There are many factors that affect the quality of parts in the process of using CNC machine tools to produce product parts. Among them, the accurate setting of tool parameters has been seldom paid attention to. To process the workpiece to the size range required by the process and meet the geometric tolerance requirements, accurate setting of the tool parameters is one of the basic requirements. The in-machine tool setting method is to use the machine tool setting device set on the worktable of the machine tool to measure the tools in the tool magazine according to the set procedure, and then compare the in-machine tool with the reference position or standard tool to obtain the length or diameter of the tool and update it automatically into the corresponding NC tool parameter table. Using the machine tool setting device for in-machine tool setting is accurate, automatic, and real-time, and there is no technical requirement for the operator; the disadvantage is that the tool setting probe needs to be configured separately.
The machine tool setter is generally composed of sensors, signal interface and tool setting macro program software. According to the working mode of the sensor, the in-machine tool setting device can be divided into contact type tool setting device and laser tool setting device. The repetitive measurement accuracy of the contact tool setter itself is 1μm, which can be further subdivided into the following categories according to the different signal transmission modes of the tool setter.
1. Cable-type tool setter
The cable-type tool setting device has the best single-piece price-performance ratio because it does not require the conversion part of the tool setting signal, so it is the most common in work. However, its disadvantage is that there is dragging of the cable, which limits its application. Therefore, this kind of tool setter is mostly suitable for small and medium-sized three-axis milling machines/machining centers.
2. Infrared tool setter
The signal transmission range of the infrared knife setter is generally within 6m. The advantage is the use of encoded HDR (high-speed data transmission) infrared technology, thereby avoiding the inconvenience and potential insecurity caused by cable towing. After the tool is set, it can be removed from the work surface at any time without occupying the processing space, and multiple machine tools can share a tool setter, which can reduce the overall cost. The disadvantage is that it is not cost-effective when used on a small machining center.
3. Wireless tool setter
The radio signal transmission range of the wireless tool setter is generally more than 10m. The advantage is that the radio signal transmission range is large and it is not easily affected by the environment. After the tool is set, it can be removed from the work surface at any time without occupying processing space, and multiple machine tools can share a tool setter, which can reduce the overall cost. This type of tool setter is mostly used for large/heavy/machine tools.
4. Laser tool setting device
The basic principle of the laser tool setter is to use a focused laser beam as the trigger medium, and a trigger signal is generated when the laser beam is shielded by the rotating tool. The laser tool setting device adopts non-contact measurement, there is no contact force when setting the tool, and it can measure very small tools without the risk of the small tool breakage due to the contact force. At the same time, since the tool rotates at a high speed at the processing speed during measurement, the measurement state is almost identical to the actual processing state, which improves the practical accuracy of tool setting. Due to the use of laser technology, the tool setter can scan the shape of the tool to measure the contour of the tool, and can monitor the damage of a single edge of a multi-edge tool. The main disadvantage is that the structure is complicated, and an additional high-quality air source is required to protect the internal structure. The cost is relatively high, and it is mainly suitable for high-speed machining centers.