Core of motor and manufacturing method thereof

Abstract

The present invention relates to a motor core and, more particularly, a core and a core manufacturing method, wherein the core has low iron loss and excellent flatness and perpendicularity. According to an embodiment of the present invention, a method for manufacturing a block laminated core comprises: a block core step of forming block cores having a first length by laminating and coupling electrical steel sheets in a first direction; a lamination step of rotating the multiple block cores by a first angle in a second direction, which is a circumferential direction, and laminating the block cores to achieve a second length in the first direction; and a welding step of forming a welding part by welding the outer circumferential surfaces of two consecutive block cores among the multiple block cores to a third length shorter than twice the first length in the first direction, wherein in the welding step, multiple imaginary lines, which are obtained by extending in the first direction from some of the multiple welding parts formed on any one of the multiple block cores, are spaced apart from each other by a predetermined interval. The block cores include block laminated cores manufactured by the method.

Description

Motor core and its manufacturing method

[0001] The present invention relates to a motor core, and to a core and a manufacturing method thereof having low iron loss occurring in the core and excellent flatness and squareness.

[0002] With carbon tax policies being implemented worldwide, the demand for energy conservation measures has become a major concern. Environmentally friendly policies are emphasizing high efficiency in electrical equipment such as motors and generators, and efficiency regulations, which began in Europe, are now being legislated worldwide.

[0003] Electrical devices such as motors consist of a stator and a rotor. Both the stator and rotor require excellent magnetic properties, while the rotor additionally requires high strength to withstand high-speed rotation. The core is a single mass of non-oriented electrical steel sheets, stacked in a single layer, allowing the magnetic field to flow smoothly in any direction between the stator and rotor.

[0004] The stator is manufactured by laminating multiple electrical steel plates and then fastening them together using various methods to secure the individual electrical steel plates. Conductor windings are then inserted into core slots to supply electricity. The rotor is then laminated and secured by multiple electrical steel plates. Permanent magnets can be inserted into the rotor core, and a magnetic source can be provided by winding or die-casting the conductor windings. Alternatively, the core itself can be constructed without any magnetic source.

[0005] Research (10-2438474 B1, KR 10-2448799 B1) on manufacturing electrical steel sheets with superior magnetic properties to improve the efficiency of electrical devices has been widely reported. Despite advances in materials technology, the efficiency of electrical devices remains difficult to meet market demands. The difficulty of material development remains high, leaving many challenges to overcome. Furthermore, the processing of materials into core components can result in properties worse than those of the raw materials. Furthermore, efficiency varies widely depending on the core structure and device configuration.

[0006] The methods for fixing cores by laminating them have mainly used interlocking and welding (KR10-0584116 B1), but recently methods for bonding electrical steel sheets to each other (KR10-2382699 B1, KR10-0950339 B1) have also been proposed. Although recent bonding methods are theoretically excellent technologies, they have limitations in that they do not provide uniform adhesion across the core surface and do not maintain strong adhesion continuously, resulting in a very high defect rate in core production. Consequently, in industries where production yield is important, interlocking and welding are mostly applied in core production.

[0007] Figure 1 illustrates a conventional core with a fully interlocked joint. Figure 1 shows that the electrical steel plate (100) of the conventional core (1) has an interlocked joint portion (200) at a time. Interlocking joint is a method of jointing in which mechanical pressure is applied to a certain portion to deform it.

[0008] Interlocking joints, even when using superior electrical steel, degrade the performance of electrical devices during the core manufacturing process due to machining and assembly, making it difficult to achieve high efficiency. Interlocking mechanically forces bending of the electrical steel, significantly degrading its magnetic properties. Because the magnetic field in the electrical steel near the interlocking joints is nearly static, distortion of the magnetic field flow occurs. The magnetic field, unable to flow through the interlocking joints, seeks alternative paths with less magnetic resistance, creating a bottleneck. This distorted magnetic field alters the frequency, resulting in the synthesis of higher frequencies onto the fundamental waveform. The magnetic field concentrated at the bottleneck increases the operating flux density. When the frequency is synthesized or the flux density is high, the core loss in the electrical steel increases dramatically, resulting in deteriorated core loss.

[0009] Figure 2 illustrates a welded core (2). Previously, as shown in Figure 2, the entire outer surface of an electrical steel plate (100) was joined by welding (300).

[0010] If an electrical steel plate is placed in a magnetic field, eddy currents are induced within the plate, resulting in eddy current loss. One way to reduce this loss is to manufacture the plate thinner and apply a highly insulating coating to the top and bottom surfaces of the plate to form electrical insulation between the plates. However, the welding used as a joining method occurs on the side of the core, which has the adverse effect of destroying the insulation between the plates and artificially creating an electrical circuit to conduct current. This causes a sharp increase in eddy current loss and a deterioration in the no-load loss of the core. A high number of welds increases the number of interlayer insulation breakdowns in the electrical steel plate and the amount of induced eddy current, which drastically deteriorates the no-load loss due to interlayer conduction.

[0011] Therefore, there is a need for a core and a method of manufacturing the core to solve the above problems.

[0012] The present invention is intended to solve the above problems, and aims to provide a core having excellent squareness and flatness and low iron loss.

[0013] In order to achieve the above-mentioned purpose, the present invention provides a motor core formed as follows and a method for manufacturing the same.

[0014] A block laminated core manufacturing method according to one embodiment of the present invention includes a block core step of laminating and combining electrical steel sheets in a first direction to form a block core of a first length, a lamination step of rotating a plurality of the block cores at a first angle in a second direction, which is a circumferential direction of the block core, and laminating them so as to have a second length in the first direction, and a welding step of forming a weld by welding the outer peripheral surface of two consecutive block cores among the plurality of block cores in the first direction to a third length shorter than twice the first length, wherein a plurality of the welds are formed, and any two adjacent welds among the plurality of welds are spaced apart from each other by a predetermined distance, and can provide a core having excellent squareness and flatness, and low iron loss and low no-load loss.

[0015] Additionally, in the block core step, the electrical steel sheets can be interlocked.

