JPS6240722B2 - - Google Patents

Description

[Detailed Description of the Invention] This invention is for cutting a workpiece using a machine tool using numerical control (hereinafter abbreviated as NC).
This is related to the NC method.

In cutting processing using conventional NC machine tools,
If there is a large difference in shape between the machining program that commands various cutting conditions and the material that is being cut, the machine operator may interrupt the machining program as appropriate during cutting using the commanded machining program. Cutting was performed under conditions that matched the cutting capacity of the machine, but cutting using the commanded machining program and interrupt operations for changing the trajectory by the machine operator were not possible at the same time, requiring complicated operations. there was.

FIG. 1 is a block diagram showing the schematic configuration of a conventional NC machine tool. 1 is paper tape, magnetic tape,
Alternatively, a machining information input medium such as a machining program storage memory built into the NC device; 2 is an input processing unit that obtains input information from the input medium 1;
This is the part that determines the command quota of the NC machining program and reads the command blocks necessary for actual machining operations. Reference numeral 3 denotes an analysis calculation unit that performs processing such as tool path calculation and speed calculation, and calculates movement commands and speed commands instructed by the machining program into calculation data for interpolation control as an NC device.

For example, when the command is G91 G01×100.Y200.Z300.F500, "X axis is 100 mm, Y axis is 200 mm, Z axis is 300
Movement control is performed using a linear command (G01) to move a distance of mm from the current position (G91) at a speed (F) of 500 mm/min. First, the feed speed is 500 mm/min in the direction of the command vector. Therefore, it is necessary to find the actual moving distance in the vector direction and the axis component ratio for accurately interpolating each axis.

Command distance in vector direction L=√ ² + ² + ² =√100 ² . +200 ² . +300 ² = 374.166 (mm) X-axis component ratio S _x = x/L = 100. /374.166=0.267 Y-axis component ratio S _y =y/L=200. /376.166=0.535 Z-axis component ratio S _z =z/L=300. /376.166=0.802 Here, x: X-axis movement amount y: Y-axis movement amount x: Z-axis movement amount. This is a processing unit that calculates the movement command value into a vector direction movement amount and an axial component ratio in order to perform interpolation control in this manner.

In addition, in the case of manual interrupt, the operation section 7 to be described later
The calculation output based on the machining program command is stopped based on the manual interrupt start signal from the controller, and the command signal from the operation unit is processed.

Reference numeral 7 denotes an operation unit for an operator who operates the machine for processing operation. This allows the operator to select the input medium for the machining program, such as a paper tape or the NC's built-in machining program memory, perform a manual handle feed operation to perform an interrupt operation described later, or start the machining program. Operations such as starting, stopping, resuming, and interrupting can be performed.

Reference numeral 8 denotes a control unit that performs interpolation control based on the calculation result from the calculation unit 3 for movement (interpolation) control and information such as start, stop, and interruption from the operation unit 7.

The interpolation data given from the calculation unit 3 are: Command distance in vector direction L = 374.166mm Feed rate in vector direction F = 500mm/min X-axis movement amount and component ratio x = 100.mm S _x =
0.267 Y-axis movement amount and component ratio y=200.mm S _y =
0.535 Z-axis movement amount and component ratio z=300.mm S _z =
It is 0.802. From these data, the control unit 8 calculates the interpolation period (△Tmsec) predetermined for the NC device.
The amount of movement of each axis to be moved in this ΔTmsec is calculated and controlled sequentially so that each of the X, Y, and Z axes moves while accurately adjusting to the command vector.

First, the amount of movement ΔL per unit time of ΔT in the vector direction is ΔL=F/60×ΔT=500/60×10=83.3μ, assuming that ΔT is 10 msec. This is “△T in the vector direction.
This means that it is necessary to move approximately 83μ every 10msec. In order to control the movement of the machine, it is necessary to control the servo motors attached to each of the X, Y, and Z axes.
It is necessary to allocate the amount to the actual movement of each axis, Y-axis and Z-axis.

