Process for forming a reduced protrusion commutator hook

Abstract

The application discloses a kind of reducing commutator hook portion both sides protruding bending hook forming process, it is characterized in that including the following steps: a.commutator is after the completion of pressure plastic process, the hook portion of commutator copper sheet is in unbent vertical state, at this time, the hook portion of commutator copper sheet is coarsely milled, so that the width size of hook portion becomes small;B.after coarsely milling hook portion, the hook portion of commutator copper sheet is bent once, and the bending angle is 70 °±10 °;C.the hook portion of commutator copper sheet is finely milled, so that the width size of hook portion reaches specified value;D.the hook portion of commutator copper sheet is bent again, until the bending angle reaches specified value.Utilize the production process of the application, commutator hook portion can reduce the protrusion of both sides of commutator hook portion after bending forming.

Description

Technical Field

[0001] This invention relates to the field of commutator manufacturing technology, and more specifically to a commutator hook forming process. Background Technology

[0002] There is a type of commutator with hooks (called a hook-type commutator), where the hooks need to be formed using a hook-forming process. The current hook-forming process is as follows: After the commutator is pressed, the hooks of the commutator copper plates are in an unbent, vertical state. At this point, a milling cutter is used to mill grooves between adjacent hooks on the commutator copper plates, ensuring the hook width reaches the specified value. Then, a hook-forming mold is used to bend the hooks of the commutator copper plates, ensuring the hook angle reaches the specified value (generally, the entire bending angle of one hook is 150°). In this process, the top of the hook has the largest bending angle and the greatest bending deformation. Furthermore, because the commutator copper plates are made of relatively soft copper, there will be approximately 0.3mm of material deformation protrusion on each side of the top of the hook. This protrusion can have adverse consequences, sometimes quite severe. 1. Impact on winding and shaping processes. Winding is difficult and easily damages insulation: The protrusions on both sides of the hook reduce the effective space inside the hook, making it difficult to smoothly embed the enameled wire or flat copper wire. Forced embedding may scratch the conductor insulation layer, creating a potential short circuit between turns. The hook joints are not tight: The protrusions on both sides prevent the hook from evenly wrapping the wire end, resulting in point contact rather than surface contact between the wire and the hook. Even after tightening, some wire ends may still be loose, increasing contact resistance.

[0003] 2. Impact on spot welding or brazing quality. Uneven welding current distribution: During spot welding, the current preferentially passes through the protruding tips, causing localized overheating and even spattering, while the hook area suffers from insufficient pressure or poor contact, resulting in incomplete welds. Incomplete welds will further oxidize due to heat during motor operation, eventually leading to detachment. Poor solder filling (brazing): Irregular gaps formed by the protrusions on both sides prevent the solder from evenly filling the space between the wire harness and the hook wall under capillary action, potentially leaving voids or unfused areas, reducing mechanical strength and conductivity.

[0004] 3. Impact on the insulation and aging performance of the commutator itself. Shortened creepage distance: The sharp angles of the protruding edges reduce the air gap between adjacent hooks, making surface creepage more likely to occur in humid or polluted environments, thus accelerating commutator aging. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a forming process that can reduce the protruding hooks on both sides of the commutator hook.

[0006] This invention is implemented through the following technical solutions: The process for reducing the protruding hooks on both sides of the commutator's hook portion is characterized by the following steps: a. After the commutator is molded, the hook portion of the commutator copper sheet is in an unbent vertical state. At this time, the hook portion of the commutator copper sheet is rough milled to reduce its width; b. After rough milling, the hook portion of the commutator copper sheet is bent once at a bending angle of 70°±10°; c. The hook portion of the commutator copper sheet is fine milled to achieve the specified width; d. The hook portion of the commutator copper sheet is bent again until the bending angle reaches the specified value.

[0007] The hook bending operation in step d is divided into two parts: a second bending operation and a third bending operation.

[0008] After the second bending operation, the hook is at a 90° right angle.

[0009] After rough milling the hook and before the first bending operation, the burrs on the commutator surface are sanded off.

[0010] After precision milling of the hook and before the secondary bending operation, burrs and copper shavings on the commutator surface and inside the hook are removed by sandblasting.

[0011] After the hook angle reaches the specified value, the commutator surface and hook are polished to remove burrs and make the surface and hook smooth.

