Common tool setting methods and in machine tool se

2022-10-04
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NC machine tools commonly used tool setting methods and machine tool setting instrument

Abstract: in the process of manufacturing product parts with NC machine tools, there are many factors that affect the quality of parts, such as NC machine tool accuracy, workpiece materials, workpiece heat treatment, processing technology, coolant, cutting tools and many other factors. Among them, the accurate setting of tool parameters has been rarely concerned and valued by everyone. Here, we will focus on the method characteristics and development trend of accurate tool setting on CNC machine tools

generally speaking, there are two coordinate systems commonly used: one is the machine coordinate system, and the other is the workpiece coordinate system. Machine tool coordinate system is the inherent coordinate system of machine tool. The origin of machine tool coordinate system is called machine tool origin or machine tool zero

for the convenience of calculation and programming, we need to establish the workpiece coordinate system in the machine coordinate system. Take a point on the workpiece as the origin of the coordinate system (also known as the program origin) to establish a coordinate system, which is the workpiece coordinate system. In daily work, we should try to make the programming benchmark coincide with the design and assembly benchmark

generally, the machine coordinate system of a machine tool is fixed, and several workpiece coordinate systems can be established according to the actual needs of the processing technology, such as g54, G55, etc. to select different workpiece coordinate systems

when NC machining is carried out for the purpose of tool setting, the path taken by the NC program is the motion path of the tool tip on the spindle. The motion path of the tool location needs to be accurately controlled in the machine coordinate system from beginning to end, because the machine coordinate system is the only benchmark of the machine tool. It is impossible for programmers to know the specific dimensions of various specifications of tools when programming. In order to simplify programming, it is necessary to adopt a unified benchmark when programming, and then offset the accurate length and radius of the tool relative to the benchmark when machining with the tool, so as to obtain the accurate position of the tool tip. Therefore, the purpose of tool setting is to determine the length and radius of the tool, so as to determine the accurate position of the tool tip in the workpiece coordinate system during machining

common tool setting methods external tool setting

tool presetter is a measuring instrument that can pre adjust and measure the length and diameter of the tool tip. If the instrument forms a DNC network with the NC machine tool, it can also remotely input the tool length and diameter data into the tool parameters in the NC of the machining center. The advantage of this method is that the tool is calibrated outside the machine tool in advance, and it can be used after installing the machine tool, which greatly saves auxiliary time. However, the main disadvantage is that the measurement result is a static value, so the tool wear or damage status cannot be updated in real time in the actual processing process, and the tool expansion and contraction caused by the thermal deformation of the machine tool cannot be measured in real time

tool setting by trial cutting method

tool setting by trial cutting method is that before the formal processing of the workpiece, the operator operates the machine tool in manual mode to cut the workpiece in a small amount. The operator determines the current position of the tool tip based on his eyes and ears, and then carries out the formal processing. The advantage of this method is that it does not need additional investment to purchase tools and equipment, which is economical. The main disadvantages are low efficiency, high requirements for the operator's technical level, and easy to produce human errors. In actual production, there are many derivative methods of trial cutting method, such as gauge block method, coloring method and so on

in machine tool setting

this in machine tool setting method is to use the measuring device (tool setting instrument) set on the workbench of the machine tool to measure the tool in the tool magazine according to the preset program, and then compare it with the reference position or standard tool to obtain that the length of the tool or the load borne by the straight diameter bone is reduced and automatically updated to the corresponding NC tool parameter table. At the same time, the detection of the tool can also identify whether the tool is worn, damaged or installed correctly

internal tool setting instrument

composition of internal tool setting instrument

internal tool setting instrument is generally composed of sensor, signal interface and tool setting macro program software

according to the working mode of the sensor, the tool setting instrument in the machine can be divided into contact tool setting instrument and laser tool setting instrument. The repeated measurement accuracy of the contact tool setting instrument is 1 μ m. It can be further divided into the following categories according to the different signal transmission modes of the tool setting instrument: cable tool setting instrument; Infrared knife setting instrument; Radio tool setting instrument

the cable tool setting instrument has the best one-piece cost performance because it does not need the conversion part of tool setting signal, so it is the most common in work, but its disadvantage is the drag of cable, which limits the application of the tool setting instrument. It is mostly suitable for small and medium-sized three-axis milling machines/machining centers

