JP2001125613A - Numerical control simulation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a numerical control simulation device which can estimate the machining shape of a work when the work is machined according to a numerical control program and driving system characteristics. SOLUTION: This device is equipped with a program read-in part 1 which reads in a numerical control program, a preprocessing part 2 which corrects a read-in command path by using correction parameters and finds a corrected path, an interpolation and acceleration/deceleration part 3 which performs interpolation, and acceleration and deceleration according to the corrected path and acceleration/deceleration parameters, a driving system model 4 which estimates tool tip positions for the interpolation and acceleration/deleration result by using servo parameters, and a 3D solid simulation part 5 which calculates an estimated machining shape by using the tool tip positions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a simulation apparatus for a numerical control program, and more particularly to a method for estimating a machining shape of a workpiece when a machining is actually performed by a numerically controlled machine tool, from the numerical control program and drive system characteristics. The present invention relates to a simulation device for a numerical control program capable of displaying an estimated machining shape.

[0002]

2. Description of the Related Art In general, it is often the case that a numerical control program or a parameter affecting a machining shape of a work is correct by a simulation before actually machining with a machine tool. A conventional numerical control simulation apparatus is described in, for example, "Functions and Usage of Cutting Simulation Software-NC-" in "Machine and Tools, Vol. 41, No. 2 (1997-2), pp. 46-pp. 50" by Okamura et al.
Take Verify as an example. " This first conventional numerical control simulation apparatus will be described with reference to FIG.

[0005] 1 is a program reading unit for reading a numerical control program, 2 is a preprocessing unit for performing preprocessing such as shape correction using a correction parameter in the read numerical control program, and 5 a is corrected by the preprocessing unit. A 3D solid simulation unit that calculates a 3D solid model of the work using the path and the material shape of the work, and 6a is a shape display unit that displays the 3D solid model.

[0004] The shape correction includes, for example, tool diameter correction, tool length correction, and processing for converting a minute line segment into a spline curve. The correction parameter is, for example, a tool diameter correction amount,
The tool length correction amount, tolerance (distance between a minute line segment and a spline curve), and the like are included. The material shape defines the shape of the work before cutting (such as a rectangular parallelepiped).
As described above, by calculating and displaying the 3D solid model from the numerical control program, it is possible to know the processing shape of the workpiece that is close to the time when the numerical control program was executed without actually performing the processing. In addition, this simulation device is developed, and a load calculation unit of 14a and a feed speed calculation unit of 15a are added, and a load at the time of cutting a workpiece is calculated from a result of simulating a numerical control program so that the load is optimized. There is also a simulation device that creates a numerical control program in which the feed rate is modified.

A second conventional numerical control simulation apparatus is described in, for example, Japanese Patent Application Laid-Open No. 3-096055. A second conventional numerical control simulation apparatus will be described with reference to FIG. 1 and 2 are the same as those of the first conventional example, and thus the description thereof is omitted. Reference numeral 3 denotes an interpolation / acceleration / deceleration unit that performs interpolation / acceleration / deceleration using the path corrected by the preprocessing unit and the acceleration / deceleration parameter. Reference numeral 4 denotes a servo parameter for the interpolation / acceleration / deceleration result in consideration of drive system characteristics. A drive system model for estimating the tool tip position by using the display unit 21 is a display unit that displays the tool tip trajectory in the simulation and the command path by the numerical control program together.

Here, the drive system is composed of elements such as a servo, a motor, and a machine, and indicates the relationship between the position of the tip of the tool with respect to the position subjected to interpolation / acceleration / deceleration. The acceleration / deceleration parameters include an acceleration / deceleration time constant, a corner deceleration angle (a parameter for setting a threshold value of an angle requiring deceleration), an accuracy coefficient, and the like. The servo parameters include a position loop gain, a feed forward gain, and the like. As described above, it is possible to simulate the tool trajectory including the drive system characteristics of the machine tool, and to compare the simulation result of the tool trajectory including the drive system characteristics with the path specified by the numerical control program. .

