# US 2026/0155718 A1 · Manufacturing method of a multi-pole magnetic circuit, multi-pole magnetic circuit, and stepper motor

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- Number: US 2026/0155718 A1
- Document ID: US20260155718A1
- Status: Published application
- Kind: A1
- Application number: 19/036,043
- Filed: 2025-01-24
- Published: 2026-06-04
- Earliest claimed: 2024-11-29
- Assignees: AAC Microtech (Changzhou) Co., Ltd.
- Applicants: AAC Microtech (Changzhou) Co., Ltd.
- Inventors: Lubin Mao; Xiujiang Si; Wei Song; Ze Fu; Suntong Zhou
- Web page: https://patentgrep.com/patent/US20260155718A1

## CPC

- H02K 15/035: on the rotor
- H02K 15/03: having permanent magnets
- H02K 37/14: with magnets rotating within the armatures
- H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53})

## Abstract

Provided is a manufacturing method of a multi-pole magnetic circuit, a multi-pole magnetic circuit, and a stepper motor. The method includes: providing first magnets each having a sector-shaped cross-section; assembling the first magnets to obtain a first cylindrical body; and grinding a side surface of the first cylindrical body to obtain a second cylindrical body, and electroplating an outer surface of the second cylindrical body to form a coating, to obtain the multi-pole magnetic circuit for a stepper motor. In the manufacturing method, by preparing the first magnets having larger dimension, assembling the first magnets to obtain the first cylindrical body having larger outer diameter, and grinding the side surface of the first cylindrical body to obtain the second cylindrical body having smaller outer diameter, difficulty of the assembly operation is reduced, roundness and concentricity as well as reliability of the magnetic circuit are improved.

## Claims

### Claim 1

A manufacturing method of a multi-pole magnetic circuit, comprising:
providing a plurality of first magnets, wherein each of the first magnets has a sector-ring-shaped cross-section ;
assembling the plurality of first magnets to obtain a first cylindrical body; and
grinding a side surface of the first cylindrical body by a grinding process to obtain a second cylindrical body, and electroplating an outer surface of the second cylindrical body to form a coating, so as to obtain the multi-pole magnetic circuit for a stepper motor.

### Claim 2 (depends on 1)

The manufacturing method as described in claim 1, wherein the first magnets are shaped by the grinding process to form second magnets, the second magnets are arranged around a central axis of the multi-pole magnetic circuit, two adjacent second magnets are magnetically opposite to each other at respective ends close to the central axis of the multi-pole magnetic circuit, and the two adjacent second magnets are magnetically opposite to each other at other respective ends.

### Claim 3 (depends on 1)

The manufacturing method as described in claim 1, wherein the grinding process comprises one or more of longitudinal grinding, plunge grinding, segmented grinding, or deep grinding.

### Claim 4 (depends on 1)

The manufacturing method as described in claim 1, whereinthe coating is a Ni metal coating formed by metal Ni electroplating, or a composite metal coating formed from Zn and Ni.

### Claim 5 (depends on 1)

The manufacturing method as described in claim 1, wherein the first magnets are sintered magnets, and two adjacent first magnets are bonded and fixed to each other by a bonding layer.

### Claim 6 (depends on 1)

The manufacturing method as described in claim 1, wherein the assembling the plurality of first magnets to obtain a first cylindrical body comprises:
providing a rotary shaft; and
arranging the plurality of first magnets circumferentially around the rotary shaft to obtain the first cylindrical body with the rotary shaft.

### Claim 7 (depends on 1)

A multi-pole magnetic circuit manufactured by the manufacturing method as described in claim 1.

### Claim 8 (depends on 7)

A stepper motor, comprising the multi-pole magnetic circuit as described in claim 7.