JPS62271653A - Adaptive control device for machine tool - Google Patents

Abstract

PURPOSE:To perform adaptive control according to an optimum control pattern suitable for a processing spot and a processing shape, by a method wherein, based on information contained in numerical control data, automatic switching between load-specifying type adaptive control and load-following type adaptive control. CONSTITUTION:Based on tool information contained in numerical control data, a discriminating means D discriminates whether load-specifying control or load- following control is to be effected. When it is decided that load-specifying control is to be made, a specified constant target load value is read by a target load value reading means E, and a speed control means F regulates a feed speed so that a load detected by a processing load detecting means A is regulated to a specified value. When it is discriminated that load-following control is to be made, a target load value changed with the progress of processing set and stored in a set memory means C is orderly read by the speed control means F, and the speed control means F regulates a feed speed so that a load detected by the processing load detecting means A is adjusted to a target load value from the set memory means C.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention (Field of Industrial Application) The present invention provides a machine tool that detects a machining load and converts the feed rate according to the detected machining load. The present invention relates to an adaptive control device.

<Conventional technology> In recent years, so-called adaptive control devices have been used in numerically controlled machine tools to control the feed rate of the tool according to changes in the machining load applied to the tool, in order to machine the workpiece under optimal conditions. Now you can. General adaptive control includes load following control that samples and stores the machining load during model machining and controls the feed rate so that the machining load during machining becomes the load during model machining to extend tool life. There is constant load control, which shortens machining time by controlling the feed so that the load is constant during machining, but conventional adaptive control devices have been equipped with only one of these control functions.

<Problems to be solved by the invention> Therefore, in conventional devices, it is not possible to change the characteristics of adaptive control in response to changes in the workpiece or the tools used, and it is not possible to Optimal adaptive control could not be performed.

<Means for solving the problem> The present invention comprises a processing load detection means A for detecting processing load;
A setting storage means C for setting and storing a constant target load value and a target load value that changes as machining progresses, and load follow-up control to determine whether feed control with a constant load should be performed based on information included in the numerical control data. If it is determined by this determining means that constant load control should be performed, a constant target load value set in the setting storage means C is read out, and the constant load control is determined by the determining means. target load value reading means E for reading out a target load value corresponding to the progress of machining from the setting storage means C when it is determined by the means that load follow-up control should be performed; and the machining load detecting means. The apparatus is characterized in that a speed control means F is provided for increasing or decreasing the feed speed so that the machining load detected at point A becomes the target load value read out by the target load value reading means E.

Based on the tool information included in the numerical control data, the determining means determines whether constant load control or load following control should be performed. When it is determined that constant load control should be performed, a constant target load value is read out by the target load value reading means, and the speed control means F sets the load detected by the machining load detection means A to a constant value. Increase or decrease the feed speed so that If it is determined that load follow-up control is to be performed, the speed control means F sequentially reads out the target load values set and stored in the setting storage means C, which change depending on the progress of machining, and the speed control means F increases or decreases the feed rate so that the load detected by the machining load detection means A becomes the target load value that can be sequentially read out from the setting storage means C.

<Example> Embodiments of the present invention will be described below based on the drawings.

In FIG. 2, lO is a numerical control device, and this numerical control device 10 includes servo motor drive circuits DUX, DUY.
, DUZ, and sequence controller 11 are connected via a circuit interface.

On the other hand, 20 is a machining center type machine tool 111Il controlled by the numerical control device 10, and the machining is performed by the rotation of the servo motors 21°22.23 driven by the servo motor drive circuits DUX, DUY, DUZ (7), respectively. a workpiece table 25 that supports the object W;
The relative position between the main shaft 26 driven by the main shaft motor SM and the main shaft head 24 is changed three-dimensionally. Further, 27 is a tool magazine that holds multiple types of tools, and the magazine indexing device and tool changing device 28 of the circuit.
The tools in the tool magazine 27 are selectively moved to the spindle 2 by
6, and the workpiece W is processed.

The sequence controller 11 is connected to a personal computer 12, which serves as an adaptive control device, and a spindle motor drive circuit 15, which controls the rotational speed of the spindle motor SM. This personal combinator 12 includes a microprocessor 12a, a clock signal generation circuit 12b, and a ROM.
It is mainly composed of an I2c, a RAM 12d, and a fixed disk 12e.

A machining load detection circuit 16 is interposed between the spindle motor drive circuit 15 and the spindle motor SM, which detects the current supplied to the spindle motor SM and outputs a voltage proportional to the detected current. The load signal output from this load detection circuit 16 is connected to the personal computer 12 via an AD converter 17 and an interface 12g.

Fixed disk 126 of the personal combinator 12
As shown in FIG. 3(a), there are multiple storage areas CDAI-CDA9 for setting and storing target load values for each tool.
9 is memorized. These multiple storage areas CDA1~
As shown in Figure 3), each CDA99 has
Control mode, sampling interval, number of signal samplings, sampling data, and threshold values are stored.

Selection of the data stored in these storage areas CDA I-CDA99 is performed by a T code included in the numerical control program. In this embodiment, the T code is composed of 5 digits, and the upper 2 digits are the storage area CDAl.
~CDA99 is selected, and the lower three digits are used to select the tool to be used.