[0016] In addition, the second length is a multiple of n of the first length, and the first angle can be expressed by the following mathematical expression 1.

[0017] Mathematical formula 1: θ1 = 360° / n

[0018] Here, θ1 is the first angle (°) and n is a natural number.

[0019] Additionally, the second length may be 3 to 8 times the first length.

[0020] Additionally, in the above welding step, the welded portion may be formed in multiple pieces spaced apart from each other in the second direction at the same position in the first direction.

[0021] In addition, a heat treatment step may be further included in which a heat treatment is performed to remove residual stress of the block core prior to the lamination step.

[0022] A block laminate core according to one embodiment of the present invention comprises a block core in which electrical steel sheets are laminated to have a first length in a first direction and a joint portion of an interlocking joint, a block laminate in which a plurality of the block cores are laminated to have a second length in the first direction, and a weld portion formed on an outer surface of the block laminate to have a third length shorter than twice the first length in the first direction to connect two adjacent block cores among the plurality of block cores included in the block laminate, thereby providing a core having excellent squareness and flatness, and low iron loss and low no-load loss.

[0023] In addition, a plurality of virtual first extension lines are formed connecting the punching line formed on the electrical steel sheet forming the block core and the center of the block core, and the first extension lines are formed at the same position in the second direction, which is the radial direction, within one block core, and an angle between the first extension lines formed on any two block cores that are adjacently arranged in the first direction among the plurality of block cores can form a first angle.

[0024] Additionally, the second length may be three to eight times the first length.

[0025] In addition, a plurality of welding portions are formed to join two identical block cores among a plurality of block cores, and a second angle, which is the smallest angle among the angles formed by two third extension lines among the plurality of welding portions joining the two identical block cores and the third extension lines connecting the centers of the block cores, may be 10 to 180°.

[0026] In addition, the electrical steel sheet may be a non-oriented electrical steel sheet containing, in wt%, Si: 0.25 to 4.8%, Al: 0.05 to 2.0%, Mn: 0.15 to 1.0%, C: 0.0015 to 0.0040%, N: 0.0005 to 0.0030%, S: 0.0005 to 0.003%, Mo: 0.0050 to 0.015%, Ti: 0.0005 to 0.0020%, Nb: 0.0005 to 0.0040%, V: 0.0005 to 0.0040%, the remainder being Fe and unavoidable impurities.

[0027] The present invention can provide a core having excellent squareness and flatness, and low iron loss and thus low no-load loss through the above structure.

[0028] Figure 1 is a perspective view illustrating a conventional core.

[0029] Figure 2 is a perspective view illustrating another conventional core.

[0030] Figure 3 is a flowchart of a block stack core manufacturing method according to one embodiment of the present invention.

[0031] FIG. 4 is a drawing illustrating a block core according to one embodiment of the present invention.

[0032] FIG. 5 is a drawing for explaining a lamination step in a block lamination core manufacturing method according to one embodiment of the present invention.

[0033] FIG. 6 is a drawing for explaining the first angle of the lamination step in the block lamination core manufacturing method according to one embodiment of the present invention, and shows the first extension line connecting the punching line of the block core laminated on one plane and the core center.

[0034] FIG. 7 is a schematic diagram of a block laminate core manufactured by a block laminate core manufacturing method according to an embodiment of the present invention, and is a drawing for explaining a welding step in the block laminate core manufacturing method.

[0035] FIG. 8 is a drawing for explaining a second angle in a block laminate core according to one embodiment of the present invention.

[0036] Hereinafter, specific embodiments of the present invention will be described with reference to the attached drawings. However, the spirit of the present invention is not limited to the presented embodiments, and those skilled in the art who understand the spirit of the present invention will be able to easily propose other regressive inventions or other embodiments included within the scope of the spirit of the present invention by adding, modifying, or deleting other components within the scope of the same spirit. However, this will also be considered to be included within the scope of the spirit of the present invention.

[0037] A core according to one embodiment of the present invention is formed using an electrical steel plate.

[0038] Electrical steel sheets are typically supplied in roll form as mother coils with a width of 980 to 1200 mm. During the rolling process, it is very difficult to precisely control the thickness of the electrical steel sheets. Therefore, the thickness of the mother coil is typically thickest near the center and thins towards the edges. This thickness variation can be as much as 5 to 10% of the total thickness. This can cause shape problems when forming the core. Because the core diameter is tens to hundreds of mm, the mother coil provided by the steel company undergoes a slitting process, which tallies the overall width to within a few hundred mm to match the core diameter. After the slitting process, multiple electrical steel sheets are stacked through a punching process to manufacture the core. During the punching process, a punching line can be formed, indicating the punching location.

[0039] Generally, problems occur due to the above-mentioned thickness deviation in the core, but especially in the case of a drive motor with a core diameter reaching several hundred mm and a stacking height of electrical steel sheets exceeding 100 mm, it is very important to secure the squareness and flatness of the core due to the thickness deviation of the electrical steel sheets depending on the position of the mother coil. The present invention manufactures a core using such a general electrical steel sheet, and thus aims to solve the above-mentioned problems.

[0040] According to one embodiment of the present invention, the electrical steel sheet of the core may be a non-oriented electrical steel sheet containing, in wt%, Si: 0.25 to 4.8%, Al: 0.05 to 2.0%, Mn: 0.15 to 1.0%, C: 0.0015 to 0.0040%, N: 0.0005 to 0.0030%, S: 0.0005 to 0.003%, Mo: 0.0050 to 0.015%, Ti: 0.0005 to 0.0020%, Nb: 0.0005 to 0.0040%, V: 0.0005 to 0.0040%, the remainder Fe and unavoidable impurities, but is not limited thereto and may be formed as an electrical steel sheet of other components.

[0041] Si: 0.25~4.8%

[0042] Silicon (Si) increases the resistivity of the material, reducing iron loss and enhancing strength through solid-solution strengthening. If too little silicon is added, the iron loss and strength improvements may be insufficient. If too much silicon is added, the material becomes brittle, drastically reducing rolling productivity. Furthermore, it can form a surface oxide layer and oxides that are detrimental to magnetism, which can be problematic. Therefore, silicon may be included in an amount of 0.25 to 4.8%, more preferably 3.2 to 3.6%.

