WO2024218842A1 - Control device and computer-readable storage medium - Google Patents

Abstract

This control device stores instructions for executing a process to: analyze a machining program; on the basis of an analysis result of the machining program, calculate a command value for each output command-period of a machining head of a machine tool; detect a change point at which a change in the command value of the control device occurs in a control period of the machine tool; and corrects a command so as to change the output of the machining head in a control period before the control period of a first candidate that includes the change point.

Description

Control device and computer readable storage medium

The present disclosure relates to a control device and a computer-readable storage medium.

　Conventionally, there are machine tools such as laser processing machines, water jet processing machines, and plasma processing machines that perform non-contact processing by applying energy such as light or water pressure to the surface of the workpiece.

Laser and water jet machines have the advantage of producing beautifully finished cut surfaces and high processing accuracy. However, generally speaking, increasing the processing speed reduces processing accuracy. There are also control device technologies that can improve the accuracy and speed of laser processing machines. For example, see Patent Document 1.

JP 2004-167549 A

One of the factors that affects the machining accuracy of non-contact machining is the discrepancy between the control cycle of the machine tool and the command cycle of the control device. If the control cycle of the machine tool is larger than the command cycle of the control device, a delay may occur between when the control device outputs a command and when the command is actually executed. This delay affects the machining accuracy.

In the field of control devices, there is a demand for improved speed and accuracy in non-contact processing machines.

The control device according to one aspect of the present disclosure includes a program analysis unit that analyzes a machining program, an interpolation unit that calculates a command value for each command cycle of the output of the machining head of the machine tool based on the analysis results of the machining program, and a command correction unit that identifies the control cycle of the machine tool in which command switching occurs, calculates the energy to be commanded during the control cycle, and calculates a correction value for the command value so that the calculated energy is equal to the energy output from the machining head during the control cycle.

FIG. 2 is a block diagram of a control device. 11 is a graph showing changes in output of a conventional machining head. FIG. 13 is a schematic diagram illustrating excessive cutting. 11 is a graph illustrating the relationship between the amount of change in output of the machining head and the response time. 11 is a graph illustrating the output of the machining head at the start of a first candidate control period and a change in the output. 11 is a graph illustrating a method of correcting a command. 11 is a graph illustrating a method of correcting a command. 11 is a graph illustrating an example in which the amount of change in output of the machining head is large. 11 is a graph illustrating an example of adjusting the output of a machining head in stages over a plurality of control periods. 4 is a flowchart illustrating the operation of the control device. 13 is a graph showing a change in output of the machining head when a command value is set to "0". 11 is a graph showing a change in output of a machining head when a command value is set to a minimum value of an effective output. FIG. 2 is a hardware configuration diagram of a control device.

This embodiment can be applied to a control device 100 that controls a machine tool that processes the surface of a workpiece in a non-contact manner, such as a laser processing machine, a water jet processing machine, or a plasma processing machine. In this embodiment, as an example, an example will be described in which the control device 100 controls the laser output of a laser processing machine.

FIG. 1 is a block diagram showing the configuration of the control device 100. The control device 100 includes a program analysis unit 11, an interpolation unit 12, a command correction unit 13, and a command output unit 14.

The program analysis unit 11 analyzes the machining program and calculates the path of the machining head, the speed of the machining head, the timing of turning the laser on and off relative to the position of the machining head, etc. The program analysis unit 11 may also calculate the path of the table and the speed of the table.

The interpolation unit 12 calculates a command value per command cycle. This includes turning the laser on and off for each command cycle. In position control, the path of the machining head is divided into movement amounts in minute time units, and the movement amounts are calculated as command values. The interpolation unit 12 calculates a command value for the output of the machining head for each command cycle, based on the position of the machining head determined by position control.

The command correction unit 13 corrects the difference between the time when the control device 100 issues a command and the time when the change in the output ends.
The graph in Figure 2 shows the relationship between the command and output of a conventional control device. The horizontal axis of the graph shows time. On the horizontal axis, the scale with short time intervals shows the command period of the control device 100, and the scale with long time intervals shows the control period of the output of the machining head.