The amount of movement per △T unit time distributed to each axis (△X, △Y, △Z) is the amount of movement per △T on the X axis △X = △L・S _x = 83.3 × 0.267 = 22.3μ Y The amount of movement of the axis per △T △Y = △L・S _y = 83.3×0.535=44.6 μ The amount of movement of the Z axis per △T △Z = △L・S _z = 83.3×0.802 = 66.8 μ. Therefore, the data sent from the control section 8 to the next drive section 5 is the amount of movement of each axis per unit time ΔT. However, with only the numerical value from the above calculation formula, the problem of fractions below the decimal point, and the problem of fractions at the command end point when divided by unit time, cannot be solved in reality.
Various improvements have been made to the NC device to minimize variations in feed rate due to calculation accuracy and variations in feed rate between command program blocks.

Furthermore, in the above-mentioned interpolation control, as an interruption by an operator operation from the operation unit 7, overwriting (%) or changing the feed rate, pausing by automatic pause, resuming movement by automatic start, or switching the operation mode, It is possible to intervene by shifting the movement path, etc., not from the machining program input medium but by an arbitrary manual movement operation by the operator. 5 is a machine tool 6 based on the movement control information from the control unit 8.
This is the drive unit that drives the.

In this conventional NC machine tool, an input medium such as a paper tape 1 containing machine coordinate values, cutting speed, and other command information is read by an input unit 2, and a calculation unit 3 uses the operation information from an operation unit 7. The calculation results are used to accurately control the position of the machine tool 6 via the drive unit 5, and cut the workpiece.

However, there are times when it is desired to change the machining path of a machining program that defines the machining path. This example is particularly applicable when the machining shape of the machining program and the shape of the material differ considerably. It is not suitable if the material is cast metal or other material with little waste, or if the machining program has been created based on a prediction of the shape of the material. It is difficult to predict the shape of the material, especially when the material is constructed by pasting together in large die engraving or the like. Therefore, it is first necessary to pre-process the material into a shape close to the finished shape. This pre-processing may be called roughing, and processing may be performed using a processing program for rough processing. In such rough machining, the shape of the material is often uneven, so a heavy load is applied to the convex parts, while the load is light to the concave parts. In areas where the convex load is heavy, the Z-axis should be moved upward to reduce the load, and in concave areas where the load is light, the Z-axis should be lowered to increase the depth of cut. In such a case,
The tool is controlled by interrupting the machining by the machining program and intervening with manual interrupt machining (as mentioned above, in the case of heavy load, the tool is moved in the direction to reduce the cutting amount, In addition, when the load was light, the tool was moved in a direction that increased the amount of cutting.

In addition, when lowering the Z-axis little by little to make a cut and repeating it many times, it was necessary to carefully operate the Z-axis to avoid cutting into the finished shape of the next process.

As mentioned above, in the conventional cutting method, cutting with the paper tape 1 had to be stopped or interrupted midway in order to obtain the appropriate load, and complicated operations were required to obtain the required depth of cut. other,
Because the machine stops moving even temporarily, the material is scratched (cut mark) at the stop position, and if there are many interrupt operations, there is a risk of cutting to the inside of the final shape.

This invention was made in order to eliminate the drawbacks of the conventional cutting method as described above, and it enables a manual interrupt operation by a machine operator at the same time as cutting using a paper tape. The purpose of this invention is to provide a function that stores the locus of the final finished shape and prevents the movement control by this manual interrupt operation from cutting into the final finished shape.

This invention will be explained in detail below.

Figure 2 shows this invention in the third control axis (Z) of a machine tool.
1 is a block diagram schematically showing an embodiment equipped on a shaft), in which the same or corresponding parts as in FIG. 1 are given the same reference numerals. As can be understood from this FIG. All movement control calculation results are sent to the pulse distributor 4' of the control section 8, and movement control calculation results from the operation section 7 are sent to the pulse distributor 4' according to the mode of the operation section 7 during independent manual operation. The signal is sent to the pulse holding circuit 4 of the control section 8 during automatic interrupt operation.

