从机制开始
Rack-and-pinion selection combines tooth geometry with the way the rack is supported over its travel.
Module/DP and pressure angle define the mesh, while rack straightness, section stiffness, mounting holes and pinion center height affect working backlash.
Rack straightness is a machine-installation problem as well as a manufacturing problem. A precise rack bolted to an uneven frame will follow the frame. Show the mounting datum and the pinion center-height adjustment method. For high travel accuracy, consider how pitch error, thermal expansion and backlash accumulate over the stroke rather than quoting only a local tooth tolerance.
报价前需冻结的输入数据
Provide rack length/section, pitch system, mounting method, pinion geometry, travel, load and positioning requirement.
尽可能将这些信息添加到受控图纸、规格说明或询价附件中。避免在非正式的沟通渠道中发布这些信息，有助于供应商比较和后续修改的管理。
什么因素会使这一假设失效？
A long unsupported rack can bow enough to change the mesh even when tooth geometry is correct.
验证策略
Check alignment and backlash at multiple positions across the working stroke.
For Plastic Rack and Pinion Selection, verify the component across the real travel or duty cycle. Local dimensional checks are useful, but the mechanism-level result should decide whether the design is ready for production.
采购清单
Before requesting a price for plastic rack and pinion selection, identify the current drawing revision, production quantity, material constraint and the feature that most strongly affects function. Ask the supplier to flag any deviation from those inputs in the quotation so technical alternatives stay visible.
针对此决策的实用设计审查
齿条的精度取决于其在整个行程范围内的安装方式。需要确定节圆线高度、安装孔基准面、直线度、配合齿轮以及支撑齿条的结构。长尼龙齿条还需要满足一定的环境条件才能通过尺寸认证。
将假设条件记录在图纸或询价单中，以便供应商在报价前进行确认。如果某个数值未知，应将其标识为待定工程项目，而不是直接复制可能与实际装配不符的通用产品目录编号。
验证工作表
- 模块/DP 和压力角
- 俯仰线高度
- 机架部分及长度
- 安装方式/直线度
- 配合齿轮/中心高度
- 旅行、负载和调节
使用第一个样品，通过尺寸验证和相关的功能检查来确认这些要点。任何可接受的偏差都应在重复生产前的受控修订中记录下来。