[0043] Al: 0.05~2.0%

[0044] Aluminum (Al) increases the resistivity of the material, thereby reducing iron loss, and enhances strength through solid solution strengthening. If too little aluminum is added, fine nitrides may form or the surface oxide layer may not form densely, making it difficult to achieve the improved magnetic properties. If too much aluminum is added, excessive nitrides may form, degrading magnetism and causing problems in all processes, such as steelmaking and continuous casting, which can significantly reduce productivity. Therefore, aluminum may be included in an amount of 0.05 to 2.0%, more preferably 0.6 to 1.0%.

[0045] Mn: 0.15~1.0%

[0046] Manganese (Mn) increases the resistivity of the material, improving iron loss and forming sulfides. If too little manganese is added, fine MnS is formed, causing magnetic deterioration. If too much manganese is added, fine MnS is excessively precipitated, promoting the formation of {111} texture, which is unfavorable for magnetism, and causing a rapid decrease in magnetic flux density. Therefore, manganese may be included in an amount of 0.15 to 1.0%. More preferably, it may be included in an amount of 0.30 to 0.75%.

[0047] C: 0.0015~0.0040%

[0048] Carbon (C) causes magnetic aging and combines with other impurity elements to form carbides, which degrades magnetic properties. However, it also plays a role in improving strength by hindering dislocation movement. If too little carbon is added, the strength-enhancing effect may be insufficient. If too much carbon is added, the formation of fine carbides increases, which can rapidly deteriorate magnetism. Therefore, carbon may be included in an amount of 0.0015 to 0.0040%, more preferably 0.0020 to 0.0038%.

[0049] N: 0.0005~0.0030%

[0050] Nitrogen (N) not only forms fine AlN precipitates within the base metal, but also combines with other impurities to form fine precipitates, inhibiting grain growth and worsening iron loss, but also playing a role in improving strength. If too little nitrogen is added, strength may not be sufficiently improved. If too much nitrogen is added, fine nitrides increase, which may rapidly deteriorate iron loss. Therefore, nitrogen may be included in an amount of 0.0005 to 0.0030%, more preferably 0.0008 to 0.0018%.

[0051] S: 0.0005~0.003%

[0052] Sulfur (S) should be kept at a low level because it forms fine precipitates, such as MnS and CuS, which deteriorate magnetic properties and hot workability. However, adding too little sulfur can reduce magnetic flux density. Therefore, sulfur may be included in an amount of 0.0005 to 0.003%, more preferably 0.0010 to 0.0025%.

[0053] Mo: 0.0050~0.015%

[0054] Molybdenum (Mo) segregates at grain boundaries during annealing, inhibiting the development of {111} texture, which is detrimental to magnetism, and forms fine carbides during cooling, thereby enhancing strength. If too little molybdenum is added, the effect may be insufficient. If too much molybdenum is added, it may promote the formation of carbides, thereby deteriorating magnetism. Therefore, molybdenum may be included in an amount of 0.0050 to 0.015%, more preferably 0.0060 to 0.0090%.

[0055] Ti: 0.0005~0.0020%, Nb: 0.0005~0.0040%, V: 0.0005~0.0040%

[0056] Titanium (Ti), niobium (Nb), and vanadium (V) have a very strong tendency to form precipitates in steel, and deteriorate iron loss by forming fine carbides, nitrides, or sulfides inside the base metal, thereby inhibiting grain growth and domain wall migration. Therefore, it is necessary to appropriately control the upper limit of titanium, niobium, and vanadium. On the other hand, if they are included in too little, the strength of the electrical steel sheet may be significantly reduced. Therefore, titanium, niobium, and vanadium may be included in an amount of 0.0005 to 0.0020%, respectively. More preferably, they may be included in an amount of 0.0007 to 0.0018%, respectively.

[0057] Electrical steel sheets may contain the above residual iron (Fe) and unavoidable impurities.

[0058] Non-oriented electrical steel sheets commonly used may have a density of 7.51 g / cm3 or more, and may be formed to have a thickness of 0.1 to 0.65 mm, but are not limited to thickness and density.

[0059] The following block laminate core and block laminate core manufacturing method are described assuming that the core is formed from the electrical steel sheet described above, but it may also be formed from an electrical steel sheet having different components and characteristics.

[0060] Figure 3 illustrates a flow chart of a block stack core manufacturing method according to one embodiment of the present invention.

[0061] A block laminate core manufacturing method according to one embodiment of the present invention includes a block core step (S10), a lamination step (S30), and a welding step (S40). In addition, the block laminate core manufacturing method may further include a heat treatment step (S20).

[0062] The block core step (S10) is a step of manufacturing a block core (10, see Fig. 4) by interlocking and laminating electrical steel sheets.

[0063] The lamination step (S30) is a step in which the block core (10) is laminated to form a block laminate (15, see FIG. 5).

[0064] The welding step (S40) is a step of connecting the plurality of block cores (10) by welding along the outer circumference of the block laminate (15) so that they are maintained in a laminated state in the lamination step (S30).

[0065] According to one embodiment of the present invention, a heat treatment step (S20) may be further included prior to the lamination step (S30) in which heat treatment is performed to remove residual stress of the block core.

[0066] The heat treatment step (S20) may be a step in which heat treatment such as atmosphere heat treatment and high-frequency heat treatment is performed, and the specific method is not limited.

[0067] The core must be heated to a maximum temperature of 750°C to 880°C, which can remove residual stress generated during the electrical steel sheet stamping process, and maintained at that temperature for a certain period of time, and a reducing atmosphere is suitable, but the maximum temperature maintenance time may vary depending on the heat treatment method.

