Why has the machining of humanoid robot reducer parts stumped a bunch of processing factories?

The mass production of humanoid robots has landed, the reducer is a core component that cannot be bypassed. The performance lifespan of the reducer are largely determined by the machining accuracy of the core components. Thin walls are prone to deformation, have high fitting accuracy, are difficult to process materials. These characteristics make it difficult for many processing factories to do well even after receiving orders. Either the samples fail the testing, the batch production yield cannot improve. This article starts actual processing scenarios, disassembles the processing difficulties of the core components of humanoid robot reducers, combines the production experience of Huiwen Zhizao to provide practical process ideas.

1、 Deformation control of thin-walled parts

In order to meet the requirements of lightweight, the core components of humanoid robot reducers, such as internal gear rings, flexible wheels, output shells, generally adopt thin-walled structures with a small ratio of wall thickness to radial size. During the machining process, deformation is prone to occur, which is the most common machining difficulty in the industry.

This type of deformation mainly comes three aspects: firstly, clamping deformation. Thin walled parts have poor rigidity, ordinary three jaw chucks are subjected to uneven force during clamping. After the parts are removed, the elasticity recovers, resulting in roundness exceeding the tolerance; The second is cutting deformation. During the machining process, the cutting force of the tool acts on the thin-walled position, causing deformation of the tool local deformation, resulting in uneven tooth profile wall thickness; The third is stress deformation, the residual internal stress after processing heat treatment is slowly released, resulting in changes in part size over time causing abnormal noise jamming after assembly.

Difficulties Countermeasures in Process Control:

To address the issue of deformation in thin-walled parts, customized soft claw fixtures clamps can be used during processing. Based on the shape of the part, a contour design can be made to evenly distribute the clamping force across the entire contact surface, avoiding excessive local stress that may cause clamping deformation; Using a five axis linkage machining center to complete multi-faceted feature machining in one clamping, reducing the number of repeated clamping times, optimizing the tool path cutting parameters, adopting a process scheme of small cutting depth fast feed to reduce tool deformation caused by cutting force; Add a stress relief process between rough machining precision machining, release residual stress through heat treatment natural aging, reserve appropriate machining allowance during precision machining to offset the dimensional changes caused by stress release.

2、 Consistency control of precision with matching features

The transmission accuracy of the reducer depends on the positional accuracy dimensional accuracy of the fitting features of the parts. The coaxiality of bearing holes, the accuracy of gear shaft hole pitch, the profile of teeth will amplify the errors in the transmission chain, directly determining the backlash, transmission efficiency, noise level of the reducer.

For example, the installation holes of the planetary gears on the planetary carrier, with a deviation in hole spacing, can cause uneven meshing clearance between the planetary gears the sun gear, as well as the inner gear ring, resulting in problems such as unbalanced load tooth punching; The tooth profile of the cycloidal gear exceeds the tolerance, which can lead to poor transmission increased backlash; Insufficient coaxiality of the bearing holes can lead to bearing wear significantly shorten the lifespan of the reducer. What is even more difficult is the consistency of accuracy during mass production. It is difficult to achieve high accuracy for a single sample, but the difficulty is that the accuracy of tens of thousands of parts is stably controlled within the tolerance range.

Difficulties Countermeasures in Process Control:

For such high-precision matching features, a five axis machining center is usually used to complete the machining of all associated features in one clamping, all positional accuracy is guaranteed by the geometric accuracy of the machine tool itself to avoid cumulative errors caused by multiple clamping; For core features such as tooth shape hole system, high-precision coordinate measuring machines can be used for full-size inspection after processing. The coaxiality, hole spacing, contour of each part are recorded in the inspection report, unqualified parts are directly intercepted; During the production process, implement the system of first article three inspections process inspections, regularly spot check key dimensions, timely compensate for dimensional deviations caused by tool wear, ensure that the accuracy deviation of batch production is controlled within the minimum range.

3、 Process adaptation for difficult to process materials

The core components of humanoid robot reducers are generally made of high-performance materials such as high-strength alloy steel, bearing steel, aviation aluminum alloy. These materials have high strength good wear resistance, but the processing difficulty is also much higher than ordinary steel: alloy steel has high toughness, it is easy to stick to the knife produce chip lumps during processing, which affects the surface quality; Bearing steel has high hardness, tool wear is fast, dimensional accuracy is difficult to maintain; Some parts are made of special aluminum alloy materials, which are prone to stress deformation after processing, the surface roughness is difficult to meet the requirements.

If the tool selection cutting parameters are matched properly, only will the machining efficiency be low, but it will also lead to poor surface quality high residual stress of the parts, which can easily cause early wear fatigue failure during subsequent use.

Difficulties Countermeasures in Process Control:

Corresponding tool materials coatings need to be matched for different material characteristics. For example, CBN (cubic boron nitride) tools can be used for processing hardened bearing steel, diamond coated tools can be used for processing aluminum alloys. At the same time, cutting parameters should be optimized according to the part structure, appropriate cooling schemes should be matched to avoid material deformation caused by high temperature during processing; Based on the heat treatment characteristics of different materials, the material heat treatment process should be clarified in advance, appropriate aging treatment should be arranged between processing steps to ensure the hardness strength of the parts while controlling the processing deformation within a reasonable range.

4、 Yield control for mass production

The common problem encountered by many gearbox manufacturers is that during the sampling stage, all parts are qualified, but various problems occur frequently during mass production, resulting in fluctuating yield rates inability to guarantee delivery cycles. The essence behind this is the standardization of the production process the issue of quality control system.

The mass production of precision parts is simply about copying the processing parameters of samples to the production line. Tool wear, machine temperature changes, operator differences, raw material batch differences all affect the final part accuracy. Without sound process control, stable yield cannot be guaranteed.

Difficulties Countermeasures in Process Control:

To achieve stable mass production, it is necessary to establish a sound quality management system, such as operating standards such as ISO 9001 IATF 16949. Starting the entry of raw materials the factory, conduct composition hardness testing to ensure that unqualified raw materials are put production; Establish a process flow card for each part, so that the processing parameters, operators, inspection results of each process can be traced; Equip specialized fixtures inspection tools for mass-produced parts to reduce the impact of human factors on accuracy; All parts undergo full-size inspection visual inspection before leaving the factory to ensure stable quality of each batch of parts delivered, thereby shortening the product validation cycle reducing overall costs.

ending

The competition for humanoid robot reducers is about whose parameters are written high, but about who can produce parts stably, in batches, with high yield. Huiwen Zhizao has long focused on robot transmission motion component processing, covering harmonics RV、 Customized processing of core structural components for all types of planetary reducers, pre process optimization, precision five axis machining to full-scale quality inspection, providing customers with full process support sampling to batch delivery, helping customers truly turn design solutions stable reliable mass-produced products, jointly promoting the landing of the humanoid robot industry.