JP3810454B2 - CNC tool diameter compensation method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a CNC tool radius correcting method for correcting a tool radius, and more particularly to a CNC tool radius correcting method for correcting a tool radius using a correction vector.
[0002]
[Prior art]
Conventionally, in a CNC (numerical control device) for controlling a machine tool, as a tool radius correction method, a tool is corrected by a path in which an offset amount corresponding to a preset tool radius is corrected with respect to a shape commanded by a command program. There is something to move.
[0003]
FIG. 5 is a diagram showing an example of a tool radius correction method using a correction vector. Here, for example, it is assumed that the command machining path L11 is commanded by command blocks N11, N12, N13, N14, and N15. On the CNC side, when the command block is read, the correction vectors V11, V12, V13, V14 at the end points of the command blocks are calculated based on the tool radius value D11, and the correction vectors V11, V12, V13, V14 are calculated. The tool is moved according to the tool path L11a that connects. Thereby, the operator can create a CNC part program without being aware of the radius value of the tool.
[0004]
However, when a pocket machining command smaller than the tool radius is issued, if the offset corresponding to the tool radius is performed, the workpiece and the tool may interfere with each other, resulting in excessive cutting.
[0005]
FIG. 6 is a diagram illustrating an example of a relationship between a command shape and a correction vector when a pocket machining command smaller than the tool radius is issued. As shown in FIG. 6, when the command machining path L21 is commanded by the command blocks N21, N22, N23, N24, N25, the correction vectors V21, V22, V23, V24 are calculated based on the tool radius D21 as in FIG. Then, the tool path L21a is generated. At this time, if the pocket shape is smaller than the tool radius value D21, the correction vectors V22 and V23 are calculated so as to intersect. When the tool is moved in accordance with the correction vectors V22 and V23, the workpiece and the tool interfere with each other, and the actual machining shape L22 becomes a shape cut more than the command machining path L21 as shown in FIG.
[0006]
Therefore, in the conventional tool radius correction method, when the correction vector is calculated as shown in FIG. 6, the movement direction of the command machining path and the tool path after the offset process is in the range of 90 ° to 270 °. If it is different, it is determined that the tool interferes with the workpiece, and the machining is stopped as an alarm immediately before the end of N21, that is, the movement of N22 is started.
[0007]
[Problems to be solved by the invention]
However, at the actual machining site, a rough machining is performed by selecting a tool compensation amount larger than the actual tool radius at the roughing stage, and then gradually finishing the tool compensation amount closer to the actual tool. There is. In this method, since the actual tool radius is small with respect to the correction amount in the rough machining, there is a case where there is no actual harm even if it is determined as tool interference. In this case, the fact that the machining is determined to be a tool interference has a problem in work efficiency.
[0008]
Therefore, conventionally, in addition to the setting for stopping the alarm, it is possible to set the machining to continue as it is based on parameters or the like. However, it is difficult for the operator to determine whether the tool actually interferes, and it is difficult to make the best setting.
[0009]
The present invention has been made in view of these points, and an object of the present invention is to provide a CNC tool radius correction method capable of preventing cutting without stopping machining even when interference is determined. To do.
[0010]
[Means for Solving the Problems]
In the present invention, in order to solve the above-described problem, in a CNC tool radius correction method in which a correction vector is used to correct a tool radius, a plurality of blocks of command blocks in a command program are prefetched, and all the prefetched command blocks When the correction vector of the tool diameter is calculated, and it is determined whether the tool interferes with the workpiece depending on whether the calculated correction vectors intersect with each other. Finding the intersection of the path shifted from the head block of the interfering command block range by the tool radius and the path shifted from the last command block of the interfering command block range by the tool radius to avoid the interference As a new correction vector for each command block, except for the last command block in the interfering command block range, Tsu calculates the interference avoidance vector from the end point to the calculated intersection point of click and performs tool movement control according to the calculated interference avoidance vector, the tool radius compensation method CNC, characterized in that there is provided.
[0011]
Also, it is set whether to execute alarm stop or interference avoidance control. When the alarm stop is set, if interference is determined, the execution of the interference avoidance vector calculation and the movement control is avoided, and the alarm is Try to stop.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing the concept of functions of this embodiment. The preprocessing means 2 pre-reads a plurality of blocks of the command block 1a in which a movement command is made in the command program 1. The correction vector calculation means 3 calculates the correction vector of the tool diameter of the tool 8 for all the pre-read command blocks 1a. The interference determination unit 4 determines the interference of the tool 8 with the workpiece 9 based on the calculated correction vector. When it is determined that interference occurs, the interference avoidance vector calculation means 5 calculates an interference avoidance vector as a new correction vector for avoiding interference. The movement control means 6 drives the servo motor 7 in accordance with the calculated interference avoidance vector and controls the movement of the tool 8.