[0068] For example, in the heat treatment step (S20), nitrogen or vacuum must be continuously supplied to the sealed heat treatment facility to maintain a reducing atmosphere. Since heat treatment of cores joined by welding may cause deformation of the welded portion and distortion of the core shape, it is advantageous to perform the heat treatment before the welding step (S40), and heat treatment may be performed after the block core step (S10), that is, on interlocked block cores. If the heat treatment temperature is low or the maximum temperature holding time is short, stress relief may not be achieved, and if the temperature is too high or the maximum temperature holding time is long, cracks may form in the coating layer on the surface of the electrical steel sheet, resulting in poor insulation. Therefore, heat treatment at an appropriate temperature may be important. The appropriate temperature may vary depending on the interlocking connection and the material and shape of the electrical steel sheet, and is therefore not limited to a specific temperature. By including the heat treatment step (S20) according to an embodiment of the present invention, a better core can be manufactured with less no-load loss.

[0069] Hereinafter, the first direction (DR1) refers to the direction in which the electrical steel plate (100) or the block core (10) to be described below is laminated, and the second direction (DR2) may refer to the circumferential direction of the block core (10). In addition, the third direction (DR3) refers to a direction perpendicular to the first direction (DR1).

[0070] FIG. 4 is a drawing for explaining a block core step in a block laminate core manufacturing method according to one embodiment of the present invention.

[0071] For example, the block core step (S10) is a step of forming a block core (10) of a first length (L1) by laminating and bonding electrical steel plates (100) in a first direction (DR1).

[0072] The first length (L1) is a preset length, and can be set by considering the fastening force for joining the electrical steel plate (100), the second length (L2, see Fig. 5), which is the length of the block laminate (15, see Fig. 5) to be described below, etc.

[0073] For example, the punched electrical steel plates (100) can be laminated and then interlocked to produce a block core (10). There is no limitation on the shape of the interlocking.

[0074] The joint (11) formed in the block core (10) may be an interlocking joint. Interlocking is a method of mechanically bending a plurality of electrical steel plates (100) into a certain shape and joining them.

[0075] There may be multiple joints (11) in one block core (10). If the number of joints (11) is small, the bonding strength is insufficient, resulting in a defect in which individual electrical steel sheets (100) fall off.

[0076] If the number of joints (11) due to interlocking fastening is large, the magnetic properties of the electrical steel plate (100) deteriorate and the iron loss deteriorates because the interlocking fastening is a method of mechanically bending the shape to join. Therefore, it is important to form an appropriate number of joints (11).

[0077] For example, it is advantageous to form at least three joints (11) according to the interlocking bond included in the block core (10), and the number may vary depending on the diameter and first length (L1) of the block core (10).

[0078] If the number of joints (11) is less than two, the fastening strength is weak, which may cause a defect in which the individual electrical steel sheets (100) easily fall off the core. If the number of joints (11) is increased, the fastening strength improves, but the iron loss deteriorates.

[0079] Therefore, the block core (10) can be combined including the connecting portion (11) 4 to 8 times.

[0080] As a comparison value, when manufacturing a core by stacking electrical steel sheets (100) at once, it is common to interlock them with at least 6 or more joints (11).

[0081] For example, in the block core stage (S10), interlocking can be performed simultaneously with the punching process within the mold to shorten the production time. Simultaneous punching and interlocking within the mold can reduce production time, and thus, can be produced in this manner.

[0082] A motor core having excellent bonding strength and excellent iron loss can be manufactured by including a block core step (S10) like this.

[0083] FIG. 5 is a drawing for explaining a lamination step in a block laminate core manufacturing method according to an embodiment of the present invention. FIG. 6 is a drawing illustrating a plurality of first extension lines included in a block laminate in a laminated state according to an embodiment of the present invention on one plane.

[0084] The lamination step (S30) according to one embodiment of the present invention may be a step of forming a block laminate (15) by rotating a plurality of block cores (10a, 10b, 10c, 10d) in a second direction (DR2), which is a circumferential direction of the block cores (10a, 10b, 10c, 10d), at a first angle (θ1) and laminating them so as to have a second length (L2) in the first direction (DR1).

[0085] For example, n block cores (10a, 10b, 10c, 10d) manufactured in the above block core step (S10) can be stacked in the first direction (DR1).

[0086] The second length (L2), which is the length of the block laminate (15) and the length of the core, is n times the first length (L1). That is, since a plurality of block cores (10a, 10b, 10c, 10d) are laminated and the block cores (10a, 10b, 10c, 10d) are formed with the first length (L1), the length obtained by multiplying the block cores (10a, 10b, 10c, 10d) in the first direction (DR1) by n times the number of laminates can be the second length (L2).

[0087] And, the block core can be rotated by a first angle (θ1) in the second direction (DR2) when stacked. If the core is manufactured by stacking the block core (10) without rotating it in the second direction (DR2), the thickness deviation existing from the mother coil is accumulated as it is, causing problems in the squareness and flatness of the electrical steel plate (100). Therefore, stacking while rotating it in the second direction (DR2) can solve the above problems and provide a coil with excellent squareness and flatness.

[0088] For example, the first angle (θ1) can follow the following [Mathematical Formula 1].

[0089] [Mathematical Formula 1]

[0090] θ1 = 360° / n

[0091] Here, θ1 is the first angle (°) and n is a natural number.

[0092] Since the core is rotated in the second direction (DR2) at a first angle (θ1) to produce excellent squareness and flatness, it may be important to evenly distribute the thickness deviation present in the mother coil throughout the block laminate (15).

[0093] Therefore, the value obtained by dividing the total internal angle of the block laminate (15), 360°, by n, the number of block cores (10a, 10b, 10c, 10d) to be laminated, can be set as the first angle (θ1).

[0094] At this time, as the first angle (θ1) decreases, the squareness and flatness of the core may improve. However, even if the squareness and flatness improve as the first angle (θ1) decreases, the number of block cores (10) that must be laminated increases accordingly, which may be disadvantageous in terms of economy and time, as the manufacturing process increases.

[0095] Therefore, the second length (L2) may be formed to be 3 to 8 times the first length (L1). In addition, according to the mathematical expression 1, the first angle (θ1) may be 45 to 120°. In addition, the number of stacked block cores (10) may be 3 to 8. However, it is not limited to the first angle (θ1) and the number of stacked block cores (10) mentioned above.

