An innovative solution was found to the problem of heat treatment deformation, but Liu Li knew that this was only the first hurdle. The persistent problem of "systemic lack of precision" in the assembly process was like another lurking obstacle, equally fatal. The assembly mode that relied on the feel of experienced craftsmen might work for ordinary products, but for export products that required extreme consistency, it had become an uncontrollable source of risk.
Just as Fu Jingchen was leading his team to build a deformation prediction model, Liu Li turned her attention to the final assembly workshop. Watching the workers adjust the bearing clearance based on experience and intuition, and make fine adjustments with hammers and pry bars, she realized that this vague operation that relied on "people" had to be given the reins of "tooling".
"We must transform 'feel' and 'experience' into quantifiable and replicable 'standard procedures'," Liu Li stated resolutely at the task force meeting. "Assembly precision cannot rely on luck; it must be guaranteed by tooling!"
She proposed a more radical "assembly revolution" concept—designing a modular, integrated set of specialized assembly tooling, along with an online testing system.
This idea was equally bold. In an era when tooling and fixtures were mostly simple and single-function, what she wanted was a "foolproof" precision system that could cover the entire assembly process of core transmission components and ensure that critical dimensions were assembled correctly on the first attempt.
"We need a reference base that can accurately position the box and eliminate the impact caused by the shape and position errors of the box itself."
"We need an adjustable but locking bearing press-fit module to ensure that the bearing is installed in place and the clearance is controlled within the theoretically calculated optimal range, rather than relying on feel to 'wobble' it."
"We need a gear shaft axial positioning module with a precision dial to replace the old method of using feeler gauges and hammers, and achieve micron-level precision positioning."
"Finally, and most importantly," Liu Li emphasized, "before the assembly bolts are fully tightened, we need an online inspection module that can quickly and accurately measure key dimensional and positional tolerances such as the parallelism and center distance of the two gear shafts after assembly. If any defects are found, adjustments should be made immediately to avoid bringing potential problems into the final tightening and testing stage!"
This idea left the experienced assembly workers present speechless. It was as if they were going to solidify all the "hand skills" they had accumulated over half a lifetime into a set of cold, impersonal tooling.
“Deputy Factory Director Liu, this…this tooling is not easy to make; the precision requirements are even higher than those for the parts!” a veteran worker said hesitantly.
"Moreover, having gotten used to the old methods, this new guy... will need some time to adapt," another person expressed concern.
Liu Li understood their concerns, but her attitude was firm: "The skills of the master craftsmen are treasures, but treasures cannot exist only in individuals; they must be passed down and replicated. This set of tooling is to solidify the most essential experience of the master craftsmen, so that any worker who has received serious training can assemble products with the same high precision! This is not to replace you, but to maximize the value of your skills through this tooling!"
She looked at Zhang Shulan: "Shulan, you are meticulous, have strong hands-on skills, and are familiar with the assembly process. You will work with the technical department to refine the usage procedures and online testing methods for this tooling and make them into the most intuitive operation manual."
“No problem!” Zhang Shulan immediately agreed, as she had long been troubled by those indescribable “feelings”.
Liu Li then looked at Fu Jingchen: "Engineer Fu, the design and precision requirements of the tooling itself require theoretical support from you, especially the quantitative relationship between bearing preload and clearance, as well as the setting of precision thresholds for online testing."
Fu Jingchen looked up from the mathematical model and adjusted his glasses: "Okay, I'll get the data sorted out as soon as possible. The tooling itself can be designed as a high-precision measuring instrument."
They got right to work. At the technical department's drawing board, engineers began the intensive design process, based on Liu Li's concept and Fu Jingchen's data. Liu Li personally participated in the review, meticulously scrutinizing every positioning structure, locking method, and measurement reference. Master Wang Jianguo was also invited in, using his discerning eye to examine every detail, ensuring the tooling was not only highly accurate but also sturdy, durable, and easy to operate.
The experienced mechanics in the machine repair shop received an extremely demanding processing task. They used every means to ensure that this "tool within a tool" met the design requirements.
A few days later, when the first set of assembly jigs, gleaming with a cold metallic sheen and featuring an intricate and complex structure, was transported to the designated "special zone" in the final assembly workshop, it attracted a large crowd of workers. Composed of several modules, it resembled a complex set of modular furniture, covered with precision guide rails, lead screws, dial indicators, and locking handles.
Zhang Shulan, along with several selected young workers, conducted their first training session according to the illustrated operating manual she had prepared. The training covered how to use a reference base to position the housing, how to use a special clamp to install bearings and read clearance values, how to adjust the positioning module to set the gear shaft position, and finally, how to use an online inspection module to quickly verify critical dimensions before tightening bolts…
At first, the workers struggled with the operation, accustomed to manual fine-tuning and finding this "step-by-step, meter-reading" method difficult to adapt to. However, under Zhang Shulan's patient guidance and strict supervision, they gradually discovered the advantages of this tooling—clear steps, well-defined objectives, and no longer needing repeated guessing and adjustments. As long as the procedures were strictly followed, the assembled gearboxes exhibited unprecedented stability in the relative positional accuracy of their core transmission components!
When the first gearbox, fully assembled on the new tooling, was sent to the test bench, the inspector in charge of noise testing was surprised to find that the background noise was significantly reduced. Although it was still far from perfect, the troublesome periodic "humming" sound had almost disappeared!
When the data feedback came back, Liu Li looked at the parallelism and center distance data that were stable within a very small range in the online detection record, as well as the preliminary results of significantly improved noise. Her tense face finally showed a relieved smile.
Technological innovation and assembly revolution, implemented simultaneously, acted like two powerful engines propelling the Red Star Factory gearbox project, which was mired in difficulties. Breaking through the darkest hour before dawn, it seemed that the first glimmer of hope could be seen.
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