A method for cutting a whole wedge core for a high-speed wire cutting machine

Abstract

The application discloses a wedge-shaped iron core integral cutting tool and method, and the tool comprises a workpiece rack, a dividing disc and a fixing seat. The cutting method comprises the following steps: 1, stacking a plurality of raw materials, and gluing and bonding the raw materials at the planned iron core to be fixed, compacting and welding the bonded stacked raw materials into a block; 2, cutting the stacked block obtained in the above step into a to-be-processed stack which is consistent with the contour of the clamping station of the wedge-shaped iron core integral cutting tool; 3, positioning the inclined surface where the tooth length of the iron core is located, and opening two side positioning holes which penetrate through the to-be-processed stack on the two sides of the iron core area; 4, clamping the to-be-processed stack obtained in the above step to the wedge-shaped iron core integral cutting tool, rotating the dividing disc in a forward direction according to the angle of the inclined surface, and performing first inclined surface line cutting from the positioning hole located at the end of the inclined surface; and 5, based on the clamping in the above step, rotating the dividing disc in a reverse direction according to the angle of the double inclined surface, and performing iron core block pole shoe end face and second inclined surface line cutting from the positioning hole located at the end of the inclined surface.

Description

Technical Field

[0001] The present invention relates to the technical fields of forming and processing technology of wedge-shaped iron cores for disc motors, and in particular to an integral cutting method of wedge-shaped iron cores for fast-wire cutting machines. Background Art

[0002] Yokeless disc motors are a publicly available technology. Their magnetic circuit orientation differs from that of traditional disc motors. The rotors, with their upper and lower polarities differing, run straight through the stator, creating a deflection in the rotor back iron to close the magnetic flux lines. Compared to traditional motors, these motors offer significantly higher power density, typically reaching 5-13 kW / kg. The uniformity of the stator core's magnetic circuit orientation allows the use of transformer materials—anisotropic magnetic materials with enhanced magnetic properties, such as laminated grain-oriented silicon steel sheets. These materials exhibit significantly superior magnetic properties in the rolling direction, providing enhanced magnetic properties for the entire motor system. The key design challenge and difficulty of yokeless disc motors lies in securing the discrete wedge-shaped stator cores, ensuring concentricity and good thermal conductivity. However, in motor system design, the saying "three parts electrical, seven parts mechanical" applies, but this emphasis on design only accounts for approximately 30% of the overall project implementation difficulty. The more crucial factor is processing technology, and the domestic adoption of these motors is primarily limited by this.

[0003] For this type of disc motor, the main difficulty in processing technology lies in the processing technology of the wedge-shaped iron core. In order to reduce the complexity of processing, foreign small-batch mass production designs use powder metallurgy soft magnetic materials with worse magnetic properties, and sacrifice magnetic properties to ensure processing characteristics. For specific solutions, please refer to YASA's patent in China, patent number CN201480050285.8, patent name "Pole Piece Bonding".

[0004] Although the magnetic properties of the wedge-shaped core made of laminated oriented silicon steel are significantly higher than those of SMC powder metallurgy soft magnetic materials, it needs to be cut into single pieces of different sizes and laminated piece by piece due to the traditional processing technology, which makes the production process complicated and leads to excessively high costs.

[0005] Grain-oriented silicon steel is primarily formed using wire cutting, specifically wire electro-discharge (EDM). The principle of EDM is that free positive ions and electrons accumulate in a field, quickly forming an ionized conductive path. During this stage, a current flows between the two plates, causing numerous collisions between particles and forming a plasma zone. This generates an arc discharge, rapidly raising the core temperature to between 8,000 and 12,000 degrees Celsius, and instantly vaporizing the material on the surfaces of the two conductors. The current is then interrupted, and the temperature suddenly drops, causing the bubbles to explode inward. The resulting momentum propels the molten material, which then recondenses into small spheres in the cooling dielectric fluid and is then expelled by the fluid.