[0013]
FIG. 2 is a block diagram showing a schematic configuration of hardware of a CNC (numerical control apparatus) according to the present embodiment. The CNC is configured around the processor 11. The processor 11 controls the entire CNC according to the system program stored in the ROM 12. As the ROM 12, an EPROM or an EEPROM is used.
[0014]
The RAM 13 uses an SRAM or the like and stores temporary calculation data, display data, input / output signals, and the like. The non-volatile memory 14 uses a CMOS backed up by a battery (not shown), and stores parameters, command programs, tool radius correction data, pitch error correction data, and the like that should be retained even after the power is turned off.
[0015]
The CRT / MDI unit 20 is disposed on the front surface of the CNC or the same position as the machine operation panel, and is used for displaying data and graphics, inputting data, and operating the CNC. The graphic control circuit 21 converts digital signals such as numerical data and graphic data into raster signals for display and sends them to the display device 22, which displays these numerical values and graphics. As the display device 22, a CRT or a liquid crystal display device is used.
[0016]
The keyboard 23 includes numeric keys, symbolic keys, character keys, and function keys, and is used for creation and editing of machining programs and operation of the CNC. The software key 24 is provided in the lower part of the display device 22, and its function is displayed on the display device. If the screen of the display device changes, the function of the software key changes corresponding to the displayed function.
[0017]
The axis control circuit 15 receives an axis movement command from the processor 11 and outputs an axis movement command to the servo amplifier 16. The servo amplifier 16 amplifies this movement command, drives a servo motor coupled to the machine tool 30, and controls the relative movement of the tool of the machine tool 30 and the workpiece. Note that the number of axis control circuits 15 and servo amplifiers 16 are provided corresponding to the number of axes of the servo motor.
[0018]
A PMC (programmable machine controller) 18 receives an M (auxiliary) function signal, an S (spindle speed control) function signal, a T (tool selection) function signal, and the like from the processor 11 via the bus 19. These signals are processed by a sequence program and output signals are output to control pneumatic devices, hydraulic devices, electromagnetic actuators, etc. in the machine tool 30. In addition, in response to signals such as a button signal, a switch signal, and a limit switch of a machine operation panel in the machine tool 30, a sequence process is performed, and a necessary input signal is transferred to the processor 11 via the bus 19.
[0019]
In FIG. 2, the spindle motor control circuit, the spindle motor amplifier, and the like are omitted.
In the above example, one processor 11 has been described. However, a multiprocessor configuration may be used by using a plurality of processors.
[0020]
Next, a specific process for the tool diameter correcting method of this embodiment will be described. FIG. 3 is a diagram showing an example of a machining shape and a correction vector for explaining the tool radius correcting method of the present embodiment. In this embodiment, when the machining shape is given by the command program as shown in the figure, the previous command block is read and decoded as much as possible according to the processing capacity and memory capacity of the processor 11. Here, a case where the command block N8 is read when the command block N1 is executed is shown.
[0021]
When the command shapes of the command blocks N1 to N8 are decoded, the correction vectors V1, V2a, V2b, V3, V4, V5, V6a, V6b, V7, etc. at the end points of the blocks are calculated based on the tool radius set as a parameter. Here, since the end points of the command blocks N2 and N6 are acute angles, two correction vectors are generated.
[0022]
When the correction vectors of a plurality of command blocks ahead are calculated in this way, the interference of all the correction paths L1, L2a, L2b, L3, L4, L5, L6a, L6b, L7, L8 is checked. For this purpose, for example, in the command block N1, whether or not the end point correction vector V1 intersects the correction vectors V2a, V2b, V3, V4, V5, V6a, V6b, V7 of the other command blocks. to decide.
[0023]
As a result of performing the interference check for all patterns, if there is an intersecting correction vector such as the correction vectors V2a, V2b, V6a, and V6b in the figure, whether the alarm stop setting or the interference avoidance control setting is set beforehand by parameter setting. Judgment is made and if the alarm stop setting is set, the alarm is stopped. On the other hand, if the interference avoidance control is set, an interference avoidance route is obtained by calculating an interference avoidance vector according to the following procedure.
