3d transposition insulation filling forming process for end of stator bar

Abstract

The present application relates to a kind of stator bar end 3D transposition insulation filling forming process, comprising: S1, flat copper wire is wound: multiple flat copper wires are arranged into two columns, each wire is sequentially with same interval twice from one column to another column, 3D transposition on multiple flat copper wires is equidistantly arranged and distributed in two side end faces;S2, extrusion forming mica mud: after adhesive and mica powder are mixed, mica mud is extruded;S3, positioning mica mud: mica mud is glued on the two side end faces of bar blank, isolation film is stripped, and spacer containing glue layer is placed between flat copper wire;S4, wrap high-temperature film;S5, embed positioning mould;S6, high-temperature high-pressure forming;S7, unloading cooling.The present application has the following advantages: effectively solve the pit filling generated by motor coil 3D transposition skewing, to damp the internal circulating current generated by coil magnetic induction.

Description

Technical Field

[0001] This invention belongs to the field of motor insulation materials, specifically relating to a 3D transposition insulation filling molding process for the ends of stator bars. Background Technology

[0002] Most existing motor coils, especially stator coils of large motors (such as steam turbine generators), are manufactured using a multi-strand wire transposition forming method. The flat copper wires in each row are transposed and wound according to a specific pattern (forming pit gaps at the 3D transposition points at the ends) to smooth out the internal circulating currents caused by different magnetic inductions in different parts of the coil. This forms transposition pits, which cannot be directly wrapped with main insulation tape and must be filled first.

[0003] Traditional stator bar replacement filler materials were originally made by impregnating mica paper with tung oil resin, then laminating and hot-pressing to a certain thickness. Later, it was developed into impregnating mica paper with epoxy resin and then making filler materials of the required thickness.

[0004] Mica paper impregnated with resin has several drawbacks, both in terms of performance and coil manufacturing processes. For example, the glass transition temperature of the Tongma mica paper-based filler material can only reach a maximum of 130℃. Due to the low glass transition temperature, when the coil is wound with VPI-impregnated resin for secondary molding (such as mica tape and anti-corona tape), voids often appear inside the manufactured coil at a curing temperature of 170℃. The insufficient heat resistance of the filler material leads to an increased product defect rate.

[0005] Furthermore, mica paper-based filler materials undergo phase separation during high-temperature hot pressing. Although the mica paper is crushed at high temperatures and shifts somewhat along with the resin, for a coil 5 meters or longer, pits and dead zones appear at locations with large transposition angles. Because the mica paper cannot flow freely, it cannot completely fill these pits, significantly impacting the coil's insulation performance. During the coil filling hot pressing process, the resin has good fluidity, while the mica paper does not, often causing resin to seep out of the mica paper and flow to the sides of the coil, affecting coil dimensional processing. Additionally, during the manufacturing process of mica paper-based filler materials, solvent residue remains after the mica paper is impregnated with resin. These volatiles often remain inside during filling and molding, creating air bubbles that affect the coil's insulation performance.

[0006] Therefore, the development of mica mud motor coil filling insulation material has made up for the shortcomings of previous filling materials in terms of performance and application process. Summary of the Invention

[0007] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a 3D transposition insulation filling molding process for the end of stator bar, which effectively solves the problem of filling the pits caused by the 3D transposition and deflection of motor coils, so as to suppress the internal circulating current generated by the magnetic induction of the coil.

[0008] The objective of this invention is achieved through the following technical solution: a 3D transposition insulation filling molding process for stator bar ends, comprising...

[0009] S1. Braiding flat copper wire: Arrange multiple strands of flat copper wire into two columns. Each strand crosses from one column to the other column twice at the same interval. The 3D transposition points on the multiple strands of flat copper wire are arranged at equal intervals on both ends, thus forming a wire rod blank.

[0010] S2, Extrusion molding of mica mud: The adhesive is mixed with mica powder and then extruded into mica mud;

[0011] S3. Positioning mica paste: Adhere the mica paste to both ends of the wire rod blank, peel off the release film, and place a gasket containing the adhesive layer between the flat copper wires.