[0096] For example, in the lamination step (S30), the first angle (θ1) may be based on the punching line (B).

[0097] Referring to FIGS. 5 and 6, the lamination of four block cores in the lamination step is exemplarily described.

[0098] Within one block core (10a, 10b, 10c, 10d), a plurality of virtual first extension lines (E1a, E1b, E1c, E1d) are formed connecting the punch lines (Ba, Bb, Bc, Bd) formed on the electrical steel plate (100) forming the block core (10a, 10b, 10c, 10d) and the center (C) of the block core, and the angles between the first extension lines (E1a, E1b, E1c, E1d) can be the same within one block core (10a, 10b, 10c, 10d).

[0099] Within one block core (10a, 10b, 10c, 10d), electrical steel sheets are laminated in the first direction (DR1) along with the punching, so that they can be laminated without rotation in the second direction (DR2). Therefore, in one block core (10a, 10b, 10c, 10d), there can be only one virtual first extension line (E1a, E1b, E1c, E1d) connecting the punching line (Ba, Bb, Bc, Bd) and the block core center (C).

[0100] In addition, the first angle may mean an angle between first extension lines (E1a, E1b, E1c, E1d) of two block cores (10a, 10b, 10c, 10d) adjacent in the first direction (DR1) among the plurality of block cores (10a, 10b, 10c, 10d), and the first angle (θ1) may be defined as an internal angle.

[0101] The stacked plurality of block cores (10) can be sequentially referred to as the first block core (10a), the second block core (10b), the third block core (10c), and the fourth block core (10d) from the bottom.

[0102] At this time, the angle formed by the first extension line (E1a) of the first block core (10a) and the first extension line (E1b) of the second block core (10b) may be the first angle (θ1). In addition, the angle between the first extension line (E1b) of the second block core (10b) and the first extension line (E1c) of the third block core (10c) and the angle between the first extension line (E1c) of the third block core (10c) and the first extension line (E1d) of the fourth block core (10d) may be the first angle (θ1).

[0103] And, n, the number of stacked block cores (10), is 4, the second length (L2) is 4 times the first length (L1), and the first angle (θ1) can be 90°. However, it is not limited to these specific figures above and can vary depending on the design.

[0104] Since the block cores (10a, 10b, 10c, 10d) included in the block laminate (15) are formed with joints (11a, 11b, 11c, 11d) that are distinguished by each block core (10a, 10b, 10c, 10d), the fastening force by the joints (11a, 11b, 11c, 11d) of the interlocking is sufficient to keep the electrical steel plates (100) of the block cores (10a, 10b, 10c, 10d) joined.

[0105] A core laminate (15) is formed by including a lamination step (S30) such as this, so that a core with excellent squareness and flatness can be manufactured.

[0106] FIG. 7 is a drawing for explaining a welding step in a block laminate core manufacturing method according to an embodiment of the present invention, and schematically illustrates a block laminate core according to an embodiment of the present invention.

[0107] For example, the welding step (S40) is a step of completing a block laminated core (3) by forming a welded portion (20) by welding a third length (L3) shorter than twice the first length (L1) in the first direction (DR1) on the outer surface of two block cores (10) continuously laminated in the first direction (DR1) among the plurality of block cores (10).

[0108] If the third length (L3) is greater than or equal to twice the first length (L1), it will affect three or more consecutively laminated block cores (10), which may cause a problem in conducting current through the block cores (10) connected by the weld (20). Therefore, the weld (20) may be formed with a third length (L3) that is shorter than twice the first length (L1).

[0109] Referring to FIG. 7, the stacked plurality of block cores (10a, 10b, 10c, 10d) can be sequentially referred to as the first block core (10a), the second block core (10b), the third block core (10c), and the fourth block core (10d) from the bottom.

[0110] At this time, if the first-second welding portion (21), which is the welding portion (20) connecting the first block core (10a) and the second block core (10b), is greater than or equal to three times the first length (L1), it is connected continuously to the third block core (10c). In this case, a problem occurs in which current flows to the third block core (10c) through the first-second welding portion (21), thereby causing current conduction. In addition, since the insulation of the electrical steel plate (100) included in the connected first to third block cores (10a, 10b, 10c) is all destroyed and current is conducted, the iron loss may rapidly increase, and therefore the welding portion (20) must be formed with a third length (L3) that is less than twice the first length (L1).

[0111] This is the same for both the 2nd-3rd welding part (22), which is a welding part (20) connecting the 2nd block core (10b) and the 3rd block core (10c), and the 3rd-4th welding part (23), which is a welding part (20) connecting the 3rd block core (10c) and the 4th block core (10d).

[0112] For example, a virtual line extending in the first direction (DR1) a portion of the plurality of welded portions (20) formed on one of the plurality of block cores (10a, 10b, 10c, 10d) may be defined as a second extension line (E2). At this time, a plurality of second extension lines (E2) are formed, and any two of the plurality of second extension lines (E2) may be formed spaced apart from each other without overlapping.

[0113] If the second extension lines (E2) overlap, heat damage on the core side may accumulate, which may cause an increase in iron loss. Therefore, the weld (20) may be positioned so that the second extension lines (E2) are not positioned on the same line.

[0114] Referring to FIG. 7, if one of the plurality of block cores (10a, 10b, 10c, 10d) is a second block core (10b), it may include a first-second welding portion (21) formed to connect the first block core (10a) and the second block core (10b), and a second-third welding portion (22) formed to connect the second block core (10b) and the third block core (10c). Therefore, a part of the first-second welding portion (21) and a part of the second-third welding portion (23) may be formed in the second block core (10b).

[0115] And, a virtual extension line extending a part of the 1-2 weld (21) in the first direction (DR1) can be defined as a 2-1 extension line (E21), and a virtual extension line extending a part of the 2-3 weld (22) in the first direction (DR1) can be defined as a 2-2 extension line (E22).

[0116] At this time, if the 2-1 extension line (E21) and the 2-2 extension line (E22) overlap, heat damage on the core side may accumulate due to the 1-2 weld (21) and the 2-3 weld (22), which may cause an increase in iron loss. Therefore, the 2-1 extension line (E21) and the 2-2 extension line (E22) may be formed spaced apart from each other.