A third conventional numerical control simulation apparatus is described in, for example, JP-A-4-302306 and JP-A-10-76444. A third conventional numerical control simulation apparatus will be described with reference to FIG. 1 to 3 are the same as those of the first and second prior arts, and thus the description is omitted. 4b is a servo amplifier that receives a command and drives the motor, 22 is a data measurement unit that measures the state quantity of the servo amplifier, and 23 is an automatic adjustment control unit that calculates sampling data and changes / controls it to desired parameters. . As described above, the parameters such as the feedforward gain and the acceleration / deceleration filter can be automatically tuned to the optimum values, and the cost for adjusting the parameter optimum values can be reduced.

[0008]

The conventional numerical control simulation apparatus is configured as described above, and the first conventional numerical control simulation apparatus does not consider interpolation / acceleration / deceleration and drive system characteristics. , Only displays the machining shape based on the trajectory drawn by the numerical control program, and the trajectory drawn by the numerical control program is different from the trajectory that the tool tip actually moves when machining the workpiece. Does not necessarily indicate the machining shape of the workpiece when machining is performed.

Therefore, even if there is no problem in the simulation, there is a possibility that a defective product will be produced when actually cutting the work, and it is impossible to judge whether the work is good or bad in the simulation. As a result, production efficiency deteriorates and costs increase. Also, regarding the simulation device that creates a numerical control program with the feed rate modified so that the load at the time of cutting the work is optimized, interpolation / acceleration / deceleration and drive system characteristics are not considered. The load of the work when cutting is different from the load of the work obtained as a result of the simulation, and it cannot be said that the optimum feed speed for actually cutting the work is obtained.

In the second conventional numerical control simulation apparatus, the result of the simulation including the drive system characteristics of the machine tool is a tool path and not a 3D solid model. It is difficult to recognize the work shape of the work. Therefore, it is impossible to judge whether the work is good or bad. As a result, production efficiency deteriorates and costs increase. Also, the parameters used for the simulation cannot be adjusted from the simulation results.

In the third conventional numerical control simulation apparatus, the parameters are automatically tuned by actually issuing a command to the servo amplifier from the numerical control apparatus to operate the motor and sampling the feedback data. The parameter cannot be adjusted unless the machine tool is actually operated. It takes time to actually operate the machine tool, and the operating rate of the machine decreases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and it is based on a numerical control program and a drive system characteristic that a work shape of a workpiece when actually processed by a numerically controlled machine tool is determined. An object of the present invention is to provide a numerical control simulation device capable of estimating and displaying an estimated machining shape.

Another object of the present invention is to provide a numerical control simulation apparatus capable of searching for an optimum value of a parameter affecting a work shape of a workpiece from a difference between an estimated work shape and a target work shape and reducing a shape error. It is.

It is another object of the present invention to provide a numerical control simulation device capable of correcting a path and a feed speed instructed to a numerical control program to optimum ones based on a difference between an estimated machining shape and a target machining shape.

[0015]

A numerical control simulation apparatus according to the present invention comprises a program reading unit for reading a numerical control program for instructing a workpiece machining path, and correcting the read instruction path using a correction parameter. A pre-processing unit for obtaining a corrected path, an interpolation / acceleration / deceleration unit for performing interpolation / acceleration / deceleration based on the corrected path and acceleration / deceleration parameters, and a servo parameter for a result of the interpolation / acceleration / deceleration. Drive system model for estimating the tool tip position by using a 3D solid simulation using the tool tip position to calculate an estimated machining shape
And a solid simulation unit.

In addition, the apparatus is provided with a shape display section for displaying the estimated machining shape.

The apparatus further comprises a shape error calculator for comparing the target machined shape with the estimated machined shape and calculating shape error data.
When displaying on the shape display unit according to the shape error data, the display attributes of the respective parts of the estimated machining shape are changed and displayed.

Further, the apparatus includes a path feature analysis unit for specifying a path corresponding to a location where the shape error data is large and analyzing the characteristics of the path, and a path characteristic display unit for displaying the characteristics of the analyzed path. Things.

Further, the apparatus is provided with a parameter change plan formulating section for formulating a plan for changing parameters affecting the processing shape of the workpiece based on the shape error data.

The parameter change is performed in consideration of the vibration at the tool tip position.