[0012] S4. Wrapping with a high-temperature resistant film: Wrapping and fixing the high-temperature resistant film around the outside of the wire rod blank to form a unified whole;

[0013] S5. Insertion and positioning mold: Insert the wire rod blank into the positioning mold, with the ends of the wire rod blank protruding from the ends of the positioning mold. Wrap the outside of the positioning mold with tape to clamp and position the wire rod blank inside the positioning mold.

[0014] S6. High temperature and high pressure molding: The positioning mold containing the wire rod blank is placed in a hot autoclave. Half pressure is applied at 125±5℃ and the temperature and pressure are maintained for 20-30 minutes. The temperature is gradually increased to 165±5℃ and full pressure is applied and maintained for curing. The temperature and pressure are within a certain range. The temperature is 100-165℃ and the pressure is 0.3-0.6MPa. At this time, the mica mud flows at high temperature. Without producing small molecule volatiles, the wire rod blank and the mica mud on the side are integrated, and the pits on the outside of the wire rod blank located at the 3D displacement are filled.

[0015] S7. Unloading and Cooling: Remove the wire rod blank from the autoclave, remove the positioning mold, and peel off the high-temperature resistant film on the outside of the wire rod blank. The wire rod blank cools naturally, thus completing the side-end repositioning, winding, insulation filling and molding.

[0016] A further improvement of the present invention is that step S2 includes,

[0017] a. Select 100-120 parts of modified high-temperature resistant epoxy resin, 30-50 parts of aromatic amine-based curing agent, and 1-3 parts of latent accelerator by weight, and mix them to form an adhesive.

[0018] b. Feed the adhesive and mica powder into a mixer to premix them into a clump, and repeatedly extrude the clump to shape it into a uniform whole;

[0019] c. Extruding the mica mud into infinitely long strips of different widths and thicknesses using a mixing equipment, and finally attaching a release film to the mica mud and rolling it into a disc or making it into long strips.

[0020] A further improvement of the present invention is that the elongated mica mud obtained in step S2 has an adhesive content of 30%-40% and a specific gravity of 1.6-1.9 g / cm³. 3 Under normal conditions, the bond strength is ≥15.3MPa and the volume resistivity is ≥1.0×10⁻⁶. 15 Ω·cm, glass transition temperature ≥175℃.

[0021] A further improvement of the present invention is that, in step S4, the high-temperature resistant film is wrapped and fixed to the outside of the wire rod blank by adhesive tape.

[0022] A further improvement of the present invention is that: the positioning mold includes an upper mold and a lower mold, the upper mold and the lower mold are spliced ​​to form a rectangular structure, and there is a rectangular cavity between the upper mold and the lower mold for accommodating the wire rod blank, the wire rod blank is placed between the rectangular cavity formed by the upper mold and the lower mold.

[0023] A further improvement of the present invention is that: both the upper mold and the lower mold include an L-shaped body, the L-shaped body includes a vertical part and a horizontal part, one end of the horizontal part has a stepped part on the inner side, the vertical part of the upper mold cooperates with the stepped part of the lower mold, and the vertical part of the lower mold cooperates with the stepped part of the upper mold.

[0024] A further improvement of the present invention is that the radial length of the rectangular cavity formed by the upper and lower dies is consistent with the width of the wire rod blank, and the height of the rectangular cavity formed by the upper and lower dies is consistent with the height of the wire rod blank.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] 1. This invention uses specially made mica mud, which is premixed into clumps and repeatedly extruded and kneaded to achieve a uniform phase between the epoxy adhesive and mica powder mixture. Finally, it is extruded and molded. The molding and use principle of mica mud utilizes the temperature difference effect. At room temperature, mica mud is a plastic material that can maintain a certain shape. Under high temperature and high pressure, it can be molded into any shape to fill the pits generated at the 3D transposition of the motor coil. Finally, it is cured and shaped into an irreversible solid at high temperature to suppress the internal circulation generated by the magnetic induction of the coil and ensure the insulation performance of the motor coil.