[0024]
In order to calculate the interference avoidance vector, first, the intersection of the correction paths L2a and L7 of the first command block N2 and the last command block N7 in the command block range (command blocks N2 to N7) where the correction path interferes Find Pa. When the intersection point Pa is obtained, all the correction vectors between the correction vectors V2a to V6b are canceled, and as shown in FIG. 4, as the correction vectors of the command blocks N2 to N6, the interference avoidance vector VC2, which faces the intersection point Pa. VC3, VC4, VC5, and VC6 are generated. This is called an interference avoidance vector.
[0025]
When the machining from the command blocks N1 to N8 is executed according to the newly generated interference avoidance vector in this way, the command blocks N3 to N6 are determined to have no movement, so that the actual tool is the path L1, LC2, LC7. , L8.
[0026]
As described above, in the present embodiment, when the correction path interferes, the interference avoidance vector for avoiding the path in the interference range is calculated, and the interference avoidance vector is set as a new correction vector. Work is not interrupted by stopping, and on the other hand, the workpiece is not cut too much without noticing the interference. This is particularly effective during rough machining.
[0027]
In this embodiment, the target point of the interference avoidance vector is set to the intersection Pa between the correction paths L2a and L7 of the first command block N2 and the last command block N7 in the command block range where the correction path interferes. Therefore, the tool can be moved on a path closer to the command shape while avoiding interference.
[0028]
Further, in this embodiment, since the interference determination is performed by reading up to the command block as far as possible from the command block being executed within the range permitted by the CNC capability, more accurate interference determination can be performed.
[0029]
Furthermore, in the present embodiment, when it is determined that interference occurs, whether to stop the alarm or to perform interference avoidance control can be set by a parameter or the like, so that it is possible to flexibly cope with processing conditions.
[0030]
【The invention's effect】
As described above, in the present invention, a plurality of command blocks of the command program are prefetched, the tool radius correction vector is calculated for all the prefetched command blocks, and the tool interference with the workpiece is calculated based on the calculated correction vector. If the interference avoidance vector is calculated as a new correction vector for avoiding the interference and the tool movement control is performed according to the calculated interference avoidance vector, the interference determination is performed. Even in the case where the cutting is performed, the cutting can be prevented without stopping the machining.
[Brief description of the drawings]
FIG. 1 is a diagram showing a concept of functions of the present embodiment.
FIG. 2 is a block diagram showing a schematic configuration of hardware of a CNC (numerical control apparatus) according to the present embodiment.
FIG. 3 is a diagram showing an example of a machining shape and a correction vector for explaining a tool radius correction method of the present embodiment.
FIG. 4 is a diagram illustrating an example after calculation of an interference avoidance path.
FIG. 5 is a diagram illustrating an example of a tool radius correction method using a correction vector.
FIG. 6 is a diagram illustrating an example of a relationship between a command shape and a correction vector when a pocket machining command smaller than a tool radius is issued.
FIG. 7 is a diagram illustrating an example of a state in which excessive cutting is performed.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Command program 1a Command block 2 Preprocessing means 3 Correction vector calculation means 4 Interference judgment means 5 Interference avoidance vector calculation means 6 Movement control means 7 Servo motor 8 Tool 9 Work 11 Processor 12 ROM
13 RAM
15 Axis control circuit 16 Servo amplifier 30 Machine tool

Claims (2)

In a CNC tool radius compensation method that performs tool radius compensation using a compensation vector, a plurality of command blocks of a command program are pre-read,
Calculate a tool radius correction vector for all the prefetched command blocks,
Determining whether or not the tool interferes with the workpiece depending on whether or not the calculated correction vectors intersect ;
When it is determined that the correction vectors intersect and interfere with each other, a path obtained by shifting the head block of the interfering command block range by the tool radius and the last command block of the interfering command block range are shifted by the tool radius. As a new correction vector for avoiding the interference, the intersection of the command block is calculated from the end point of each command block to the calculated intersection except for the last command block. The interference avoidance vector of
Tool movement control is performed according to the calculated interference avoidance vector.
CNC tool diameter correction method characterized by the above.   Set whether to perform alarm stop or interference avoidance control, and when the alarm stop is set, if interference is determined, avoid the execution of the interference avoidance vector calculation and the movement control, and stop the alarm. The CNC tool diameter correcting method according to claim 1, wherein the method is performed.

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