[0117] However, the second extension line (E2) of a part of the weld (20) formed on a block core (10a, 10b, 10c, 10d) other than the same block core (10a, 10b, 10c, 10d) among the plurality of block cores (10a, 10b, 10c, 10d) may not be spaced apart. For example, the second extension line (E2) extending a part of the 1-2 weld (21) formed on the first block core (10a) and the second extension line (E2) extending a part of the 3-4 weld (23) formed on the 3rd block core (10c) may be the same extension line as the 2-1 extension line (E21).

[0118] For example, in the welding step (S40), a plurality of welded portions (20) may be formed at the same position in the first direction (DR1) and spaced apart from each other in the second direction (DR2).

[0119] There are multiple welds (20) formed at the same location in the first direction (DR1), and multiple welds (20) can be formed spaced apart from each other in the second direction (DR2).

[0120] Referring to FIG. 7, the first-second welding portion (21), which is a welding portion (20) connecting the first block core (10a) and the second block core (10b), may be spaced apart in the second direction (DR2) and a plurality of first-second welding portions (21a, 21b, 21c) may be formed. This is because, when connecting two adjacent block cores (10) in the first direction (DR1), if only one welding portion (20) is used, the bonding strength may not be sufficient. The same may apply to the second-third welding portions (22, 22a, 22b) and the third-fourth welding portions (23, 23a, 23b, 23c).

[0121] In addition, in the welding step (S40), the location where the weld (20) is formed may be the outer peripheral surface of the core. Partial welding on the inner side of the slot or on the side of the core including the gap between the rotor and the stator reduces the space for winding the winding conductor, which worsens the winding space factor and acts as friction when the electric device rotates, so it may be advantageous to form the weld on the outer peripheral surface rather than the inner peripheral surface.

[0122] For example, in the welding step (S40), the welding method may be TIG or laser welding, but is not limited thereto and may include all welding methods used in the industry.

[0123] By including a welding step (S40) like this, a core with low iron loss, easy manufacturing, and economical manufacturing cost can be manufactured.

[0124] FIG. 8 is a drawing of a method for manufacturing a block laminate core according to an embodiment of the present invention, showing a state in which a first block core and a second block core adjacent in a first direction are joined by a first-second welding portion, as viewed from a first direction.

[0125] For example, a plurality of welding portions (20) that connect two identical block cores (10) among a plurality of block cores (10) are formed, and a second angle (θ2), which is the smallest angle among the angles formed by two third extension lines among the plurality of welding portions (20) that connect the two identical block cores and the third extension lines that connect the centers of the block cores (10), may be 10 to 180°.

[0126] Referring to FIG. 8, a third extension line (E3, E3a, E3b, E3c, E3d, E3e, E3f), which is a virtual extension line connecting the first and second welding parts (21, 21a, 21b, 21c, 21d, 21e, 21f) that joins the two block cores (10a, 10b) that are the same as the center (C) of the first block core (10a) or the second block core (10b), can also be formed in multiple numbers, and among the multiple third extension lines (E3, E3a, E3b, E3c, E3d, E3e, E3f), the smallest angle among the angles formed by two third extension lines (E3, E3a, E3b, E3c, E3d, E3e, E3f) adjacent in the second direction (DR2) is the second angle (θ2), which can be formed in a range of 10 to 180°. Since six first-second welding portions (21, 21a, 21b, 21c, 21d, 21e, 21f) are formed, the second angle (θ2) can be 60°. The second angles (θ2) may be different from each other, but it may be advantageous for the bonding strength to have the same second angle (θ2) formed by the welding portions (20) that join the two identical block cores (10). Accordingly, it is possible to manufacture an excellent core having sufficient bonding strength to maintain the laminated state of the block laminate (15) in which a plurality of block cores are laminated while having low iron loss.

[0127] Hereinafter, in the block laminate core according to an embodiment of the present invention, the same configuration, content, and effects as those described in the block laminate core manufacturing method will be cited unless otherwise specified. In addition, the block laminate core according to an embodiment of the present invention will be described with reference to FIGS. 4 to 8.

[0128] A block laminate core (3) according to one embodiment of the present invention comprises a block core (10) in which electrical steel plates (100) are laminated to have a first length (L1) in a first direction (DR1) and which includes a joint portion (11) of an interlocking joint, a block laminate (15) in which a plurality of the block cores (10a, 10b, 10c, 10d) are laminated to have a second length (L2) in the first direction (DR1), and a weld portion (20) formed on an outer surface of the block laminate (15) in the first direction (DR1) to connect two adjacent block cores (10a, 10b, 10c, 10d) among the plurality of block cores (10a, 10b, 10c, 10d) included in the block laminate (15) to have a third length (L3) that is shorter than twice the first length (L1).

[0129] For example, a plurality of first extension lines (E1), which are virtual extension lines connecting the punch lines (Ba, Bb, Bc, Bd) formed on the electrical steel plate (100) and the centers (C) of the block cores (10a, 10b, 10c, 10d), are formed, and the first extension lines (E1) are formed at the same position in the second direction (DR2) so that the angle between the first extension lines (E1) is 0 within any one block core (10a, 10b, 10c, 10d) among the plurality of block cores (10a, 10b, 10c, 10d), and the angle between the first extension lines (E1) formed in any two block cores (10a, 10b, 10c, 10d) adjacently arranged in the first direction (DR1) among the plurality of block cores (10a, 10b, 10c, 10d) is the first angle (θ1). It can be achieved, and the first angle (θ1) can be constant.

[0130] For example, the second length (L2) may be 3 to 8 times the first length (L1).

[0131] For example, a plurality of the above welding portions (20) that join two identical block cores (10a, 10b, 10c, 10d) among a plurality of block cores (10a, 10b, 10c, 10d) are formed, and the second angle (θ2), which is the smallest angle among the angles formed by any two of the third extension lines (E3) that are extension lines connecting the centers of the block cores (10a, 10b, 10c, 10d) and the plurality of welding portions (20) that join the two identical block cores (10a, 10b, 10c, 10d), may be 10 to 180°. Accordingly, the block laminate core (3) can provide an excellent fastening strength effect while preventing the entire electrical steel plate (100) from being energized.