Further, the apparatus is provided with a target machining shape creating section for creating a target machining shape by 3D solid simulation from a command path designated by the numerical control program.

Further, a load calculation unit for calculating a load from the estimated machining shape and the material shape, and a feed speed calculation unit for calculating a feed speed from the calculated load are provided, and numerical control described by an optimum feed speed is provided. Create a program.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. Embodiment 1 FIG. FIG. 1 is a block diagram showing a numerical control simulation apparatus according to Embodiment 1 of the present invention. 1
Is a program reading unit that reads a numerical control program, 2 is a preprocessing unit that performs preprocessing such as shape correction on the read program, and 3 is an interpolation / acceleration / deceleration that performs interpolation / acceleration / deceleration based on the preprocessed result. Department. Reference numeral 4 denotes a drive system model for estimating the tool tip position in consideration of the drive system characteristics with respect to the result of interpolation / acceleration / deceleration, which is disclosed in, for example, Japanese Patent Application Laid-Open No. Hei 3-095605. Reference numeral 5 denotes a 3D solid simulation unit that performs a 3D solid simulation using the tool tip position to calculate an estimated machining shape, and 6 denotes a shape display unit that displays the estimated machining shape.

In the numerical control simulation apparatus configured as described above, the 3D solid simulation unit 5 calculates the estimated machining shape based on the tool tip position estimated in consideration of the drive system characteristics. The shape becomes closer to the machining shape when the workpiece is actually machined by the machine tool than the 3D solid model shown in the first conventional technique. In addition, by displaying the estimated machining shape on the estimated shape display unit 6, a machining shape similar to that when the workpiece is actually machined by the machine tool is displayed before actually machining the workpiece by the machine tool. Therefore,
Good or bad work can be determined on a simulation, and as a result, production efficiency can be increased and costs can be reduced.

Embodiment 2 FIG. 2 is a block diagram showing a numerical control simulation apparatus according to Embodiment 2 of the present invention. Since 1 to 6 are the same as those described in the first embodiment, the description is omitted. 7 is a shape error calculator for comparing the target machining shape with the estimated machining shape,
Reference numeral 8 denotes a shape error display unit that changes the display attribute of each part of the estimated machining shape when displaying the shape on the shape display unit according to the size of the shape error.

FIG. 3 shows an example in which the target processing shape and the shape error data are superimposed and displayed on the shape error display section 7. At a glance, a portion where there is an error between the estimated machining shape and the target machining shape can be found. Also, by using the shading as the display attribute, it is possible to see at a glance how the magnitude of the shape error changes. It goes without saying that colors, fill patterns, and the like can be used as display attributes. Further, since the boundary at which the display attribute changes can be defined by numerical values, it is possible to see at a glance how large the shape error is. This definition can be made by the shape error display parameter, and can be set by the operator. Here, the target processing shape is a shape when designed by CAD or the like. As described above, based on the difference between the estimated machining shape and the target machining shape, it is possible to search for the optimal value of the parameter that affects the machining shape of the workpiece, and reduce the shape error.

Embodiment 3 FIG. 4 is a block diagram showing a numerical control simulation device according to Embodiment 3 of the present invention. Since 1 to 8 are the same as those described in the second embodiment, the description is omitted. Reference numeral 9 denotes a route feature analysis unit that identifies a block route corresponding to a location having a large shape error and analyzes the features of the route. Reference numeral 10 denotes a route feature display unit that displays route features.

In order to realize the path feature analysis unit 9, first, a shape error is generated in any block of the numerical control program using the shape error data (error map) and the estimated machining shape (Z coordinate map). Must be identified. For this purpose, when creating the estimated machining shape in the 3D solid simulation unit 5, the relationship that the cutting at this position on the estimated machining shape was performed by the command of this block of the numerical control program (map of the block number) ) May be stored.

When displaying the path characteristics on the path characteristic display unit 10, it is more preferable to display the path locus of the tool tip position obtained by the drive system model 4 because the path error can be seen at a glance.

