CN111376095A - Automatic tool changing mechanism of machine tool and control method thereof - Google Patents

Abstract

An automatic tool changing mechanism of a machine tool and a control method thereof are provided, the automatic tool changing mechanism comprises: a base; the cutter head is combined on the base and is provided with a plurality of cutter sleeves; a cutter head motor controlled to drive the cutter head to rotate; the cutter changing arm is arranged on one side of the cutter head; a tool changing motor controlled to drive the tool changing arm to rotate; a broach structure for driving one of the knife sleeves to swing between a first position and a second position; a host controller for issuing a first command and a second command; and the frequency converter is used for receiving the first command and the second command, outputting a first control signal to the cutter head motor corresponding to the first command, and outputting a second control signal to the cutter head motor corresponding to the second command. Thereby executing the tool changing operation and reducing the occurrence probability of failure.

Description

Automatic tool changing mechanism of machine tool and control method thereof

technical field

The invention relates to a tool changing system of a machine tool; in particular, it refers to an automatic tool changing mechanism and a control method of the tool machine.

Background technique

The automatic tool changing mechanism of the existing machine tool adopts two sets of induction motors to drive the tool disc or the tool changing arm to rotate respectively. The induction motor performs braking and deceleration actions through the equipped brakes. However, the use of the brakes is prone to wear and tear, which makes the positioning of the rotating cutter head or the cutter arm inaccurate, which increases the trouble.

In order to improve the above-mentioned lack of brakes, a new patented technology of Taiwan Announcement No. M470720 was produced. The patented technology discloses the use of a frequency converter and two relays to drive a tool magazine (or a cutter head) motor or a motor of an automatic tool changing mechanism respectively, thereby controlling the rotation of the tool magazine or the tool changing arm. Although the patented technology eliminates the defects caused by the use of brakes, the switching structure of the relay is still based on the principle of mechanical actuation. Therefore, when the relay is used to switch the connection between the inverter and the tool magazine motor, or the connection between the inverter and the motor of the automatic tool changing mechanism, it is still easy to cause damage or poor induction after each relay performs the switching action for a long time. , so that the control signal output by the inverter will be disturbed by noise and control failure occurs. Therefore, the patented technology is still not perfect.

SUMMARY OF THE INVENTION

In view of this, the purpose of the present invention is to provide an automatic tool changing mechanism of a machine tool and a control method thereof, in which the frequency converter directly controls the cutter head motor and the tool changing motor, so as to reduce the influence of noise interference during signal transmission, and has accurate and precise control. Executes the efficacy of the control, reduces the occurrence of failures, and improves the ease of use.

In order to achieve the above purpose, the present invention provides an automatic tool changing mechanism for a machine tool, including: a base; a cutter head, which is combined with the base, and a plurality of cutter sleeves are arranged on the cutter head; a cutter head motor , which is controlled to drive the cutter head to rotate; a cutter arm is arranged on one side of the cutter head; a cutter motor is controlled to drive the cutter arm to rotate; a broach structure is used to drive one of the cutter heads The knife sleeve pivots between a first position and a second position; an upper controller is used to issue a first command and a second command; a frequency converter is electrically connected to the cutter head motor and the tool changer The motor and the upper controller, the frequency converter has a command input port and a command output port, the command input port is electrically connected with the upper controller to receive the first command and the second command; the command output port It is electrically connected with the cutter head motor and the cutter head motor; the frequency converter outputs a first control signal to the cutter head motor in response to the first command to drive the cutter head to rotate; the frequency converter outputs corresponding to the second command A second control signal is sent to the tool changing motor to drive the tool changing arm to rotate.

In order to achieve the above object, the present invention provides a control method for an automatic tool changing mechanism of a machine tool. The automatic tool changing mechanism includes: a cutter head with a plurality of tool pockets on the cutter head; a cutter head motor controlled by to drive the cutter head to rotate; a cutter arm is arranged on one side of the cutter head; a cutter motor is controlled to drive the cutter arm to rotate; a broach structure is used to drive one of the cutter sleeves on A pivot between a first position and a second position; a host controller; a frequency converter electrically connected to the cutter head motor, the tool change motor and the host controller; a tool pocket position detector for Detecting the position state of the tool pocket, and sending a first detection signal when the tool pocket is at the first position, and sending a second detection signal when the tool pocket is at the second position; the control The method includes the following steps: before sending a first command to the inverter, the upper controller judges whether the first detection signal is received, and if the upper controller receives the first detection signal, outputting For the first command, if the upper controller does not receive the first detection signal, it will not output the first command; when the inverter receives the first command, it will output a first control signal to the tool correspondingly A disc motor to drive the cutter head to rotate.