[0027] 2. The mica mud in this invention does not volatilize due to the absence of solvents. Under high temperature and pressure, there are no small molecule volatiles, thus ensuring that no volatiles are generated during the filling and molding of the coil. This effectively guarantees the insulation of the coil. Since the mica mud has no reinforcing material for support, the physical properties of the cured material depend entirely on the organic combination of epoxy resin and mica mud. The glass transition temperature of the cured mica mud can reach above 175℃, exhibiting good heat resistance and mechanical properties. This avoids the occurrence of voids inside the coil during the secondary heat molding of the motor coil, which would lead to insufficient heat resistance of the filling material and a low product defect rate. Attached Figure Description

[0028] Figure 1 This is a side view of the wire rod blank in step S1 of the present invention.

[0029] Figure 2 This is a top view of the wire rod blank in step S1 of the present invention.

[0030] Figure 3 This is a schematic diagram of the structure of the wire rod blank after positioning the mica mud and wrapping it with a high-temperature resistant film in this invention.

[0031] Figure 4 This is a schematic diagram of the positioning mold in this invention.

[0032] Figure 5 This is a schematic diagram of the upper or lower mold in the positioning mold of the present invention.

[0033] Numbering on the map:

[0034] 1-Wire rod blank, 2-Mica mud, 3-High temperature resistant film, 4-Positioning mold;

[0035] 41-Upper mold, 42-Lower mold, 43-Rectangular cavity; 441-L-shaped body, 442-Vertical part, 443-Horizontal part, 444-Stepped part. Detailed Implementation

[0036] To enhance understanding of the present invention, the present invention will be further described in detail below with reference to embodiments and accompanying drawings. These embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0037] In the description of this invention, it should be understood that the terms indicating orientation or positional relationship, such as those based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the structure or unit referred to must have a specific orientation, and therefore should not be construed as a limitation of this invention.

[0038] In this invention, unless otherwise explicitly specified and limited, terms such as “connection,” “provided with,” and “have” should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection. They can be described as a mechanical connection, a direct connection, or a connection through an intermediate medium. Those skilled in the art can understand the basic meaning of the above terms in this invention according to the specific circumstances.

[0039] A 3D transposition insulation filling molding process for stator bar ends, characterized by: including...

[0040] S1. Braiding flat copper wire: Arrange multiple strands of flat copper wire into two columns. Each strand crosses over from one column to the other twice at equal intervals. The 3D transposition points on the multiple strands of flat copper wire are evenly distributed on both end faces, thus forming wire rod blank 1. (Refer to...) Figure 1 , Figure 2 ;

[0041] S2, Extruded Mica Mud 2: The adhesive and mica powder are mixed and then extruded to form mica mud 2;

[0042] S3. Positioning mica mud: Adhere mica mud 2 to both ends of the wire rod blank, peel off the release film, and place a gasket containing the adhesive layer between the flat copper wires.

[0043] S4. Wrapping with high-temperature resistant film: Wrapping and fixing the high-temperature resistant film 3 around the outside of the inline bar blank 1 to form a unified whole;

[0044] S5, Insertion and Positioning Mold 4: Refer to Figure 4 , Figure 5 The wire rod blank 1 is embedded in the positioning mold 4, with the ends of the wire rod blank 1 protruding from the ends of the positioning mold 4 respectively. The tape is wrapped around the outside of the positioning mold 4 to clamp and position the wire rod blank 1 in the positioning mold 4.

[0045] S6. High temperature and high pressure molding: The positioning mold 4 containing the wire rod blank 1 is placed in the autoclave. Half pressure is applied at 125±5℃ and the temperature and pressure are maintained for 20-30 minutes. The temperature is gradually increased to 165±5℃ and full pressure is applied and maintained for curing. The temperature and pressure are within a certain range. The temperature is 100-165℃ and the pressure is 0.3-0.6MPa. At this time, the mica mud flows at high temperature. Without producing small molecule volatiles, the wire rod blank and the mica mud on the side are integrated, and the pits on the outside of the wire rod blank located at the 3D displacement are filled.

[0046] S7. Unloading and Cooling: Remove the wire rod blank 1 from the autoclave, remove the positioning mold 4, and peel off the high-temperature resistant film 3 on the outside of the wire rod blank 1. The wire rod blank cools naturally, thus completing the side-end repositioning, winding, insulation filling and molding.