FIG. 5 shows an example in which the trajectory of the commanded path and the path trajectory of the tool tip position are superimposed and displayed on the path characteristic display section 10. The trajectory of the command path has the linear length of one block command,
Displaying the angle information to be formed together with the straight line command of the next block is useful for estimating which block causes a shape error in which block. For example, in the example shown in the drawing, since it can be seen at a glance that the angles formed by the minute line segments are smaller than the corner deceleration angle, the operator can estimate that a shape error has occurred without decelerating the corner. In the case where the command is not a minute line segment as in the example in the figure, for example, in the case of a circular arc command, it is effective to display radius information.

Embodiment 4 FIG. FIG. 6 is a block diagram showing a numerical control simulation apparatus according to Embodiment 4 of the present invention. Steps 1 to 8 are the same as those described in the second or third embodiment, and a description thereof will be omitted. Reference numeral 11 denotes a parameter change plan formulation unit that formulates a plan for changing parameters.

When formulating a parameter change plan based on the shape error data from the shape error calculation unit 7 in the second embodiment, the parameter change plan formulating unit 11 sets a range in which the locus of the tool tip position does not become oscillatory. Among them, a plan to increase the gain of the servo parameter so as to reduce the shape error is presented. The presented plan is used for the next processing after the operator confirms it.

FIG. 7 is a flow chart for finding optimum values of parameters such as a position loop gain and a feed forward gain. Step 1: The operator sets the allowable amount of the shape error. Step 2: Simulation is performed. Step 3: It is determined based on the information from the drive system model 4 whether or not the vibration is generated. Step 4: If it is determined in step 3 that the image is vibratory, the parameter amount is reduced until the image no longer vibrates. Step 5: The shape error calculation section 7 obtains the shape error amount of the shape error existing portion. Step 6: It is determined whether the shape error amount is smaller than the allowable shape error amount. Exit if smaller, ste if larger
Proceed to p7. Step 7: The parameter amount is increased by the parameter change amount. Step 8: Simulation is performed. Step 9: It is determined based on the information from the drive system model 4 whether or not the vibration occurs. Steady if vibrating
Proceed to p12, and if not vibratory, proceed to step10.

Step 10: The shape error calculator 7 calculates
The shape error amount of the shape error existing portion is obtained. Step 11: The shape error amount of the previous time and the current time is compared. If the shape error amount is reduced, the process proceeds to step 13, and if not, the process proceeds to step 12. Step 12: If it is determined in step 9 that it is vibratory, or if the shape error amount has increased from the previous time in step 11, the parameter amount is temporarily restored, the parameter change amount is reduced to half, and the process returns to step 7. Step 13: It is determined whether or not the shape error amount is smaller than the allowable shape error amount. Exit if smaller, st if larger
Return to ep7. Alternatively, the shape error amounts of the previous time and the current time are compared, and if they are almost the same, it is determined that the shape error cannot be reduced by increasing the parameter amount, and the processing ends.
Return to ep7.

The parameter change plan formulation section 11 formulates a parameter change plan based on the route feature data from the route feature analysis section 9 in the third embodiment.
In the case of the minute line segment command as shown in FIG. 5, a plan for changing the corner deceleration angle is presented. The presented plan is used for the next processing after the operator confirms it.

FIG. 8 is a flowchart for obtaining an optimum corner deceleration angle. Step 21: The operator sets the allowable amount of the shape error. Step 22: The shape error calculator 7 obtains the shape error amount of the shape error existing portion. Step 23: It is determined whether or not the shape error amount is smaller than the allowable shape error amount. Exit if smaller, st if larger
Proceed to ep24. Step 24: The route feature analysis unit 9 obtains the feature of the route of the part where the shape error exists. Step 25: It is determined whether or not the cause of the shape error is that the angle formed by the straight line command is smaller than the corner deceleration angle and the vehicle is not decelerated where deceleration should be performed. If so, the process proceeds to step 26; Is ste
Proceed to p29.

Step 26: As a result of the determination in step 25, the shape error is reduced by resetting the corner deceleration angle to a small value. Step 27: Calculate the shape error with the new corner deceleration angle. Step 28: It is determined whether or not the shape error amount becomes smaller than the allowable shape error amount by reducing the corner deceleration angle. Step 29: Since it has been determined that changing the corner deceleration angle cannot reduce the shape error amount, the accuracy coefficient is adjusted.

