Meow's GeneralNote - Bearings 轴承
Bearings 轴承
Overview 概述
轴承 (Bearing)是让一个零件绕着另一个零件顺滑转动（或滑动）的机械元件。它的核心作用是把”滑动摩擦”变成”滚动摩擦”，让转动更省力、更安静、磨损更少，同时支撑住转轴上的重量。自行车轮、滑板、风扇、电机、汽车、洗衣机、硬盘、3D 打印机里都有轴承。本文从零开始介绍：轴承由哪些部分组成、受力方向、常见种类、型号怎么读、后缀（ZZ、2RS）是什么意思、怎么选、怎么安装和保养。
A bearing is a machine part that lets one part spin (or slide) smoothly around another. Its core job is to turn sliding friction into rolling friction, so motion takes less effort, makes less noise and causes less wear, while also carrying the load on the shaft. Bearings are inside bicycle wheels, skateboards, fans, motors, cars, washing machines, hard drives and 3D printers. This note starts from zero: the parts of a bearing, load directions, common types, how to read a part number, what suffixes such as ZZ and 2RS mean, how to choose one, and how to install and maintain it.
1. Why Bearings Work 轴承为什么有用
想象推一个重箱子：直接在地上推（滑动）很费力，在箱子下面垫几根圆木（滚动）就轻松得多。轴承就是把这几根”圆木”做成小钢珠或滚子，装进两个圆环之间。
Picture pushing a heavy box: dragging it across the floor (sliding) is hard work, but rolling it over a few logs (rolling) is much easier. A bearing shrinks those logs into small steel balls or rollers and packs them between two rings.
- 降低摩擦：滚动摩擦远小于滑动摩擦，转动更省力、发热更少。/ Less friction: rolling friction is far lower than sliding friction, so turning takes less effort and makes less heat.
- 支撑负载：把转轴上的重量和冲击传递给外壳或机架。/ Carries load: passes the weight and shocks on the shaft into the housing or frame.
- 定位转轴：让转轴保持在正确位置，不晃、不偏。/ Locates the shaft: holds it in the right position without wobble or drift.
- 减少磨损：转轴和外壳不直接接触，寿命更长。/ Reduces wear: the shaft never rubs against the housing, so both last longer.
2. Anatomy of a Bearing 轴承的结构
以最常见的深沟球轴承为例：
Using the most common type, the deep groove ball bearing, as the example:
| 部位 Part | 说明 | Description |
|---|---|---|
| 内圈 Inner ring | 套在转轴上，通常跟着轴一起转 | Fits on the shaft and usually turns with it |
| 外圈 Outer ring | 装进外壳（轴承座、轮毂），通常不动 | Fits in the housing (bearing seat, wheel hub) and usually stays still |
| 滚动体 Rolling elements | 钢珠或滚子，在内外圈之间滚动 | Steel balls or rollers that roll between the rings |
| 滚道 Raceway | 内外圈上让钢珠滚动的凹槽 | The groove in each ring that the balls roll in |
| 保持架 Cage / Retainer | 把钢珠隔开、均匀分布，防止互相摩擦 | Keeps the balls evenly spaced so they do not rub each other |
| 防尘盖/密封圈 Shield / Seal | 挡住灰尘、水，锁住润滑脂 | Keeps dirt and water out and grease in |
| 润滑脂 Grease | 填在内部，减少摩擦、防锈 | Packed inside to reduce friction and prevent rust |
Three Key Dimensions 三个关键尺寸
| 尺寸 Dimension | 符号 Symbol | 说明 | Description |
|---|---|---|---|
| 内径 Bore | d | 内圈孔的直径，要和转轴一样粗 | Diameter of the inner ring hole; must match the shaft |
| 外径 Outer diameter | D | 外圈的直径，要和外壳孔一样大 | Diameter of the outer ring; must match the housing bore |
| 宽度 Width | B | 轴承的厚度 | Thickness of the bearing |
规格通常写成 内径 x 外径 x 宽度，例如 8 x 22 x 7 mm。
Sizes are usually written bore x OD x width, for example 8 x 22 x 7 mm.