[0047] In this embodiment, step S2 specifically includes,

[0048] a. Select 100-120 parts of modified high-temperature resistant epoxy resin, 30-50 parts of aromatic amine-based curing agent, and 1-3 parts of latent accelerator by weight, and mix them to form an adhesive.

[0049] b. Feed the adhesive and mica powder into a mixer to premix them into a clump, and repeatedly extrude the clump to shape it into a uniform whole;

[0050] c. Extruding the mica mud into infinitely long strips of different widths and thicknesses using a mixing equipment, and finally attaching a release film to the mica mud and rolling it into a disc or making it into long strips.

[0051] This invention uses specially made mica mud, which is premixed into clumps and repeatedly extruded and kneaded to achieve a uniform phase between the epoxy adhesive and mica powder. Finally, it is extruded and molded. The molding and use principle of mica mud utilizes the temperature difference effect. At room temperature, mica mud is a plastic material that can maintain a certain shape. Under high temperature and high pressure, it can be molded into any shape to fill the pits generated at the 3D transposition of the motor coil. Finally, it is cured and shaped into an irreversible solid at high temperature to suppress the internal circulation generated by the magnetic induction of the coil and ensure the insulation performance of the motor coil.

[0052] The mica mud in this invention, due to its solvent-free nature, produces no small-molecule volatiles under high temperature and pressure. This ensures that no volatiles are generated during the filling and molding of the coil, effectively guaranteeing the coil's insulation. Since the mica mud has no reinforcing material for support, the physical properties of the cured material rely entirely on the organic combination of epoxy resin and mica mud. The glass transition temperature of the cured mica mud can reach above 175℃, exhibiting excellent heat resistance and mechanical properties. This avoids the occurrence of voids inside the coil during subsequent secondary heat molding of the motor coil, which could lead to insufficient heat resistance of the filling material and a high product defect rate.

[0053] The following is a comparison between traditional mica paper and the mica paste described in this application in the process of transposition winding insulation filling molding of motor coils:

[0054]

[0055] Based on this embodiment, the elongated mica mud obtained in step S2 has an adhesive content of 30%-40% and a specific gravity of 1.6-1.9 g / cm³. 3 Under normal conditions, the bond strength is ≥15.3MPa and the volume resistivity is ≥1.0×10⁻⁶. 15 Ω·cm, glass transition temperature ≥175℃.

[0056] Based on this embodiment, in step S4, the high-temperature resistant film 3 is wrapped and fixed to the outside of the wire rod blank 1 by adhesive tape.

[0057] The positioning mold 4 includes an upper mold 41 and a lower mold 42. The upper mold 41 and the lower mold 42 are spliced ​​to form a rectangular structure, and there is a rectangular cavity 43 between the upper mold 41 and the lower mold 42 to accommodate the wire rod blank 1. The wire rod blank 1 is placed between the rectangular cavity 43 formed by the upper mold 41 and the lower mold 42.

[0058] Furthermore, both the upper mold 41 and the lower mold 42 include an L-shaped body 441. The L-shaped body 441 includes a vertical portion 442 and a horizontal portion 443. One end of the horizontal portion 443 has a stepped portion 444 on its inner side. The vertical portion 442 of the upper mold 41 and the stepped portion 444 of the lower mold 42 are engaged with each other.

[0059] Furthermore, the radial length of the rectangular cavity 43 formed by the upper mold 41 and the lower mold 42 is consistent with the width of the wire rod blank 1, and the height of the rectangular cavity 43 formed by the upper mold 42 and the lower mold 42 is consistent with the height of the wire rod blank 1. Example 1

[0060] A 3D transposition insulation filling molding process for stator bar ends, characterized by: including...

[0061] S1. Braiding flat copper wire: Arrange multiple strands of flat copper wire into two columns. Each strand crosses from one column to the other column twice at the same interval. The 3D transposition points on the multiple strands of flat copper wire are arranged at equal intervals on both ends, thus forming wire rod blank 1.