The effect of the present invention is that the design of directly transmitting the control signal to the cutter head motor or the cutter motor through the frequency converter can effectively reduce the influence of noise interference during the transmission of the control signal.

Description of drawings

1 and 2 are perspective views showing an automatic tool changing mechanism of a machine tool according to an embodiment of the present invention;

FIG. 3 is a front view showing that the first detector of the present embodiment detects the movable rod;

FIG. 4 is a front view showing that the second detector of the present embodiment detects the movable rod;

FIG. 5 is a schematic diagram showing the structure of the automatic tool changing mechanism of the machine tool of the present embodiment;

6 to 9 are flowcharts of the control method of the present embodiment.

【Symbol Description】

[this invention]

Automatic tool changer for 100 machine tools

10 Pedestals

12 knife disc 12a knife cover

14 cutter head motor

16 Transmission structure

18 broach structure 18a movable rod

20 tool changer arm

22 tool change motor

24 upper controller 25 control box

26 Inverter 27 Box

26a Command input port 26b Command output port 26c Power input port

26d Tool pocket position signal input port 26e Tool change arm position input port

28 First detector 30 Second detector

32 signal wheel 34 detection switch

1,2,3,4 terminals

E city electricity

OUT1 first output terminal OUT2 second output terminal

S1 first detection signal S2 second detection signal

S3 third detection signal

P1 first position P2 second position

P3 third position P4 fourth position

Detailed ways

In order to illustrate the present invention more clearly, an embodiment is given and described in detail with the accompanying drawings as follows. Referring to FIGS. 1 to 5, an automatic tool changing mechanism 100 of a machine tool according to an embodiment of the present invention includes: a base 10, a cutter head 12, a cutter head motor 14, a broach structure 18, a A tool change arm 20 , a tool change motor 22 , a host controller 24 and a frequency converter 26 .

The base 10 can be assembled on a frame (not shown). The cutter head 12 is combined with the base 10, and is driven by the cutter head motor 14 to rotate relative to the base 10, and the cutter head 12 is provided with a plurality of cutter sleeves 12a. In this embodiment, It also includes a transmission structure 16, which is arranged on the base 10. The cutter head motor 14 drives the transmission structure 16 to drive the cutter head 12 to rotate; the cutter sleeve 12a is spaced along the periphery of the cutter head 12. , and each tool sleeve 12a can be used to combine a tool (not shown).

3 and 4 , the knife sleeve 12 a located at the bottommost edge of the knife disc 12 is driven by the broach structure 18 disposed on the base 10 and can move between a first position P1 and a first position P1 Pivoting between the two positions P2, when the knife sleeve 12a is located at the first position P1, it belongs to a standby position for storing tools, and when the knife sleeve 12a is located at the second position P2, it belongs to a tool changing position to prepare for changing tools, for example, it can be The tool is removed from the pocket 12a, or the tool is placed in the pocket 12a. In this embodiment, since the cutter head 12 is set upright, and each cutter sleeve 12a is arranged perpendicular to the disk surface of the cutter head 12, the cutter head 12a is in a horizontal state when it is located at the first position P1; When the knife sleeve 12a is located at the second position P2, it is in a vertical state. But in other applications, for example, when the cutter head is set horizontally and the cutter cover is set perpendicular to the disc surface of the cutter head, the cutter head may also be vertical when the cutter head is in the first position, and the cutter head may also be vertical when the cutter head is at the second position. may be horizontal and not limited to the above description.

Further, in this embodiment, the broach structure 18 includes a movable rod 18a, the movable rod 18a is used to drive the knife sleeve 12a to pivot between the first position P1 and the second position P2, and can be shown in FIG. 3 . A third position P3 shown and a fourth position P4 shown in FIG. 4 are reciprocated.

The tool changing arm 20 is arranged on one side of the tool head 12 and is arranged behind the base 10 together with the tool changing motor 22 . The tool changing arm 20 is connected to the tool changing motor 22 and is driven by the tool changing motor 22 And it can be rotated for tool changing.