3. Load Directions 受力方向
选轴承之前，先搞清楚力从哪个方向来。
Before choosing a bearing, work out which direction the force comes from.
| 受力 Load | 方向 Direction | 例子 Example |
|---|---|---|
| 径向力 Radial load | 垂直于转轴（从侧面压） / Perpendicular to the shaft (pushing from the side) | 自行车轮承受车重、皮带拉扯电机轴 / A bike wheel carrying the rider, a belt pulling on a motor shaft |
| 轴向力 Axial / Thrust load | 沿着转轴方向（从端头推） / Along the shaft (pushing on the end) | 转椅底座、懒人转盘、电钻钻头往下压 / Swivel chair base, lazy Susan, a drill bit pushing down |
| 复合力 Combined load | 两者都有 / Both at once | 汽车轮毂转弯时 / A car wheel hub while cornering |
4. Bearing Types 轴承种类
4.1 Rolling Bearings 滚动轴承
| 类型 Type | 样子 | Look | 受力 Load | 典型用途 Typical uses |
|---|---|---|---|---|
| 深沟球轴承 Deep groove ball | 两个圆环夹一圈钢珠 | Two rings with one row of balls | 径向为主，可承受少量轴向 / Mainly radial, some axial | 最常见：电机、风扇、滑板、3D 打印机 / The most common: motors, fans, skateboards, 3D printers |
| 角接触球轴承 Angular contact ball | 滚道有斜角，常成对使用 | Angled raceways, often used in pairs | 径向 + 单方向轴向 / Radial plus one-way axial | 机床主轴、高速设备、自行车花鼓 / Machine tool spindles, high-speed gear, bike hubs |
| 推力球轴承 Thrust ball | 两片平垫圈中间夹钢珠 | Balls between two flat washers | 只承受轴向 / Axial only | 转椅、转盘、立式转轴 / Swivel chairs, turntables, vertical shafts |
| 圆柱滚子轴承 Cylindrical roller | 用圆柱滚子代替钢珠 | Cylinders instead of balls | 重径向 / Heavy radial | 齿轮箱、大型电机 / Gearboxes, large motors |
| 圆锥滚子轴承 Tapered roller | 滚子是锥形的 | Cone-shaped rollers | 重径向 + 重轴向 / Heavy radial and axial | 汽车轮毂、拖车轮 / Car wheel hubs, trailer wheels |
| 滚针轴承 Needle roller | 又细又长的滚针 | Long, thin needles | 径向，空间很小时用 / Radial in tight spaces | 变速箱、万向节、电动工具 / Transmissions, U-joints, power tools |
| 调心轴承 Self-aligning (ball / spherical roller) | 外圈滚道是球面 | Spherical outer raceway | 可容忍轴有偏斜 / Tolerates shaft misalignment | 长轴、农机、输送带 / Long shafts, farm machinery, conveyors |
4.2 Plain Bearings / Bushings 滑动轴承 / 轴套
- 没有钢珠，就是一个光滑的套筒，轴在里面直接滑动。/ No balls; just a smooth sleeve that the shaft slides inside.
- 常见材料：铜（青铜）、含油烧结铜（自带润滑油）、尼龙、PTFE（特氟龙）。/ Common materials: bronze, oil-impregnated sintered bronze (self-lubricating), nylon, PTFE (Teflon).
- 优点：便宜、安静、耐冲击、体积小；缺点：摩擦比滚动轴承大，不适合高速。/ Pros: cheap, quiet, shock-resistant, compact. Cons: more friction than rolling bearings and not suited to high speed.
- 常见于：门铰链、小型电风扇、园林工具、低速转轴。/ Found in door hinges, small desk fans, garden tools and slow shafts.
4.3 Special Forms Common in DIY DIY 中常见的特殊形式
| 类型 Type | 说明 | Description | 例子 Example |
|---|---|---|---|
| 法兰轴承 Flanged bearing | 外圈带一圈凸边，装进孔里不会穿过去 | Outer ring has a lip so it cannot slide through the hole | F623, F608；3D 打印机惰轮 / 3D printer idlers |
| 直线轴承 Linear bearing | 沿着光轴直线滑动，不是转动 | Slides along a smooth rod instead of rotating | LM8UU（配 8 mm 光轴）/ LM8UU (for 8 mm rods) |
| 带座轴承 Pillow block / Mounted bearing | 轴承装在一个带螺丝孔的铸铁座里 | A bearing inside a cast housing with bolt holes | UCP 系列；木工机械、输送带 / UCP series; woodworking machines, conveyors |
| 转盘轴承 Lazy Susan bearing | 两片方形钢板中间夹钢珠 | Balls between two square steel plates | 旋转餐桌、电视底座、展示台 / Rotating tables, TV stands, display turntables |
| 滑轨 Ball-bearing drawer slide | 抽屉滑轨里的一排钢珠 | A row of balls inside a drawer runner | 抽屉、键盘托 / Drawers, keyboard trays |
5. Reading Part Numbers 型号怎么读
5.1 Deep Groove Ball Bearing Numbers 深沟球轴承编号
以 6204-2RS 为例：
Take 6204-2RS as an example:
6= 类型：深沟球轴承。/ Type: deep groove ball bearing.2= 尺寸系列：0 特轻、2 轻、3 中，数字越大越粗壮、承载越大。/ Size series: 0 extra light, 2 light, 3 medium; a higher number means a stockier, stronger bearing.04= 内径代号。/ Bore code.-2RS= 后缀：两面橡胶密封（见下一节）。/ Suffix: rubber seals on both sides (see the next section).
