JPH04360754A - Tool life control method - Google Patents

Abstract

PURPOSE:To provide a correct tool life control method. CONSTITUTION:The tool length or diameter of a tool is measured to obtain the measured value (step S4), and the life limit value of the length or diameter of the tool is set. The measured value is compared with the life limit value (step S5), and the tool is judged to have reached its life limit when the measured value becomes smaller than the life limit value. The length or diameter of the tool is measured to obtain the wear quantity of the tool, and the wear limit value of the length or diameter of the tool is set. The obtained wear quantity is compared with the wear limit value, and the tool is judged to have reached its life limit when the wear quantity becomes larger than the wear limit value.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a tool life management method for a numerical control device (CNC) that manages the tool life of a machine tool, and in particular, a tool life management method that allows accurate determination of when a tool has reached the end of its life. Regarding management methods.

0002

2. Description of the Related Art Conventionally, a numerical control system (CNC) manages the tool life of a machine tool in order to maintain machining accuracy and prevent tool breakage. That is, when it is determined that a tool has reached the end of its life, the tool is automatically replaced with an alternative tool. To determine whether a tool has reached the end of its life, the wear state of the tool is indirectly estimated by measuring the number of times the tool is used for machining or the amount of time the tool is used, and comparing the measured value with a reference value. This was done using a method of discrimination.

0003

[Problem to be Solved by the Invention] However, even if the number of times the tool is used and the time it is used is the same, the actual state of tool wear varies depending on the work being machined and machining conditions such as override. Time cannot be an accurate indicator of the actual state of tool wear, and therefore, tool life management based on the number of times a tool is used or the amount of time it is used cannot be said to be an accurate tool life management method. The present invention has been made in view of these points, and an object of the present invention is to provide an accurate tool life management method.

0004

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a tool life management method for a numerical control device (CNC) that manages the tool life of a machine tool. determine the measured value, set a life limit value for the tool length or tool diameter of the tool, compare the measured value with the life limit value, and when the measured value becomes smaller than the life limit value. , a tool life management method is provided, characterized in that it is determined that the tool has reached the end of its life.

[0005] Furthermore, in a tool life management method for a numerical control device (CNC) that manages the life of a tool of a machine tool, the tool length or tool diameter of the tool is measured to determine the wear amount of the tool, and Setting a wear limit value for the tool length or tool diameter, comparing the wear amount with the wear limit value, and determining that the tool has reached the end of its life when the wear amount becomes larger than the wear limit value. A tool life management method is provided.

[0006]

[Operation] Measures the length or diameter of the tool to obtain the measured value, and also sets the life limit value of the length or diameter of the tool. The measured value is compared with the life limit value, and when the measured value becomes smaller than the life limit value, it is determined that the tool has reached the end of its life.

[0007] Furthermore, the tool length or tool diameter of the tool is measured to determine the wear amount of the tool, and a wear limit value of the tool length or tool diameter is set. Compare the wear amount with the wear limit value, and when the wear amount becomes larger than the wear limit value,
It is determined that the tool has reached the end of its life.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Figure 2 shows a numerical control device (
FIG. 2 is a block diagram of the hardware of CNC. In the figure, a processor 11 reads a system program stored in a ROM 12 via a bus 21, and controls the overall operation of the numerical control device 10 in accordance with this system program. A DRAM is used as the RAM 13, and temporary calculation data, display data, etc. are stored therein. The non-volatile memory 14 is composed of CMOS and is backed up by a battery (not shown), and stores tool measurement values, tool correction amounts, pitch error correction amounts, NC programs, parameters, etc., which will be described later. The life limit value for each tool is input into the parameter in advance. The life limit value is a value below which the tool cannot be used, and the life limit value is set to a slightly larger value with some margin.

The interface 15 is an interface for external equipment, and external equipment 31 such as a paper tape reader, paper tape puncher, paper tape reader/puncher, etc. is connected thereto. The NC program is read from the paper tape reader, and the NC program edited within the numerical control device 10 can be output to the paper tape puncher.

A PMC (programmable machine controller) 16 is built into the numerical control device 10 and controls the machine side using a sequence program created in a ladder format. That is, the M function and S function commanded by the NC program.
According to the functions and T functions, the sequence program is converted into necessary signals on the machine side and output from the I/O unit 17 to the machine side. This output signal drives a magnet, etc. on the machine side, and operates a hydraulic valve, a pneumatic valve, an electric actuator, etc. Further, the PMC 16 receives signals from limit switches on the machine side, switches on the machine operation panel, etc., performs necessary processing, and sends the signals to the processor 11. This PMC 16 performs tool exchange control using the T function and M function, which will be described later.

The graphic control circuit 18 converts digital data such as the current position of each axis, alarms, parameters, image data, etc. into image signals and outputs the image signals. This image signal is sent to the display device 26 of the CRT/MDI unit 25,
Is displayed. Interface 19 receives data from keyboard 27 in CRT/MDI unit 25 and passes it to processor 11. Interface 20 is connected to and receives pulses from manual pulse generator 32 . A manual pulse generator 32 is mounted on the machine operation panel and is used to manually move the machine moving parts precisely.