The host controller 24 is electrically connected to the inverter 26 , and the host controller 24 is used to issue a first command and a second command to the inverter 26 . In this embodiment, the upper controller 24 is disposed in a control box 25, and the upper controller 24 may be but not limited to a PLC.

The frequency converter 26 is electrically connected to the cutter head motor 14, the tool change motor 22 and the upper controller 24, and the frequency converter 26 has a command input port 26a and a command output port 26b, and the command input port 26a is connected to the command input port 26a. The upper controller 24 is connected to receive the first command and the second command, and the command output port 26b is electrically connected to the cutter head motor 14 and the cutter motor 22 . The frequency converter 26 can output a first control signal to the cutter head motor 14 in response to the first command to drive the cutter head 12 to rotate; and output a second control signal to the cutter head motor 22 in response to the second command, to drive the tool changing arm 20 to rotate. In this embodiment, the frequency converter 26 is arranged in a casing 27, and the casing 27 is adjacent to the cutter head motor 14. In addition, in other applications, the frequency converter 26 can also be arranged in other positions, instead of It is limited to being provided in the casing 27 .

In this embodiment, the command input port 26a includes terminals 1, 2, 3, and 4. Terminal 1 is used to input a command for controlling the forward rotation of the cutter head 12 in the first command, and terminal 2 is used to input the first command. In the command, the command used to control the reverse rotation of the cutter head 12; Reverse command.

Further, the frequency converter 26 also includes a power input port 26c, which is connected to an external power source for receiving a power from the external power source. For example, in this embodiment, the power input port 26c is Connected to a commercial power E, the frequency converter 26 can receive the commercial power E and output a control signal with a specific frequency to the cutter head motor 14 and the cutter motor 22 through the command output port 26b.

In this embodiment, the command output port 26b includes a first output end OUT1 and a second output end OUT2, the first output end OUT1 is connected to the cutter head motor 14, and the frequency converter 26 receives the first output end OUT1. When a command is received, the first control signal is output to the cutter head motor 14 through the first output terminal OUT1 to drive the cutter head 12 to rotate. When the second command is received, the second control signal is output through the second output terminal OUT2 to the cutter head. The tool change motor 22 is used to drive the tool change arm 20 to rotate. Further, in this embodiment, the output voltages of the first control signal and the second control signal are higher than the voltage of the commercial power E.

Through the above design, the automatic tool changing mechanism 100 of the machine tool of the present invention can directly transmit control signals to the cutter head motor or the tool changing motor through the frequency converter 26, thereby effectively reducing the influence of noise interference when transmitting the control signals, thereby reducing Improve the accuracy of signal transmission.

In addition, in one embodiment, the automatic tool changing mechanism 100 further includes a tool pocket position detector, which is electrically connected to the upper controller 24 and the frequency converter 26, and the tool pocket position detector is used to detect the tool pocket 12a, a first detection signal S1 is issued when the tool pocket 12a is located at the first position P1, and a second detection signal is issued when the pocket 12a is located at the second position P2. In this embodiment, the tool pocket position detector includes a first detector 28 and a second detector 30, the first detector 28 and the second detector 30 are disposed on the base The front side of 10 is adjacent to the movable rod 18a. In this embodiment, the first detector 28 and the second detector 30 can be, but are not limited to, light sensors. When the knife sleeve 12a is located at the first position P1, that is, when the movable rod 18a of the broach structure 18 is located at the third position P3, the first detector 28 generates a first detector 28 by detecting the movable rod 18a in front. Detecting signal S1; please match as shown in FIG. 4 , when the second detector 30 is driven by the broach structure 18 to pivot to the inverted second position P2, the second detector 30 will The detector 30 detects the movable rod 18a moving up to the fourth position P4 and generates a second detection signal S2.

Please cooperate with FIG. 5 , in one embodiment, the host controller 24 is electrically connected to the first detector 28 and the second detector 30 for receiving the first detection signal S1 and the second detection signal S1 Signal S2; the frequency converter 26 has a tool pocket position signal input port 26d, which is electrically connected to the first detector 28 and the second detector 30 for receiving the first detection signal S1 and the second detector 30. Detection signal S2.