[0006] Existing wire-cutting machines can be categorized by wire speed: high-speed wire-cutting, slow-speed wire-cutting, and vertical self-rotating wire-cutting machines. High-speed wire-cutting machines, however, require a taper head to achieve a beveled surface. However, the maximum rotation angle is limited to 1.5 degrees, making them insufficient for some users' needs for cutting large angles. Switching to a slow-speed wire-cutting machine significantly increases costs.

[0007] Silicon steel sheets need to be clamped and positioned using tooling during wire cutting, but existing silicon steel tooling only serves the functions of clamping, fixing, and positioning.

[0008] Since China is currently only in the prototype development stage of this new type of motor (disc motor), there are few manufacturers with high-cost precision equipment such as large-scale slow-wire wire cutting, and the order cost loss of small-batch prototype processing is even higher. Therefore, there are almost no large domestic suppliers trying technical research in this direction. This technology can only be discussed in theory among universities, and it is difficult to complete the transformation process of industry, academia and research. This phenomenon will also aggravate the gap between domestic and foreign industrial technologies. Summary of the Invention

[0009] As we all know, high-speed wire cutting machines require an external taper head to cut bevels, and the maximum cutting angle is only 1.5 degrees, which cannot meet the user's work requirements for cutting large-angle bevels.

[0010] To solve this bottleneck problem in prototype production, we have improved the previous high-cost processing method and summarized a new, cost-effective integral cutting technology for wedge cores using a low-cost single-axis high-speed wire cutting machine. This technology can solve the problem of using a single-axis high-speed wire cutting machine to cut two inclined surfaces with different angles from laminated silicon steel sheets.

[0011] Specifically, the present invention provides a wedge core integral cutting tool:

[0012] The tooling is divided into three parts: indexing plate, material rack and fixed seat.

[0013] The overall profile of the work rack is approximately square, specifically a right-angled U-shape formed by three side edges. End caps are installed at the openings and can be fastened to the work rack using fasteners. Thus, the three side edges and end caps form a clamping station for clamping the oriented silicon steel sheet stack.

[0014] Specifically, the three side portions are implemented as: a first side portion clamped relative to the cover plate, and two second side portions clamped relative to each other.

[0015] In order to facilitate clamping and fixing, a series of positioning structures are set up in the clamping station:

[0016] For example, the first side portion is implemented as a keyway, and two keyways are arranged vertically on the first side portion; the second side portion is implemented as a step and a slide, the step is formed at the lower edge of the second side portion, and the slide is arranged on the upper side of the step.

[0017] Install the fixing seat or indexing plate on the outer side of the second side portion:

[0018] The second side edges on either side correspond to a fixed seat or indexing plate. Because the tooling frame requires stable flipping capabilities, the fixed seat and indexing plate maintain the same rotation axis. The position of the rotation center relative to the second side edge can be arbitrary, but it is obvious that the rotation center at the center of the second side edge is more stable and more conducive to flipping changes during wire cutting.

[0019] Specifically, the second side of one side of the material rack engages with the indexing plate via a circular shaft through a hole provided at its center. This shaft is also engaged by two square shafts on either side. The second side of the other side is mounted via a fixed shaft on the fixed rack. A circular disc is coaxially fixed to the fixed shaft, and the circular disc is connected to the material rack via two square shafts arranged on either side of the fixed shaft, allowing the material rack to rotate at a certain angle.

[0020] Therefore, the workpiece carrier is connected to the indexing plate via a circular shaft, allowing the carrier to rotate around the indexing plate axis during rotation. At the same time, two square shafts between the two plates secure the workpiece carrier and prevent slippage during rotation, thereby ensuring accuracy. The fixed shaft and two square shafts on the other side of the workpiece carrier ensure that the workpiece carrier can rotate while also sharing some of the stress, thereby increasing the service life of the tooling.

[0021] Based on the above-mentioned tooling structure, the present invention further describes a cutting method based on the above-mentioned wedge core integral cutting tooling.

