Sesame chain structure—one of the earliest watchmaking techniques, it seems that in recent years, it has faced a strong return. Modern watchmakers are refocusing on this …
An eternal topic that has long puzzled the watchmaking world is that since its birth 600 years ago, it has never been sincerely satisfied with any invention aimed at achieving ‘isochronism’! (Regardless of the amplitude, when the duration of the balance wheel remains the same, it is ‘isochronous.’ The meaning of ‘isochronous’ is to make the clock move more accurately.)
In order to fully understand the solution to this problem, we must first understand the natural law of clockwork in the power transmission process: when the mainspring of the full chain is fully tightened, the power reaches its peak, which appears as the highest point on the curve; At this time, the balance vibration is the most regular and orderly, and the isochronism is the strongest, that is, the most accurate. And when the mainspring slowly relaxes, the power shows a curve-like slowly falling state; the isochronism gradually decreases until the spring is nearly released by two-thirds, and the power transmission efficiency suddenly suddenly depletes, showing a straight drop on the graph . It is precisely because of this physics principle that under normal circumstances, the isochronism of clock movement, that is, the accuracy correspondingly shows a gradual decrease after a gradual decrease. Imagine that if the part of the movement must swing regularly, it is difficult to achieve stable power supply. This is as difficult as stepping on the accelerator while maintaining the speed while driving!
Over the years, many wise men and women who have not lost their wisdom and wisdom to Leonardo da Vinci have devoted themselves to the solution of this problem. However, it must be said that the structure that Da Vinci used to design similar to today’s ‘sesame chain’ is still a good strategy to effectively offset the decreasing torque in the spring release process.
The word sesame chain, fusee chain, originated in French fusée and Latin fusata, which meant a spindle full of threads. It is said that it first appeared in the early 15th century, and the exact beginning has no place to test. It is named after its name. It contains a concentric layered and gradually decreasing pagoda-shaped gear plate, and a chain wrapped around it like a grain of sesame. It is closely connected with the main power shaft of the mainspring. Connected.
If you dive into the micro world to study the extremely complicated sesame chain structure, the difficulty is really too abrupt, you can compare the speed change bicycle sprocket gears around you, and so on. The gear shifter allows the rider to shift gears according to the crawling gradient or desired cadence, strength, and speed: placing the chain in one of a set of overlapping gears with larger or smaller diameters, so that the pedal can be changed at any time Frequency, power and the distance of a single tread, that is, speed.
This is similar to the effect of the ‘sesame chain’ in clocks. When the clockwork barrel is gradually full, its tension gradually reaches the strongest, and the power shaft continuously tightens the sesame chain and winds it to the circle with the smallest circumference at the top of the pagoda gear. When the clockwork is gradually released, the tension gradually weakens, and The tension was relaxed, and the sesame chain slowly wound around the larger diameter disc until it reached the outermost circle. To put it more clearly, the greater the tension, the smaller the length of the sesame chain wound around the pagoda wheel; the smaller the tension, the greater the length of the winding section. Since then, the ‘torque’ as the product of the two has always been the same (‘ ‘Moment’ = force * distance from the point of force to the shaft), and the release of the mainspring force always keeps the torque relatively consistent, the balance wheel also achieves relatively stable vibration frequency, and the clock travels relatively accurately. The effectiveness of the sesame chain transmission system was widely recognized in the 17th century. At that time, it was mainly used in marine clocks. At that time, the life of all crew members on the entire ship relied on this complex mechanical structure. If facts are the only criterion for testing truth, it is self-evident that today’s Sesame Chain has regained the hearts of many ‘big names’, and it has solved the shortcomings of the birth of the clockwork structure. A. Lange & Söhne Since 1995, Pour le Mérite sesame chain watches have been launched in at least 4 versions, Breguet launched the red gold version of the Tradition 7047 sesame chain tourbillon in 2012, and Christophe Colombe Hurricane of Zenith, constant-powered tourbillon with sesame chain from DeWitt, and more.
At the beginning of the 15th century, purely hand-designed and manufactured precision mechanical structures that are also challenging for ‘CNC machine tools’ today are truly amazing, but at that time the sesame chain was mainly used for large-scale nautical clocks; today in micro-inches with a diameter of 40 mm, Nearly 700 tiny parts are assembled in a space of no more than 0.3 cubic centimeters and run smoothly. This is really another miracle of the development of human civilization!
Today’s ‘improved version’ of sesame chain has also corrected and overcome the original disadvantages, such as replacing the traditional concentric pagoda disc structure with a slowly rotating turbine structure. Since the turbine and the barrel are always on the same plane, the force can be straight-lined. Transmission, so the chain is greatly shortened; the size of the ‘sesame’ chain link is increased accordingly, and some brands also use ruby bearings at the joints, which greatly reduces the side effects caused by friction and improves durability. It is precisely because of these improvements that the Sesame Chain has revived its life and glory today, six centuries after its birth!