结论：折叠机构要同时考察两件事——还能不能折，以及展开后还锁不锁得住
折叠机构的循环试验，很多人只关注一件事：折叠几千次之后还能不能正常折叠。这只覆盖了一半。
另一半更重要：展开状态下的锁定是否仍然可靠。 折叠机构磨损之后，即使还能折叠，展开锁定的配合可能已经变松，而锁定失效的后果是使用中轮椅突然折叠，这是直接的安全问题。
循环次数怎么估
估算依据是使用场景：
家用产品可能一周折叠一两次，主要用于放进后备箱；机构用产品可能每天折叠多次，用于周转和存放；租赁产品的折叠频次更高。
把日均次数乘以设计寿命年数，得到总循环次数。这个估算要基于实际调查，不要直接沿用同行的数字。 不同定位的产品差异可能是数量级的。
估算时还要考虑一点：折叠通常由护理者或家属完成，操作力度和规范程度不如专业人员，实际磨损可能比理想操作下更快。可以在估算次数上留一定系数。
试验中该记录什么
只记录「完成多少次未失效」信息量太小。建议记录这几项：
折叠力与展开力的变化。 每隔一定次数测一次，看趋势。力变大说明卡滞，变小说明配合松动。
锁定到位的确认。 每隔一定次数检查展开后锁定机构是否完全到位，有没有需要额外用力或多次尝试才能锁上的情况。
配合间隙的变化。 铰链和锁定部位的间隙，耐久前后对比。
异响出现的时间点。 异响通常是磨损的早期信号，记录它第一次出现的循环数有参考价值。
润滑状态。 试验过程中不补充润滑，观察润滑失效后磨损速率的变化。
锁定可靠性怎么单独考察
建议把锁定可靠性作为独立项目，而不是附在折叠循环里。考察内容包括：
锁定状态下的受力保持。 在展开锁定状态施加载荷，看锁定会不会被推开。这一项应当在耐久前后各做一次。
误操作防护。 使用中意外触碰解锁机构，会不会导致折叠。特别要考察使用者坐在车上时的情形。
未完全锁定的识别。 如果锁定没到位，使用者能不能察觉。有视觉或触觉提示的设计更安全。
部分锁定状态的承载。 锁定只到位一半时的承载能力如何，会不会突然失效。
第三项和第四项在事故分析中出现的频率较高。 使用者以为锁好了，实际没有，坐上去之后突然折叠。
折叠与承载的相互影响
折叠轮椅的车架在折叠处必然存在不连续，这个位置同时也是受力路径上的关键点。于是出现一个矛盾：
折叠机构要转动灵活，就需要一定间隙；承载要稳固，就要求间隙尽量小。间隙的大小是这两个需求之间的折中，而磨损会让间隙单向变大，也就是说承载性能会随使用逐渐下降。
这意味着折叠轮椅的强度验证不应当只在新件状态做。建议在耐久之后补测一次强度，看下降幅度。如果下降明显，说明间隙控制或材料选择需要改进。
不同折叠形式的差异
交叉式折叠。 结构简单可靠，但折叠后体积仍较大。关注交叉铰点的磨损。
纵向对折。 折叠后体积小，但铰链承受较大弯矩。关注铰链强度与锁定。
靠背前翻加座椅折叠的组合。 涉及多个机构协同，要关注操作顺序错误时是否会造成损坏。
快拆加折叠。 部件可拆卸使体积进一步减小，但增加了接口磨损和装配可靠性的考察点。
设计上的改进方向
针对磨损导致的间隙增大，可行的方向包括：在关键铰点使用耐磨衬套，磨损集中在可更换的衬套上而非结构件；设计可调的锁定机构，间隙变大后可通过调整补偿；在锁定部位采用楔形或锥形配合，这类配合对间隙变化不敏感；提供明确的到位提示，降低未完全锁定的风险。
不同折叠形式的耐久关注点
| 折叠形式 | 主要磨损部位 | 耐久试验重点 |
|---|---|---|
| 交叉式 | 交叉铰点、下管座 | 铰点间隙、展开后横向刚度 |
| 纵向对折 | 主铰链、锁定销 | 铰链弯曲变形、锁定保持力 |
| 靠背前翻组合 | 翻转铰链、限位块 | 多机构协同、误操作耐受 |
| 快拆加折叠 | 拆装接口加折叠铰点 | 两类磨损叠加后的总间隙 |
最后一行值得注意：两种可分离结构叠加时，间隙是累加的。单看每一处都在允许范围内，整体的晃动量可能已经超出可接受程度。验证时要测整体，不能只测单点。
操作力的变化趋势
折叠力和展开力的变化方向能说明问题性质。力持续变大通常是润滑失效或磨屑积累；力先变小后变大，可能是初期磨合之后进入磨损阶段；力持续变小则是配合松动。
把力值按循环次数画出来，趋势比单点数值更能说明机构的状态。这条曲线也可以用来确定润滑或保养的建议周期。
试验中断与恢复的处理
长周期的循环试验中途可能因设备维护、断电等原因中断。中断本身对结果有影响：停机期间润滑分布改变、温度回落，重新启动后的初期状态与连续运行不同。
所以试验记录里应当注明中断的次数、时长和发生在第几次循环。数据出现异常时，这些记录是排查的第一依据。
我们的做法
做折叠机构耐久时，我们会按一定间隔记录折叠力、展开力和锁定状态，形成一组趋势数据，而不只在结束时给结论。趋势比终点更有价值——它能显示性能什么时候开始下降，据此可以确定维护周期。
同时建议把锁定可靠性在耐久前后各做一次，对比下降幅度。这一项与安全直接相关，值得单独出数据。
有需要可以把折叠机构的形式和使用频次估计发过来一起定试验条件，或者直接联系：132 4819 8029。检测能力见服务介绍，产品分类见手动轮椅检测与电动轮椅检测，案例见案例。
English version
Conclusion. Endurance testing of a folding mechanism is often judged on one thing: whether it still folds after several thousand cycles. That covers only half the question. The other half matters more: whether locking in the deployed state remains reliable. Once worn, a mechanism may still fold while the deployed lock has loosened, and a lock failure means the chair folding during use, which is a direct safety hazard.
Estimating cycle count. Base it on the use scenario. A domestic product may be folded once or twice a week to go in a car boot; an institutional product may be folded several times a day; a rental product more often still. Multiply daily frequency by design life in years. Base this on actual investigation rather than borrowing a competitor's figure, since products in different positions can differ by an order of magnitude. Allow a factor for the fact that folding is usually done by carers or family, whose technique is less consistent than a professional's, so real wear may exceed that under ideal operation.