| 代号 Code | 内径 Bore |
|---|---|
| 00 | 10 mm |
| 01 | 12 mm |
| 02 | 15 mm |
| 03 | 17 mm |
| 04 及以上 / and up | 代号 x 5（04 = 20 mm，05 = 25 mm） / Code x 5 (04 = 20 mm, 05 = 25 mm) |
| 单个数字（小轴承） / Single digit (small bearings) | 直接就是内径，如 608 的 8 = 8 mm / The digit is the bore, e.g. the 8 in 608 = 8 mm |
5.2 Suffixes 后缀
| 后缀 Suffix | 意思 | Meaning | 特点 Notes |
|---|---|---|---|
| （无 none） | 开式 | Open | 两面都敞开，摩擦最小，但要自己润滑、容易进灰 / Both sides open; lowest friction but needs lubrication and lets dirt in |
| Z | 单面铁盖 | Metal shield on one side | 一面防护 / Protected on one side |
| ZZ / 2Z | 双面铁防尘盖 | Metal shields on both sides | 不接触内圈，摩擦低、转速高，挡大颗粒灰尘，不防水 / Shields do not touch the inner ring: low friction and high speed, blocks coarse dust, not waterproof |
| RS | 单面橡胶密封 | Rubber seal on one side | 一面密封 / Sealed on one side |
| 2RS / 2RS1 / DDU | 双面橡胶密封圈 | Rubber seals on both sides | 密封唇贴住内圈，防水防尘好，摩擦稍大、极限转速稍低 / Seal lips touch the inner ring: good water and dust protection, slightly more drag and lower top speed |
| 2RZ | 双面非接触橡胶盖 | Non-contact rubber seals on both sides | 介于 ZZ 和 2RS 之间 / Between ZZ and 2RS |
| C3 | 游隙比标准大 | Larger internal clearance than standard | 用于发热较高、配合较紧的场合（如电机） / For hot running or tight fits, such as motors |
| F（前缀 prefix） | 法兰 | Flanged | 如 F608ZZ / e.g. F608ZZ |
| S（前缀 prefix） | 不锈钢 | Stainless steel | 如 S608-2RS / e.g. S608-2RS |
| MR（前缀 prefix） | 公制微型 | Metric miniature | 如 MR85 = 5 x 8 x 2.5 mm / e.g. MR85 = 5 x 8 x 2.5 mm |
：干净、要转得快、转得轻（3D 打印机、风扇）选 ZZ；潮湿、多灰、户外（自行车、户外滑轮、电动工具）选 2RS。
ZZ or 2RS: choose ZZ for clean, fast, free-spinning jobs (3D printers, fans); choose 2RS for wet, dusty or outdoor jobs (bicycles, outdoor pulleys, power tools).
6. The 608 Bearing 608 轴承：最常见的”万能”轴承
- 尺寸：内径 8 mm、外径 22 mm、宽 7 mm。/ Size: 8 mm bore, 22 mm OD, 7 mm wide.
- 为什么常见：最早作为滑板轮轴承大量生产，所以便宜、到处都能买到，后来被各种 DIY 项目借用。/ Why it is everywhere: it was mass-produced for skateboard wheels, so it is cheap and easy to find, and DIY projects adopted it.
- 用在哪里：滑板（每块板 8 个）、直排轮、指尖陀螺、3D 打印机惰轮和挤出机、小型滑轮、木工夹具上的导轮。/ Where it is used: skateboards (8 per board), inline skates, fidget spinners, 3D printer idlers and extruders, small pulleys, guide wheels on woodworking jigs.
- 配合螺丝：一根 M8 螺栓 + 两片 M8 垫圈 + 一个 M8 防松螺母，就能把 608 做成一个导轮（螺丝知识见 Meow’s GeneralNote - Screws 螺丝）。/ With screws: an M8 bolt, two M8 washers and an M8 lock nut turn a 608 into a guide wheel (see Meow’s GeneralNote - Screws 螺丝 for screw basics).