Please cooperate with FIG. 6 to FIG. 8 , the control method of the machine tool support automatic tool changing mechanism of this embodiment includes the following steps:

First, before the upper controller 24 sends the first command to the inverter 26, it is to determine whether the first detection signal S1 is received. If the upper controller 24 receives the first detection signal S1, it outputs the first command. If the upper controller 24 does not receive the first detection signal S1, it does not output the first command.

Then, if the inverter 26 receives the first command, it outputs the first control signal to the cutter head motor 14 correspondingly to drive the cutter head 12 to rotate.

Further, when the inverter 26 receives the first command or outputs the first control signal, it is further judged whether the inverter 26 has received the first detection signal S1, if the inverter 26 has received the first detection signal S1. If the detection signal S1 is detected, the cutter head motor 14 is controlled to run at a first speed. If the first detection signal S1 is not received, the cutter head motor 14 is controlled to run at a second speed, wherein the first speed is higher than the second speed. In this embodiment, when the frequency converter 26 receives the first detection signal S1, the frequency converter 26 outputs a first control signal with a higher frequency to the cutter head motor 14, so that the cutter head motor 14 can operate at a higher speed. When the frequency converter 26 does not receive the first detection signal S1, the frequency converter 26 outputs the first control signal with a lower frequency to the cutter head motor 14, so that the cutter head motor 14 runs at a lower frequency run at the second speed.

Afterwards, when the cutter head motor 14 drives the cutter head 12 to rotate to the position at the first speed, the upper controller 24 sends a first stop command to the inverter 26. When the inverter 26 receives the first stop command , corresponding to outputting a control signal to control the cutter head motor 14 to stop running. In addition, when the cutter head motor 14 drives the cutter head 12 to rotate at the second speed, it is further detected and judged whether the cutter sleeve 12a is in the horizontal state (the first position P1). A detection signal S1, if yes, it means that the tool pocket 12a is in the first position P1 (horizontal state), or the tool pocket 12a has been normally moved to the first position, after that, the frequency converter 14 will continue to detect the cutter head motor 14 Whether the operation is normal, for example, it can be judged whether the operation time of the cutter head motor 14 exceeds a warning value. If it is, it means that the cutter head motor 14 has been running for too long and an abnormality occurs, and the inverter 26 will issue an alarm message. The alarm message can notify The upper controller 24, when the upper controller 24 receives the alarm message, sends a first stop command to the inverter 26, so that the inverter 26 controls the cutter head motor 14 to stop running; in addition, in one embodiment, the The alarm message can be notified to maintenance personnel at the same time for subsequent troubleshooting; in addition, in one embodiment, when the frequency converter 26 sends out an alarm message, the upper controller 24 may not be notified, and the cutter head motor 14 can be directly controlled to stop operation, or, in an embodiment, when the upper controller 24 is notified of the alarm message, the cutter head motor 14 can be controlled to stop running.

In addition, when the cutter head 12 rotates to the positioning under normal operation, for example, the cutter head 12 is controlled to rotate to the positioning within the predetermined operation time of the cutter head motor 14, and the operation time does not exceed the warning value, the upper controller 24 is A first stop command is issued to the inverter 26, and when the inverter 26 receives the first stop command, it outputs a corresponding control signal to control the cutter head motor 14 to stop running. In addition, when the tool holder 12a is still not in a horizontal state, the cutter head motor 14 is controlled to stop, and the cutter head motor 14 is notified that the cutter head motor 14 is stuck and stopped abnormally.

In an embodiment, preferably, the tool pocket position detector sends the first detection signal S1 to the upper controller 24 and the frequency converter 26 at the same time. Through the above design, when the upper controller 24 issues a first command to control the rotation of the cutter head motor 14, the frequency converter 26 further determines the position state of the tool pocket, and determines whether the frequency converter 26 receives the first detection signal S1. Controlling the speed at which the cutter head motor 14 operates can effectively reduce the risk of misoperation when commands or signals are lost. For example, when controlling the rotation of the cutter head 12, if the position of the cutter pocket 12a is abnormal, the cutter pocket position detector will not send the first detection signal S1, at this time, even if the inverter 26 has received the first command And about to control the operation of the cutter head motor 14, because the frequency converter 26 will further receive the signal from the tool pocket position detector to determine the operation speed of the cutter head motor 14 to be controlled, because the frequency converter 26 does not receive the first detection signal S1 , so the cutter head motor 14 will be controlled to run at a relatively low second speed, therefore, the cutter head 12 will rotate at a relatively slow speed, and if during this period, the cutter sleeve 12a has returned to the first position P1, Then the frequency converter 26 can receive the first detection signal S1, and can control the cutter head 12 to run at the first speed, and if the cutter sleeve 12a still does not return to the first position P1, and collides with other components of the machine tool, Also, because the cutter head 12 is running at a lower speed, it can be stopped immediately, thereby reducing the risk of damage to the cutter pocket or other components.

