1 Related concepts of machining center and tool magazine
1.1 Machining Center
Machining Center (Machining Center) is a typical mechatronics high-tech product in CNC machine tools, and it is also an indispensable process equipment for advanced manufacturing technology. It integrates the latest technologies in microelectronics, computers, automatic control, precision measurement, machine tool manufacturing, etc. It is a symbol of the development direction of the contemporary machine tool industry and advanced productivity. The machining center with multiple coordinates (5 coordinates) and above is also an advanced manufacturing industry. Important strategic materials. A machining center is composed of a machine tool (mechanical part) and a control system (electrical part). The machine tool is the main body of the T-plus center, and the control system is the core of the machining center. The main machine of a machining center is usually composed of (bed, column, worktable) and spindle components, automatic tool storage exchange system (ATC) and other auxiliary functional components.
1.2 Tool magazine structure
The tool magazine is a device used to store tools in the CNC machining process. There are many types of tool magazine structures in machining centers, and the following four are commonly used:
(1) Disc tool magazine: also called fixed address tool change magazine, that is, each tool position has a number, generally from 1 to 12, 16, 18, 20, 24, etc., and Yan is the tool number address. After the operator installs a tool into a certain tool position, no matter how many times the tool is changed, it will always be in the tool position. The manufacturing cost of the disc-type tool magazine is low, and the main components are the tool magazine body and the index plate, as long as the machining accuracy of these two components is guaranteed. The indexing of the tool magazine in the moving parts uses a very classic “Markov mechanism”, and cylinders are mainly used for front and back, up and down movement. It is convenient to assemble and adjust, and easy to maintain. General machine tool manufacturers can make their own: the principle of counting tool numbers is generally to install a non-contact switch at the tool change position. Install the baffle on the No. 1 tool position: the tool magazine must “return to zero” every time the machine is turned on. When the tool magazine is rotating, as long as the baffle is close to the contactless switch (the distance is about 0.3mm), the CNC system defaults to 1 No. knife, and use this as the counting benchmark. The “Ma’s Institution” has been turned several times, and now it is the number one knife.
(2) Chain-type tool magazine: also called multi-ring chain-type tool magazine. The shape of the tool magazine is relatively compact, and it occupies a small space. It is suitable for large-capacity tool magazines. When increasing the storage of tools for a few days, the length of the chain can be increased without increasing the diameter of the sprocket. Therefore, the circumferential speed of the sprocket will not increase, and the inertia of the tool magazine is not as much as that of the disk-type tool magazine. Based on these advantages, the chain-type tool magazine is widely used in machining centers, which is suitable for processing large-scale parts with complex structures.
(3) Lattice box type tool magazine (also called array type tool magazine): The tool magazine has large capacity, compact structure, and high space utilization, but the layout is not flexible, and the tool magazine is usually placed on the workbench. Sometimes even when using a tool on one side, the tool seat plate on the other side must be replaced.
(4) Linear tool magazine: This type of tool magazine is characterized by simple structure and small tool magazine capacity. Generally used for CNC lathes, CNC drilling machines, and some machining centers are also used.
2 Automatic tool changer and its common troubleshooting
2.1 Automatic tool changer
In the automatic tool changer of CNC machine tools, the device that realizes the transfer and loading and unloading of tools between the tool magazine and the machine tool spindle is called the tool changer. The most commonly used automatic tool changer is the manipulator tool change, which is the most widely used tool change method on CNC machine tools. The tool change process is more convenient, and its task is when a process is completed. Unload the unused tools from the spindle and return them to the tool magazine, and load the tools for the next process into the spindle at the same time. Then the manipulator returns to the original position and waits for the next working cycle. The regular movement of the manipulator is realized by the three-phase asynchronous motor, gear transmission and other components and the air distribution system. The air pressure of the air distribution system must be kept above 6 ml. The manipulator can successfully replace the tools: the tool holder in the tool magazine follows the T code instructions Run to the tool change position, and then perform tool exchange. In the working process of the machine tool, the tool will make the manipulator take or install the tool according to the instruction. Therefore, the electrical system is required to complete each action accurately and reliably in accordance with the movement sequence of the tool change process.
2.2 Common faults and troubleshooting
(1) When the tool magazine is rotating, the brake cannot be positioned: Reason: the tool magazine counting sensor switch LSIO is damaged. At this time, in the “inching” mode, every time you press the tool magazine rotation button, the tool magazine will stop rotating after only one tool position, and the tool position cannot stop at the specified tool change position. Solution: replace the sensor switch .
(2) The CRT screen displays an alarm: 2023 ATC NOT HOME POSTION (the automatic tool changer is not at the origin position). Reason: The counting sensor switch that controls the rotation of the tool magazine is damaged. Or the wiring of the sensor switch is broken. Or the sensing distance is too far. Remedy: Check the wiring status of the induction switch; adjust the induction distance within 1-5mm, if it is invalid, replace the induction switch.
(3) The CRT screen displays an alarm: 2027 NOOL CLAMP()] tool is not clamped), reason: ①There are iron filings and other dirt attached to the sensor surface of the position sensor switch in the rotating state of the tool magazine. ②The tool sleeve on the tool magazine is not in place, and the pressure of the tool sleeve lifting cylinder is insufficient. Remedy: ①Clean the sensor switch. ②Check the cylinder and its secret pipeline for leakage, and make the pressure reach 0.392—0.49Mpa.
(4) The CRT screen displays an alarm: 2028 ATC ARM NOT HOME POSI—TION (the tool arm of the automatic tool changer is not at the origin position). Reason: ①The surface of the induction switch that controls the rotation of the tool arm is attached with iron filings and other dirt. ②The induction switch controlling the rotation of the knife arm is damaged or the wiring is bad. Remedy: ①Clean the surface of the sensor switch. ②Check the wiring of the sensor switch, if it is invalid, replace the sensor switch.
(5) The CRT screen displays an alarm: 2029 POT NOT CP (ZI sleeve is not in the rising state) Reason: ①The knife cover up limit switch is broken; the contact lever is not flexible; the contact lever cannot be pressed in after the knife cover is raised. ②The lower limit switch of the knife cover is broken; the contact lever is not flexible: the contact lever cannot be ejected after the knife cover is raised. Remedy: ① Check whether the contact lever of the limit switch is flexible, if it is invalid; replace the limit switch. ②Check whether the contact lever of the limit switch is flexible. If it is invalid, replace the limit switch.
Tool magazine and automatic tool changer are the key technologies of machining centers. The four different tool magazine structures have their own principles and application ranges. Understanding and mastering the common faults in automatic tool change technology and finding the corresponding solutions are of great significance to the use of machining centers.
1 Related concepts of machining center and tool magazine