This article, written by Huang Feng of the Wuhan Mitsubishi Industrial Control Technology Center, describes the use of Mitsubishi CNC dedicated tool change commands in the cap-type tool magazine and robotic tool magazine of machining centers. Currently, tool magazines in machining centers and milling/turning centers can generally be divided into two types: one where the tools in the tool holders are fixed, meaning that the tools in each tool holder are fixed during operation. The cap-type tool magazine is representative of this type. The other type of tool magazine allows the tools in each tool holder to change during operation; the robotic tool magazine is representative of this type. Because these two types of tool magazines have different tool changing methods, debugging personnel must use different methods when writing tool change programs. Mitsubishi CNC's PLC development software provides dedicated tool change commands. The following is a detailed description, combined with the tool change macro program of the robotic tool magazine: 1. Terminology Due to the somewhat confusing terminology in the GX-DEVELOP software application manual, the following standardization is provided in this article: 1.1 Tool: Refers to the tool used to cut the workpiece. Each tool can be numbered, and the tool number is directly specified when selecting a tool. 1.2 Tool Holder: Refers to the device that holds the tool. The tool holder also has a number. 1.3 Rotating body in the tool magazine. Drives the tool holder to move. 1.4 Tool changing position A specific position in the tool magazine; only tools in this position can be changed onto the spindle. [IMG=Fig. 1 Tool Magazine and Tool Changing Parameter Settings]/uploadpic/THESIS/2007/11/2007111415084062117Y.jpg[/IMG] Fig. 1 Tool Magazine and Tool Changing Parameter Settings 2 Sequence of Actions During Tool Changing 2.1 Tool Changing Sequence of the Hat-Type Tool Magazine Each axis (X, Y, Z axis) moves to the first tool changing point—tool magazine advances and jams—spindle releases tool—Z axis rises to the second tool changing point—tool magazine retracts—rotates to select tool—tool magazine advances—Z axis descends to the first tool changing point—spindle locks tool—tool magazine retracts—tool changing complete 2.2 2.3 Vertical Tool Magazine Tool Changing Sequence: Z-axis movement to the first tool changing point – spindle releases tool and blows chips – Z-axis movement to the second tool changing point – shuts off chip blowing and pulls out the positioning pin – tool turret rotation selects tool – inserts the tool turret positioning pin – Z-axis descent to the first tool changing point – spindle locks tool – Z-axis movement to the origin – tool changing complete. 2.4 Robotic Arm Tool Magazine Tool Changing Sequence (Use the T command to select tool before the M6 ​​tool changing command) – tool turret rotation completes tool selection – tool holder lowers vertically – Z-axis movement to the first tool changing point – robotic arm rotation locks tool – spindle releases tool – robotic arm rotation changes tool – spindle locks tool – robotic arm returns to the origin – tool holder retracts horizontally into the tool magazine – tool changing complete. 2.5 Simple Turret Tool Changing Sequence: X and Z axes move to the tool changing point – turret rotates forward to select tool – pauses for 0.3 minutes – turret rotates in the reverse direction to lock – tool changing complete. [IMG=Figure 2 Writing All Tool Numbers at Once]/uploadpic/THESIS/2007/11/2007111415122852186J.jpg[/IMG] Figure 2 Writing All Tool Numbers at Once [IMG=Figure 3 Nearest Tool Selection Rotation Command]/uploadpic/THESIS/2007/11/2007111415130910549Y.jpg[/IMG] Figure 3 Nearest Tool Selection Rotation Command 3 Tool Change Commands Dedicated to Mitsubishi GX-DEVELOP Software The Mitsubishi GX-DEVELOP software offers 13 dedicated tool change commands. These include tool number search, tool head rotation, spindle tool change, tool number writing, tool number reading, nearest tool selection rotation direction, rotation step determination, and creating a ring counter. The use of these dedicated tool change commands will be detailed below, taking a hat-shaped tool magazine and a robotic tool magazine as examples. 3.1 Setting the Tool Magazine and Tool Changing Parameters: When using dedicated tool changing instructions, file registers R2950-R3639 are designated for special purposes of tool changing instructions and must be appropriately set through the PLC program. The PLC program is shown in Figure 1. 