JPS603537B2 - Tool chucking control device for machine tools with ATC - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic tool attachment/detachment device for an ATC-equipped machine tool, and is a tool chucking control device that has an added function of detecting a tool chucking error and rechucking the tool.

In conventional automatic tool attachment/detachment devices, a motor attached to the rear end of the drawing port (hereinafter referred to as the drawbar) inserted into the main shaft rotates the drawbar forward and backward, and the male screw at the tip of the drawbar, which is seen through the taper hole of the main shaft, connects to the female screw in the tool shank. The tool holder is screwed into the main shaft tapered hole.

By the way, it is known that for some reason the male screw of the trover is not screwed into the female screw of the tool shank, and the tool holder is not fastened to the spindle at a rate of about 1 out of 10. In such a case, the tool holder may fall due to incomplete vertical mounting of the tool shank, and the function of the automatic tool changer cannot be fully utilized. As a countermeasure to this problem, various methods have been implemented, such as examining the shape of the tip of the male screw and the accuracy of the screw, but none of them are perfect. As described above, the present invention has a detection function for the chucking error with the tool spindle that occurs approximately once every several hundred times, and when a chucking error occurs, performs a re-chucking operation and performs a re-chucking operation. When the chucking error is not resolved despite the chucking operation, the chucking operation is performed repeatedly, and when a predetermined number of times or a predetermined time is exceeded, the chucking operation is deemed impossible and the chucking operation is stopped. It is something.

The present invention, as the best technical means to achieve the above object, detects the engagement state of the tool shank from the load current of the drawbar motor. In other words, if the motor load current becomes excessive after a certain period of time, the tool shank is completely engaged. If this is detected, the chucking operation is terminated. If the current is normal, it is detected as a tool shank connection failure, the drawbar motor is reversed, the male screw at the tip of the drawbar is separated from the female screw on the tool shank, and the chucking operation is terminated. By repeating the chucking action of rotating the motor in the normal direction and screwing both screws together, we succeeded in eliminating chucking errors.

Then, the number of repetitions for chucking mistakes is set with a preset counter, or the timer is operated only within the set time, and when the re-chucking setting device operates, chucking is deemed impossible and the chucking operation is stopped.
This protects the male screw at the end of the drawbar, prevents tool holders from falling, and enables early detection of defective tools. The apparatus of the present invention will be explained below with reference to embodiments shown in the drawings.

First, the machine tool shown in Fig. 1 is a vertical milling machine F equipped with an automatic tool changer, and the main parts are a base 1, column 2, knee 3, saddle 4, table 5, spindle head 6, spindle 7, and spindle drive. It consists of a motor Mo. TM is a tool storage magazine that stores a large number of tool holders T,
TA is a tool holder T chucked to the spindle 7;
and a tool holder T in the tool storage magazine TM. 10 is an automatic tool attachment/detachment device mounted on the top of the spindle head 6, which is connected to the top end of the drawbar 8 inserted into the spindle 7 as shown in FIG. 2, and drives the drawbar motor M in forward and reverse rotation. The drawbar 8 is rotated in the forward and reverse directions to attach and detach the tool holder T to and from the tapered hole 7a of the spindle 7.

That is, the tip male screw 8a of the drawbar 8, which looks into the taper hole 7a of the main shaft, is connected to the female screw 11a at the top of the shank 11 of the tool holder T, which is held by the tool change arm TA and inserted into the taper hole 7a. As shown in the figure, this is supported by the rise of arm TA. Subsequently, the drawbar 8 rotates in the normal direction by the forward rotation drive of the drawbar motor M, and the male screw 8a screws into the female screw 11a, and as shown in FIG. Pull it into the hole 7a and tighten it. However, when the male screw 8a cannot be screwed into the female screw 11a and continues to idle and the predetermined chucking time has elapsed, the drawbar 8 stops rotating in the state shown in FIG. Releasing the grip of T will cause the tool holder T to fall. The gist of the embodiment of the present invention is to repeat the chucking operation when a chucking error occurs, and the outline will be explained with reference to the flowchart shown in FIG.