The control unit 8 is configured to execute the following three types of mode control, the details of which will be described later with reference to FIG. The above three modes include [] a case where the movement pulses sent from the pulse distributor 4' are directly sent to the drive section 5 (normal mode), and a case where the movement pulses sent from the operation section 7 are manually operated. In the case where the movement pulses are sent as they are to the drive section 5 (interrupt mode A), the movement pulses sent from the pulse distributor 4' are temporarily calculated in the pulse storage circuit 4, and then sent from the operation section 7. The integrated value of the pulse accumulator circuit 4 is set as an allowable value, and the manually operated moving pulses sent from the operation unit 7 are sent to the drive unit 5 with priority, and the pulse accumulator is If the integrated value of the circuit 4 exceeds the allowable value, the output of the moving pulse by manual operation is prohibited, and the integrated value of the pulse storage circuit 4 is changed by the moving pulse sent from the pulse distributor 4'. As a result, if there is a possibility that the current interrupt position due to manual operation may exceed the allowable value, the movement pulses sent from the pulse distributor 4' are sent to the drive unit 5, and the integrated value of the movement pulses due to manual operation is also changed. There are two cases: a case where the interrupt operation is automatically pushed up (interrupt mode B), and a case where the interrupt operation is automatically pushed up.
It will be held in Note that the details of the interrupt mode B will become clear in the section of operation description to be described later. FIG. 3 is a block diagram showing the configuration of the pulse storage circuit 4 in the control section 8 of FIG. 10 is a switch, 11 is an interpolation pulse temporary storage section, 12 is an interrupt pulse temporary storage section, 13, 15 and 20 are adders/subtractors, and 14 is an interpolation pulse accumulation unit. section, 16 is an interrupt pulse integration section, 17 is a comparator, 18A, 18B
and 19 are gates. In FIG. 3, when the operation unit 7 (see FIG. 2) selects [normal mode], the switch 10 is connected to 10A,
The interpolated pulse I is stored in the interpolated pulse temporary storage section 11 and output as is as the output pulse C.
When the operating section 7 selects [interrupt mode A], the switch 10 is connected to the switch 10B, and the interrupt operation pulse LOW is stored in the interrupt operation pulse temporary storage section 12 and output as is as the output pulse C. Further, when the operation unit 7 selects [interrupt mode B], the switch 10 is connected to the switch 10C. The interpolated pulse I is stored in the interpolated pulse temporary storage section 11 and at the same time is accumulated in the interpolated pulse accumulator 14 by the adder/subtractor 13. The interrupt operation pulse low is stored in the interrupt pulse temporary storage section 12 and at the same time is accumulated in the interrupt pulse accumulating section 16 by the adder/subtractor 15.

A comparator 17 compares the magnitudes of the two interpolation pulse integration sections 14 and interrupt pulse integration section 16, and when the interpolation pulse integration section 14 is smaller, the comparator 17 is turned off (17A is 0, 17B is 1). The gate 18A is closed, the gate 18B is opened, and the movement pulse of the interrupt pulse 12 is output. On the other hand, when the interrupt pulse integrator 16 is smaller, the comparator 17 is on (17A is 1, 17B is 0), and the gate 1
Open gate 7A and close gate 18B. As a result, a moving pulse of the interpolation pulse 11 is output. When this interpolation pulse is output to C through the gate 18A, it must also be integrated into the interrupt pulse integration unit 16 through the adder/subtractor 20 at the same time, and the interrupt pulse integration unit is also synchronized while the output is controlled (moved) by the interpolation pulse. This is so that when an interrupt is made in the positive direction of the Z axis to reduce the load, it is made effective immediately.

To summarize the above, the control is in the following four states.

(1) When there is no position change due to interpolation control, but a manual interrupt operation is performed (a) When manual interrupts are freely possible When the interpolation pulse accumulator 14 is smaller than the interrupt pulse accumulator 16, interrupts can be freely executed. This is an area where it is possible. In other words, interrupt operations can be performed when the tool is above the interpolated path.

(b) When manual interrupts are prohibited Lower the Z-axis (tool) from the above state where interrupts can be freely performed (interrupt pulse accumulator 1
6) when attempting to enter a region smaller than the interpolation pulse integrator 14, the comparator 17
is reversed and manual interrupts are prohibited.

(2) When there is no manual interrupt, but the interrupt prohibited area changes due to an interpolation command (a) Interpolation control below the interrupt prohibited area Interpolation control in an area smaller than the interrupt pulse integrator 16 does not appear to cause any movement of the machine.

(b) When exceeding the interrupt prohibited area during interpolation Interpolation progresses in the above area with the Z-axis command of the machining program in the positive direction, and the interpolation pulse integration section gradually becomes larger and becomes larger than the interrupt pulse integration section 16. Then, the comparator 17 is inverted,
outputting the interpolated pulse through gate 18A;
The machine is moved (pushed up) and interpolated pulses are integrated into the interrupt pulse integration section 16 to raise the interrupt boundary position.