In addition, when the upper controller 24 receives the second detection signal S2, it means that the selected tool pocket 12a is driven by the broach structure 18 to move to the second position P2 and is ready for tool change. The host controller 24 can output a second command to the inverter 26, and the inverter 26 outputs a second control signal to the tool changing motor 22 in response to the second command, so as to drive the tool changing arm 20 to rotate to execute the tool changing operation.

In addition, as shown in FIG. 5 , in one embodiment, the automatic tool changing mechanism 100 further includes a signal wheel 32 and a detection switch 34 , and the signal wheel 32 changes with the rotation of the tool change arm 20 . For the rotation angle, the detection switch 34 detects the rotation angle of the signal wheel 32 and generates a third detection signal S3. In this embodiment, the detection switch 34 is electrically connected to the upper controller 24 and the inverter 26 , and can output a third detection signal S3 to the upper controller 24 and the inverter 26 . The frequency converter 26 has a tool changing arm position input port 26e, which is connected to the detection switch 34 for receiving the third detection signal S3.

Please cooperate as shown in FIG. 9 , when the inverter 26 receives the second command, it determines the operating speed of the tool change motor based on whether the third detection signal S3 is received. When the inverter 26 receives the third detection signal At S3, the tool changing motor 22 is controlled to run at a third speed. If the inverter 26 does not receive the third detection signal S3, the tool changing motor 22 is controlled to run at a fourth speed, wherein the third speed is higher than Fourth speed. In this embodiment, when the frequency converter 26 receives the third detection signal S3, the frequency converter 26 outputs a second control signal with a higher frequency to the tool change motor 22, so that the tool change motor 22 can operate at a higher speed. When the frequency converter 26 does not receive the third detection signal S3, the frequency converter 26 outputs a second control signal with a lower frequency to the cutter head motor 14, so that the cutter motor 22 operates at a lower frequency run at the fourth speed.

In addition, in an embodiment, when the upper controller 24 does not receive the third detection signal S3, for example, the state of having received the third detection signal S3 is changed to the state of not receiving the third detection signal S3. In the state, the upper controller 24 does not output the second command, or stops outputting the second command. In addition, further, in an embodiment, the host controller 24 will further notify the inverter 26, so that the inverter 26 controls the tool changing motor 22 to run at the fourth speed until the host controller 24 sends a signal to the inverter 26. until the command stops.

Through the above design, when the upper controller 24 sends a second command to control the rotation of the tool change motor 22, the inverter 26 further determines the position state of the tool change arm 20, and according to whether the inverter 26 receives the third detection signal S3 is used to control the running speed of the tool change motor 22, which can effectively reduce the risk of misoperation when the command or signal is lost. That is, when the frequency converter 26 receives the third detection signal S3, the position of the tool changing arm 20 can be effectively grasped, and the rotation of the tool changing arm 20 can be controlled compared with the high-speed third speed. When the third detection signal S3 is reached, the tool changing arm 20 is controlled to rotate at a relatively low fourth speed.

Through the above design, in the control method of the present invention, the position of the tool pocket and the position of the tool changing arm can be confirmed by the upper controller and the inverter. When the signal is lost, the inverter can still drive the cutter head motor and the tool change motor, and perform the tool change operation at a lower speed.

The above are only feasible embodiments of the present invention, and all equivalent changes made by applying the description and claims of the present invention should be included in the patent scope of the present invention.

