Ra(S) ≤ 12, the above-mentioned surface roughness Ra(S) is the surface roughness Ra in the direction of the main magnetic flux flowing through the above-mentioned steel plate when the above-mentioned laminated iron core is excited, or the surface roughness Ra in the rolling direction of the above-mentioned steel plate, with the unit of μm, the above-mentioned surface roughness Ra(D) is the surface roughness Ra in the lamination direction of the above-mentioned steel plate, with the unit of μm, the above-mentioned core block opposing end faces are the end faces among the end faces of the above-mentioned core blocks that are located at positions opposing other above-mentioned core blocks in the above-mentioned laminated iron core In the roughness adjustment step, at least one pair of the core block facing end faces is adjusted to have a surface roughness that satisfies 1 <Ra(D) / Ra(S)≤12, The pair of core block facing end surfaces are two core block facing end surfaces arranged at positions facing each other.

Images