Writing of data to each of the storage areas CDAl to CDA99 is performed via the keyboard 14 of the personal computer 12, but a large number of sampling data for load follow-up control are processed by model processing to keep the processing load constant at this time. It is obtained by sampling every hour. Note that in the case of constant load control, the target load value is written at the position where sampling data 1 is written.

When the execution of the numerical control program is started, the microprocessor 12a of the personal computer 12 starts the process shown in FIG. 11 to the personal computer 12, the microprocessor 12a
The data in the storage area specified by the upper two digits of the code is read from the fixed disk 12e (41), (42
).

Thereafter, it is determined whether the adaptive control mode is constant load control or load following control based on the control mode data in the selected storage area (43).

Then, if it is constant load control, set the constant load mode flag (44), and if it is load following control, reset the constant load mode flag (45).The M code that commands the start of adaptive control is a numerical value. This data is read by the control device 10 and sent to the sequence controller 1.
1 to the personal computer 12 via the microprocessor 1 of the personal computer 12.
2a sets time data corresponding to the sampling interval in the clock generation circuit 12b, and causes the microprocessor 12a to interrupt at time intervals corresponding to the sampling interval (47), (48).

The microprocessor 12a executes the process shown in FIG. 4(b),
It is checked whether an M code instructing the end of adaptive control has been sent, and then the control mode is determined based on the state of the constant load mode flag (52).

If the control mode is constant load control, then read out the target load value OL written at the beginning of the sampling data area (53), and set the upper limit value U by adding the threshold value in the positive direction to this value. L, and the lower limit value LL obtained by subtracting the negative threshold value from the target load value55), and then,
The actual load is read from the AD converter 17 (56) and compared with the upper limit value UL and lower limit value LL (57), (59).

If the detected load exceeds the upper limit value UL, the override value output to the numerical control device 10 via the sequence controller 11 is lowered (58), and the detected load is below the lower limit value LL. If so, the override value is increased (60). As a result, as shown in FIG. 5), the feed rate is controlled so that the machining load falls within the constant target addition zone LZ2.

On the other hand, when it is determined that the control mode is load following control, sampling data corresponding to the elapsed time from the start of adaptive control is read from the selected storage area (54).
, Add and subtract positive and negative threshold values to this read sampling data to calculate the upper limit value UL and lower limit value LL55),
The override value is increased or decreased so that the detected machining load falls within the upper and lower limits (56) to (60). As a result, as shown in FIG. 5, the feed rate is controlled so that the machining load falls within a load zone LZl that changes in accordance with load fluctuations during model machining.

In this way, constant load adaptive control and load follow-up adaptive control can be selectively used for each tool, so follow-up control can be performed for tools where cutting tool friction is a problem, reducing machining time. The desired machining location or workpiece can be machined with constant load control.

In the above embodiment, the storage area for the target load data was selected using the upper two digits of the T-code data, but the correspondence between the tool number and the number specifying the storage area is stored as a table, and the T-code can be used to select the storage area for the target load data. The number of the storage area in which the target load data of the specified tool is stored may be detected by referring to the table, or other codes such as M code may be used to select the storage area and set the constant load mode. The load following mode may also be switched.

<Effects of the Invention> As described above, the present invention automatically switches between constant load adaptive control and load-following adaptive control as each tool, machining location, or workpiece changes. Since it can be used, adaptive control can be performed with an optimal control pattern that is consistent with the processing location and processing shape, which has the advantage of realizing highly flexible and optimal adaptive control.

[Brief explanation of the drawing]

Figure 1 is an overall configuration diagram for clearly demonstrating the present invention, Figures 2-
FIG. 5 shows an embodiment of the present invention, FIG. 2 is an overall view of a machine tool equipped with an adaptive control device, and FIG. 3 shows a storage area formed on the fixed disk 12e in FIG. Figure 4 shows the data stored in the storage area.
FIG. 5 is a flow chart showing the operation of the microprocessor 12a in the figure, and FIG. 5 is a time chart showing the difference between load following control and constant load control. DESCRIPTION OF SYMBOLS 10... Numerical control device, 12... Personal computer, 12a... Microprocessor, 12e...
・Fixed disk, 16...Load detection circuit, 17...
AD converter, 20...machine tool.

Claims (1)

[Claims] (1) In an adaptive control device for a machine tool that detects a machining load and changes the feed rate according to the detected machining load, a machining load detection means for detecting the machining load;
Setting storage means for setting and storing a constant target load value and a target load value that changes as machining progresses, and load follow-up control to determine whether feed control with a constant load should be performed based on information included in the numerical control data. and if the determining means determines that constant load control should be performed, a constant target load value set in the setting storage means is read out, and the determining means reads out a constant target load value set in the setting storage means, and when the determining means determines that constant load control should be performed, the determining means target load value reading means for reading out a target load value corresponding to the progress of machining from the setting storage means when it is determined that control should be performed; and a machining load detected by the machining load detection means. an adaptive control device for a machine tool, comprising speed control means for increasing/decreasing the feed speed so that the load value corresponds to the target load value read by the target load value reading means.