Automatic operation stop system for machine tool

Abstract

[Problem] The purpose of the present invention is to provide a system that does not need to be connected to a PLC on a machine-tool side and can easily add an automatic operation stop function irrespective of manufacturer or model. [Solution] This CNC-controlled machine tool is characterized in that: the CNC control unit has a main machining program and a subprogram for monitoring a macro variable; and when the macro variable is rewritten, the subprogram automatically stops machining of a workpiece and / or generates an alarm.

Description

Automatic shutdown system for machine tools

[0001] The present invention relates to a system that can stop automatic operation when an abnormality occurs in machining due to breakage of a tool in a machine tool or the like.

[0002] In the field of machine tools, when workpieces are machined continuously through automatic operation, various sensors are used to monitor tool processing information, and if an abnormality such as tool damage is detected, the automatic operation of the machine tool is stopped to prevent machining defects. Conventionally, when an abnormality is detected by a sensor, the information is sent to the machine tool via a PLC (ladder program), and automatic operation is stopped. However, this requires editing the sequence program used in the PLC, and PLC structure and wiring arrangement vary depending on the manufacturer and model, making it difficult to install an automatic operation stop function.

[0003] For example, Patent Document 1 proposes that a current sensor that detects two-phase current information for each of a plurality of drive motors be attached to an existing device to determine whether the equipment is malfunctioning. However, even in this case, it is necessary to arrange the wiring for attaching the sensor according to each machine tool, each of which has different specifications.

[0004] Japanese Patent No. 7194069

[0005] The present invention aims to provide a system that does not require connection to a PLC on the machine tool side and that can easily add an automatic operation / stop function regardless of the manufacturer or model.

[0006] The automatic operation stop system for a machine tool according to the present invention is a CNC-controlled machine tool, wherein the CNC control unit has a main machining program and a subprogram that monitors macro variables, and when the macro variables are rewritten, the subprogram automatically stops machining of the workpiece and / or issues an alarm.

[0007] Here, it is preferable that the macro variables are common variables for the main machining program and the subprograms, and the M-codes used to command the operation of auxiliary functions in NC programming can be used to call the subprograms. In the present invention, stopping automatic operation also includes pausing, and an alarm can also be issued.

[0008] Here, a subprogram refers to a program that can be called while the main machining program is running, and it can acquire machining information, detect abnormalities such as tool damage, and be inserted in advance at a location where automatic operation is desired to be stopped.

[0009] In the present invention, the CNC control unit of the machine tool is connected to an edge device for communication, and the edge device acquires machining information through the communication connection with the CNC control unit of the machine tool and rewrites the macro variables when it detects an abnormality such as tool damage. Here, the edge device refers to a communication terminal that constitutes a network, and may be a communication terminal connected to a LAN or a communication terminal connected to the Internet.

[0010] Here, abnormalities such as tool breakage include not only abnormalities such as chipping of the cutting edge of the tool, but also cases where machining defects occur due to tool wear, etc., and refer to cases where the machining of the workpiece is not performed normally for some reason.

[0011] In the present invention, the edge device is an IoT device that is asynchronously connected to a server and is also communicatively connected to a user interface, and the user interface can be used to remotely control or otherwise set the tool for which damage is to be detected and the sensor for acquiring processing information.

[0012] Here, the tool for which damage detection is desired refers to a tool to be monitored from among multiple tools used in a machine tool, and the sensor for acquiring machining information refers to various sensors such as vibration sensors, acceleration sensors, current sensors, temperature sensors, and photoelectric sensors attached to the spindle, tool spindle, or turret. These tools and sensors can be connected to an edge device via a network, and the tools and sensors to be monitored can be set on the edge device side. The communication connection with the edge device can be either on-premise or cloud-based. The IoT device can be various IoT devices such as a Raspberry Pi, gateway, or router. The communication terminal can be various communication terminals such as a smartphone or tablet.

[0013] This invention utilizes the macro function in NC programming and connects various edge devices to the machine tool side by communication, making it possible to add an automatic operation stop function with a simple program change regardless of manufacturer or model. Also, by connecting the IoT device to the CNC control unit on the machine tool side by communication, the IoT device can obtain processing information from various tools and sensors on the machine tool side and determine abnormalities.

[0014] This shows the flow of monitoring the operating status and tool state of the machine tool, and outputting an operation stop signal. M code: This shows an example of calling a subprogram with M98. This shows an example of using the macro call function with M code. This shows an example of a subprogram.