First, a chucking command is issued from the NC device at the time of tool exchange to start the drawbar motor M. As shown in Fig. 3, when the tool shank 11 is inserted into the tapered hole 7a, the chucking operation starts with the forward rotation of the drawbar motor M, and whether or not the chucking is successful is determined by the current sensor of the drawbar motor after a predetermined time. detected by. If chucking is successful (YES), a counter serving as a rechucking setter is reset and the rechucking mode is cleared. On the other hand, chucking failure (NO) is detected because the motor current after the timer setting time (delay time) $ec is a normal value, and is counted as 11 for rechucking, and the change arm is lowered.
When the drawbar is reversed (0.5~.ec) and the change arm TA descends to the bending point b of the horizontal turning section, a change command is issued by actuation of the switch, the change arm rises, and the chucking operation is repeated again. Motor M. Rotate forward. Successful chucking (YES), unsuccessful chucking (
NO) is detected by the current sensor in the same way as the previous time, and if it is unsuccessful, the re-chucking will be 12 and the third chucking operation will proceed, but the re-chucking will be 13.
When it is counted, an alarm is displayed and the chucking operation is stopped. Of course, if the chucking is successful (YES), the tool exchange is completed, the main shaft rotates, and the next tool is moved on. If a time limit timer is used as the re-chucking setting device, an alarm will be displayed when the timer exceeds the set time, and the chucking operation will be stopped. A first embodiment of the apparatus for carrying out the chucking operation shown in the above flowchart is shown in FIGS. 6 and 7.

First, the rechucking circuit CE, which is the core of the present invention, is
Timer To, counter Co, and 3 sets of OR elements ○, ~0
3, which are organically connected to the NC device, the drawbar motor control circuit MC, and the change arm control circuit AC to perform the rechucking function. That is, the input terminal A of the timer To in the re-chucking circuit CE and the two OR elements 02 and 03 detect when the NC device and the change arm TA come to the horizontal rotation part (b to c), and the output from the mitt switch The wires are connected so that the chucking command is sent, and the timer To starts at $e from the input of the chucking command.
After c, it is output to the time-up terminal, and this becomes a release command and the reverse relay D of the drawbar motor control circuit MC is output.
R is energized and the change arm control circuit AC is controlled as a change arm lowering command. Further, the glue set signal to the timer round glue set end C is input as the adjacent completion signal i output from the current sensor CS of the drawbar motor control circuit MC, and this engagement completion signal is input to the timer T. The release command and change arm lowering signal are not outputted earlier than the time-up time $ec. Furthermore, the engagement completion signal is input to the OR element ○, the processing continuation signal k to the NC device, and the OR element 03 connected to the reset terminal C of the counter Co, which is the re-chucking setting device.
Reset counter Co. The input to the input terminal A of the counter Co is performed by the time-up signal ta from the time-up terminal of the timer To. The reset switch inputs the ON operation signal to OR element 02 and sends a change arm raising command to the change arm control circuit AC, and also sends a chucking command to the drawbar motor control circuit MC to activate the forward rotation relay of the motor M. The DF is energized to perform a chucking operation. Timer To, which was reset at the same time as this chucking operation, is activated by limit switch L.
It is restarted (time measurement) upon receiving a signal from S. Then, when the timer To sends the time-up signal ta three times to the counter Co without the engagement completion signal i being transmitted from the current sensor CS, the count-up signal ca is outputted from the output end of the counter Co and the alarm lamp AL is activated. While it lights up, it sends a motor stop command to the drawbar motor control circuit MC and also sends a stop command to the NC device. The connections of the forward/reverse relays DF and DR of the drawbar motor M and the current sensor CS are as shown in FIG. That is, forward rotation relay DF of motor M,
Then, the point f... is interposed in the exposed paths a, b, c, and the contact r of the reversing relay DR is connected to the exposed path a~
Branch lines a', b', and c' are interposed so as to interchange and connect the two wires a and c of c (interphase switching). Further, the overload current of the motor M is picked up by a current converter CC placed close to the exposed circuits a to c, and when the current value is detected by the current sensor CS and exceeds a set value 13, an engagement completion signal j is output. Next, the preset counter Co, which is a re-chucking setting device, is connected to the time-limited timer TL,
The second embodiment of the rechucking circuit CE changed to
This will be explained with a diagram. That is, the time limit timer TL inputs the chucking command of the NC device to its input terminal A, starts energizing (time measurement) of the timer TL with this command, and inputs the chucking command from the drawbar motor control circuit MC to the reset terminal C. The configuration is such that a meshing completion signal i is input and this command causes the energization (time measurement) of the timer TL to be stopped. Then, the time limit timer TL sets the delay time (set time) from this energization until outputting the time-up signal tb to the output machine mouth, and the time required to repeat the re-chucking operation three times (6 to 7 seconds per time).
c, the time is set to 21 seconds, which is three times this value. The output terminal of the time limit timer TL above is the alarm lamp A.
OR element 0 of L and motor stop command. and is connected as a stop command for the NC device. Therefore, "the set time (21 seconds) from the start of the chucking operation of the tool holder T until the timer TL outputs a time-up signal"
), if the re-chucking operation is repeated,
The timer TL is not reset by the engagement completion signal j,
A time-up signal tb is output. Now, the time-up signal turns on the alarm lamp AL and inputs it as a motor stop command to the drawbar motor control circuit MC to stop the motor M, and also sends it to the NC register as a stop command to restart the chucking operation. Come to a complete stop. Of course, timer TL. Timer T is energized within the set time of
L, is set upon receiving the engagement completion signal i from the drawbar motor control circuit MC. Now, timer TL,
energization is stopped and the time-up signal tb is not output to the output terminal, and the operation of the NC device continues. As mentioned above, when the time limit timer TL is used as a re-chucking setting device, the setting of the number of times of re-chucking of the tool holder T is determined by a multiple of the re-chucking time, but it is not possible to directly set the number of times using the preset counter Co. It can be said that they essentially operate in the same way.

