In the past, EDM was considered to have little to do with precision and microfabrication. However, due to the implementation of Sodick's NC, today, EDM machines have established an indispensable position as a working machine.
Now Sodick's ultra-precision and micro-machining is taking linear technology as an innovative method and becoming the subject of technological innovation under the conditions of nano-fields. Since the beginning of NC EDM, Sodick has continued to focus on the development of nano-machine tools "Ultra NaNo-100 (Ultra-fine Nano 100)" and "the most advanced technology in the field of ultra-precision and micro-fabrication". SPACE (space) series.
4 main technologies supporting nanotechnology
In December 2001, Sodick began to develop nanomachine tools. As a trigger for the linear technology innovation, it began in the autumn of 1998 to commercialize the world's first linear motor-driven EDM machine (AM35L). Prior to this, it was very difficult to achieve a machining accuracy of 1 μm or less. The decision to break the status quo is based on the judgment that in the conventional driving method, it is difficult to break the limit of 1 μm or less with the "feed mechanism of the ball screw and the rotary electric machine", so it is decided to replace all the machine tools with the linear motor drive. .
The four main technologies supporting nanotechnology are ceramics, linear motor drives, CNC and NC devices, and drive controllers. To maximize the superiority of each cutting-edge technology, these major technologies have been developed by Sodick and require all the features to be intact. In the end, in a very short period of time, the ultra-precision, micro-machining and machine tool performance that can provide excellent cost performance were successfully achieved.
The following is a summary of the superiority of ultra-precision and micro-machining related to various major technologies.
Ceramic
In order to ascertain the effectiveness of the discharge energy, mechanical parts with superior insulating materials have been an important issue. This is the origin of a technology related to ceramics. As a material of ceramics, the price is low, and it is easy to get it. In addition to the insulation properties, the characteristics of the ceramics are as follows: light weight, high rigidity, abrasion resistance and excellent stability under a hot environment.
The reason why materials that achieve such superiority are not actively used as mechanical parts is that general common sense is considered to be lower in toughness. The so-called "hot-pressed" ceramics do have the disadvantage of cracking, but it is not a problem to fully observe, analyze, and verify that the processing may be used as a mechanical part. In the actual production of Sodick's EDM machine, in addition to external factors, the probability of ceramic cracking is zero.
In fact, the use of the ceramic as a mechanical component material has become an important technical basis for the superiority of linear motor drive, that is, the characteristics of the ceramic itself can maximize the speed of the linear motor drive. High acceleration and high response characteristics, and effective results in implementing effective thermal countermeasures in order to obtain high-precision characteristics.
In the case of a nanomachine tool, the ceramic is used for a guiding mechanism of a high-stiffness air-floating guide rail, and extremely excellent linear precision can be achieved. At the same time, its combination with linear motor drive has played an important role in achieving nano-level control characteristics.
2. Linear motor drive
The linear motor drive in which the rotary motor is classified into a plate is a direct drive. There is no need for a feed screw that transmits power, so there is no influence of gap, creep, twist, and lag caused by the feed screw, thus establishing extremely smooth The sporty characteristics enable excellent responsiveness to produce highly accurate shaft drives.
Since a high-precision, high-resolution linear grating is used as the position detecting device, it is just controlling its own drive. Therefore, it is possible to perform high-precision position control on a continuous time axis. For EDM, the servo characteristics required for high response are an important factor in controlling the machining performance. Linear motor drive is an ideal actuator.
With the traditional feed screw, it is not impossible to achieve a certain degree of positioning accuracy through high-precision control technology, but in the very small field of nanometers, in order to ensure excellent processing performance, it is necessary to control under extremely high frequency conditions. characteristic. Therefore, in the friction state of the feed screw, in addition to the problem of aging change due to wear, the disadvantage that the initial performance cannot be maintained is also difficult to avoid.
From a general unfavorable impression, there are several sounds related to productivity, thermal efficiency, and suspicion of being affected by magnetic forces. However, Sodick's linear motors were developed by themselves, so the basic performance was verified intact and the control characteristics of each machine were set to optimal conditions. Therefore, such concerns are not a problem, and technology development has been completed.
In fact, it is also an important issue to consider a mechanical component that does not impair the performance/performance ratio of performance without sacrificing safety in terms of stopping, starting, and stopping such a simple operation. In addition to performance, many of the issues that should be addressed have been overcome, and Sodick has gathered exclusive technical tips.
3. Numerical control device and NC power supply
After years of construction of control technology and superior EDM experience, Sodick has developed a highly reliable NC power supply unit. In all discharge states, the discharge characteristics are not impaired, and in order to realize the superiority of the linear motor drive, a comprehensive numerical control device and an NC power supply must be developed. Considering the hardware aspects of ergonomics-based software aspects and production performance, it also requires a high degree of technical competence in both areas.
4. Drive controller
The more minimized the drive control unit, the more slowly the control system reacts, which becomes a fatal flaw in the control characteristics mismatch. For linear motor drives that do not rely on friction, especially in terms of their technical control, there are still some practical situations in which not all machine tools can be driven by linear motors.