[0022] Traditionally, wedge-shaped cores made of laminated oriented silicon steel sheets require cutting into individual sheets of varying sizes. This complicated the production process and resulted in high costs. The fixture structure of the present invention allows for the integral cutting of laminated oriented silicon steel sheets, without the cutting angle restrictions of high-speed wire cutting.

[0023] The tooling of this invention utilizes the ability of the indexing plate to rotate at specific angles to achieve the removal of inclined surfaces. It also applies glue to the silicon steel sheet along a specific trajectory before cutting to complete the entire cut. While this can be accomplished using a relatively low-cost single-axis high-speed wire-cutting machine, using a slow-speed wire-cutting machine would eliminate the need for auxiliary positioning tools, but the cost would increase exponentially.

[0024] Furthermore, the cutting method specifically comprises the following steps:

[0025] 1. The initial material for processing is silicon steel coils, which are cut into individual pieces and stacked together and welded into blocks. During the stacking process, glue can be applied along the straight line connecting the cores according to the drawings. The amount of glue used and the coating area should be controlled to ensure that the thickness of the stack is not affected and that the glue does not overflow along the cutting edge of the wedge core, thereby affecting the required conductivity for wire cutting. Generally, the glue application amount is controlled by the thickness of the glue, which should be kept within 1-3μm, as the layer insulation thickness of ordinary grain-oriented steel is 1-3μm.

[0026] 2. The stacked silicon steel block is wire-cut to create keyways and a neat outer contour for tooling positioning. Due to the glue applied during the stacking of the raw materials, the entire silicon steel block will not break into individual pieces. After the entire block is cut, the cut intermediate material is placed in the tooling.

[0027] 3. According to the digital model sent to the wire cutting equipment, the dividing plate is operated to rotate the core inclined surface in the positive direction to the required inclination angle to complete the cutting of the inclined surface. This inclination can complete the cutting of the trajectory of the first inclined surface, because a closed area is not cut out, and the silicon steel sheets are glued together, and the solid silicon steel block will not fall apart.

[0028] 4. After the first inclined surface is cut, the tooling remains in place and the indexing plate is rotated in the negative direction by twice the angle (the angle used in step 3). The core block pole piece end faces and the second inclined surface are then cut according to the core contour in the digital model, achieving a closed-loop cut of the entire core.

[0029] 5. Due to the presence of glue injection, the iron core will not fall apart after cutting. There may be slight warping on the edge. This problem can be solved by press-fitting and potting after winding, and it does not affect the overall performance.

[0030] In the above steps, it should be noted that the overall cutting of the core contour needs to be carried out in steps 3 and 4 after the square material is cut once as described in step 2. The specific reason is to avoid the problem caused by the positioning accuracy difference, which occurs when cutting the end face of the stator core block pole shoe. The two cutting trajectories are closed due to the small gap and difficult to align, thereby generating a subtle boss, which in turn affects the spatial distribution of the air gap magnetic field.

[0031] Furthermore, because the tooling must be rotated during the step-by-step cutting process in steps 3 and 4, the indexing disk's rotation will cause the wire routing position to shift slightly on the surface of the cut material, affecting the positioning of the wire cutting thread. Therefore, the tooling should be used to pre-drill positioning holes outside the core area corresponding to the bevels to be cut. Positioning holes can be drilled at both ends of the core to serve as the starting points for the cutting routing trajectory and are used for initial positioning, primarily due to the different angles of the bevels on both sides.

[0032] The displacement of the wiring position on the upper surface of the silicon steel sheet stack caused by the rotation of the indexing plate can be calculated from the angle of rotation of the indexing plate and the thickness of the core block after one cutting. This calculated value can be used for positioning correction or deviation correction.

[0033] Preferably, during the process of this tooling, two grooves and steps need to be cut on both opposite sides of the workpiece when the square material is cut once in step 2, and a keyway needs to be cut on one end face. These structures can be used to clamp and fix the silicon steel to ensure that the center axis of the silicon steel does not change, thereby achieving its positioning effect and improving the accuracy of wire cutting.

