JP2004030421A - Nc machine tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an NC machine tool which manages wear of a tool, thermal deformation of a machine, etc., and automatically sets correction values by being equipped with a managing means for wear correction values inputted at proper time during work machining. <P>SOLUTION: The wear correction values by tools which are inputted by an operator during the work machining are stored in the form of a history database together with information specifying a work, the elapsed time from the start of operation of the machine, machining quantities after the tools are replaced, etc., and inputted corrected values or absolute correction values as their integrated values are displayed in a graph while being associated with the elapsed time and machining quantities to store wear correction values inputted to respective machine tools in the machining field of the work. The stored correction values and absolute correction values are usable as data for examining machine characteristics and tool wear characteristics and correction values can automatically be set according to the stored data. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an NC machine tool, and more particularly, to an NC machine tool provided with a means for managing a wear correction value which is input during machining of a workpiece.
[0002]
[Prior art]
When the same work is continuously machined by a machine tool, errors in the machined work change with time due to wear of the tool, thermal deformation of the machine, and the like. In order to correct this error and obtain a work with more accurate dimensions, finish the work by measuring the dimensions of the machined work for a certain period of time or every time a certain number of works are processed, and using a correction value to correct the error from the commanded dimension. Input is performed for each tool to correct the amount of movement of the tool during finishing.
[0003]
FIG. 2 is a diagram showing an example of an input screen for the wear correction value of the NC turret lathe, which is a screen displayed on a display provided in the NC device. On the left side of this screen, the position of the X or B axis of the selected turret is displayed. By clicking the wear button 20 on this screen, a wear correction value input window 21 on the right side of the screen is opened. In this window 21, correction value input boxes 12, 13,... In the X-axis direction (direction perpendicular to the main axis) and the Y-axis direction (main axis direction) are provided for each of the tools W1, W2,. The operator actually measures the machined workpiece and, for example, if the diameter of the workpiece is larger than the target value by 10 microns, the operator inputs -10 in the input box in the X-axis direction of the tool. Since the type of the finishing tool to be used is known depending on the processing part of the work, a correction value for canceling the error of the part is input to the input boxes 12, 13,... Of the tool. Then, when the processing of the work is restarted, the turret moves by the corrected feed amount, and the work of the correct size is processed.
[0004]
As another method of correcting tool wear, there is a method called quantitative correction. The quantitative correction is to perform processing by automatically setting a predetermined correction amount every time a predetermined number of workpieces are processed. When there is a large number of machining results of the same workpiece, the relationship between the dimensional error due to tool wear and the number of machining after replacing the tool is linearly approximated, The processing can be performed by automatically setting a fixed amount of correction value each time the processing is performed.
[0005]
The dimensional error of a work generated when a large number of works are processed is largely caused by wear of a tool, but also includes an error caused by thermal deformation of a machine. It is considered that the error due to the wear of the tool is substantially proportional to the number of machining after the tool is replaced. On the other hand, the error due to the thermal deformation of the machine changes depending on the elapsed time after starting the machine and the room temperature, and it is difficult to automatically correct the error based on a simple proportional relationship or the like. According to the former method in which the operator manually inputs a correction value, errors due to thermal deformation of the machine are also corrected, and processing with higher accuracy is possible.
[0006]
[Problems to be solved by the invention]
In the former conventional method, the correction value input by the operator is used only in the subsequent processing of the work, and when a new correction value is input, the absolute correction value is changed with that value, and thereafter, Of the workpiece. Therefore, the input correction value history data does not remain in the NC device or a personal computer connected to the NC device. For this reason, most of the correction value data input when processing a certain workpiece is erased without being recorded, and only limited data such as when performing test machining and tool tests is recorded by the operator. Therefore, there is a problem that data indicating behaviors such as tool wear and thermal deformation of a machine when working various types of workpieces is not accumulated. The accumulation of such data is based on where the machine temperature is measured to compensate for thermal deformation, what kind of material and what shape is used when machining a workpiece, It is an important source of information for considering whether to process in such a procedure.
[0007]
[Means for Solving the Problems]
According to the present invention, a wear correction value for each tool input by an operator at the time of machining a workpiece, information for identifying a workpiece such as a machining program name, an elapsed time after starting operation of a machine, and after a tool is exchanged. By storing the input correction value or the absolute correction value, which is an integrated value thereof, in association with the elapsed time and the number of processed pieces in a graph, the respective correction values are stored together with the number of processed pieces and the like as a history database. The above-mentioned problem has been solved by accumulating the wear correction values input in the above section so that they can be used as data when examining mechanical characteristics and tool wear characteristics.
[0008]
An NC machine tool according to the invention of claim 1 of the present application is an NC machine tool provided with input means for a correction value for a tool movement amount commanded from a machining program. History database creating means for sequentially storing the absolute correction value, which is the integrated value, together with the number of processed workpieces after the tool change and the elapsed time since the start of the machine tool; and the number of processed or elapsed stored correction values or the absolute correction values. Graph display means for displaying a change with respect to time in a graph on a display of the NC device.
[0009]
According to a second aspect of the present invention, in the NC machine tool having the above configuration, the history database creating means creates a history database of the correction value or the absolute correction value for each type of work. .
[0010]
According to a third aspect of the present invention, there is provided an NC machine tool having the configuration according to the first or second aspect, wherein an arithmetic means for associating the stored correction value or absolute correction value with the number of processed workpieces and the elapsed time; When an input is instructed, an automatic correction value setting means is provided for automatically setting a correction value obtained by the calculation means from the number of processed workpieces or the elapsed time in the current work processing.