- ABEC 等级（ABEC-1/3/5/7/9）只代表尺寸精度，不代表滑板一定更快；对于滑板，干净和润滑比等级更重要。/ ABEC ratings (ABEC-1/3/5/7/9) only describe dimensional precision, not speed; for a skateboard, cleanliness and lubrication matter more than the rating.
7. Common Sizes 常用轴承规格与应用场景
| 型号 Model | 内径 x 外径 x 宽 (mm) | 典型应用场景 | Typical uses |
|---|---|---|---|
| MR85 / 685 | 5 x 8 x 2.5 / 5 x 11 x 3 | 航模、微型电机、遥控车 | RC models, micro motors, RC cars |
| 623 | 3 x 10 x 4 | 3D 打印机小惰轮、配 M3 螺丝的小滑轮 | Small 3D printer idlers, tiny pulleys on M3 screws |
| 625 | 5 x 16 x 5 | 3D 打印机皮带轮、小型风扇 | 3D printer belt idlers, small fans |
| 688 | 8 x 16 x 5 | 薄型 8 mm 轴、指尖陀螺、轻型导轮 | Thin 8 mm shafts, fidget spinners, light guide wheels |
| 608 | 8 x 22 x 7 | 滑板、直排轮、3D 打印机、DIY 导轮 | Skateboards, inline skates, 3D printers, DIY guide wheels |
| 6000 | 10 x 26 x 8 | 电动工具、小型电机 | Power tools, small motors |
| 6200 | 10 x 30 x 9 | 电机、洗衣机、园林机械 | Motors, washing machines, garden machinery |
| 6204 | 20 x 47 x 14 | 带座轴承、木工机械、电动车 | Pillow blocks, woodworking machines, e-bikes |
| 6205 | 25 x 52 x 15 | 洗衣机滚筒、农机、输送带 | Washing machine drums, farm machinery, conveyors |
| LM8UU | 8 x 15 x 24 | 3D 打印机光轴直线滑动 | Linear motion on 3D printer 8 mm rods |
8. Choosing a Bearing 怎么选轴承
- 先量轴和孔：用游标卡尺量转轴直径（= 内径）和外壳孔直径（= 外径），再量能放多宽（= 宽度）。/ Measure the shaft and hole first: use calipers on the shaft (= bore), the housing hole (= OD) and the space available (= width).
- 判断受力方向：只有侧向力选深沟球；有明显轴向力选推力或角接触；又重又有冲击选滚子。/ Decide the load direction: side load only means deep groove ball; real axial load means thrust or angular contact; heavy loads with shocks mean roller bearings.
- 选密封方式：干净高速选 ZZ，潮湿多灰选 2RS。/ Pick the seal: ZZ for clean and fast, 2RS for wet and dusty.
- 选材质：室内用普通铬钢（GCr15 / 52100）；户外、潮湿、接触食物选不锈钢（S 前缀、440C）；追求极低摩擦选陶瓷混合轴承（陶瓷珠，贵）。/ Pick the material: chrome steel (GCr15 / 52100) indoors; stainless (S prefix, 440C) for outdoor, damp or food-contact use; hybrid ceramic (ceramic balls, pricey) for the lowest friction.
- 不知道型号时：按尺寸搜，如”8x22x7 bearing”，比猜型号可靠。/ If the model is unknown, search by size, such as “8x22x7 bearing”; it is more reliable than guessing the number.
9. Installation 安装
9.1 Fits 配合
- 过盈配合 Interference fit（紧配合）：轴比内径略大一点点，要压进去，不会打滑。转动的那一圈通常用紧配合。/ The shaft is a hair bigger than the bore and must be pressed in, so it cannot slip. The ring that rotates usually gets the tight fit.
- 间隙配合 Clearance fit（松配合）：能用手推进去。不转的那一圈可以稍松，方便拆装。/ Slides in by hand. The stationary ring can be slightly loose for easy assembly.
- 3D 打印轴承座：打印机的孔通常会偏小，先打印一个小测试件，试出合适的孔径再打正式件。/ 3D-printed bearing seats: printers usually make holes undersized, so print a small test piece to find the right hole size before the real part.
9.2 Pressing It In 怎么压进去
- 只压正在安装的那一圈
：装到轴上就压内圈，装进孔里就压外圈。力如果从另一圈经过钢珠传过去，会在滚道上压出小凹坑（压痕 Brinelling），之后轴承就会发出咔咔声。/ Press only on the ring being fitted: push the inner ring when fitting onto a shaft, the outer ring when fitting into a hole. Force that travels through the balls from the other ring dents the raceway (brinelling) and the bearing will click from then on.