[0034] Advantageously, the tool can be used to cut multiple cores simultaneously on the same stock. By properly planning the core positions and wire routing, it is possible to simultaneously cut multiple cores of the same size, or to mix and cut multiple cores of different sizes.

[0035] Because the size of the stock is determined by the tooling, the required motor size (inner and outer diameters of the stator) determines how many wedge-shaped core stator segments can be cut from a single piece of stock. A larger motor will result in a larger wedge-shaped core, and the maximum volume of the core that can be cut will not exceed the total volume of the stock. A smaller motor will also result in a smaller wedge-shaped core, allowing many wedge-shaped cores to be cut from a single piece of stock.

[0036] Regardless of the cutting requirement, this tooling and cutting method facilitates forming and processing. Simply adjust the tooling angle to perform a first bevel cut on the stacked, bonded, and fixed rough material. Then, reverse the tooling angle and perform a second bevel cut. By controlling positioning and cutting accuracy, the final wedge core is formed.

[0037] The advantage of the method of the present invention is that, through the use of a rotatable tooling design, this integral cutting technology can complete the integral cutting of different stator wedge cores used in such motors. Ultimately, this enables the low-cost processing of stator wedge cores of such motors with different outer diameters and different pole slot combinations, significantly reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0039] Figure 1 This is a structural diagram of the wedge core integral cutting tool;

[0040] Figure 2 A three-dimensional diagram of a finished wedge core produced by the tooling and method of the present invention;

[0041] Figure 3 It is a gluing track diagram when the wool materials are laminated;

[0042] Figure 4 This is a trajectory diagram of the step-by-step cutting and routing of a single iron core in the method of the present invention;

[0043] Figure 5 This is a trajectory diagram for cutting 9 iron cores from a single piece of raw material;

[0044] Among them, 1. material rack; 2. fixed seat; 3. dividing plate; 11. cover plate; 12. keyway; 13. slide; 14. step. DETAILED DESCRIPTION Example

[0045] Wedge core integral cutting tool:

[0046] The tooling is divided into three parts: the indexing plate 3, the work material rack 1 and the fixed seat 2.

[0047] The material rack 1 is square in shape. One side of the material rack 1 is connected to the indexing plate 3 via a circular shaft through a hole set in the center, so that the material rack 1 rotates around an axis during rotation. At the same time, the material rack 1 and the indexing plate 3 are also connected by two square shafts, which play a role in fixing and continuously sliding during rotation to ensure accuracy and fixation.

[0048] The other side of the work material rack 1 is connected through a fixed shaft on the fixed frame 2, the fixed shaft is connected to the disc, and the disc is connected to the tooling through two square shafts, so that the tooling can rotate at a certain angle, ensuring that the work material rack 1 performs rotational motion while also sharing part of the stress to increase the service life of the tooling.

[0049] The silicon steel is secured within the fixture by a step 14, a slide 13, a keyway 12, and a cover plate 11. The fixture rotates at a predetermined angle to complete the cutting of the wedge-shaped core for yokeless disc motors. A single-axis high-speed wire EDM machine is used to cut the wedge core in one piece, significantly reducing costs and meeting the processing needs of small-batch yokeless disc motors. Example

[0050] Method for cutting a single wedge core:

[0051] 1. The initial material is a silicon steel coil, which is cut into pieces and stacked together and welded into a block. Since the cutting accuracy of the pieces is very rough, the thickness direction cannot be aligned. In the traditional method, the silicon steel sheet is cut into pieces and then stacked and welded. Therefore, during the stacking process of the present method, the glue can be applied along the straight line direction of the core according to the drawing, and the amount of glue and the coating area should be controlled to ensure that the thickness of the stacked block is not affected, and the glue should not overflow along the edge of the wedge-shaped core to be cut, thereby affecting the required conductivity of the wire cutting. The trajectory of the glue injection is shown in Figure 3 .

[0052] 2. The stacked silicon steel block is wire cut as a whole, and the key groove and the neat outer contour for tool positioning are cut. At this time, due to the glue applied during the stacking of the pieces, the whole silicon steel block will not be scattered into single pieces. After the whole cutting is completed, the cut intermediate square material is placed in the tool.

[0053] 3. According to the digital model sent to the wire cutting equipment, the required inclination angle of the core bevel is rotated in the positive direction by operating the protractor to complete the cutting of the inclined surface. This inclined surface can complete the cutting of the first inclined surface track, because a closed area has not been cut, and the silicon steel sheets are glued and bonded, so the silicon steel block will not be scattered. The first cutting track is shown by the dashed line in Figure 4 . Figure 2 Only the cutting of a single core block is shown as an example, and the same cutting principle is applicable to multiple core blocks in practice.

[0054] 4. After the cutting of the previous step is completed, the position of the tool is not changed, and the protractor is rotated in the negative direction by twice the inclination angle (i.e. the inclination angle operated in step 3). Then, according to the core contour track in the digital model, the core block pole piece end surface and the second inclined surface track are cut, thereby realizing the cutting of the closed track of the whole core. The second cutting track is shown by the solid line in Figure 4 .

[0055] 5. Due to the presence of glue, the cut core will not be scattered, and there may be slight warping at the edge. This problem can be solved by winding and then pressing, filling and sealing, which does not affect the overall performance.

[0056] In the above steps, it should be noted that the overall cutting of the core contour should be carried out in steps 3 and 4 after the first cutting of the square material described in step 2. The specific reason is to avoid the problem that due to the difference in positioning accuracy, when cutting the pole piece end surface of the stator core block, the two cutting tracks at the closed part are difficult to align due to a small gap, thereby producing a slight boss, which affects the spatial distribution of the air gap magnetic field.

[0057] In addition, since the tooling needs to be rotated during the step-by-step cutting in steps 3 and 4, and the indexing plate rotates, the wire routing position will produce a certain displacement on the upper surface of the cut material due to the rotation, which will affect the positioning of the wire cutting threading position. Therefore, this tooling should be used in advance to drill positioning holes outside the core area corresponding to the inclined surface to be cut, such as Figure 4 The positioning holes are pre-arranged on the trajectory path. The positioning holes can be opened on the edges of the square material at both ends. They serve as the starting point of the cutting trajectory and are used for initial positioning, mainly because the angles of the bevels on both sides are different. Example

[0058] Method for cutting multiple wedge cores as a whole:

[0059] Cut 9 cores from a silicon steel block, such as Figure 5 shown.

[0060] Because the total volume of the silicon steel sheet blank is the same, if more iron cores are cut from a single piece of blank, it means that the outer diameter of the stator finally assembled by the iron core will be smaller; vice versa.

[0061] In this case, it is only necessary to reasonably plan the position of the iron core and the wiring sequence on the raw material, and then one tool can ensure the production of motors of different outer diameters.

[0062] Specifically, according to the wire cutting routing requirements, multiple cores are cut on a single piece of raw material, and the routing path needs to minimize the waste of residual material. At the same time, the routing path needs to be clear and non-interfering, avoiding dimensional and surface errors caused by positioning and track overlap. Figure 5 As shown, nine cores are cut from a raw silicon steel block. The first cut simultaneously forms the first bevel path for all nine cores. After the tooling changes the angle, the second cut simultaneously forms the second bevel path for all nine cores. The blank holes in the image are punched by the electric spark punch. The four holes at each end of the raw material are locating holes for threading. The hole in the center of the core serves as a welding groove for laser welding in a subsequent step to prevent the oriented silicon steel laminate from spreading.