The command period of the control device 100 is shorter than the control period of the machining head. Therefore, a discrepancy occurs between the command period of the control device 100 and the control period of the machining head. For example, when the control device 100 issues a command to set the command value to "v" at the position indicated by the arrow in Figure 2 (hereinafter referred to as command "A"), the machine tool starts executing the command in the next control period.

To change the output of the machining head according to a command, it takes a response time according to the amount of change until the command value is reached. In the case of Figure 2, the output reaches the command value at the position indicated by arrow B. There is a discrepancy between the time "T" of command "A" and the time "B" when the output changes to the command value.

Misalignment can cause excessive cutting, as shown in Figure 3, and affect machining accuracy. For example, in fly-cutting, the cutting head moves at high speed and the cutting area is controlled by turning the output on and off. When the cutting head moves at high speed, excessive cutting increases and the effects of misalignment become greater.

The command correction unit 13 detects the change point of the command value and corrects the command timing and command value at the change point so that the output of the machining head approaches the command value.

A response function is used to correct the command. The response function formula is shown below.

The response function is a function of the amount of change in output and time. In the response function, W is the amount of change in output, and T is the response time. The response function is known based on the specifications of the processing head, etc.
It is assumed that the response time depends on the amount of change in the command. In other words, the larger the amount of change, the longer the response time. In the upper graph of Figure 4, the response time is large in response to the amount of change in the command, and in the lower graph, the response time is small in response to the amount of change in the command.

The relationship between the output of the machining head at the start of the first candidate control period and the output of the machining head after the first response time "T ₁ " will be described with reference to Fig. 5. The command value changes with command "A". The command value of command "A" is "v", and the time when the control device 100 outputs command "A" is "T".
In the following description, the control period including the change point is referred to as the "first candidate" control period, and the control period immediately preceding the first control period is referred to as the "second candidate" control period. The control periods immediately preceding the first control period are successively referred to as the "third candidate" control period, the "fourth candidate" control period, and so on. The control period following the change point is referred to as the "pre-correction" control period.

The command correction unit 13 calculates the time from the start of the first candidate control period to the command "A". This time is called the first response time "T ₁ ". The command correction unit 13 uses a response function to determine the amount by which the output of the machining head changes during the first response time (the first amount of change "Q ₁ ").

If the command period of command "A" is corrected to the second candidate control period, the machine tool executes command "A" at the start of the first candidate control period. The output of the machining head at the start of the first candidate control period will be (1), (2), and (3).

When the command period of command "A" is corrected to the second candidate control period of the first candidate (the control period immediately preceding the control period of the first candidate), execution of command "A" starts at the start of the control period of the first candidate. When execution of command "A" starts at the start of the control period of the first candidate, the time at which command value "v" is reached differs in each of the cases (1), (2), and (3).
In the case of (1), the output at the start of the control period of the first candidate is equal to the sum "v+ _Q1 " of the command value "v" of the command " _A " and the first change amount "Q1". In this case, the time "T" at which the control device 100 plans to issue the command "A" coincides with the time at which the output of the machining head reaches the command value "v".
In the case of (2), the output of the first candidate control period is greater than the sum "v+ _Q1 " of the command value "v" of the command "A" and the first change amount " _Q1 ". In this case, the output of the machining head reaches the command value "v" after time "T".
In the case of (3), the output of the first candidate control period is smaller than the sum "v+ _Q1 " of the command value "v" of the command "A" and the first change amount " _Q1 ". In this case, the output of the machining head reaches the command value "v" before the time "T".

　As with conventional methods, when execution begins in the next control cycle of command "A", the output of the machining head reaches command value "v" at the time indicated by arrow B. By correcting the timing of command "A" to be earlier by one control cycle, the time at which the output of the machining head reaches command value "v" can be brought closer to the time "T" at which command "A" is scheduled to be issued. This makes it possible to reduce the distance of excessive cutting.

The command correction unit 13 combines a plurality of commands to more accurately bring the time at which the output of the machining head reaches the command value "v" closer to the time "T".
When the output of the machining head at the start of the control period of the first candidate is (2) or (3), the command correction unit 13 corrects the command "A" using multiple commands. Specifically, the output of the machining head is adjusted stepwise over multiple control periods so that the output of the machining head at the start of the control period of the first candidate becomes "v+ _Q1 ."