[0012] By implementing the above technical solution, the hook of the commutator copper sheet is first rough milled to appropriately reduce the width of the hook to facilitate bending deformation. Then, after the hook of the commutator copper sheet is bent at 70°±10° for the first time (approximately half of the entire bending angle of 150°), the width of the hook is finely milled to reach the specified value. At this time, the material deformation protrusions on both sides of the top of the hook are also removed. Subsequently, the hook is bent again to reach the specified angle. In this way, although the subsequent bending operation will still cause some material deformation protrusions on both sides of the top of the hook, it will obviously be significantly improved. Tests show that the material deformation protrusion of about 0.3mm on one side can be reduced to less than 0.15mm. The rationale behind the above process arrangement lies in the fact that, due to the forming of the hook, there will be material deformation and protrusion on both sides of the top of the hook. As a result, the thickness of the top of the hook will become thinner due to the material being squeezed out to both sides. Therefore, the fine milling of the hook is set after the first bend, which not only facilitates the subsequent bending of the hook, but also ensures the strength of the hook. Otherwise, if the hook angle is fully reached before the fine milling operation is performed to make the width of the hook reach the specified value, then the protrusion on both sides of the top of the hook will be gone, and the thickness will become thinner, which may really affect the strength of the commutator hook, which is absolutely unacceptable. Attached Figure Description

[0013] The present invention includes the following figures: Figure 1 This is a process flow diagram of the present invention. Figure 2 This diagram shows the working state when using two milling cutters to finish mill the hook. Figure 3 This is a comparison of product photos showing the process of this invention with that of conventional processes. Detailed Implementation

[0014] like Figure 1 , 2 As shown, the process for reducing the protruding hooks on both sides of the commutator hook portion according to the present invention includes the following steps: a. After the commutator is completed in the compression molding process, the hook portion of the commutator copper sheet is in an unbent vertical state with a hook width of 3.7mm. At this time, the hook portion of the commutator copper sheet is rough milled using a milling cutter to reduce the width of the hook portion. After rough milling, the width of the hook portion is W1=2.5mm. Then, the burrs on the surface of the commutator are sanded off using sandpaper; b. After rough milling, the hook portion of the commutator copper sheet is bent once using a hook forming mold. The bending angle is about 75°, but in practice, 60°-80° is acceptable; c. The hook portion of the commutator copper sheet is fine milled using a combination of two milling cutters. Figure 2 As shown), the width of the hook reaches the specified value W2=1.51mm. Then, sandpaper and a polishing wheel are used to remove burrs and copper shavings from the commutator surface and inside the hook. d. Using a hook forming mold, the hook of the commutator copper sheet is bent a second time and a third time. After the second bending operation, the hook is at a 90° right angle. After the third bending operation, the bending angle of the entire hook is 150°, that is, the hook angle is 30°. The hook angle reaches the specified value. After the hook angle reaches the specified value, a polishing wheel is used to polish the commutator surface and the hook to remove burrs from the surface and hook, making the surface and hook smooth. Thus, the commutator hook forming work, which reduces the protrusions on both sides of the commutator hook, is completed.

[0015] pass Figure 3 As can be seen from the actual product photos, the hook top of the commutator product made with conventional technology has a larger two-sided protrusion, while the hook top of the commutator product made with this technology has a very small two-sided protrusion.

Claims

1. A process for reducing the protruding hooks on both sides of the commutator hook, characterized in that... Includes the following steps: a. After the commutator is pressed, the hook of the commutator copper strip is in a vertical, unbent state. At this time, the hook of the commutator copper strip is rough milled to reduce the width of the hook; b. After rough milling the hook, the hook of the commutator copper strip is bent once, with a bending angle of 70°±10°; c. The hook of the commutator copper strip is fine milled to make the width of the hook reach the specified value. d. Bend the hook of the commutator copper strip again until the bending angle reaches the specified value.

2. The forming process for reducing the protruding hooks on both sides of the commutator hook as described in claim 1, characterized in that: The hook bending operation in step d is divided into two parts: a second bending operation and a third bending operation.

3. The forming process for reducing the protruding hooks on both sides of the commutator hook as described in claim 2, characterized in that: After the second bending operation, the hook is at a 90° right angle.

4. The forming process for reducing the protruding hooks on both sides of the commutator hook as described in claim 3, characterized in that: After rough milling the hook and before the first bending operation, the burrs on the commutator surface are sanded off.

5. The forming process for reducing the protruding hooks on both sides of the commutator hook as described in claim 4, characterized in that: After precision milling of the hook and before the secondary bending operation, burrs and copper shavings on the commutator surface and inside the hook are removed by sandblasting.

6. The forming process for reducing the protruding hooks on both sides of the commutator hook as described in claim 5, characterized in that: After the hook angle reaches the specified value, the commutator surface and hook are polished to remove burrs and make the surface and hook smooth.

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