As a comprehensive system of Sodick, the exclusive drive controller "SMC (Sadick Drive)" which can realize the linear motor drive performance has been successfully developed. Under the conditions of establishing nanotechnology, based on modern control theory, using the most advanced control methods to "immediately move technology at a specified position (high speed)" and "the technology to stop it at a specified position" (High-precision)" Both have the latest ultra-precision and micro-machining examples for the control range below 1 nm
1. Small EDM machine "APlL Premium"
As a basic structure for precision machining, APlL Premium uses a three-sided automatic upper and lower machining groove to improve the complicated working process for small parts processing. At the same time, it can also flexibly respond to automation and labor saving by using high-speed multi-joint robots. On the X, Y, and Z axes, a small high-thrust linear motor developed by Sodick can provide excellent positioning accuracy and high responsiveness without gaps.
The newly developed high-speed, high-grade precision SVC power supply has greatly improved the discharge pulse control, and can provide high-efficiency and uniform discharge pulses to the poles, so that the current front edge can be improved unprecedentedly, so the machining area is refined. The optimum surface roughness reaches the limit, and the high-grade processing that achieves uniform discharge pits and uniform surface roughness reduces the difficulty of polishing fine and minute shapes, and contributes to shortening processes, improving quality, and maintaining stability.
In the precision machining of EDM, it is necessary to consider various errors involved. When the machining is approaching the specified position, the edge measurement is performed, and the machining process is performed to obtain the dimensional accuracy. However, when the measurement is performed, since the machined surface is reworked after cleaning and the machining is started from the tar-free state, the portion where the gap is narrowed is not subjected to the electric discharge machining, so that the processing is finished, and generally, it is difficult to reach 1 μm or less. Additional processing.
This time, the APlL Premium machine tool has been able to use the linear motor drive position high-precision detection and the discharge start point detection to optimize the micro-level additional machining.
2. Ultra-precision wire cutting machine "EXClOOL"
The EXCl00L machine is equipped with an air-floating guide (air-floating slide) made by Sodick in the X and Y axes of the machine. The drive transmission part is equipped with a non-core linear motor made by Sodick. In terms of the world, the world's first fully non-contact linear motion guide system was established.
Since all the components of the X and Y axes use the ceramics made by Sodick, the ultimate reliance on high responsiveness is achieved, and the state of change caused by external heat is minimized. It achieves stable linear accuracy and maintains long-term accuracy. Due to the improvement in the positioning accuracy, the discharge state of the extremely thin electrode wire which tends to be unstable can be stabilized. Since the broken wire due to concentrated discharge is avoided, the roundness and pitch precision of the ultra-fine electrode wire can achieve high-precision machining of 1 μm or less or high-precision machining of the fine gear.
3. Precision wire cutting machine "AP200L"
The low-sliding, high-strength cross-roller guide is used as a direct-acting guide to drive high-precision machining features using a linear motor developed by Sodick. The wire electrode trace is generated by the cantilever made of ceramic, so that the cumulative error of the actual machining can be limited to 1 μm.
The utility model effectively utilizes the characteristics of the mechanical part, the NC device and the spare oil tank to be integrated on the integrated base, and the straight-type operating parts and the carrier handling parts are basically arranged in the same space as the standard machine, thereby realizing the Small automation systems are compatible.
With the high response performance of the linear motor drive, the stable discharge characteristics are maintained, and the tension of the wire is controlled by the tension servo function, which suppresses the deformation of the workpiece even in the processing of thick plates and complicated shapes, and achieves high precision with excellent straightness. machining.
High precision and high grade processing of AP1L Premium and AP200L
It is not only the size of the drawing, but the document with zero error as the target, which is combined into an ultra-precision and ultra-fine mold that is “made with the current product†and “no need for polishing and refurbishingâ€. The quality of the processing mold is stable and no need to try again. The increase in mass production efficiency shows the superiority of improving mold reliability. The guide groove of the knockout pin also plays a functional role in the ultra-precision mold. The movable side was incorporated into 100 pneumatic pines for the number of parts. Mass production was carried out to achieve unbiased quality, and original indirect and planning were implemented. In the production process of the movable side air pressure pin, the end shape of the air pressure pin is processed on the assembly block by the AP200L machine tool, and the next step is performed on the end portion with the AP1L Premium machine tool to complete the high-precision shape of the corner R10μm.
At this time, since the position of the pneumatic pin can be prepared by the processing accuracy of the AP200L, the forming electrode for the spot spark machining can also be manufactured by means of the AP200L, because there is no problem of the machine position error, and the electric power can be completed with high precision and stability. Spark processing. Thereby, the trouble of each process and positioning of the pneumatic pin is saved, and the production efficiency is greatly improved. If the cumulative accuracy of the parts is considered, it has been proved that the parts can reach the machining accuracy below micron.
The combination between AP1Lpremium and AP200L is indeed a high-precision, high-grade processing.
Nano-EDM Processing of Linear Motors and Future Prospects
The SPACE series is a general term for a group of ultra-high nanomachines driven by linear motors. The minimum driving unit is 1 to 5 nm or less. The processing shape accuracy is 5 to 100 nm or less. In particular, the Z-axis structure has excellent position control characteristics and high responsiveness due to the influence of gravity, and it is possible to achieve the processing performance as in the production of space, and to position the ultra-precision micro-linear machine tool, so SPACE ( The name of the universe.
The AE05 is the next-generation machine tool, and the main technology in the nano field is applied to EDM, thus achieving the "the smallest ultra-fine hole (SUS304, t=10μm) of 4μm in the world of EDM." Answering new applications that are impossible to achieve with conventional nanomachine cutting and grinding, and establishing the next generation of nanotechnology.
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