A method of correcting the command will be described with reference to FIGS.
When the output of the machining head at the start of the first candidate control cycle is (2), the command correction unit 13 corrects the command "A" based on the machining program to a combination of command "D" and command "E", as shown in Figure 6.
The timing for issuing the command "D" is during the control period of the third candidate, and the command value is "v+ _Q1 ."The timing for issuing the command "E" is during the control period of the second candidate, and the command value is "v."
By correcting the command in this way, the machine tool obtains command "D" in the third candidate control period. The machine tool starts executing command "D" at the start of the second candidate control period. In accordance with command "D", the machine tool reduces the output of the machining head to the command value "v+ _Q1 ".
The machine tool obtains command "E" in the second candidate control period. The machine tool starts executing command "E" at the start of the first candidate control period. The machine tool reduces the output of the machining head in accordance with command "E". The output of the machining head reaches command value "v" at time "T".

When the output of the machining head at the start of the first candidate control cycle is (3), the command correction unit 13 corrects the command "A" based on the machining program to a combination of command "F" and command "G", as shown in Figure 7.
The timing for issuing the command "F" is during the control period of the third candidate, and the command value is "v+ _Q1 ."The timing for issuing the command "G" is during the control period of the second candidate, and the command value is "v."
By correcting the command in this way, the machine tool obtains command "F" in the third candidate control period. The machine tool starts executing command "F" at the start of the second candidate control period. In accordance with command "F", the machine tool increases the output of the machining head to the command value "v+ _Q1 ".
The machine tool obtains command "G" in the second candidate control period. The machine tool starts executing command "G" at the start of the second candidate control period. The machine tool reduces the output of the machining head in accordance with command "G". The output of the machining head reaches command value "v" at time "T".

The command correction unit 13 can also correct the command by combining three or more control cycles. For example, as shown in Fig. 8, when the change amount of the command is large and the output of the machining head does not reach "v+ _Q1 " during the second candidate control cycle, the command correction unit 13 corrects the command "A" to a combination of commands of three or more control cycles.

When the change in output is large, the command correction unit 13 adjusts the output of the machining head in stages over multiple control periods. Fig. 9 shows an example of adjusting the output of the machining head in two stages, the control period of the second candidate and the control period of the third candidate. In order to control the output in stages, the command correction unit 13 issues a command "H" to the machine tool in the control period of the fourth candidate and a command "D" in the control period of the third candidate. The command value of the command "H" is not particularly limited. It is sufficient that the output of the machining head reaches "v+ _Q1 " by the start of the control period of the first candidate.

The operation of the control device 100 will be described with reference to the flowchart in FIG. 10. The program analysis unit 11 analyzes the machining program (step S1). The analysis results of the program analysis unit 11 include the path of the machining head, the speed of the machining head, and the command value for the output of the machining head.

The interpolation unit 12 divides the path of the machining head into minute movement amounts and calculates command values for the output of the machining head at the divided coordinates (step S2).

The command correction unit 13 detects a change point of the command value (step S3). The command correction unit 13 selects a command correction method (step S4). The command correction method includes a method of advancing the command by one control cycle, and a method of adjusting the output of the machining head using multiple control cycles.

If the method of advancing the command by one control period is selected (step S5; Yes), the command correction unit 13 moves the timing of the command "A" to the second candidate control period (step S6). The output of the machining head changes according to the response characteristics as shown in (1), (2), and (3) of Figure 5, and reaches the command value "v".

When the method of adjusting the output of the machining head using multiple control periods is selected (step S5; No), the command correction unit 13 corrects the command "A" across multiple control periods so that the output of the machining head in the second candidate control period becomes "v+ _Q1 " and the output of the machining head in the first candidate control period becomes "v" (step S7). The command output unit 14 outputs the command corrected by the command correction unit 13 to the machine tool.