[0062] S2, Extruded Mica Clay 2:

[0063] a. Select 100-120 parts of modified high-temperature resistant epoxy resin, 30-50 parts of aromatic amine-based curing agent, and 1-3 parts of latent accelerator by weight, and mix them to form an adhesive.

[0064] b. Feed the adhesive and mica powder into a mixer to premix them into a clump, and repeatedly extrude the clump to shape it into a uniform whole;

[0065] c. Extruding the mica mud 2 into infinitely long strips of different widths and thicknesses using a mixing equipment, and finally attaching a release film to the mica mud 2 and rolling it into a disc or making it into a long strip;

[0066] S3. Positioning mica mud: Adhere mica mud 2 to both ends of the wire rod blank, peel off the release film, and place a gasket containing the adhesive layer between the flat copper wires.

[0067] S4. Wrapping with a high-temperature resistant film: Wrap and fix the high-temperature resistant film 3 around the outside of the inline bar blank 1 to form a unified whole;

[0068] S5. Insertion and positioning mold 4: The positioning mold 4 includes an upper mold 41 and a lower mold 42. The upper mold 41 and the lower mold 42 are spliced ​​to form a rectangular structure, and there is a rectangular cavity 43 between the upper mold 41 and the lower mold 42 to accommodate the wire rod blank 1. The wire rod blank 1 is placed between the rectangular cavity 43 formed by the upper mold 41 and the lower mold 42. The ends of the wire rod blank 1 protrude from the ends of the positioning mold 4. The tape is wrapped around the upper mold 41 and the lower mold 42 to clamp and position the wire rod blank 1 in the positioning mold 4.

[0069] S6. High temperature and high pressure molding: The positioning mold 4 containing the wire rod blank 1 is placed in the autoclave. Half pressure is applied at 125±5℃ and the temperature and pressure are maintained for 20-30 minutes. The temperature is gradually increased to 165±5℃ and full pressure is applied and maintained for curing. The temperature and pressure are within a certain range. The temperature is 100-165℃ and the pressure is 0.3-0.6MPa. At this time, the mica mud flows at high temperature. Without producing small molecule volatiles, the wire rod blank and the mica mud on the side are integrated, and the pits on the outside of the wire rod blank located at the 3D displacement are filled.

[0070] S7. Unloading and Cooling: Remove the wire rod blank 1 from the autoclave, remove the positioning mold 4, and peel off the high-temperature resistant film 3 on the outside of the wire rod blank 1. The wire rod blank cools naturally, thus completing the side-end repositioning, winding, insulation filling and molding. Example 2

[0071] Unlike Example 1, in step S2, 120 parts by weight of modified high-temperature resistant epoxy resin, 50 parts by weight of aromatic amine-based curing agent, and 3 parts by weight of latent accelerator are selected and mixed to form an adhesive. Example 3

[0072] Unlike Example 1, in step S2, 110 parts by weight of modified high-temperature resistant epoxy resin, 40 parts by weight of aromatic amine-based curing agent, and 2 parts by weight of latent accelerator are selected and mixed to form an adhesive.

[0073] The table below shows a comparative analysis of data from Examples 1 to 3 and traditional mica paper (comparative example) as filler material in the insulation filling molding process of motor coil transposition winding:

[0074]

[0075] Among them, the higher the volume resistivity, the better the insulation performance; the higher the glass transition temperature, the better the heat resistance. The mica mud in Example 2 is superior to the comparative example, Example 1, and Example 3 in terms of adhesive content, specific gravity, bonding strength under normal conditions, volume resistivity, and glass transition temperature. It has high insulation performance and avoids the product defect rate caused by insufficient heat resistance of the filling material due to the void inside the coil when the motor coil is subjected to secondary heating and molding in the later stage. This is the best implementation method.