3.2 Setting Tool Numbers (Taking 24 tools as an example): Sequentially write tool numbers to R3000-R3079 in the tool magazine (as shown in Figure 2). (The tool magazine is like a circular hotel room system; R3000-R3024 are the fixed room numbers, and the tools are the guests staying in each room. The S.ATC.K11 instruction sequentially arranges all guests into the rooms.) 3.3 Nearest Tool Selection Instruction (as shown in Figure 3): Nearest tool selection: rotates the tool head according to the shortest stroke. When programming a PLC, the core concept is "tool selection." This involves issuing a tool selection command to drive the tool magazine to rotate forward or backward until the "tool number at the tool change position" matches the "selected tool number." Only then does the tool turret stop rotating, allowing subsequent tool changing actions to proceed. The "tool change position" is a fixed position on the tool magazine; only tools at this position can be changed onto the spindle. The tool number in the "tool change position" changes continuously as the tool turret rotates. In the PLC program, a power-off retained file register R represents the "tool change position" (e.g., R3000). When the tool turret rotates, the counting pulses of the tool turret counter change the value of R3000. The "data" of R3000 is the "tool number" at the "tool change position." The "selected tool number" is the tool number selected using the T instruction in the main machining program. The "nearest tool selection" instruction automatically drives M200 to ON or OFF based on the value of the "tool number at the tool change position" and the selected tool number. When M200=ON, the tool turret rotates forward; when M200=OFF, the tool turret rotates backward. However, several settings must be configured before using this instruction, as shown in the following example: (Rn—R500—Used to specify the starting address of the parameter setting buffer. Within the specified parameter setting buffer, no specific content is set; only the address of the file register storing the specific data is set. For example, if a file register address—513—is specified in R500, then file register R513 is used to set relevant parameters for tool turret rotation, such as whether the tool turret starts counting from "0" or "1", and whether to select the nearest tool. (Rn+1)—R501—Specifies the address of the "tool change position" file register, which is stored in R501. (Rn+2)—R502—Specifies the address of the "selected tool number" file register, which is stored in R502. (Rn+3) — R503 — Specifies a file register address number stored in R503. The value in this file register is the number of steps the tool turret should rotate, calculated by the NC for tool selection. An example of the initial settings for the rotation command is shown in Figure 4. After the above settings, R513 — is used to set the tool magazine rotation parameters, R3000 — tool change position register, R636 — selected tool number register, R1920 — number of rotation steps register. The tool turret rotation action is shown in Figure 5. In Figure 5, the M15 tool turret rotation start command is issued by the main machining program. M200 is used to determine the forward and reverse rotation of the tool turret. It is issued by the nearest tool selection command. M750 tool number equality is used to cut off the forward and reverse rotation of the tool turret. 3.4 Acquisition of tool data in the "Tool Change Position" register The rotation of the tool magazine is detected by the tool magazine counter. As the tool turret rotates continuously, the tool data in the "Tool Change Position" register also changes continuously. The detection of the data in the "Tool Change Position" register is completed by the following two commands. 3.4.1 Tool turret forward rotation (as shown in Figure 6) [IMG=Figure 4] [Preliminary settings for rotation command]/uploadpic/THESIS/2007/11/2007111415281617623K.jpg[/IMG] Figure 4 Preliminary settings for rotation command [IMG=Figure 5 Rotation of the tool head]/uploadpic/THESIS/2007/11/2007111415282940195U.jpg[/IMG] Figure 5 Rotation of the tool head [IMG=Figure 6 Forward rotation command for the tool head]/uploadpic/THESIS/2007/11/2007111415284361865P.jpg[/IMG] Figure 6 Forward rotation command for the tool head [IMG=Figure 7 Reverse rotation command for the tool head]/uploadpic/THESIS/2007/11/2007111415285752208M.jpg[/IMG] Figure 7 Tool turret reversal command [IMG=Figure 8 Binary Conversion]/uploadpic/THESIS/2007/11/2007111415290868622T.jpg[/IMG] Figure 8 Binary Conversion [IMG=Figure 9 Spindle Tool Change Command]/uploadpic/THESIS/2007/11/2007111415291961052M.jpg[/IMG] Figure 9 Spindle Tool Change Command [IMG=Figure 10 Correspondence between Tool Holder Label and Actual Tool]/uploadpic/THESIS/2007/11/2007111415293166848T.jpg[/IMG] Figure 