[0063] Then, the key to this step can be said to be the pole shoe end face of the wedge core, that is, the end face that directly contacts the air gap, which needs to be cut in one go. In this way, there will be no bosses caused by dimensional deviation when cutting in two sections, and the cutting process will not affect the air gap magnetic field of the motor.

[0064] The embodiments of the present invention are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical concepts disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A method for integrally cutting a wedge core for a high-speed wire cutting machine, characterized in that: include: S1. Prepare the stock: stack multiple pieces of stock and glue them together at the planned cores. Firmly bond the stacked stock, compact it, and weld it into a block. The glued area at each core should be equal to or less than the area of ​​the core itself. Glue should be applied along the straight line connecting the cores, and the amount of glue applied should be controlled to ensure no glue overflow at the edges of the cuts. S2 cutting preparation; the step obtained by cutting the raw material stack block into a wedge core in line with the overall cutting tool clamping station contour to be processed stack; S3. Inclined surface positioning; positioning the first and second inclined surfaces where the core tooth length is located, and since the inclined surfaces on both sides have different inclination angles, the first and second positioning holes are opened on the corresponding inclined surfaces on both sides of the core area outside the core area, parallel to the inclined surface angles on both sides and corresponding to each other, and the first and second positioning holes are opened through the stack to be processed as the starting point; S4. The first bevel cutting; the stack obtained in the previous step is clamped to the wedge core as a whole on the cutting tool, according to the bevel angle, the indexing plate is rotated forward, and the first positioning hole at the end of the bevel is cut according to the first trajectory for the first bevel alignment; S5. Second bevel cutting; Based on the clamping in the previous step, the indexing plate is rotated in the opposite direction according to twice the bevel angle, and the end face of the core block pole shoe and the second bevel line are cut from the second positioning hole at the end of the bevel according to the second track, and the end faces of the two core block pole shoes are located on the second track; The starting point and the end point of the first trajectory and the second trajectory are four non-overlapping points outside the core contour; The first track and the second track travel along the core contour without overlapping; The first trajectory and the second trajectory have and only have two intersection points, and the two intersection points are not starting points or end points; The tracks between the two intersection points of the first track and the second track together enclose the overall outline of the core, thereby achieving closed cutting of the overall track of the core; The wedge core integral cutting tool comprises: The work material rack comprises: a main body for clamping the oriented silicon steel sheet stack, and a cover plate detachably connected to the main body; the main body comprises a clamping station penetrating the main body and for placing the oriented silicon steel sheet stack; The fixing frame comprises: a shaft arranged in the same direction as the longitudinal direction of the core teeth and capable of providing a turning of the cutting plane by its self-rotation; both ends of the shaft are respectively mounted on the fixing frame and the body; The indexing plate is arranged in a coaxial relationship with the shaft holding position, and the indexing plate is connected to the body by assembly; the clamping station of the body includes steps, slides, and keyways for placing and positioning the oriented silicon steel sheet stacks; The body is a rectangular structure formed by three side portions and a cover plate; the body includes: a first side portion clamped relative to the cover plate, and two second side portions clamped relative to each other; the first side portion includes the keyway; the second side portion includes the step and the slide; The steps and the slide are both arranged along the length direction of the second side portion.

2. The method for integrally cutting a wedge core for a high-speed wire cutting machine according to claim 1, characterized in that: The key groove is extended along the thickness direction of the oriented silicon steel sheet stack, and the silicon steel sheet stack includes a protrusion that matches the key groove.

3. The method for integrally cutting a wedge core for a high-speed wire cutting machine according to claim 1, wherein: The shaft is sleeved in the shaft hole of the disc, and the disc is connected to the body through square shafts distributed on both sides of the shaft hole on its end surface.

4. The method for integrally cutting a wedge core for a high-speed wire cutting machine according to claim 1, characterized in that: The indexing plate includes two square shafts for connecting with the body.

5. The integral cutting method of a wedge core for a high-speed wire cutting machine according to claim 1, characterized in that: The fully cut wedge core is press-fitted and potted after winding to prevent its edges from warping.

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