infrared tool setting instrument, the signal transmission range is generally within 6m. Its advantage is that it adopts encoded HDR (high-speed data transmission) infrared technology, which avoids the inconvenience caused by cable dragging. Whether the top of the force measuring piston is against the steel bowl and the potential security threat. After tool setting, it can be removed from the workbench at any time without occupying processing space, and multiple machine tools can share a tool setting instrument, thus reducing the comprehensive cost. Its disadvantage is that it is not cost-effective when used in small machining centers. Due to its characteristics, this kind of tool setting instrument is mostly used for medium-sized machine tools and large-scale CNC vertical lathes

radio langteng has exported its products to Russia, Europe, India, Arabia, Singapore, Hong Kong and other countries and regions. The radio signal transmission range is generally more than 10 meters. Its advantage is that the radio signal transmission range is large and it is not easy to be affected by the environment. After tool setting, it can be removed from the workbench at any time without occupying processing space, and multiple machine tools can share a tool setting instrument, which can reduce the comprehensive cost. This kind of tool setting instrument is mostly used for large/heavy machine tools

laser tool setting instrument, such as hexcon's lts35.60, the basic principle of this product is to use the focused laser beam as the trigger medium. When the laser beam is shielded by the rotating tool, a trigger signal is generated. Essentially different from the contact tool setting instrument, the laser tool setting instrument adopts non-contact measurement, and there is no contact force during tool setting, so it can measure extremely small tools without worrying about the damage of small tools caused by contact force. For example, the straight diameter of tools that can be measured by lts35.60 can be as small as 0.008mm (such as drill bits, taps or micro milling cutters), and its own repeated measurement accuracy reaches 0.2 μ m。 At the same time, because the tool rotates at high speed at the machining speed during measurement, the measurement state is almost identical to the actual machining state, which improves the practical accuracy of tool setting. Due to the use of laser technology, the tool setting instrument can scan the tool shape and measure the contour of the tool, and can monitor the damage of a single edge of a multi edge tool. Its main disadvantage is that its structure is complex, requiring additional high-quality air source to protect the internal structure, and its cost is high. It is mainly suitable for high-speed machining centers

common functions and advantages of the tool setting instrument in the machine

(1) automatic measurement and parameter update of tool length/diameter: when the tool is rotating, the length/diameter is dynamically measured, and the measurement parameters include the end run out/radial run out error of the machine tool spindle, so as to obtain the "dynamic" offset value of the tool during high-speed machining; At the same time, the automatic measurement of tool parameters can be carried out at any time, which greatly eliminates the "change" of tool parameters caused by the thermal deformation of the machine tool; The measurement results are automatically updated to the parameter table of the corresponding tool, completely avoiding the potential risks caused by manual tool setting and parameter input

(2) automatic monitoring of tool wear/damage: in the actual production process, when the tool is worn or broken (broken), it is difficult for the operator to find and correct it in time (especially the drill bit tools with small diameter), resulting in more subsequent tool losses and even workpiece scrapping. Using the tool setting instrument in the machine, the length of the tool can be automatically measured once after the tool is processed and before it is put back into the tool magazine. If normal wear occurs, the wear value can be automatically updated to the tool damage parameter. If excessive wear occurs, it can be regarded as tool damage (fracture), so as to select a new tool to process the next workpiece or automatically stop the alarm to prompt the operator to replace the tool. In this way, the product quality is improved and the tool loss or scrap rate is reduced

(3) automatic compensation of machine tool thermal deformation: when the machine tool is in production and processing, with the change of ambient temperature and workload, the thermal deformation of the machine tool occurs at any time, which drives the tool to change. As a result, the dimensional accuracy of the products processed by the same machine tool in the workshop at different times in the morning, middle and evening fluctuates greatly. After using the tool setting instrument in the machine, the tool parameters can be automatically measured and updated at any time before or during processing. Each measurement is the tool setting under the current thermal deformation state of the machine tool, which greatly reduces the error caused by the thermal deformation of the machine tool

(4) measurement and monitoring of tool contour: in special processing, such as forming tools, it is time-consuming and complex to use the external tool aligner to measure the tool contour and judge the tool state, and at the same time, it also has high requirements for the operator's tool alignment skills. At this time, if you use the laser tool setting instrument in the machine, you can use the laser beam to scan, measure or monitor the tool contour at any time, and automatically update the corresponding parameters as needed

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