In the second embodiment, the other circuit configurations are the same as those in the first embodiment shown in FIG. 6, so the same reference numerals are used and the explanation of the configuration is omitted. The chucking control device of the present invention is constructed as described above, and its operation will be explained below using a first embodiment using a preset counter Co.

Now, as shown in FIGS. 1 and 2, a new tool shank 11 held by the tool changing arm TA is in a position to be inserted into the tapered hole 7a of the main spindle 7 for tool changing. When the tool is replaced earlier than this time, a chucking command is output from the NC device to the re-chucking circuit CE. Now, the counter Co is reset to zero and $
The timer To set in ec starts to run for seconds, and furthermore, a chucking command is sent from the re-chucking circuit CE to the drawbar motor control circuit MC, and the forward rotation relay DF starts the motor M, in the forward rotation, and changes. An arm raising command is sent to the change arm control circuit AC, and the arm TA is raised. Then, as shown in Fig. 3, the tool holder T,
The female screw 11a at the top of the taper comes into contact with the male screw 8a at the tip of the normally rotating drawbar 8, and the screwing of both 8a and 11a begins here. As a result, as shown in Figure 4. When the male screw 8a of the bar is fully screwed into the female screw 11a of the tool shank 11, the tool shank 11 is fastened into the tapered hole 7a,
Motor M. Rotation is restricted when overload current is applied. FIG. 9 shows transient phenomena from the start of the drawbar motor M to the overload current state. That is, when starting the motor M, a large starting current 1 flows and becomes a steady current 12 during the chucking operation, and from the time point t when the tool is fastened, the rotation of the motor M is stopped and an overload current lo
begins to flow, and exceeds the set current value 13 set by the current sensor CS after a period of time. The engagement completion signal j sent from the current sensor CS earlier than t3=$ec resets the timer To and also resets the counter counter Co. In addition, the engagement completion signal becomes a motor stop command, deenergizes the forward rotation relay DF of the drawbar/motor control circuit MC, and stops the motor M, and is sent to the NC device as a machining continuation signal k, which causes the arm to arm. The main shaft 7 is driven by closing the gripping claws. The above-mentioned chucking operation was performed when the tool shank 11 was smoothly fastened to the main shaft 7, but the operation when the tool shank 11 is not fastened to the main shaft 7 will be described below.

That is, if the steady current 12 during the chucking operation is maintained even after the time t2 (approximately Sec) at which the engagement completion signal is transmitted, the tool holder T rotates integrally with the drawbar 8. Therefore, the timer To is the set time t.
The time-up signal ta is output at 3 (Sec). The above signal becomes an IJ lease command to the drawbar motor control circuit MC, which energizes the reversing relay DR to reverse the motor M, (drawbar 8) for =0.5~lsec, and at the same time, the time-up signal The change arm lowering signal activates the change arm control circuit AC, and the tool holder T
, lowers the tool change arm TA holding the tool. It is also input to the counter Co and incremented by 11. With this, the female screw 1 1a of the tool shank 1 1, which is incompletely engaged with the male tip 8a of the drawbar 8, is separated from the drawbar tip.
Eventually, the tool change arm turns the IJ mitt switch LS, O.
N works. The load current change of motor M during the above period is:
It becomes as shown by the chain line in FIG. In other words, "reverse relay DR
When energized, the motor M rotates in the reverse direction, and its starting current flows in the opposite direction as shown by the chain line, and then becomes a steady current, t4 = 0.5.
~1. After $ec, the limit switch is turned on, and the chucking command deenergizes the reverse relay DR of the drawbar motor control circuit MC, and the motor current becomes zero for a short time t5. The limit switch can be turned on by turning on the drawbar.
The motor control circuit MC energizes the forward rotation relay DF to start the motor M in forward rotation, while the timer To starts operating (counting down) and the change arm control circuit AC raises the tool change arm TA. With this, the second re-chucking operation starts, and as shown in FIG.
a, and the two 11a and 8a begin to mesh. Here, as shown in FIG. 4, when the screwing of both 11a and 8a is completed and an overload current flows through the motor M, the current sensor C
When the current sensor exceeds the set value 13 determined by S, the mesh completion signal i is output from the current sensor.
The timer To (in the middle of the second session) and the printer Co calculated in 11 are reset, respectively, and sent to the NC device as a machining continuation signal k. The current change from the start of the motor M until the overload current is reached is the same curve as the previous time, as shown on the right side of FIG. However, the timer T still remains incompletely screwed together between both 11a and 8a.

When the set time t3 (Sec) has elapsed, the time-up signal ta is output and the reversing relay DR of the drawbar motor control circuit MC is energized to reverse the motor M, while the change arm control circuit AC is activated. The arm TA is lowered and the counter Co is added to 12.The female screw 11a of the tool shank 11, which is incompletely screwed or cannot be screwed into the drawbar tip male screw 8a and remains attached, is now separated. ,
, limit switch LS turns ON for the second time when arm TA falls. This signal resets the timer To and starts counting down, and further drives the change arm TA upward and causes the motor control circuit MC to rotate the motor M in the forward direction. With the above operation, the third chucking action to fasten the tool shank 11 to the taper hole of the spindle is started, and this time as well, the meshing completion signal i is not output from the current sensor CS within the time-up time of the timer To (insect ec). Then, a time-up signal Ca is output from the counter Co, which is incremented by 13 by the time-up signal ta. This time-up signal turns on the alarm lamp AL, and also sends a motor stop command to the drawbar motor control circuit to stop the motor M, and also sends a stop command to the NC device to indicate that the change arm TA has failed as shown in Figure 3. The tool holder T is stopped with the tool holder T inserted into the tapered hole 7a.If the draw fly odor shank!1 is not fully engaged as described above, the chucking operation is performed several times (three times in the above example). (may be an appropriate number of times), and the chucking operation is repeated to achieve complete engagement by re-chucking operation, and when complete engagement is not achieved even after acting a predetermined number of times, the chucking and the operation of the NC device are stopped. .

In the two embodiments described above, the NC device is connected to send a chucking command to the re-chucking circuit CE at the time of tool exchange, but this connection may be omitted. In this case, the first chucking command to the re-chucking circuit CE is the horizontal turning section (b to c) of the change arm TA that starts operating in response to a tool change command issued by the NC device.
This is a chucking command from the mitt switch LS, which is turned on when it rises to . According to the present invention, the drawbar motor control circuit for forwarding and reversing the drawbar is provided with a current sensor that detects an overload current when the tool shank is fastened and outputs a meshing completion signal, and the re-chucking circuit is provided with a chucking time-up signal. A timer that outputs a timer and a re-chucking setting device that repeats a predetermined chucking operation are provided, and when a meshing completion signal is output from the current sensor within the time-up time set by the timer, the re-chucking setting device is reset. Sends a machining continuation signal to the NC device, and when the engagement completion signal is not output, a time-up signal sends a re-chucking command to the drawbar motor control circuit and change arm control circuit, and either the engagement completion signal is output or re-chucking is performed. Since the configuration is such that the chucking operation is repeated up to the set number of times determined by the setting device, there are dozens of cases in which the male screw of the drawbar is not engaged with the female screw of the tool shank for some reason, and the tool is not fastened to the spindle.
It is possible to eliminate the chucking that occurred approximately once in 0 times, and thereby prevent accidents of tool shank falling due to incomplete tightening of the tool shank, and improve the AT of the machine tool.
This has the effect of fully demonstrating the functions of the C device.

In addition, wear and tear on the male screw at the end of the drawbar and the female screw on the tool shank can be detected at an early stage.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a vertical milling machine with ATC equipped with the device of the present invention, Fig. 2 is a partially cutaway sectional view of the spindle head, and Figs. 3 and 4 are states in which the tool shank is fastened to the main spindle taper hole. FIG. 5 is a flowchart showing the operation of the device of the present invention, FIG. 6 is a block diagram showing the first embodiment of the control device system centered on the rechucking circuit of the present invention, and FIG. A wiring diagram of the drawbar motor, FIG. 8 is a block diagram showing the second embodiment, and FIG. 9 is a time chart. 6...Spindle head, 7...Spindle, 7a...7per hole, 8.
... Drawbar, 8a... Male screw, 10... Automatic tool loading/unloading device, T. ...Tool holder, 11...Tool shank, 11a...Female screw, M,...Drawbar motor, M〇...Drawbar motor control circuit, TA...Tool change arm, AC...Change arm control circuit, C.S.
...Current sensor, CC. ...Current Con/Yu, NC. ...NC device, CE...rechucking circuit, To...timer, Co...counter, TL. ...Time limit timer, 0, ~03...OR element, DF...Forward rotation relay, DR...Reverse rotation relay, LS, limit switch, A
L...Alarm lamp, 1. ... Starting current, Z... Operating current (chucking current), 13... Set value current
・・Overload current, ra...time-up time, i...
Meshing completion signal "X... Processing continuation signal, ta, tb...
Time up signal, ca...Count up signal. Chrysanthemum Figure 2 Figure 6 Figure 3 Figure 4 Sardine Figure 5 Figure 7 Boar 8 Figure 0

Claims (1)

[Claims] 1 The drawbar motor control circuit that rotates the drawbar in the forward and reverse directions is equipped with a current sensor that detects overload current when the tool shank is fastened and outputs an engagement completion signal, and the re-chucking circuit is equipped with a timer that outputs a chuck time-up signal. A re-chucking setting device is provided to repeat a predetermined chucking operation, and when a meshing completion signal is output from the current sensor within the time-up time set by the timer, the re-chucking setting device is reset and a processing continuation signal is sent to the NC device. When the meshing completion signal is not output, the timer's time-up signal sends a re-chucking command to the drawbar motor control circuit and the change arm control circuit, and the chucking operation is repeated until the meshing completion signal is output or the number of times set by the re-chucking setting device. A tool chuck control device for a machine tool with ATC, characterized in that it is configured as follows.