Design of automatic tool setting instrument for th

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Design of automatic tool setting instrument for NC machine tools

Abstract: This paper puts forward a simple automatic tool setting method used together with the NC system of machine tools, and according to the different characteristics of turning and key milling, it is excluded from the following three aspects, and the different structures of the sensor elements of the automatic tool setting instrument are analyzed

key words: NC machining; Workpiece coordinate system; Automatic tool setting instrument

Chinese drawing classification number: tg659 document identification code: b

in NC machining, after the workpiece coordinate system is determined, the position of the tool location in the workpiece coordinate system must also be determined, that is, tool setting. At present, most of the tool setting before NC machine tool processing adopts manual trial cutting and depends on manual control, so the preparation time is long and the tool setting accuracy is unstable. This paper tentatively discusses adding a relatively independent automatic tool setting program module to realize simple automatic tool setting control with the support of machine tool numerical control system software

I. automatic tool setting system and its implementation mechanism

the automatic tool setting system is composed of a tool setting control device and an automatic tool setting instrument, which is used in conjunction with the CNC system of machine tools. The automatic tool setting instrument is composed of a tool setting receiving circuit (Figure 1) and a standard tool setting bar. The working principle of tool setting is continuous automatic feeding and receiving mode. In this process, the keyboard sends out the tool setting command, which is recognized and processed by the tool setting control device, and then transmitted to the designated drive unit of the machine tool NC system to control the automatic positioning and edge finding movement of the tool to the surface of the standard tool setting bar. At the moment when the tool tip touches the surface of the tool bar, the high level on the sensor will have a negative jump through the tool tip pair, and the signal will be sent to the tool setting control device to interrupt the program to control the servo mechanism of the NC system of the machine tool to stop moving: the computer will withdraw a certain distance in time after extracting the coordinate data of the tool setting reference point of the axis; then continue to make positioning and edge finding movement along the other coordinate direction, In order to cause interruption again and remember the coordinate data of the tool setting reference point of this axis, which will be used as the zero point of the preset workpiece coordinate system after calculation. The implementation process of edge finding, positioning and tool setting is shown in Figure 2

II. Automatic tool setting instrument

the standard tool setting bar of the automatic tool setting instrument is a sensor component as the tool setting size benchmark, which is composed of three parts: mandrel, insulating sleeve and tool setting ring. The tool setting ring structure should adopt different designs according to the different tool setting methods of turning and lock milling

1. The tool setting instrument for NC lathe

should fully consider the diversity of turning tools and the influence of measurement error on machining accuracy. Therefore, the tool setting ring is designed into four measuring surfaces with an outer circle, an inner hole, an inner and outer cone, or three test pieces with brittle fracture surfaces (Figure 3 because many details need to be paid attention to in the installation process). They fell 12.3% year-on-year On the whole this year, it is used to measure the position of tool location of external turning tools, internal hole turning tools and end face turning tools. Its tool setting operation steps are very convenient. First, move the turning tool to the vicinity of the outer circle of the tool setting ring by inching, and then directly start the automatic tool setting program, and the tool will carry out automatic tool setting movement. When the tool setting instrument is used on open-loop CNC lathe, it should be considered to eliminate the tool setting error caused by transmission clearance. For this reason, the clearance elimination process can be inserted in the flow chart, that is, when the tool retreats X 'according to the specified requirements, then let it advance a distance of △ x (△ x) along the X axis

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