JPS6219347A - Control method when surface is cut by rotary toll - Google Patents

Abstract

PURPOSE:To enable a tool to decrease its vibration so as to improve a life of the tool and its cutting efficiency, by controlling a cutting feed speed, given in a region when an edge of the rotary tool starts cutting and retracts from a work, to be in a low value for a cutting feed speed command. CONSTITUTION:When a rotary tool is in a 16phi diameter, the method, commanding in N10 a main spindle to 2,000rpm to be rotated by M3 in N11 and commanding an adaptive control in VMPC1=#20H, assigns a tool depth of cut in regions VD1=18, VD2=26. Next the method, positioning the tool in N12 by a quick feed speed to a position of X13, Y50 before a cutting position, quickly feeds the tool in N13 to a position of Z-15 in the position of N12 before the cutting position. while the method commands the tool in N14 by a cutting feed speed F800 to a position X-313. In this way, the method, turning off the adaptive control in the region VD1=18, from the present position of N13 to a feed command value X-313, that is, from the position X13 to X-5, and performing 100% feed spindle speed override,performs the adaptive control in the region after the position X-5 to the region VD2=26 before the assigned value X-313.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for controlling plane cutting using a rotary tool suitable for rough cutting of a workpiece using an end mill or a milling tool in a machine tool, particularly a machining center.

Conventional technology When rough cutting a material workpiece such as a casting using an end mill or milling tool, there is an intermittent cutting at the beginning of the tool's entry and exit, resulting in large impact vibrations and the casting surface is chilled and hard. Therefore, it is easy to wear out the blade.Also, when adaptive control is activated during cutting, as shown in Figure 7, the adaptive control is activated as soon as the cutting load starts to be applied, and the workpiece and tool are not in sufficient contact at the beginning of cutting, resulting in cutting. Since the load is small, the feed speed is naturally faster. However, since the tool has discontinuous uneven contact, increasing the feed rate causes the tool to escape, causes vibration, and accelerates tool wear.

The problem to be solved by the invention is to minimize the vibration of a rotary tool to extend the life of the tool and improve cutting efficiency.

Means for Solving the Problems The present invention is to control the cutting feed rate in the areas where the blade of the rotary tool begins to enter and when the blade exits so as to have a low deviation relative to the cutting feed rate command.

Embodiment In FIG. 1 showing a block diagram of a circuit for carrying out the method of the present invention, 1 is a machine body such as a machining center, 2 is
is an NC device, 3 is a main shaft drive unit and feed shaft drive unit that operate according to the commands of the NC device 2, 4 is a machining center drive motor, 5 is a shunt that detects the load current of the motor 4 at no load and during cutting, and 6 is a detection The current is converted into a digital value using an A/D converter. 7 is a no-load current storage circuit, and 8 is a subtracter that subtracts the no-load current value from the cutting load current value to calculate the actual cutting load current value.

9 is an average value calculation circuit for 20 times of the actual cutting load current sampled every 0.01 seconds, that is, 0.2 seconds, and 10 is a circuit for calculating the average value of the actual cutting load current of the tool. A memory circuit 11 uses the maximum value of the average value every 2 seconds as a control value, and 11 compares the data of the actual cutting load current average value calculation circuit 9 during cutting of the workpiece with the control value of the control value memory circuit 10 to determine the magnitude. Comparison circuit to output, 1
2 is an override speed command circuit that reduces the override of the feed speed of the feed axis by 10% when it is large and increases it by 10% when it is small depending on the magnitude of the output value of the comparison circuit.
'A W 2 is entered with that value. Based on this override command, the NC device 2 controls the drive unit 3. 13 is an input section for a user machining program; 14 is an input section for cutting position commands, spindle speed, cutting feed rate, and coolant; 15 is an adaptive control command input section;
16 is a VD1 command input section, 17 is a VD2 command input section, and a VD33 command input section is added if necessary. These input sections are input by tape or MDI, and the command values are NC
It is input to device 2. Reference numeral 18 denotes a touch sensor stored in a magazine or the like of the machine body 1, which is attached to the spindle by ATC and outputs a touch signal as a control signal to the NC device 2 when and during contact with a workpiece.

Note that a touch sensor may not be specially provided, and the tool may be configured to establish continuity between the tool and the workpiece, and a signal during contact may be extracted. Reference numeral 19 denotes a table, a position detector for the spindle head, which inputs the current value of the workpiece to the NC device 2. The control circuit is the block diagram shown in Fig. 1 of Japanese Patent Application No. 1987-92087, which was previously proposed by the applicant. It complies with the following.

Next, control will be explained using a program.

Program example 1 (Figure 2) When touch signals are not used, the rotary tool diameter is 16φ.

NIO5200O Nil M3 VMPCI-#20HDI-18 D2-26 N12 Go X13 Y5O N13 Z-15 N14 GI X-313F80ON15 GO
Y100 N16 GI
Adaptive control 1 is commanded at 20H, VDI-18, VD2-
At 26, the amount of penetration of a rotary tool, such as an end mill, into the workpiece is designated. At N12, in front of the cutting position X13.
Position the tool at the Y2O position at rapid traverse speed. N1
3, fast forward to position Z-15 at position N12 before cutting position 1. Cutting feed rate F80 at N14
Command to X-313 at 0. As a result, from the current position of N13 to the feed command value X-313, the adaptive control is turned off from the current position of N13 to the feed command value
After -5, adaptive control is entered until VD2=26 before the designated value X-313.

In other words, VD2-26 in front of X-313 commanded by N14,
That is, after performing adaptive control up to X-287, the adaptive control is turned off from X-287 to X-313.

When the adaptive control is turned off by the NC device, the override is not suddenly reduced to 100%, and the feed axis speed override is reduced to 10% every 0.2 seconds from the override before the adaptive control was turned off.
Forcibly decrease by % and send at 100%. At N15, move to the next cutting point of Yloo by rapid traverse. Similar cutting is performed thereafter, and the machining is completed.

Program example 2 (Fig. 3) When touch signals are not used, the rotary tool diameter is 16φ.

NIO5200O Nil M3 VMPC1=#20HVD1=18 D2-26 D3-8 N12 Go X13 Y5O Nl 3 Z-l 5 N14 GI X-313F80ON15 Go
Yloo This program is a version of program example 1 in Nil with VD3-8 added, and in N14, the command value X-3 is set at cutting feed F2O3.
-313+26 due to VD2=26 before 13, i.e. -313+8 due to VD3=8 from X-287, i.e. X-
The difference is that the adaptive control up to 305 is turned off.

Program example 3 (Fig. 4) When a contact signal (touch signal) is used to confirm that the tool and the workpiece are in contact and that they are in contact, for example, the conduction between the tool and the workpiece is used. is 16φ.

NIO52000G38 F120ONil M3
VMPCI-#20HDI-18 VD2=26 N12 GOX13 Y5O N13 Z-15 N14 GI X-313F80ONIO commands spindle rotation 200Or, p, m Define feed speed when touch signal is off as F1200, spindle rotation adaptive control command at N11 Position where the tool enters half the diameter + 5fi 18. and command the position 26 before the cutting command value, X at N12
13. Fast forward to position at Y2O, and at N13, position to Z-15 by fast forward. X in N14
A cutting feed command is given at a feed rate of F800 up to -313, but
Adaptive system iTJ command and VD1=18. Since VD2=26 is commanded, feed from X13 to N8 where a touch signal is issued at a feed rate of F1200, and from N8 where a touch signal is issued to X-5, processing is performed at a feed rate of F800 with adaptive control off. From then on, the rotary tool will not move the workpiece. VD2 = 26, that is, X before exiting from
-287, the adaptive control is turned off until the touch signal from X-287 is cut off, and from the moment the rotary tool passes through the workpiece, it is rapidly fed to X-313 at a feed rate of F1200.

Program example 4 (Figure 5) NIO, M3,056,5180. Hl, Nl1,
FMILR, XO, YO, Z O, 1600°J400
．． KO, 2, F70. Q5. RIO, D.I.
, specify spindle rotation speed 18 Or, p, m in F40O NIO, H
Define to use tool length correction of l, specify spindle rotation, width of area in X direction (workpiece length) in Nil 16
00. Width of area in Y direction (in workpiece) J400 Finishing allowance KO for post-process.

2. Specify the tool diameter during one cutting as a percentage P70 for 160 in this example, specify the depth of cut Q5 possible in one cut with the cutter used, specify the height RIO which is the base point for making the cut, The tool radius D1 is specified as 80 in this example, and the feed rate F400 is specified.

Under these conditions, specify FMILR and cut the cutting movement in the direction of
The cutting situation based on the program example 4 in which the coordinates are determined as shown in FIG. 5 will be explained based on the flowchart in FIG. 6 and the cutting state diagram in FIG. 5.

At step SL (J-Y)/CP/10OX2
XD1) is calculated to find the number of cuts A in the Y-axis direction. That is (400-0) / (70/100X2X80)-
3, 6. In step S2, the value of A is rounded up to an integer, A=4. In step S3, (J-Y)/A is calculated to obtain the feed amount B per time in the Y-axis direction.

That is, B-(400-0)/4-100. In step S4, B-DI is calculated to determine the distance C-20 of the cutter center path from the end of the workpiece during the first cutting. In step S5, the command value of X - (DI+5).

The value determined by y-c, that is, X is O-(80+5)--8
5. Position Y at point 20 in fast forward motion. In step S6, the base point RIO for cutting in the X-axis direction is positioned by rapid traverse. In step S7, the Z command value 0 is compared with the command value minus the Z current value -Q. That is, 0+0.
Since 2<10-5, YES, in step S8, the current Z value -Q, that is, 10-5-5, is set to the value of 2.

If NO in step S7, the Z value is set to the Z command value 10 and the command value, that is, O+0.2.

In step SIO, override 100 to 5 in the flow of step S8 or 0°2 in the flow of step S9
Cutting feed in the X-axis direction with F40Q of %, cutting feed in the X-axis direction with F200 of override 50% to the X command value 15, that is, the 0 point of 0+5 in step Sll, Step 312
I-(D1+5) or 600-(8(1+5)
Cutting feed in the X-axis direction with F400 with 100% override until point C, I+5, 600+5 in step 313
Cutting feed in the X-axis direction with F200 with override 50% up to two points, compare whether Y current value ≦ J-B in step 514, and if YES in step 315, override 50% to Y current value 10B, that is 20 + 100 points. F2 of
Cutting feed in the X-axis direction at 00, in step S16! −
5 i.e. 50% F2 to point 600-5
00 is the cutting feed in the X-axis direction, step S17 is the X command value + (DI + 5), that is, 0 + (80 + 5), and F400 with 100% override to point G is the cutting feed in the X-axis direction, and in step 318, the X command value is -5, that is, O-5. Cutting feed in the X-axis direction at F200 with 50% override to point Q, and in step S19, Y current value ≦ J-B, that is, 400-100
If YES, in step 320, Y-
Y current value 10B, i.e. 120 + 100 point override 5
Cutting feed is performed at 0% F200, and thereafter steps are repeated in the same manner from the glue point to the nu point in FIG. 5, and cutting is performed along the dotted line path. In step 321, Y current value + B, that is, 22
Cutting feed in X-axis direction at F200 with 50% override to 0+100 point, I-5 or 60 in step 322
Cutting feed in the X-axis direction with F200 with 50% override to the 0-5 point, feed in the X-axis direction with F400 with 100% override to the X command value +5, that is, 0+5 point in step 323,
In step 324, cut feed in the X-axis direction with F200 with 50% override to the X command value -5, that is, 0-5 W point, and in step S25, compare whether the Y current value ≦J-B, that is, 320≦300, and the result is NO. , In step 326, cut feed in the X-axis direction with F2O3 with 100% override to the X command value - (D1 + 5), that is, 0 - (80 + 5) to the force point, and in step S
27, compare whether Z current value = K and if YES,
In step 528, processing is completed by fast forwarding to Z=R, that is, Zlo. If No in step 514 on the way, T+(DI+5), that is 60, is determined in step S29.
0+ (80+5) Override 1 in a position symmetrical to the point of force
It can be passed by cutting feed in the X-axis direction with i00% F2O3. After that, the process moves to step S27. In this case, A is an odd number. If NO in step S19, the X command value - (DI+5) is determined in step S30.
That is, 0-(80+5) F with 100% override to O point.
Cutting is fed in the X-axis direction at 2O3, and then the process moves to step S27. Further, if No in step S27, the current Z value is set to 21 in step 531. Step S
At 32, it is fast-forwarded in the Z-axis direction to Z-R, that is, to ZlO.

In step S33, X command value -(DI+5), Y-C, that is, x is o-<8o +5), and Y is 20. The data of zl becomes Z in step S34, and cutting feed in the X-axis direction is performed using F2O3 with 100% reoverride, and then the process moves to step S7.

Effects As detailed above, in the present invention, the feed rate during cutting is lowered at the beginning of cutting and when the tool is coming out, which is closer to the feed rate in the middle of the cut, so it is more similar to manual operation by the operator. This enables adaptive control of tool vibration and tool wear, and enables stable cutting of small diameter or long tools that are prone to breakage, extending tool life.

It has the effect of improving machining accuracy.

[Brief explanation of drawings]

Fig. 1 is a block diagram of control for implementing the method of the present invention, Fig. 2 is a diagram showing the relationship between the first tool position and feed axis speed of the embodiment of the present invention in end mill cutting, and Fig. 3 is a program example. Figure 4 shows the relationship between the start of cutting and the tool wave in Program Example 3. Figure 5 shows the relationship between the tool position and the feed axis speed in Program Example 4 when cutting an end mill. Figure 6 shows the flowchart in program example 4, Figure 7 shows the relationship.
The figure is a conventional relationship diagram between tool position and feed rate. 2...NC device 3...Drive device 6...A/D
Converter 7...No-load current memory circuit 8...Subtractor 9...Actual cutting load 11 current average value calculation circuit IO...Control value memory circuit 11...Comparison circuit 12...Override speed command circuit

Claims (5)

[Claims] (1) In controlling flat surface cutting with a rotary tool, the cutting feed rate in the area where the rotary tool blade begins to enter and the blade exits is controlled to a value lower than the cutting feed rate command value. A control method for plane cutting using a rotating tool. (2) A control method during plane cutting with a rotary tool according to claim 1, wherein the midway cutting feed rate control is adaptive control. (3) The program command indicates that the area where the blade begins to enter is a position that is half the rotary tool diameter + several mm from the position determined by the program command, and the area where the blade exits is just before a part of the tool begins to come out of the workpiece. 3. The method of controlling plane cutting using a rotary tool according to claim 2, wherein the cutting distance is from a rotary tool radius determined by a rotary tool radius or a rotary tool radius + several mm to a position determined by a program command after the tool has completely pulled out. (4) The area where the blade begins to enter is a position that is half the diameter of the rotary tool + several mm from the position where the rotary tool contacts the workpiece, and the area where the blade exits is determined by the program command. Half the diameter of the tool before it starts to come out +
3. The method of controlling plane cutting using a rotary tool according to claim 2, wherein the cutting time is from a position of several mm to a position where the rotary tool is separated from the workpiece. (5) The area where the blade begins to enter is half the diameter of the rotary tool + number from the cutting feed start point determined by self-calculating the degree of engagement of the rotary tool on the workpiece by the control device based on the machining program commanded by the user. This is the position where the center of the rotary tool is located up to mm, and the area where the blade is about to come out is determined by the control device self-calculating the degree to which the rotary tool will come out of the workpiece based on the machining program commanded by the user. The center of the rotary tool is several meters from the position that is half the diameter of the rotary tool + several mm in front of the position where it starts to come out.
A method of controlling flat surface cutting using a rotary tool according to claim 1, wherein the rotating tool is up to a position where the rotating tool passes by m.