- 不要用锤子直接敲轴承；用套筒、旧轴承或专用压装工具垫着，均匀用力。/ Never hit the bearing directly with a hammer; use a socket, an old bearing or a bearing driver as a spacer and press evenly.
- 小技巧：把轴放冰箱冷冻（变细），或者用吹风机加热外壳（变大），更容易装进去。/ Tip: freezing the shaft (shrinks it) or warming the housing with a hair dryer (expands it) makes fitting easier.
- 保持垂直：歪着压进去会卡住，也会损坏轴承。/ Keep it square: pressing at an angle jams and damages the bearing.
10. Maintenance and Failure Signs 保养与故障信号
10.1 Maintenance 保养
- 密封轴承（2RS、ZZ）通常不用加油，坏了直接换，便宜又省事。/ Sealed bearings (2RS, ZZ) usually need no oiling; replace them when they fail, since they are cheap.
- 开式或可拆盖的轴承（如滑板轴承）：拆下盖子，用异丙醇或专用清洗剂洗干净，晾干后加专用轴承油或润滑脂。/ Open or removable-shield bearings (such as skate bearings): pop the shield, clean with isopropyl alcohol or bearing cleaner, dry, then add bearing oil or grease.
- WD-40 主要是清洁和防锈，不是长期润滑剂；用它”保养”反而会把原来的润滑脂冲掉。/ WD-40 is mainly a cleaner and rust preventer, not a long-term lubricant; using it for “maintenance” washes out the original grease.
- 不要让轴承泡水；泡过水要尽快擦干、重新润滑。/ Keep bearings out of water; if one gets soaked, dry and re-lubricate it soon.
10.2 Failure Signs 故障信号
| 现象 Symptom | 可能原因 Likely cause |
|---|---|
| 转起来有沙沙声、咯噔感 / Gritty or notchy feel when spinning | 进灰、滚道有压痕 / Dirt inside or a dented raceway |
| 尖锐的啸叫 / High-pitched squeal | 缺润滑 / Lack of lubrication |
| 晃动、有间隙 / Wobble or play | 磨损，或内圈在轴上打滑 / Wear, or the inner ring slipping on the shaft |
| 发烫 / Running hot | 太紧、润滑脂太多或太少、负载过大 / Too tight a fit, too much or too little grease, or overload |
| 生锈、发红 / Rust or red stains | 进水 / Water got in |
11. Common Mistakes 常见错误
- 安装时压错圈，或用锤子直接敲，造成压痕。/ Pressing on the wrong ring or hammering directly, which dents the raceway.
- 只受轴向力的地方用深沟球轴承，导致很快磨损。/ Using a deep groove bearing where the load is mostly axial, which wears it out fast.
- 户外、潮湿环境用 ZZ 铁盖轴承，进水生锈。/ Using ZZ shielded bearings outdoors or in the wet, where water gets in and rusts them.
- 用 WD-40 代替轴承油。/ Using WD-40 in place of bearing oil.
- 只看型号不量尺寸，买回来装不上。/ Buying by model number without measuring, then finding it does not fit.
- 为了”更快”买高 ABEC 等级的滑板轴承，却不清洁保养。/ Buying high-ABEC skate bearings for speed while never cleaning them.
Key Takeaways
- 轴承把滑动摩擦变成滚动摩擦，同时支撑和定位转轴。/ A bearing turns sliding friction into rolling friction and also supports and locates the shaft.
- 规格看三个数：内径 x 外径 x 宽度，如 608 = 8 x 22 x 7 mm。/ Size comes down to three numbers: bore x OD x width, e.g. 608 = 8 x 22 x 7 mm.
- 编号
62xx：6 是深沟球，2 是尺寸系列，最后两位 04 以上乘 5 就是内径。/ In62xx, 6 is deep groove ball, 2 is the size series, and from 04 up the last two digits times 5 give the bore. - ZZ 铁盖适合干净高速，2RS 橡胶密封适合潮湿多灰。/ ZZ metal shields suit clean and fast work; 2RS rubber seals suit wet and dusty work.
- 安装只压正在装的那一圈，永远不要让力通过钢珠传递。/ When installing, press only the ring being fitted; never let force pass through the balls.
References
- ISO 15 (rolling bearings, radial, boundary dimensions)
- SKF bearing designation system and suffix guide
- ABEC / ISO 492 bearing tolerance classes
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