As described above, the control device 100 detects a change point of a command that changes the output of the machining head, and moves the timing of the command "A" to one control cycle before the first candidate control cycle (the control cycle of the first candidate) so that the command is executed in the control cycle before the change point (the control cycle of the first candidate). Furthermore, the command correction unit 13 calculates a first response time from the control cycle of the first candidate and the time "T" of the command "A", and calculates a first change amount "Q ₁ " based on the first response time. The command correction unit 13 corrects the command value of the second candidate control cycle or a plurality of commands including the control cycle of the second candidate so that the output of the machining head at the start of the control cycle of the first candidate becomes the sum "v + Q ₁ " of the command value "v" of the command "A" and the first change amount "Q ₁ ".
This allows the timing at which the control device 100 issues a command to coincide with the timing at which execution of the command is completed, eliminating any discrepancy between the two timings, thereby improving machining accuracy.

It should be noted that the difference between the two timings does not necessarily have to be perfectly matched. It is sufficient to simply correct the command and reduce the amount of difference. Reducing the amount of difference will improve machining accuracy.

Next, a specific example of the command value "v" will be given.
11 shows the change in output of the machining head when the command value is set to "0". As a premise, a command "A" before correction based on the machining program is a command to turn off the output of the machining head. The command "A" before correction commands a command value of "0" at time "T".
The command correction unit 13 corrects this command "A" into two commands, command "D" and command "E". The timing for issuing command "D" is the control cycle of the third candidate, and the command value is " _Q1 ". The machine tool executes command "D" at the start of the control cycle of the second candidate, and the output of the machining head becomes " _Q1 " during the control cycle of the second candidate. The timing for issuing command "E" is the control cycle of the second candidate, and the command value is "0". The machine tool executes command "E" at the start of the control cycle of the first candidate. The output of the machining head decreases in accordance with the response characteristics, and reaches the command value "0" at time "T".

Alternatively, the output of the machining head can be turned off using the effective output. If the minimum value of the effective output is "min", cutting will be turned off below the minimum value "min" even if the output of the machining head has not reached "0". In order to reach "min" at time "T", the output at the start of the control period of the first candidate should be "min+ _Q1 ".

A method of correcting a command will be described with reference to Fig. 12. The command correction unit 13 corrects the command "A" into two commands, a command "H" and a command "I". The timing for issuing the command "H" is during the control period of the third candidate, and the command value is "min+ _Q1 ". The machine tool acquires the command "H" in the control period of the third candidate. The machine tool starts executing the command "H" at the point in time of the control period of the second candidate. The machine tool reduces the output of the machining head to the command value "min+ _Q1 " in accordance with the command "H".
The timing for issuing command "I" is the command value "0" during the second candidate command cycle. The machine tool acquires command "I" in the second candidate control cycle. The machine tool starts executing command "I" at the start of the first candidate control cycle. The machine tool reduces the output of the machining head in accordance with command "I". The output of the machining head decreases by a first change amount "Q ₁ " in a first response time. The output of the machining head reaches the minimum effective output value "min" at time "T". Even after time "T" has passed, the output of the machining head continues to decrease until the command value becomes "0".
If the output is less than the minimum effective output value "min", no machining is performed. The command correction unit 13 regards the portion below the minimum value as the end of output and performs correction.

Below, the hardware configuration of the control device 100 to which this disclosure is applied will be described. FIG. 13 is a hardware configuration diagram of the control device 100. As shown in FIG. 13, the control device 100 comprises a CPU 111 that controls the entire control device 100, a ROM 112 that records programs and data, and a RAM 113 for temporarily expanding data, and the CPU 111 reads out a system program recorded in the ROM 112 via a bus and executes a workaround in accordance with the system program.

The non-volatile memory 114 retains its stored state even when the control device 100 is powered off, for example by being backed up by a battery (not shown). The non-volatile memory 114 stores various data such as programs read from the external device 120 via the interfaces 115, 118, and 119 and operation inputs entered via the input unit 30. The non-volatile memory 114 may store programs and data for executing the control device 100 of this embodiment.

