MINTROBOT Co., Ltd., a manufacturer of industrial robots, has spoken that it was developed and produce more than 70% parts for robots with its own technology. We interviewed the most important precision gear reducer among the core parts that they made.
Q: Could you explain more specifically about the precision speed reducer?
A: Reducer means a kind of power converter. Generally, motors used in robots can rotate at very high speeds, but the force (torque) itself is very weak. However, the robots need that it requires a driver that gives a great deal of power at slow speeds. Therefore, it needs a device that converts a high speed and low power motor to a high power of a slow speed, which is the gearbox. Among the speed reducers, the reducers used in robots are special precision speed reducers with low backlash characteristics. Backlash refers to a small clearance present in a type of gearbox, but if the backlash is large, the robot can not move precisely. So, the reducer used in the robot is called a zero backlash reducer with almost no backlash, and it is very difficult to make such a precise speed reducer.
There are two types of precision speed reducers used in robots.
First, there is a well-known Harmonic drive. The Harmonic drive method is a method of implementing a gear reducer that operates very precisely using the elastic deformation characteristics of metallic materials. This method can reduce the size of the reducer, but the output is low, so it is usually used in small robots. The harmonic drive method requires not only the precision machining required for manufacturing but also the material and heat treatment technology to operate correctly without damaging the reducer. Therefore, it is very difficult to make and the price is very expensive. Since the patents have recently expired, the same products are manufacturing in domestic, Chinese and Taiwanese companies. However, HDS's manufacturing know-how is so excellent that it actually achieves, much better performance. There is no company that can manufacture a precision speed reducer that has more performance than this.
The second method is called a Cycloid drive. Cycloid drives are difficult to miniaturize like Harmonic drives, but their output is so large that they are usually used for medium and large robots. Cycloid drives are relatively easy to produce compared to harmonic drives.However, it is still difficult to get it to work precisely, and it is the RV reducer that has been improved to make the Cycloid drive system more sophisticated, the most commonly used method for industrial robots around the world. A speed reducer is a device that controls speed. In fact, the reducer is used not only in robot arm but also in many machines including motor vehicles. It is also a device that can give more power while controlling the speed of rotation of the motor.
Q: It is not common for robot companies to make precision speed reducers. Is there a background for making speed reducers?
A: Our biggest goal is to become a leader in the popularization of robots at low prices. Indeed, key components are in the making of cooperative and industrial robots. First, the precision reducer takes up about 34% of the total robot cost price. And the motors, encoders, and drivers are called Servo motor system, which is about 24% of the price. These two parts are the core parts that enter the joints of the robot, and the joint costs about 60% of the cost of the robot. In fact, it is extremely rare for a robot company to make precision speed reducers. It is no exaggeration to say that MINTROBOT is unique in the world today. In order for small start-ups like ours to survive in the competition, we must eventually compete in price competitiveness. However, no matter how you try to make a price, if you use the core parts from abroad, there is a fundamental limitation in lowering prices. So we decided to make precision gear reducer which is the most difficult to make and the most important.
Q: Is the MINTROBOT's Precision Reducer different from other Precision Reducers?
A: Yes. Both of the above-mentioned two types of speed reducers are manufacturing by introducing the technology in China and overseas, including domestic ones, since all the patent has been expired now. However, our reducers do not use the existing two ways but reflect our unique design. We designed an Elacloid Drive reducer to realize the precision of a conventional harmonic drive reducer in a more easily manufactured cycloid drive reducer. The reducer we designed is very precise, like a conventional harmonic drive reducer, and it is a reducer that can produce higher output like a cycloid reducer. In addition, the price is about half that of conventional harmonic drive type reducers.
Q: Could you tell us about the features of the Elacloid Drive?
A: The Elacloid Drive is a patented product developed in a unique structure by MINTROBOT. We have three features that More Small, More lightweight, More cost-effective. Actually, the driving principle of our reducer is the Cycloid drive. However, the internal design is slightly different from the structure of a typical Cycloid drive reducer. We changed the part of the part that affects precision in the Cycloid drive reducer to a form that can be elastically deformed like a spring. By using this, the cost of equipment investment for manufacturing a speed reducer can be reduced to 20% by raising the precision of a Cycloid reducer to the same level of accuracy like a Harmonic drive reducer. In addition, it can be made smaller and lighter. As a result, you can create a speed reducer that delivers high performance for your manufacturing cost. It's very good news for start-up robot manufacturers like us.
Q: What is the current lineup?
A: Our first Elacloid drive is a hollow unit type. It is the most stabilized model with many improvements over the years. The smallest size, from 70mm to 120mm, is now available. In the future, there is a plan to manufacture a reducer with a size of 160 mm or more. The deceleration rate is currently 40: 1, 80: 1, 100: 1, and an additional 60: 1 is planned. Currently, this model is called C type. (Cylinder).
The second type is F type (Flange), which is not a hollow type but a general type of speed reducer. It is manufactured to match the size of the CSG model, which is the model of the harmonic drive reducer, which is most commonly used for users who used the harmonic drive reducer. Therefore, there is an advantage that the products which used the existing HSD products can be used without changing the design without changing the reducer.
Q: Most workers would have a lot of questions about the performance of Elacloid drive.
A: At present, MINTROBOT Bucheon No.1 factory and R&D Center have introduced equipment to directly test the performance of the product, collecting objective data, as well as improving many deficiencies, and improving performance. But the real problem is how much better performance we have with our reducer in the robot and what the problem is. This can take a lot of time. Of course, in the past, we have used our products in large companies as well as overseas companies. Ultimately, we will be demonstrating this by attaching our speed reducer directly to our own robot, Pal. Once again, I think that the actual performance of the product can be seen by users over a long period of time, rather than objective data. In order to do this, we must strive to export our own speed reducers as well as sell our own robots at home and abroad.
Q: What are the difficulties in manufacturing a speed reducer?
A: The structure of the reducer is not difficult. The difficult part of the production of precision instruments such as speed reducers is to do the actual machining and assembly. As you know in the field workers, structure/design and processing are difficult to match 100%. A good structure means a structure/design that works well even considering the machining error, and good machining means machining to match the design as closely as possible. I think that depending on how well these two things are a combination, that decide whether or not we can make good precision equipment products. We need to be very precise in manufacturing the reducer, so we must minimize the errors that can occur in machining. That's why we need skilled workers who are more skilled in precision machining. Assembly is also not easy. The reducer itself is a very large part of the hands of a professional person. So, if you do not make a product with craftsmanship, it is difficult to get real performance.