[0011]
The arithmetic means may be a universal method of generating an arithmetic expression and performing an operation using the arithmetic expression, but more simply, for example, the following means is possible. Generally, a correction value is input every time a fixed number of workpieces are processed, and thus, for example, correction value data for 100, 200, 300,... Are accumulated. In other words, if the number of processes is 100 for each tool change, a plurality of data for 100 are stored together with the elapsed time. Therefore, it is possible to plot the correction value obtained after machining 100 pieces as a function of the elapsed time, approximate those data to a straight line or a quadratic curve, and input the elapsed time at the time of the current machining into this approximate expression. Thus, a wear correction value to be automatically corrected can be obtained. The correction value in each case where the number of processes is 200, 300,... Can be obtained by the same method. The automatically set correction value is not registered in the history database.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings, taking an NC lathe as an example. FIG. 1 is a diagram schematically showing a hardware configuration. Reference numeral 1 denotes a headstock, 2 denotes a work chuck mounted on a spindle supported by the headstock 1, and 3 denotes a work gripped by the work chuck 2. Work, 4 is a turret tool post, 5 is a tool mounted on the turret tool post, 6 is a Z feed motor that feeds the turret tool post in the spindle direction, 7 is an X feed motor that sends the turret tool post 4 in the direction perpendicular to the spindle. Reference numeral 8 denotes an NC device that controls the Z feed motor 6 and the X feed motor 7, 9 denotes a display of the NC device, and 10 denotes an operation panel of the NC device. Z) is provided.
[0013]
In the NC device 8, in addition to the conventional feed amount correction means, correction value input screen display means, and correction value setting means, history database creation means, graph display means, calculation means, and automatic correction value setting means are registered. ing. The feed amount correction means adds (or subtracts) the absolute correction value set to the feed amount calculated by the machining program, and passes it to the drivers of the feed motors 6 and 7. The correction value input screen display device displays a correction value input screen as shown in FIG. 2 on the display 9 of the NC device. The correction value setting means changes the absolute correction value set by reading the numerical values in the input boxes 12 and 13 when the enter key 11 of the correction value input means is pressed.
[0014]
The data items of the history database storing the correction values include, for example, a work ID, the number of processed parts, an elapsed time, an X-axis correction value, a Z-axis correction value, an X-axis absolute correction value, and a Y-axis absolute correction value, as shown in FIG. , Date, etc. The work ID can be obtained from the machining program being executed. The elapsed time and the number of processes are read from the management data of the NC device. The X-axis correction value and the Y-axis correction value are read from the input boxes 12 and 13, respectively, and the X-absolute correction value and the Y-absolute correction value are the correction values newly input to the currently set absolute correction value. It is obtained by addition and subtraction. A new record in the history database is additionally recorded by the history database creating means every time the operator inputs a correction value and presses a confirmation button when a predetermined correction value is input. This history database file is created for each tool and / or work to be used, or one file is used as a search key using the tool ID and the work ID.
[0015]
The graph display means, when commanded to display a graph of the correction value, searches the history database for a corresponding tool of the corresponding work based on the work ID and the tool ID given as arguments, and displays the elapsed time on the horizontal axis. The change in absolute correction value in each of the X and Y directions is displayed on the vertical axis as shown in FIG. When the continuous processing of the same work is repeated many times, the correction value data is accumulated in the history database, and the graph 14 is created using the average value thereof. This graph shows characteristics such as thermal deformation of the machine, wear of the tool, and the amount of error of each machine, so that it can be used to improve the machine to reduce machining errors and improve the machining method. Can be planned.
[0016]
When data is accumulated in the history database, it becomes possible to automatically set a correction value based on the data. The automatic correction value setting means searches the history database for correction value data corresponding to the number of processed workpieces for each tool when the number of processed workpieces after the tool change has reached the number at which correction values should be input. When a plurality of records are detected from the history database, the calculating means approximates the relationship between the elapsed time of each record and the correction value with a straight line or a quadratic curve, and substitutes the current machine elapsed time to obtain the correction value. Is automatically obtained, and the correction value automatic setting means sets the value in the NC device. The automatically calculated correction value is not registered in the history database. Since the correction value set in this way is a correction value that includes the thermal deformation of the machine and the error amount specific to each machine, a correction value with much higher accuracy than the conventional quantitative correction is automatically input. It becomes possible to do.
[Brief description of the drawings]
FIG. 1 is a block diagram of an embodiment apparatus. FIG. 2 is a diagram showing an example of a correction value input screen. FIG. 3 is a diagram showing an example of items in a history database. FIG. 4 is a diagram showing an example of a graph display screen. Description]
8 NC device 9 Display 10 Operation panel 11 Enter key 12, 13 Input box 14 Graph

Claims (3)

In an NC machine tool equipped with a means for inputting a correction value for a tool movement amount commanded from a machining program, every time a correction value is input, the correction value or an absolute correction value as an integrated value of the correction value is input to the workpiece after the tool change. History database creating means for sequentially storing the number of processed pieces and the elapsed time after the start of the machine tool, and graph display means for graphically displaying on the display of the NC device a change in the stored correction value or absolute correction value with respect to the number of processed pieces or the elapsed time. An NC machine tool comprising: 2. The NC machine tool according to claim 1, wherein said history database creating means creates a history database of said correction values or absolute correction values for each type of workpiece. Calculating means for associating the stored correction value or absolute correction value with the number of processed pieces and elapsed time; and calculating means for calculating the number of processed pieces or elapsed time in the current workpiece processing when a correction value input is instructed. The NC machine tool according to claim 1, further comprising: a correction value automatic setting unit configured to automatically set the correction value.

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