The interface 115 is an interface for connecting the control device 100 to an external device 120 such as an adapter. Programs, various parameters, and the like are read from the external device 120.
The interface 118 is an interface for connecting the control device 100 to a display unit 70 such as a liquid crystal display. The display unit 70 displays various data loaded into the memory, data obtained as a result of executing a program, and the like.
The interface 119 is an interface for connecting the control device 100 to an input unit 30 such as a keyboard, a pointing device, etc. The input unit 30 passes instructions, data, etc. based on operations by an operator to the CPU 111 via the interface 119.

Although the present disclosure has been described in detail, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible to these embodiments without departing from the gist of the present disclosure, or without departing from the gist of the present disclosure derived from the contents described in the claims and their equivalents. These embodiments can also be implemented in combination. For example, in the above-mentioned embodiments, the order of each operation and the order of each process are shown as examples, and are not limited to these.

The following supplementary notes are further disclosed regarding the above-described embodiment and modified examples.
(Appendix 1)
The control device (100) comprises a program analysis unit (11) that analyzes a machining program, an interpolation unit (12) that calculates a command value for each command period of the output of the machining head of the machine tool based on the analysis results of the machining program, and a command correction unit (13) that detects a change point at which a change in the command value of the control device occurs in the control period of the machine tool, and corrects the command so as to change the output of the machining head in a control period including the change point, which is a control period earlier than a first candidate control period.
(Appendix 2)
The command correction unit (13) calculates a first response time between the start point of the first candidate control period and the time when the command value changes, calculates a first amount of change by which the output of the machining head changes during the first response time, and corrects the command to be executed in the second candidate control period so that the output of the machining head in a second candidate control period that is one period before the first candidate control period becomes the sum of the first amount of change and a predetermined value.
(Appendix 3)
The predetermined value is a changed command value of the first candidate control period.
(Appendix 4)
The predetermined value is the minimum value of the effective output of the processing head.
(Appendix 5)
The command correction unit (13) adjusts the output of the machining head in a plurality of control cycles including the second candidate, and corrects the command so that the output of the machining head in the control cycle of the second candidate becomes the sum of the first change amount and the specified value.
(Appendix 6)
The storage medium (112, 113, 114) stores instructions to cause one or more processors (111) to execute the following process: analyzing a machining program, calculating a command value for each command period of the output of the machining head of the machine tool based on the analysis results of the machining program, detecting a change point at which a change occurs in the command value of the control device in the control period of the machine tool, and correcting the command to change the output of the machining head in a control period that is earlier than a first candidate control period that includes the change point.

Reference Signs List 100 Control device 11 Program analysis unit 12 Interpolation unit 13 Command correction unit 14 Command output unit 111 CPU
112 ROM
113 RAM
114 Non-volatile memory

Claims (6)

A program analysis unit that analyzes a machining program;
an interpolation unit that calculates a command value for each command period of an output of a machining head of a machine tool based on an analysis result of the machining program;
a command correction unit that detects a change point at which a change occurs in a command value of the control device in a control period of the machine tool, and corrects a command to change an output of the machining head in a control period including the change point that is earlier than a first candidate control period;
A control device comprising: The control device according to claim 1, wherein the command correction unit determines a first response time between the start of the control period of the first candidate and the time at which the command value changes, determines a first amount of change in the output of the machining head during the first response time, and corrects the command to be executed in the control period of the second candidate so that the output of the machining head in the control period of a second candidate that is one period before the control period of the first candidate is the sum of the first amount of change and a predetermined value. The control device according to claim 2, wherein the predetermined value is a changed command value of the first candidate control period. The control device according to claim 2, wherein the predetermined value is the minimum effective output of the machining head. The control device according to claim 2, wherein the command correction unit adjusts the output of the machining head in a plurality of control periods including the second candidate, and corrects the command so that the output of the machining head in the control period of the second candidate becomes the sum of the first change amount and the predetermined value. One or more processors,
Analyze the machining program,
Calculating a command value for each command cycle of the output of the machining head of the machine tool based on the analysis result of the machining program;
detecting a change point at which a change occurs in a command value of a control device in a control period of a machine tool, and correcting the command so as to change the output of the machining head in a control period that is earlier than a first candidate control period that includes the change point;
A computer-readable storage medium that stores instructions for executing a process.

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