[0076] Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to this invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A stator bar end 3D transposition insulation filled molding process characterized by: Comprising S1, winding flat copper wire: arrange the multiple flat copper wires into two columns, and each wire is crossed from one column to another twice with the same interval, and the 3D transposition on the multiple flat copper wires is arranged at equal intervals on the two side end faces, thereby forming a wire rod blank (1); S2, extruding mica mud (2): mixing the adhesive and mica powder and then extruding the mica mud (2); S3, positioning the mica mud: gluing the mica mud (2) on the two side end faces of the wire rod blank, peeling off the release film, and placing the gasket containing the adhesive layer between the flat copper wires; S4, wrapping the high-temperature-resistant film: wrapping and fixing the high-temperature-resistant film (3) on the outside of the wire rod blank (1) to form a unified whole; S5, embedding and positioning the mold (4): embedding the wire rod blank (1) in the positioning mold (4), and the ends of the wire rod blank (1) protrude from the ends of the positioning mold (4), and the adhesive tape is wrapped around the outside of the positioning mold (4) to clamp and position the wire rod blank (1) in the positioning mold (4); S6, high-temperature and high-pressure forming: placing the positioning mold (4) containing the wire rod blank (1) in the hot press tank, adding half pressure at 125±5℃ for 20-30min, and then increasing the temperature in stages to 165±5℃ to add full pressure and pressure solidification, the temperature and pressure are in the range of 100-165℃ and 0.3-0.6MPa, at this time the mica mud flows at high temperature, without generating small molecule volatile substances, so that the wire rod blank and the mica mud on the side end form an integral whole, and the recess at the 3D transposition on the outside of the wire rod blank is filled; S7, discharging and cooling: taking out the wire rod blank (1) from the hot press tank, removing the positioning mold (4), and peeling off the high-temperature-resistant film (3) on the outside of the wire rod blank (1), and then naturally cooling the wire rod blank, thereby completing the side end transposition winding insulation filling and forming.

2. The stator bar end 3D transposition insulation filled molding process of claim 1, wherein: The step S2 comprises, a, selecting modified high-temperature-resistant epoxy resin 100-120 parts, aromatic amine-based curing agent 30-50 parts, and latent accelerator 1-3 parts by weight, and mixing to form an adhesive; b, feeding the adhesive and mica powder into a mixer to pre-mix into a lump, and repeatedly extruding the lump to form a uniform body; c, extruding the mica mud (2) into an infinite long strip type with different widths and thicknesses through a mixing device, and finally attaching a release film to the mica mud (2) to roll it into a disc shape or make it into a long strip shape.

3. The stator bar end 3D transposition insulation filled molding process of claim 2, wherein: The adhesive content of the long strip mica paste prepared in the step S2 is 30%-40%, the specific gravity is 1.6-1.9 g / cm 3 , the normal bonding strength is ≥15.3 MPa, the volume resistivity is ≥1.0×10 15 Ω·cm, and the glass transition temperature is ≥175℃.

4. The stator bar end 3D transposition insulation filled molding process of claim 3, wherein: In the step S4, the high-temperature-resistant film (3) is wrapped and fixed on the outside of the wire rod blank (1) by the adhesive tape.

5. A process for 3D transposition and potting of end turns of stator bars as claimed in claim 4 wherein: The positioning mold (4) comprises an upper mold (41) and a lower mold (42), the upper mold (41) and the lower mold (42) are spliced to form a rectangular structure, and the upper mold (41) and the lower mold (42) have a rectangular cavity (43) for embedding the wire rod blank (1), and the wire rod blank (1) is arranged between the rectangular cavities (43) formed by the upper mold (41) and the lower mold (42).

6. A process for 3D transposition and potting of end turns of stator bars as claimed in claim 5 wherein: The upper die (41) and the lower die (42) each comprise an L-shaped body (441) comprising a vertical portion (442) and a horizontal portion (443), one end of the horizontal portion (443) having a stepped portion (444) inside, the vertical portion (442) of the upper die (41) being matched with the stepped portion (444) of the lower die (42), and the vertical portion (442) of the lower die (42) being matched with the stepped portion (444) of the upper die (41).

7. A process for 3D transposition and potting of end turns of stator bars as claimed in claim 6 wherein: The rectangular cavity (43) formed by matching the upper die (41) and the lower die (42) has a radial length consistent with the width of the wire rod blank (1), and a height consistent with the height of the wire rod blank (1).

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