Under the conditions in step 25, it is conceivable that the cause of the shape error is that the angle formed by the linear command is larger than the corner deceleration angle and the vehicle is decelerated where deceleration is not necessary. In that case ste
This can be dealt with by increasing the corner deceleration angle in p26.

Embodiment 5 FIG. 9 is a block diagram showing a numerical control simulation apparatus according to Embodiment 5 of the present invention. Since 1 to 8 are the same as those described in the second embodiment, the description is omitted. Reference numeral 13 denotes a target machining shape creation unit that creates a target machining shape by 3D solid simulation from a path specified by the numerical control program.

The target machining shape creating section 13 is used in the second embodiment.
Then, the target machining shape that had to be prepared separately from the numerical control program is calculated from the numerical control program itself, so that the target machining shape does not have to be prepared.

Embodiment 6 FIG. FIG. 10 is a block diagram showing a numerical control simulation device according to Embodiment 6 of the present invention. Since 1 to 6 are the same as those described in the first embodiment, the description is omitted. Reference numeral 14 denotes a load calculation unit that calculates a load from the estimated machining shape. Reference numeral 15 denotes a feed speed that is corrected so that the calculated load becomes constant, or is fed at a rapid traverse where cutting is not actually performed. This is a feed speed calculation unit. Here, the load is, for example, a cutting torque.

The feed speed corrected by the feed speed calculation unit 15 is written in a numerical control program. Estimated machining shape by numerical control program with corrected feed rate,
Since the estimated machining shape by the numerical control program before the correction is different, the corrected numerical control program is further read into the program reading unit 1 and a simulation based on the drive system characteristics is performed. If the created numerical control program is no longer modified, it means that the numerical control program described at the optimum feed rate has been created.

[0043]

As described above, according to the present invention, a program reading section for reading a numerical control program for instructing a work machining path, and correcting the read command path using the correction parameters to obtain a corrected path. A pre-processing unit, an interpolation / acceleration / deceleration unit that performs interpolation / acceleration / deceleration based on the corrected path and the acceleration / deceleration parameters, and estimates the tool tip position using servo parameters for the interpolation / acceleration / deceleration results. 3 using drive system model and tool tip position
By providing a 3D solid simulation unit that performs D solid simulation and calculates an estimated machining shape, the operator can machine a workpiece close to the time when machining is actually performed by the numerically controlled machine tool before actually machining the workpiece. You can know the shape.

Further, by providing the shape display section, the obtained estimated machining shape can be displayed.

The apparatus further comprises a shape error calculator for comparing the target machined shape with the estimated machined shape and calculating shape error data.
By changing the display attribute of each part of the estimated machining shape and displaying it on the shape display unit according to the shape error data, the operator can visually check the error ratio of the part where the error exists. Can be.

Also, a route feature analysis unit for specifying a route corresponding to a location where the shape error data is large and analyzing the feature of the route, and a route feature display unit for displaying the feature of the analyzed route are provided. Accordingly, the operator can help estimate the cause of the location where the shape error is large.

Further, by providing a parameter change proposal formulating section for formulating a plan for changing parameters affecting the processing shape of the work based on the shape error data, the information of the identified portion having a large shape error can be obtained. It is possible to search for an optimum value of a parameter that also affects the processing shape of the tool, automatically set the parameter, and reduce the shape error. Alternatively, by presenting the operator with recommended values of parameters that improve the accuracy of the work shape of the work, it is possible to help the operator set parameters that affect the work shape of the work, thereby reducing the shape error. Can be.

Further, by changing the parameters in consideration of the vibration of the tool tip position, the gain of the servo parameter can be increased and the shape error can be reduced within a range where the trajectory of the tool tip position does not vibrate. .

Further, since a target machining shape creating section for creating a target machining shape by 3D solid simulation from a command path instructed by the numerical control program is provided, it is not necessary to prepare target machining shape data separately. Numerical control program simulation can be performed using only a program.