Next, a specific example of operation will be explained. Figure 4 shows the trajectory (O-A-B-C) indicated by the thick solid line for the Z-axis in the three-dimensional coordinate system of X, Y, and Z for the operation in [interrupt mode B]. In the program (final finished shape), the trajectory shown by the broken line (O-A1-B1-C1) is the trajectory when no interrupt operation is performed, and is the trajectory projected onto the XY plane. The following command machining program example (A) is an interrupt mode operation example (A1).

Command machining program example (A) (1) GolX (x ₁ ) Y (y ₁ ) Z (z ₁ ) F (f ₁ ) * (2) GolY (y ₂ ) Z (z ₂ ) * (3) Go1Y ( y ₃ ) Z (z ₃ ) * Interrupt mode operation example (A1) (11) Go1X (x ₁ ) Y (y ₁ ) F (f ₁₁ ) * (12) Go1Y (y ₂ ) F (f ₁₂ ) * (13) Go1Y(y ₃ )F(f ₁₃ )* However The shaded area shown by the thin solid line in Figure 4 (C-
A-B-C-C1-B1-A1-O)
is the part that can be interrupted by [interrupt mode]. An interrupt operation is possible above the broken line portion on the Z axis, but an interrupt operation is not possible below the area indicated by the thick solid line. In other words, interrupt operations are prohibited as the final finished shape indicated by the commanded machining program.

Next, the trajectory O-D-E-F shown in Fig. 5 is the trajectory according to the command machining program using paper tape 1.
-D1-E1-F1 is the projection locus on the X-Y plane when no interrupt operation is performed even though it is in interrupt mode, and OG is the locus projected when an interrupt operation is performed in [interrupt mode B]. The interrupt trajectory is F-G
When performing an interrupt operation using [interrupt mode B], the machining program trajectory rises and intersects, so the interrupt trajectory is automatically pushed up by the machining program trajectory and moves in synchronization with the machining program. It is a trajectory.

Although a pulse reservoir circuit is used in the embodiment described above, this is merely an example, and it is clear that various modifications can be made without departing from the gist of the invention.

As described above, according to the present invention, the execution of the commanded machining program and manual interrupt operation are simultaneously performed so as not to cut into the final finished shape while memorizing the trajectory of part or all of the commanded machining program using the paper tape. Since it can be easily carried out during operation, it has a great effect on improving cutting efficiency in rough machining of materials, etc.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the general configuration of a conventional NC machine tool, and Figure 2 is a block diagram showing the general configuration of a conventional NC machine tool.
A block diagram schematically showing an embodiment equipped on a control axis, FIG. 3 is a block diagram showing details of the control section in FIG. 2, and FIG. 4 is a diagram showing a specific operating range.
FIG. 5 is a diagram showing a specific example of operation. Note that the same symbols in the figures indicate the same or equivalent parts, 1 is the input medium, 2 is the input section, 3 is the calculation section, 4' is the pulse distributor, 4 is the pulse storage circuit, 5 is the drive section, and 6 is the machine tool. , 7 is an operation unit, 8 is a control unit, 10 is a switch, 11 is an interpolation pulse temporary storage unit, 12 is an interrupt pulse temporary storage unit, 13, 15, 20 are adders/subtractors,
14 is an interpolation pulse accumulation section, 16 is an interrupt pulse accumulation section, 17 is a comparator, and 18 and 19 are gates.

Claims (1)

[Claims] 1 An input unit that reads machining information that defines the movement trajectory of the machine tool, an operation unit that controls the machine based on machining instructions from the machine operator, and a control unit that controls start, stop, trajectory analysis, speed control, etc. based on these conditions. A numerical control device having an arithmetic unit that performs operation and a drive unit that performs mechanical movement, including a program coordinate register that always manages a program position according to machining information, and an interrupt coordinate register that always manages an interrupt position according to a manual interrupt operation, In addition, by having means for monitoring the relative positional relationship between the contents of both coordinate registers and automatically moving the interrupt position to a safe area so that the contents of the interrupt coordinate register do not become smaller than the contents of the program coordinate register, the machine operator can A numerical control method characterized by the ability to simultaneously control automatic operation and manual interrupt operations in parallel without cutting into the material due to the shape of the machining program.