[0132] Below, Table 1 shows a table comparing block laminate cores formed by a block laminate core manufacturing method according to one embodiment of the present invention with comparative examples.

[0133] The no-load loss was measured under the condition that a copper winding was wound around a core that was laminated so that the height of a single core was 100 mm by punching a non-oriented electrical steel plate with a thickness of 0.27 mm to a diameter of 230 mm and connecting an inverter to supply power.

[0134] When pressed electrical steel sheets are laminated without rotation and fastened, the accumulated thickness variation of the electrical steel sheets results in poor squareness and flatness, which represent the core shape. Furthermore, since there is no fastening, fastening strength cannot be measured. Since there is no processing stress due to fastening, the no-load loss in this situation is set to 100%.

[0135] Under the above conditions, when the block cores are laminated, the rotation angle, which is the first angle, is gradually reduced, and when laminated without rotation, it is changed to 180°, 120°, 90°, and 45°, and as a result of the experiment, it was confirmed that the squareness and flatness gradually improved, and based on this, the experiment as shown in the table below was conducted.

[0136] 1st angle (°) Electrical steel plate fastening method and heat treatment interlocking fastening number Welding section internal angle (°, 2nd angle) and welding vertical angle and flatness of joining two block cores No-load loss ratio (%) Fastening strength Comparative example 190 Overall interlocking 6 - Excellent 108.50 Poor Comparative example 290 Overall interlocking 12 - Excellent 115.30 Poor Comparative example 390 Overall welding - 180 degrees / 2 Poor 117.60 Poor Comparative example 490 Overall welding - 90 degrees / 4 Good 131.60 Excellent Comparative example 590 Overall welding - 60 degrees / 6 Excellent 142.30 Excellent Comparative example 690 After block core interlocking Overall welding 690 degrees / 4 Excellent 147.90 Excellent Example 1120 After block core interlocking Partial welding 690 degrees / 4 Good 115.10 Excellent Example 290 Partial welding after block core interlocking 690 degrees / 4 Excellent 114.70 Excellent Example 390 Partial welding after block core interlocking 645 degrees / 8 Excellent 118.50 Excellent Example 490 Partial welding and heat treatment after block core interlocking 645 degrees / 8 Excellent 109.50 Excellent

[0137] In Comparative Example 1, four block cores are laminated to form a block laminate, but the individual block cores do not have joints. In addition, the laminates are laminated while rotating the first angle by 90°. After that, the entire block laminate is interlocked at six locations at 60-degree intervals. In this case, although the squareness and flatness of the cores are excellent, a defect occurs in which the core fastening strength is not secured. Therefore, when the top part of the core is lifted, a part of the core falls off or the gap between the electrical steel sheets included in the block cores becomes significantly widened. In Comparative Example 2, a block laminate is manufactured in the same manner as Comparative Example 1, but the number of interlocking fastenings is increased to 12 and fastened at 30-degree intervals. Although the fastening strength is improved compared to Comparative Example 1, it is somewhat insufficient to be judged as a good product. When the top part of the cores is lifted, the gap between the cores is less widened compared to Comparative Example 1, but a side impact test showed that the cores fell off due to a slight external impact.

[0138] Here, the side impact test is an experiment to compare the degree of bonding by applying a weak impact to the side of the core with a hammer, and is a test regarding the impact that may occur during core transportation.

[0139] Comparative Example 3 forms a block laminate by laminating four block cores like Comparative Example 1, but the individual block cores have no joints and are laminated while rotating at a first angle of 90°. After that, full welding is performed on the outer surface of the block laminate using the TIG welding method. The second angle between adjacent welded portions is 180°, forming two full welded portions. Since Comparative Example 3 performs welding by pressurizing the cores with an appropriate pressure, a springback phenomenon occurs in which the unwelded portion swells when welding at 180 degrees, resulting in poor squareness and flatness.

[0140] Comparative Example 4 forms a block laminate by stacking four block cores in the same manner as Comparative Example 3, but the individual block cores are stacked while rotating at a first angle of 90° without a joint. After that, the entire outer surface of the block laminate is welded using the TIG welding method. At this time, unlike Comparative Example 3, four welds are formed with an internal angle of 90° between the welds. Comparative Example 4 showed good squareness and flatness, but a problem occurred in which the no-load loss ratio deteriorated rapidly to 131.6%.

[0141] Comparative Example 5 forms a block laminate similar to Comparative Example 3 and performs full welding. Unlike Comparative Example 3, six full welds are formed with an internal angle of 60° between welds. Comparative Example 5 has excellent core shape and joint strength, but the no-load loss is very poor at 142.3%.

[0142] Comparative Example 6 produces a block core by laminating electrical steel sheets and interlocking them in six sections. The block cores are then laminated while rotating the first angle by 90°. Then, four complete welds are formed with an internal angle of 90° between the welds. In this case, the no-load loss is the worst at 147.90%.

[0143] Confirmation is made regarding Examples 1 to 4 according to one embodiment of the present invention.

[0144] After manufacturing a block core (10), a block laminate core (3) is manufactured by performing a step of rotating and laminating it according to a first angle (θ1) and welding only a part of the outer surface, which corresponds to Examples 1 to 4. In addition, only Example 4 was manufactured by additionally including a heat treatment step (S20). In the examples, the third length (L3) is formed to extend up and down by 1 / 4 of the first length (L1) based on the laminated surface, and the total length corresponds to 1 / 2 of the first length (L1).

[0145] In Example 1, three block cores (10) are laminated at a first angle (θ1) of 120°, and the second angle (θ2) is 90°, and the number of welds at the same position in the first direction (Dr1) is four. Accordingly, a block laminate core (3) formed by a total of three block cores (10) is manufactured by forming a total of 12 welds (20).