A load control unit for calculating a load from the estimated machining shape and the material shape, and a feed speed calculation unit for calculating a feed speed from the calculated load, the numerical control program being described with an optimum feed speed By calculating the load, the load is calculated from the estimated machining shape of the work taking into account the obtained drive system characteristics, and the feed rate is determined so that the load is constant. A numerical control program can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a numerical control simulation device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a numerical control simulation device according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram in which a target machining shape and shape error data are superimposed and displayed on a shape error display unit 7 of the numerical control simulation device of FIG. 2;

FIG. 4 is a block diagram showing a numerical control simulation device according to a third embodiment of the present invention.

5 is an explanatory diagram in which a path of a command path and a path of a tool tip position are displayed in a superimposed manner on a path feature display unit 10 of the numerical control simulation apparatus of FIG. 4;

FIG. 6 is a block diagram showing a numerical control simulation device according to a fourth embodiment of the present invention.

FIG. 7 is a flowchart for obtaining optimum values of parameters such as a position loop gain and a feed forward gain in the numerical control simulation apparatus of FIG. 6;

FIG. 8 is a flowchart for finding an optimum corner deceleration angle in the numerical control simulation device of FIG. 6;

FIG. 9 is a block diagram showing a numerical control simulation device according to a fifth embodiment of the present invention.

FIG. 10 is a block diagram showing a numerical control simulation device according to a sixth embodiment of the present invention.

FIG. 11 is a block diagram showing a first conventional numerical control simulation device.

FIG. 12 is a block diagram showing a second conventional numerical control simulation device.

FIG. 13 is a block diagram showing a third conventional numerical control simulation device.

[Explanation of symbols]

1 Program reading section, 2 Preprocessing section, 3 Interpolation /
Acceleration / deceleration section, 4 drive system model, 4b servo amplifier,
5, 5a 3D solid simulation section, 6 estimated shape display section, 6a 3D solid display section, 7 shape error calculation section, 8 shape error display section, 9 path feature analysis section, 1
0 path feature display section, 11 parameter change plan formulation section, 1
3 target machining shape creation unit, 14, 14a load calculation unit,
15, 15a Feed speed calculation unit, 21 display unit, 22
Data measurement unit, 23 automatic adjustment control unit.

Claims (8)

[Claims] A program reading unit for reading a numerical control program for instructing a workpiece machining path; a preprocessing unit for correcting the read command path using a correction parameter to obtain a corrected path; An interpolation / acceleration / deceleration unit for performing interpolation / acceleration / deceleration based on a set path and acceleration / deceleration parameters, a drive system model for estimating a tool tip position using servo parameters with respect to the interpolation / acceleration / deceleration results, and the tool A numerical control simulation device comprising: a 3D solid simulation unit that performs a 3D solid simulation using a tip position and calculates an estimated machining shape. 2. The numerical control simulation apparatus according to claim 1, further comprising a shape display section for displaying an estimated machining shape. 3. Comparing a target machining shape with an estimated machining shape,
3. The apparatus according to claim 2, further comprising a shape error calculator for calculating the shape error data, wherein when displaying on the shape display unit according to the shape error data, the display attributes of the respective parts of the estimated machining shape are changed and displayed. The numerical control simulation device according to the above. 4. A route feature analysis unit for identifying a route corresponding to a location having a large shape error data and analyzing the feature of the route, and a route feature display unit for displaying the feature of the analyzed route. 4. The numerical control simulation device according to claim 3, wherein: 5. The apparatus according to claim 3, further comprising a parameter change plan formulating section for formulating a plan for changing a parameter affecting a processing shape of the workpiece based on the shape error data.
Or the numerical control simulation device according to 4. 6. The numerical control simulation apparatus according to claim 5, wherein the parameter change is performed in consideration of the vibration of the tool tip position. 7. The numerical control simulation apparatus according to claim 3, further comprising a target machining shape creating section that creates a target machining shape by 3D solid simulation from a command path instructed by the numerical control program. 8. A numerical control described with an optimum feed speed, comprising: a load calculator for calculating a load from an estimated machining shape and a material shape; and a feed speed calculator for calculating a feed speed from the calculated load. 2. The numerical control simulation apparatus according to claim 1, wherein the program is created.