[0015] An example of an automatic machine tool operation shutdown system according to the present invention will be described below with reference to the drawings. Figure 1 shows an example of a flow in which a website user interface WebUI,1 is connected to an IoT device 2 to monitor the machine tool and tools, and to stop the operation of the machine tool when damage to the tools or the like is detected. WebUI,1 is connected to the IoT device 2, which is in turn connected to the NC control unit 10 of the machine tool. A predetermined machining program 11 is installed in the NC control unit, and a subprogram 12 for monitoring macro variables is installed.

[0016] The operator sets the sensors and tools to be monitored in the IoT device 2 from the Web UI 1 and sets monitoring macro variables. After initializing the macro variables, the operator presses the automatic start button, and the machine tool executes the machining program 11. During this time, sensors on the machine tool and tool sides are activated, and the machining status is monitored using machining information communicated to the IoT device 2. If damage to the tool or the like is detected during the machining process, the macro variables are rewritten and the subprogram 12 is called. In this example, once it is confirmed that the macro variables have been rewritten, an automatic operation stop command is sent to the machine tool, and an alarm is displayed at the same time.

[0017] There are various possible methods for calling the subprogram 12. For example, as shown in Figure 2, M98, one of the M codes used to command the operation of auxiliary functions for machining in NC programming, can be used to call the subprogram by specifying the program number as argument P. M99 is a subprogram call end command.

[0018] 3, there is a method in which an M code number is designated in an NC parameter, for example, M999 calls program number O9020 (NO. 6080=999). An example of a subprogram in this case is shown in FIG.

[0019] The present invention may also be applied to constructing a system by connecting a communication terminal serving as a user interface, such as a tablet, to an IoT device using a cloud server on a network.

[0020] In this embodiment, an NC control unit is incorporated in the machine tool, and various sensors may be attached to the machine tool later, including sensors that are attached to the machine tool in advance.

[0021] The IoT device has an NC communication control unit and a server communication control unit, and the NC communication control unit is connected to the NC control unit of the machine tool via a LAN, and the server communication control unit is connected to the cloud server communication control unit via asynchronous communication using LTE.

[0022] Next, the operator inputs the machine tool name and location into the IoT device using a tablet or a terminal installed on the machine tool control panel. A list of tool post names, tools, etc. is displayed, allowing the operator to select from the list. When the operator issues an automatic machining command, the workpiece is automatically and repeatedly machined. If an abnormality is detected in the machine tool's operating status or the tool's machining status, the IoT device determines the abnormality based on sensor data from the sensor. When an abnormality signal is output, the IoT device rewrites macro variables, calls a subprogram monitoring them, and issues a command to stop operation. While this embodiment uses a cloud server, it may also be connected to the server using an on-premises method. Furthermore, using an LTE router to connect to the Internet eliminates the need for changes to existing network settings or wiring, such as port and IP address settings, and allows operation via a communication terminal connected to the Internet. Here, the communication terminal may be a smartphone, tablet, or the like, or may be connected via various SNSs.

[0023] Various sensor data can be used to detect abnormalities in the operating status of a machine tool, the machining status of a tool, etc. For example, analytical data on the current flowing through various motors used in the machine tool can be used. In this case, for example, a current sensor that detects the current flowing through the motor and a fluctuation detection means that detects the fluctuation range of the current detected by the current sensor can be used, and an abnormality can be detected from the value of the current fluctuation by setting a predetermined threshold value for the magnitude of the fluctuation range, excluding the range in which the motor accelerates / decels off and the range in which the motor stops.

[0024] The present invention can add an automatic operation stop function by utilizing a macro function in NC programming, regardless of the manufacturer or model of the machine tool.

[0025] 1 Web UI 2 IoT device 10 Machine tool 11 Main machining program 12 Subprogram

Claims

1. An automatic operation stop system for a CNC-controlled machine tool, wherein the CNC control unit has a main machining program and a subprogram that monitors macro variables, and when the macro variables are rewritten, the subprogram automatically stops workpiece machining and / or issues an alarm.

2. The automatic operation / shutdown system for a machine tool according to claim 1, wherein said macro variables are common variables of said main machining program and subprograms.

3. The automatic operation / stop system for a machine tool according to claim 1, wherein an M code used to command the operation of an auxiliary function in NC programming is used to call the subprogram.

4. The automatic operation shutdown system for a machine tool according to claim 1, characterized in that the CNC control unit of the machine tool is connected to an edge device for communication, the edge device acquires processing information through the communication connection with the CNC control unit of the machine tool, and rewrites the macro variable when it detects an abnormality such as tool damage.

5. The automatic operation shutdown system for machine tools according to claim 4, characterized in that the edge device is an IoT device, which is connected for asynchronous communication with a server and is also connected for communication with a user interface, and which allows the user interface to set the tool for which damage is to be detected and the sensor for obtaining processing information.

6. A machine tool characterized by using the automatic operation and shutdown system for machine tools according to any one of claims 1 to 5.

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