What to record. Recording only the number of cycles completed without failure carries little information. Measure folding and deployment forces at intervals and look at the trend: rising force indicates binding, falling force indicates loosening. Check at intervals whether the lock fully engages, and whether extra force or repeated attempts are becoming necessary. Compare clearance at hinges and lock points before and after. Note the cycle count at which unusual noise first appears, since noise is often an early wear signal. Do not replenish lubricant during the test, so that the change in wear rate after lubrication fails can be observed.
Assessing locking reliability separately. Treat this as its own item rather than an adjunct to the folding cycles. Apply load in the deployed and locked state to see whether the lock can be forced open, before and after endurance. Examine protection against inadvertent release, particularly with the user seated. Examine whether incomplete locking is detectable by the user, since visual or tactile confirmation is safer. And examine load capacity in a partially locked state and whether it fails abruptly. The last two appear frequently in incident analysis: the user believes the chair is locked, it is not, and it folds when sat in.
Folding versus load capacity. A folding frame is necessarily discontinuous at the fold, and that point also lies on the load path, creating a conflict. Smooth folding needs clearance; secure load carrying wants minimal clearance. The chosen clearance is a compromise, and wear only increases it, meaning load-carrying performance declines gradually with use. Strength verification should therefore not be confined to new condition; retest strength after endurance and examine the reduction. A marked drop indicates clearance control or material choice needs improvement.
Differences between folding types. Cross-brace folding is simple and robust but leaves a larger folded volume; watch wear at the cross pivot. Longitudinal folding gives a smaller package but subjects the hinge to greater bending; watch hinge strength and locking. Combinations of backrest fold and seat fold involve several mechanisms and need checking for damage if operated out of sequence. Quick-release combined with folding reduces volume further but adds interface wear and assembly reliability to the assessment.
Design directions. Use replaceable wear bushes at key pivots so wear concentrates in a serviceable part. Provide adjustable locking so increased clearance can be compensated. Use wedge or taper engagement at the lock, which is less sensitive to clearance change. And give clear engagement feedback to reduce the risk of incomplete locking.
How we handle it. We record folding force, deployment force and lock engagement at intervals to produce a trend rather than only a final verdict, because the trend shows when performance begins to decline and supports setting a maintenance interval. We also suggest measuring locking reliability before and after endurance, since it relates directly to safety and deserves its own data.
Send us the mechanism type and a usage frequency estimate and we will set conditions. Phone or WeChat: +86 132 4819 8029.