10 Correspondence between Tool Holder Label and Actual Tool 3.4.2 Tool turret reversal (as shown in Figure 7) When the forward or reverse pulse of the tool turret drives the above command, the data in the tool change position R3000 changes continuously. The value of R3000 represents the tool number appearing in the "tool change position". The "selected tool number" is represented by the data in R36, which is already defined in the NC. Since R3000 and R36 contain BCD code, binary conversion must be performed before comparison (as shown in Figure 8). After processing as shown in Figure 8, the tool number data of the "tool change position" and the tool number data of the "selected tool number" are obtained, which can be compared to obtain the stop rotation condition. The rotation direction is obtained through the S. ROT. K1 command, and finally the rotation tool selection is completed. 3.5 The biggest difference between a robotic tool magazine and a traditional tool magazine is that in a traditional tool magazine, the tool holder number always corresponds to the tool number, and the tool numbers are always arranged in a circular pattern. However, in a robotic tool magazine, the tool holder number and tool number are not consistent. This is because during tool changing, the robotic tool magazine uses a robotic arm to exchange the spindle tool with the tool at the tool change position, so the tool numbers are not arranged in a circular sequence but rather in a random circular pattern. Therefore, the processing in the PLC program is slightly more complex. There is a dedicated tool change instruction for spindle tool changing (as shown in Figure 9). This instruction means that when the tool change signal is ON, the spindle tool number is exchanged with the tool number at the tool change position. Appropriate settings must be made before this instruction is executed. 3.6 Correspondence between Tool Holder Labels and Actual Tools On the NC's "Tool Registration" screen, each time the "Tool Head Forward Rotation" or "Tool Head Reverse Rotation" instruction is driven, the data in MG1-MG80 (corresponding to R3000-R3079) can be observed changing, which is actually a circular movement. If a spindle tool change command is executed, the circular tool arrangement will not be sequential but random. In actual debugging, for the robotic arm tool magazine, after multiple tool changes, the actual tools corresponding to the tool holder labels will be completely different. Users require real-time information about the actual tool in each tool holder, which can be observed on the "Tool Registration" screen after program processing. In the PLC program, a circular counter is created to represent the actual movement of the tool holders. The value of this circular counter is then sent to the pointer register R2965 specified by a dedicated instruction. This allows the actual tool in each tool holder to be observed on the "Tool Registration" screen. The PLC program processing is shown in Figure 10. In summary: Using dedicated tool change commands, the entire tool magazine can be viewed as a circular group of guest rooms in a hotel. R3000-R3079 are fixed room numbers. The tools are the guests staying in each room. Each rotation of the tool magazine causes the "guests" in the room to move clockwise or counter-clockwise once. In a conical tool magazine, the "guests" are arranged in a circular sequence, while in a robotic tool magazine, the tool holder numbers and tool numbers are not consistent; the "guests" are arranged randomly in a circular pattern. A tool magazine can be viewed as three motion systems. R3000-R3079 are fixed room numbers, their values ​​determined by the tool magazine's motion commands. The tool holders can also be considered a circular motion system, with a circular counter indicating their position. Assigning their value to pointer R2965 allows the actual tool corresponding to the MG tool holder to be observed on the display screen. The tool also performs a circular motion, driven by S.ATC.K7/S.ATCK8, with its tool number reflected in R3000-R3079. Furthermore, whenever the S.ATC.K7/S.ATCK8 command is activated, MG1-MG80 immediately display the corresponding values ​​from R3000 to R3079 on the screen. While other commands can be used to program tool changes, using dedicated tool change commands is faster. Moreover, tool changes can be observed on the screen, which is particularly suitable for robotic tool magazines. However, the initial setup for using dedicated commands is more complex and should be carefully considered during use. (Proceedings of the 2nd Servo and Motion Control Forum, Proceedings of the 3rd Servo and Motion Control Forum)