Axis control circuits 41-44 receive movement commands for each axis from processor 11, convert them into speed command signals, and output them to servo amplifiers 51-54. Servo amplifiers 51-54 amplify the speed command signal and drive servo motors 61-64 for each axis. The servo motors 61 to 64 have a built-in pulse coder for position detection, and a position signal is fed back from the pulse coder as a pulse train. In some cases, a linear scale is used as a position detector. Furthermore, a speed signal can be generated by performing F/V (frequency/velocity) conversion on this pulse train. Additionally, a tacho generator may be used for speed detection. In the figure, these position signal feedback lines and velocity feedback lines are omitted.

The spindle control circuit 71 receives a spindle rotation command, a spindle orientation command, etc., and outputs a spindle speed signal to a spindle amplifier 72. The spindle amplifier 72 receives this spindle speed signal and rotates the spindle motor 73 at the commanded rotation speed. Further, the spindle is positioned at a predetermined position by an orientation command.

A position coder 82 is connected to the spindle motor 73 by a gear or a belt. Therefore, the position coder 82 rotates in synchronization with the spindle motor 73 and outputs a feedback pulse, which is read by the processor 11 via the interface 81. This feedback pulse is used to move other axes in synchronization with the spindle motor 73 to perform processing such as thread cutting.

The measuring instrument 92 measures the length or diameter of the tool according to the instruction signal from the measurement control circuit 91, and the measured value is converted into a digital signal by the measurement control circuit 91 and sent to the processor 11. As the measuring device 92, a laser length measuring device, an optical measuring device, etc. are used. FIG. 1 shows that the processor 11
2 is a flowchart illustrating a procedure for tool life management performed by the operator. In the figure, the number following S indicates the step number.

[S1] According to the T-code instructed by the machining program, the next tool to be used is selected, and the tool changer is moved to the standby position. [S2] When M06 is instructed in the machining program, the tool is replaced. [S3] It is determined whether the parameters stored in the non-volatile memory 14 include a signal instructing to perform tool life management based on tool length or tool diameter. If there is this instruction, proceed to steps S4 to S8, otherwise step S9
Proceed to. Note that when execution of the machining program is started with the tool to be used already installed, tool life management starts from this step.

[S4] The tool length or tool diameter is measured by the measuring device 92 under the control of the measurement control circuit 91. [S5] Tool length or tool diameter (
The measured value) is compared with the life limit value of the tool among the life limit values set in advance in the non-volatile memory 14 for each tool. As a result of the comparison, if the measured value is smaller than the life limit value, it is determined that the tool should not be used, and step S
On the other hand, if the measured value is equal to or greater than the life limit value, it is determined that the tool can still be used and the program is terminated.

[S6] The tool determined to be unusable in step S5 is returned to the tool magazine. [S7] Data indicating that the tool cannot be used is written in the item of the tool in the tool database. [S8] Skip the unusable tool from the tool magazine and take out a replacement tool to be used next and install it. After executing this step, the process returns to step S4 in order to manage the life of this newly installed tool. [S9] Execute conventional tool life management based on tool usage time and number of uses, and end this program.

In the above embodiment, the measured value of the tool length or tool diameter is compared with the life limit value, which is the limit tool length or tool diameter that the tool can use, and when the measured value is smaller than the life limit value, The tool is determined to be unusable, but as another example, a wear limit value, which is the maximum limit of the amount of wear at which the amount of wear on the tool increases and the tool becomes unusable, is set in advance for each tool. Set it in non-volatile memory 14,
Instead of executing step S4, measure the tool length or tool diameter of the tool and then calculate the wear amount, and instead of executing step S5, compare the calculated wear amount with the wear limit value of the corresponding tool, It may be determined that the tool is unusable when the amount of wear is greater than the wear limit value.

[0020]

As explained above, in the present invention, the tool length or tool diameter of the tool is used as a criterion for determining the tool life, so it is possible to accurately determine when the tool life is reached. Therefore, accurate tool life management is possible.

[Brief explanation of the drawing]

FIG. 1 is a flowchart illustrating the steps of a tool life management method according to the present invention.

FIG. 2 is a block diagram of hardware of the numerical control device.

[Explanation of symbols]

10 Numerical control device 11 Processor 14 Non-volatile memory 16 PMC 91 Measurement control circuit 92 Measuring instruments

Claims (2)

[Claims] 1. A tool life management method for a numerical control device (CNC) that manages the life of a tool of a machine tool, wherein the tool length or tool diameter of the tool is measured to obtain a measured value, and the tool length or tool diameter of the tool is determined. A tool diameter life limit value is set, the measured value is compared with the life limit value, and when the measured value becomes smaller than the life limit value, it is determined that the tool has reached the end of its life. Tool life management method. 2. In a tool life management method for a numerical control device (CNC) that manages the life of a tool of a machine tool, the tool length or tool diameter of the tool is measured to determine the amount of wear of the tool, and the amount of wear of the tool is determined. Setting a wear limit value for the tool length or tool diameter, comparing the wear amount with the wear limit value, and determining that the tool has reached the end of its life when the wear amount becomes larger than the wear limit value. A tool life management method featuring: