JPS63108409A - Operation control mechanism and its method in nc machine tool - Google Patents

Abstract

PURPOSE:To attain the improvement of program forming efficiency, to reduce the working time and to attain the safety for the job by detecting the contact state of a tool, alternating the operating parameter of the tool in the working program so as to apply working. CONSTITUTION:When a Z axis motor 40z is driven while a drive signal is transferred to a servo drive section 42, the motor 40z moves a drill to allow it to make drilling, and when the tip of the drill is in contact with a work and its speed is converted into a working speed (f) from the rapid feed F0 and then its tip is made to cut into the work by a moment of inertia, a command alternation means 54 uses a position data detected by a position detector 58z and stored in a register 52c to correct a value of a command (k) of a register 52b and transfers it to a digital differentiation analyzer 56. Thus, the cut depth due to the feed F0 of the drill is corrected and a hole having an accurate depth is drilled.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a motion control mechanism and method for an NC machine tool, and more particularly, the present invention relates to a motion control mechanism and a method thereof for an NC machine tool. The present invention relates to an operation control mechanism and method for an NC machine tool that improves the efficiency of creating a machining program and shortens machining time by changing the operating parameters of a tool and performing machining operations.

There is an NC machine tool that automatically controls the operation of a tool based on numerical information and performs processing such as drilling holes and surface cutting on a workpiece. In this case, the numerical information is usually input to the NC machine tool as a machining program using a perforated tape, magnetic tape, or the like together with a control code indicating the content of the work.

Therefore, an example of hole drilling using a conventional NC machine tool will be explained based on FIGS. 1 and 2. In this case, N
C machine tool Z
The hole portion 8 is bored in the workpiece 6 by displacing it in the direction. That is, the NC machine tool corrects the position of the holder 2 by the drill length HOI according to the control code G43 based on the machining program shown in FIG.
Fast forward at speed F0 until Then, the control code GOI
Accordingly, the hole 8 is drilled by moving the drill 4 at a machining speed f to 2480 degrees.

In this machining program, in order to shorten the machining time, the drill 4 is fast-forwarded to the position 2510 at a speed Fo, and then the work is stopped to drill a hole in the workpiece 6 at a machining speed f (f<FO). Is going. In this case, in order to prevent the drill 4 from colliding with the machining surface 6a of the workpiece 6 at the rapid traverse speed F0 and damaging its tip, the drill 4 is moved from a position a predetermined distance before the machining surface 6a. is controlled to run at a low machining speed f. Therefore, drill 4
In order to machine the workpiece 6 without damaging the workpiece, it is necessary to create a machining program by calculating two coordinates at a position in front of the actual machining surface 6a by a predetermined clearance. It is also necessary to consider the length of the drill 4. Therefore, it has been pointed out that the tool length data defined by the HOI must be input into the NC machine tool every time the tool is changed, which is a cumbersome task. Furthermore, if the two coordinates or the tool length data are incorrectly set, there is a risk that the drill 4 will collide with the workpiece 6 and the drill 4 or holder 2 will be damaged.

The present invention has been made to overcome the above-mentioned disadvantages, and the present invention detects the state of contact of the tool with the workpiece using a contact detection means, and changes the operating parameters of the tool in the machining program based on the detection signal. An operation control mechanism in an NC machine tool that can improve the efficiency of creating the machining program, shorten the machining time of the workpiece, and perform safe machining operations by machining the workpiece. The purpose is to provide a method for doing so.

To achieve the above object, the present invention includes a processing means for creating a tool drive signal from operation parameters specified by a machining program that defines the operation of a tool, and a servo for driving the tool based on the tool drive signal. a driving means;
The present invention is characterized by comprising a contact detection means for detecting a contact state of the tool with the workpiece and outputting a detection signal, and a changing means for changing the operation parameter based on the detection signal.

Moreover, when the present invention drives a tool based on the operation parameters of a machining program to machine a workpiece, a contact detection means detects that the tool has contacted the workpiece, and the detection signal is used to control the operation parameters. and then driving the tool based on the changed operating parameters.

Next, preferred embodiments of the motion control mechanism in the NC machine tool according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 shows a motion control mechanism in an NC machine tool according to the present invention.
This is to control the operation when drilling the hole 6. In this case, the operation control mechanism controls the drill 1 based on the machining program.
4, and a contact detection device 20 that detects when the tip of the drill 14 contacts the workpiece 12 and outputs a signal to the NC device 18 to change the machining operation. It basically consists of.

The contact detection device 20 includes a vibration detection sensor 22 fixed to the support table 10 of the workpiece 12, an amplifier 24 for amplifying the output signal from the vibration detection sensor 22, and an amplifier 2.
4, and a rectifier 26 for rectifying the signal amplified by the NC device 1.
Comparator 28 outputs a detection signal (RESP) for 8.
including. Here, the vibration detection sensor 22 detects a specific vibration that occurs when the drill 14 contacts the workpiece 12, and the vibration detection sensor 22 receives a test signal (REQ) output from the NC device 18. ) is integrally attached to a test vibration generator 30 that vibrates based on the following. Note that it is preferable that the vibration detection sensor 22 and the test vibration generator 30 are formed of piezoelectric elements.

On the other hand, as shown in FIG. 4, the NC device 18 includes a tape reader 32 that reads a machining program recorded on an NC tape, a decoder 34 that translates the machining program into machine language, and a machine language that is translated by the decoder 34. a buffer register 36 for storing one line of the machining program;
a calculation section 38 that performs predetermined calculation processing on command values (operation parameters) of the machining program and outputs the command values as drive signals for each unit time;
X-axis motor 40x that displaces 4 in the x, y, and z directions, respectively.
, a servo drive section 42 that drives a Y-axis motor 40y and a Z-axis motor 40z.

Here, in addition to the conventional control code shown in FIG. 2, the machining program input from the NC tape includes, for example,
There is a G code indicated by control code G401 shown in the figure. In this case, the line number N of the machining program indicated by the G code is recorded in the G code register 44 in the decoder 34. Note that this G code register 44 is
8 outputs a test signal (REQ) to the test vibration generator 30 of the contact detection device 20 when processing the Nth line machining program. In this case, the test signal (RE
Q) is manually input to the AND gate 46 along with the detection signal (RESP) from the contact detection device 20, and the AND gate 46
The output is sent to the decoder 3 together with the output of the G code register 44.
4 is input to the AND gate 48. Furthermore, the detection signal (RESP) and the output signal (ENBL) of the AND gate 48 are connected to each other.
) are respectively input to the gate circuit 50. Here, the gate circuit 50 outputs a switching signal (CNT) when the detection signal (RESP) is at H level.

The calculation unit 38 has first to third registers 52a to 52c.
, a command value changing means 54 that changes the command value (operation parameter) specified by the machining program, and a digital differential analyzer (hereinafter referred to as D) that outputs the command value as a drive signal.
(referred to as DA) 56. The target coordinates of the drill 14 and the command value of its movement speed are stored in the first register 52a, and the second register 52b stores the depth data of the hole 16 drilled by the drill 14 and the speed of the drill 14 at the time of drilling. The command value of machining speed is stored.

Further, the third register 52c has an X-axis motor 40X.

Position data from position detectors 58x to 58z attached to the Y-axis motor 40y and the Z-axis motor 402 is stored. The command value changing means 54 switches the path for the DDA 56 from the first resistor 52a to the second register 52b based on the switching signal (CNT) from the gate circuit, and also changes the depth data of the hole 16 stored in the second register 52b. is corrected as necessary based on the position data stored in the third register 52c and transferred to the DDA 56.

On the other hand, the drive signal output from the calculation section 38 is output to the servo drive section 42 via the gate circuit 60. In this case, the gate circuit 60 is configured to be closed by a switching signal (CNT) from the gate circuit 50, and opened by a release signal from the command value changing means 54. The servo drive unit 42 includes a servo register 62 that stores the drive signal supplied via the gate circuit 60.
, a D/A conversion circuit 64 that converts the drive signal into an analog signal, an X other motor 40x, a Y other motor 40y, and a Z other motor.
It is composed of a driver 66 that drives another motor 40z.

The operation control mechanism in the NC machine tool according to the present invention is basically constructed as described above, and its operation and effects will be explained next.

First, the tape reader 32 reads an NC tape on which a machining program is recorded, and the decoder 34 translates the machining program into machine language.

In this case, the decoder 34 controls each line (
N-2), (N-1), N... are translated into machine language sequentially, and when control code G401 shown in FIG. 5 is detected in the Nth line machining program, the line number N is converted into G code. Store in register 44.

Next, the processing program translated by the decoder 34 is transferred to the arithmetic unit 38 via the buffer register 36.

Here, if the control code of the machining program on the (N-2)th line is the conventional control code shown in FIG. 2, the command value set in the machining program is stored in the registor 52a. The command value is DDA56
The signal is converted into a drive signal and transferred to the servo drive unit 42 via the gate circuit 60. Therefore, after the drive signal is once stored in the servo register 62, it is converted into an analog signal by the D/A conversion circuit 64, and the driver 66
As a result, the other X motors 40x, the other Y motors 40y, or the other Z motors 40z are driven by a predetermined amount, and the drill 14 performs the desired operation.

Next, when the above operation is completed, the arithmetic unit 38 sends the decoder 3
A completion signal is output to 4. In this case, the decoder 34 checks whether or not there is a G code in the next (N-1)th line machining program using the G code register 44, and outputs the result to one input terminal of the AND gate 48.

Here, if the G code shown in FIG. 5 is not attached to the (N-1)th line machining program, the G code register 4
4 to the AND gate 48 becomes L level, and the output signal of the AND gate 48 is input to the gate circuit 50 as L level.

Therefore, the gate circuit 50 does not output a switching signal (CNT) to the command value changing means 54 in the calculation section 38, and
8 drives the drill 14 by performing arithmetic processing based on the command value related to the (N-1)th line machining program stored in the registor 52a.

When the operation specified by the (N-1)th processing program is completed, the calculation unit 38 outputs a completion signal to the decoder 34 again.

Therefore, in the next Nth line machining program, the G shown in FIG.
The processing steps when a code is attached will be explained based on the flowchart of FIG.

Upon receiving the completion signal of the (N-1)th line machining program from the calculation unit 38, the decoder 34 outputs the G code register 44.
Check whether or not there is a G code in the Nth line machining program, and if the G code shown in Fig. 5 is attached,
That is, when the control code is 0401, an H level signal is output to one input terminal of the AND gate 48.

Further, the decoder 34 outputs a test signal (REQ) to the contact detection device 20 (<5TPI).

Here, the contact detection device 20 receives the test signal (REQ).
In response to this, the test vibration generator 30 generates vibration.

This vibration is transmitted to the vibration detection sensor 22, and then, if the vibration detection sensor 22 operates normally, the vibration is converted into an electrical signal by an amplifier 24, a rectifier 26 and a comparator 22.
AND gate 4 as a detection signal (RESP) through 8
It is output to one input terminal of 6. The test signal (REQ) at H level is input to the other input terminal of the AND gate 46, and the output terminal of the AND gate 46 outputs an H level signal to the other input terminal of the AND gate 48. The signal will be output. Therefore, the H level output signal (ENBL) from the AND gate 48 is input to the gate circuit 50, and it is confirmed that the vibration detection sensor 22 operates normally (SrF2).

On the other hand, a predetermined period of time (To) has elapsed since the test signal (REQ) was output from the decoder 34 to the contact detection device 20.
If the detection signal (RESP) is not obtained even after the elapse of time (SrF2), the NC device 18 issues an alarm to notify that the vibration detection sensor 22 is malfunctioning (SrF2).

Next, a case where the vibration detection sensor 22 is operating normally will be described. In this case, assuming that the drill 14 operates based on the machining program shown in FIG. 5, the Z coordinate 2 of the target point shown in FIG. The moving speed F, (assumed to be set in advance) is stored in the second register 52b.
The depth k and machining speed f of 6 are stored.

Therefore, first, when the Z coordinate 2 of the target point is set as shown in FIG.
Based on this, a predetermined drive signal is output to the servo drive section 42 via the gate circuit 60.

The servo drive section 42 sends the drive signal to the servo register 62.
After storing the signal in
to drive the Z-axis motor 40z. As a result, the drill 14 is directed toward the workpiece 12 at a rapid traverse speed F in the Z direction.

Start moving at (SrF5).

The drill 14 moves a predetermined amount in the Z direction, and the tip reaches the workpiece 1.
2, the vibrations generated at the time of contact are detected by the vibration detection sensor 22.

The output signal from the vibration detection sensor 22 is amplified by an amplifier 24, then rectified by a rectifier 26, and then sent to a comparator 28.
The detected signal is compared with a reference signal in the step SrF2, and if the signal is higher than a predetermined level, it is outputted to the NC device 18 as a detection signal (RESP) (SrF2). The signal output from the vibration detection sensor 22 has, for example, the characteristics shown in FIG. It is possible to easily detect what has happened.

Therefore, the detection signal (RE S
P) drives the gate circuit 50 to
A switching signal (CNT) is outputted to the command value changing means 54 and the gate circuit 60, respectively.

In this case, the gate circuit 60 is closed by the switching signal (CNT) and stops sending the drive signal to the servo drive unit 42. On the other hand, the command value changing means 54 corrects the command value stored in the second register 52b as necessary based on the switching signal (CNT) and transfers it to the DDA 56. The DDA 56 outputs a drive signal to the gate circuit 60 based on the command value. At this time, the command value changing means 54
outputs a release signal to open the gate circuit 60, the drive signal is transferred to the servo drive unit 42, and as a result, the Z-axis motor 40z is driven. In this case, the Z-axis motor 40z moves the drill 14 in the Z direction at a machining speed r by the command value to drill the hole 16 (SrF7).

Here, the tip of the drill 14 comes into contact with the workpiece 12,
When the speed is converted from the rapid feed speed F0 to the machining speed f, it is conceivable that the tip end has bitten into the workpiece 12 by a predetermined amount due to inertial force. , in such a case,
The command value changing means 54 is the position detector 5 of the Z-axis motor 40z.
If the command value of the second register 52b is corrected using the position data detected by the 8z and stored in the third register 52c and transferred to the DDA 56, the amount of penetration due to the rapid feed speed F0 of the drill 14 is corrected and accurate. Hole 16 with a depth of
It is possible to drill. Note that there are various methods of correction, but for example, it is also possible to calculate the servo error α at the time of generation of the switching signal (CNT) and provide "k-α" to the DDA 56.

On the other hand, as shown in FIG. 7, when the Z coordinate of the target point is set slightly in front of the machining surface of the workpiece 12, the drill 14 operates as follows. That is, when the drill 14 moves by 2 in the Z direction at the rapid traverse speed F0 (STP8)
, the command value changing means 54 inputs the second register 52 to the DDA 56.
The command value f stored in b is transferred, and the drill 14 is moved in the Z direction at a machining speed f within a preset tolerance value z (STP9). When the tip of the drill 14 contacts the workpiece 12, the vibration detection sensor 22 detects the contact state, and the contact detection device 20 outputs a detection signal (RE
SP) is output to the gate circuit 50 (STPIO)
. In this case, the gate circuit 50 outputs a switching signal (CNT) to the command value changing means 54 and the gate circuit 60. Therefore, the command value changing means 54 outputs the command value stored in the second register 52b to the DDA 56 and opens the gate circuit 60. Therefore, the DDA 56 outputs a predetermined drive signal to the servo drive unit 42 via the gate circuit 60, and the servo drive unit 42 drives the Z-axis motor 40z to move the drill 14 by k in the Z direction at a processing speed f. A hole portion 16 is bored (STP7).

Note that the detection signal (RE S P) is not output from the contact detection device 20 even after a predetermined period of time has elapsed, and the drill 14
If the amount of movement in the Z direction exceeds the allowable value z1 (STP
II) The NC device 18 issues an alarm signal to notify abnormal operation of the device (STP12).

In the above-described embodiment, the hole 16 is drilled in the workpiece 12 using the drill 14, but for example, a milling cutter may be used to cut the surface of the workpiece in any shape. That is, as shown in FIGS. 9a and 9b, when a workpiece 70 having a boss 68 made of an irregular curved surface is surface-cut by the milling canker 72, the peripheral edge of the milling scuff turf 2 is cut by the boss 68.
If the vibration when the milling cutter 72 contacts the boss 68 is detected by the vibration detection sensor 22 and its operating parameters are changed by the command value changing means 54, the coordinates of the contact point A between the milling cutter 72 and the boss 68 can be extremely easily calculated without having to calculate the coordinates of the contact point A between the milling cutter 72 and the boss 68. Based on the machining program, surface cutting work can be performed along the route shown by the dashed line.

As described above, according to the present invention, the contact state of the tool with respect to the workpiece is detected by the contact detection means, and the operating parameters of the tool are changed based on the detection signal to perform the machining operation. ing. Therefore, unlike in the past, there is no need to create a machining program by taking into consideration data such as coordinate data and tool shape just before the tip of the tool contacts the workpiece, and therefore the creation time of the machining program is reduced. The advantage is that it is significantly shortened. Further, there is no risk of damage to tools etc. due to a setting error in the data, unlike in the conventional case. Furthermore, since the tool can be moved at a rapid traverse speed until it comes into contact with the workpiece, it is possible to shorten the time required for machining the workpiece.

Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to these embodiments, and various improvements and changes in design can be made without departing from the gist of the present invention. Of course.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a method for machining a workpiece according to the prior art, Fig. 2 is an explanatory diagram of a machining program according to the prior art, and Fig. 3 is an explanatory diagram of the configuration of a motion control mechanism in an NC machine tool according to the present invention. 4 is a block diagram of the configuration of the motion control mechanism in the NC machine tool according to the present invention, FIG. 5 is an explanatory diagram of a machining program applied to the motion control mechanism in the NC machine tool according to the present invention, and 6 The figure is a flowchart showing the operation control method in the NC machine tool according to the present invention, Figures 7a and b are explanatory diagrams of the operation control method in the NC machine tool according to the present invention, and Figure 8 is the vibration detection shown in Figure 3. 9A and 9B are an explanatory plan view and a cross-sectional view showing another application example of the operation control method in an NC machine tool according to the present invention. 10... Support table 12... Workpiece 1
4...Drill 18...NC device 20
... Contact detection device 22 ... Vibration detection sensor 30 ... Test vibration generator 32 ... Tape reader 34 ... Decoder 36 ... Buffer register 38 ... Arithmetic unit 40
x...X-axis motor 40y...Y-axis motor 4
0z...Z-axis motor 42...Servo drive section 44...G code register

Claims (5)

[Claims] (1) processing means for creating a tool drive signal from operation parameters specified by a machining program that defines the operation of the tool; a servo drive means for driving the tool based on the tool drive signal; An operation control mechanism for an NC machine tool, comprising a contact detection means for detecting a contact state of a tool and outputting a detection signal, and a changing means for changing the operation parameter based on the detection signal. (2) In the mechanism set forth in claim 1, the contact detection means is constituted by a vibration detection sensor that is fixed to a support table of a workpiece and detects vibrations generated when a tool contacts the workpiece. A motion control mechanism for NC machine tools. (3) In the mechanism set forth in claim 2, the vibration detection sensor is equipped with a vibration generator that generates pseudo vibration based on a test signal output from the processing means to test the operation of the vibration detection sensor. A motion control mechanism in an NC machine tool. (4) When driving the tool based on the operation parameters of the machining program to machine the workpiece, the contact detection means detects that the tool has come into contact with the workpiece, and the operation parameters are changed based on the detection signal. and then driving the tool based on the changed operation parameters. (5) In the method according to claim 4, the machining program has a control code for changing operation parameters, and the contact detection means is enabled to operate based on the control code. .