[0146] In Example 2, four block cores are laminated with a first angle (θ1) of 90°, and the second angle (θ2) is 90°, similar to Example 1, and the number of welded portions (20) at the same position in the first direction (DR1) is four. Therefore, a total of 16 welded portions (20) are formed and manufactured on a block laminated core (3) formed with a total of four block cores (10), and the maximum value of the third length (L3) is set smaller in Example 2 than in Example 1.

[0147] Example 3 is similar to Example 2 in that the first angle is 90° and four block cores (10) are laminated, but the second angle (θ2) is 45° and the number of welded portions (20) at the same position in the first direction (DR1) is eight. Accordingly, a total of 32 welded portions (20) are formed on the block laminated core (3) formed with a total of four block cores.

[0148] Example 4 is manufactured in the same manner as Example 3, but a heat treatment step (S20) is performed before laminating the block core to relieve residual stress resulting from processing.

[0149] The joint (11) that fastens the block core is an interlocking fastening, and was manufactured in the case of six in all of Examples 1 to 4. This was set as a standard because, according to Comparative Example 6, when six interlocking fastenings were performed internally, the fastening strength was excellent.

[0150] According to the results of Example 1, the core shape, squareness and flatness, were good, the fastening strength was excellent, and the no-load loss was good at 115.10%. The results of Example 2 showed that the no-load loss was about 114.7%, which showed a tendency to decrease compared to Example 1. This can be interpreted as the effect of further alleviating the thickness deviation of the electrical steel sheet, thereby forming the magnetic field within the core more evenly. In addition, the squareness and flatness were better than those of Example 1. That is, it can be seen that the smaller the first angle, the better the squareness and flatness.

[0151] Looking at the results of Example 3, the number of welds (20) at the same location in the first direction (DR1) increased, which was more disadvantageous than Examples 1 and 2 due to the current flow between the electrical steel plates, resulting in a no-load loss of 118.5%. Although not shown in Table 1, the joint strength is better than that of Example 2. Example 4 has the same conditions as Example 3, but additionally performed a heat treatment step (S20). At this time, the heat treatment conditions were to inject 100% nitrogen at a maximum temperature of 820 degrees for 1 hour. Accordingly, it can be seen that the no-load loss ratio was lowered to 109.50% compared to Example 3.

[0152] In the above Table 1, Comparative Examples 4 to 6 can be seen as cores manufactured according to the existing manufacturing method. Comparing with these, it can be seen that Examples 1 to 4 can manufacture cores having excellent squareness and flatness, and similar or better fastening strength than the existing cores, while having a much lower no-load loss ratio.

[0153] If incorporated into a motor used in an electric vehicle, the block-laminated core (3) according to one embodiment of the present invention will significantly extend the driving range of the electric vehicle and enhance safety. Of course, the performance of motors generally used, not just for electric vehicles, can also be significantly enhanced.

[0154] Although the present invention has been described above with reference to examples, the present invention is not limited to the above-described examples, and it goes without saying that modifications can be made and implemented by those skilled in the art without changing the technical idea of ​​the present invention as claimed in the claims.

Claims

1. A block core step of forming a block core of a first length by laminating and combining electrical steel sheets in a first direction; A laminating step of rotating a plurality of the above block cores at a first angle in a second direction, which is a circumferential direction, and laminating them so that they have a second length in the first direction; and A welding step of forming a weld by welding a third length shorter than twice the first length in the first direction to the outer surface of two consecutive block cores among the plurality of block cores; In the above welding step, A method for manufacturing a block laminate core in which a plurality of virtual lines extending in the first direction from a portion of the plurality of welded portions formed in one of the plurality of block cores are spaced apart.

2. In paragraph 1, In the above block core step, the electrical steel sheets are interlocked and bonded to a block laminate core manufacturing method.

3. In paragraph 2, The above second length is a multiple of n of the above first length, The above first angle is a block laminate core manufacturing method according to the following mathematical formula 1. Mathematical formula 1: θ1 = 360° / n Here, θ1 is the first angle (°) and n is a natural number.

4. In paragraph 3, The above second length is, A method for manufacturing a block laminate core having a length 3 to 8 times longer than the first length.

5. In paragraph 1, In the above welding step, The above welding part, A method for manufacturing a block laminate core, wherein a plurality of block laminate cores are formed at the same position in the first direction and spaced apart in the second direction.

6. In paragraph 1, A block lamination core manufacturing method further comprising a heat treatment step in which a heat treatment is performed to remove residual stress of the block core prior to the lamination step.

7. A block core including a joint of interlocking bonds, in which electrical steel sheets are laminated to have a first length in a first direction, and A block laminate in which a plurality of the above block cores are laminated to have a second length in the first direction, A block laminate core including a welded portion formed on the outer surface of the block laminate with a third length that is shorter than twice the first length in the first direction to connect two adjacent block cores among the plurality of block cores included in the block laminate.

8. In paragraph 7, A plurality of virtual first extension lines are formed connecting the punching line formed on the electrical steel sheet forming the block core and the center of the block core, and the first extension lines are formed at the same position in the second direction, which is the radial direction, within one block core. A block laminate core in which the angle between the first extension lines formed on any two block cores adjacent to each other in the first direction among the plurality of block cores forms a first angle.

9. In paragraph 8, A block laminate core wherein the second length is 3 to 8 times the first length.

10. In paragraph 9, A block laminate core in which a plurality of welding portions are formed to join two identical block cores among a plurality of block cores, and a second angle, which is the smallest angle among the angles formed by two third extension lines among the plurality of welding portions joining the two identical block cores and the third extension lines connecting the centers of the block cores, is 10 to 180°.

11. In paragraph 7, The above electrical steel sheet is, in weight %, Block-laminated core, a non-oriented electrical steel sheet containing Si: 0.25~4.8%, Al: 0.05~2.0%, Mn: 0.15~1.0%, C: 0.0015~0.0040%, N: 0.0005~0.0030%, S: 0.0005~0.003%, Mo: 0.0050~0.015%, Ti: 0.0005~0.0020%, Nb: 0.0005~0.0040%, V: 0.0005~0.0040%, the remainder being Fe and unavoidable impurities.

Images