Claims (12)

1. An automatic tool changing mechanism of a machine tool, characterized in that it comprises:

a base;

the cutter head is combined on the base and is provided with a plurality of cutter sleeves;

a cutter head motor controlled to drive the cutter head to rotate;

the cutter changing arm is arranged on one side of the cutter head;

a tool changing motor controlled to drive the tool changing arm to rotate;

a broach structure for driving one of the knife sleeves to swing between a first position and a second position;

a host controller for issuing a first command and a second command;

the frequency converter is electrically connected with the cutter motor, the cutter changing motor and the upper controller and is provided with a command input port and a command output port, and the command input port is electrically connected with the upper controller and used for receiving the first command and the second command; the command output port is electrically connected with the cutter motor and the cutter changing motor; the frequency converter outputs a first control signal to the cutter motor corresponding to the first command so as to drive the cutter to rotate; the frequency converter outputs a second control signal to the tool changing motor corresponding to the second command to drive the tool changing arm to rotate.

2. The automatic tool changing mechanism of a machine tool according to claim 1, further comprising a tool sheath position detector for detecting a position state of the tool sheath, and for emitting a first detection signal when the tool sheath is at the first position, and for emitting a second detection signal when the tool sheath is at the second position; the upper controller is electrically connected with the cutter sleeve position detector and is used for receiving the first detection signal and the second detection signal, outputting the first command if the upper controller receives the first detection signal, and not outputting the first command if the upper controller does not receive the first detection signal.

3. The automatic tool changer of claim 2, wherein the transducer is electrically connected to the tool holder position detector for receiving the first detection signal, and when the transducer receives the first command, the transducer determines whether the first detection signal is received, and if the first detection signal is received, the transducer controls the cutter motor to operate at a first speed, and if the first detection signal is not received, the transducer controls the cutter motor to operate at a second speed, wherein the first speed is higher than the second speed.

4. The automatic tool changing mechanism of claim 3, wherein after the cutterhead motor is controlled to operate at the second speed, and after the upper controller receives the first detection signal, if the upper controller issues a first stop command to the frequency converter or the frequency converter issues an alarm message, the cutterhead motor is controlled to stop operating.

5. The automatic tool changing mechanism of a machine tool of claim 1, further comprising a signal wheel and a detecting switch, wherein the signal wheel changes the rotation angle with the rotation of the tool changing arm, and the detecting switch detects the rotation angle of the signal wheel and generates a third detecting signal; the upper controller is connected with the detection switch and is used for receiving the third detection signal.

6. The automatic tool changing mechanism of a machine tool of claim 5, wherein the transducer is electrically connected to the sensing switch for receiving the third sensing signal; when the frequency converter receives the second command, whether the third detection signal is received or not is judged, if the third detection signal is received, the tool changing motor is controlled to operate at a third speed, and if the third detection signal is not received, the tool changing motor is controlled to operate at a fourth speed, wherein the third speed is higher than the fourth speed.

7. A control method of an automatic tool changing mechanism of a machine tool is characterized in that the automatic tool changing mechanism comprises: the cutter head is provided with a plurality of cutter sleeves; a cutter head motor controlled to drive the cutter head to rotate; the cutter changing arm is arranged on one side of the cutter head; a tool changing motor controlled to drive the tool changing arm to rotate; a broach structure for driving one of the knife sleeves to swing between a first position and a second position; an upper controller; the frequency converter is electrically connected with the cutter motor, the cutter changing motor and the upper controller; a knife sleeve position detector for detecting the position state of the knife sleeve, and sending a first detection signal when the knife sleeve is positioned at the first position, and sending a second detection signal when the knife sleeve is positioned at the second position; the control method comprises the following steps:

A. the upper controller judges whether the first detection signal is received or not before sending a first command to the frequency converter, if the upper controller receives the first detection signal, the first command is output, and if the upper controller does not receive the first detection signal, the first command is not output;

B. when the frequency converter receives the first command, a first control signal is correspondingly output to the cutter motor so as to drive the cutter to rotate.

8. The control method according to claim 7, further comprising:

C. when the frequency converter receives the first command, whether the first detection signal is received or not is judged, if the frequency converter receives the first detection signal, the cutter motor is controlled to operate at a first speed, and if the frequency converter does not receive the first detection signal, the cutter motor is controlled to operate at a second speed, wherein the first speed is higher than the second speed.

9. The control method according to claim 8, further comprising:

D. after the cutter motor is controlled to run at the second speed, and after the upper controller receives the first detection signal, if the upper controller sends a first stop command to the frequency converter or the frequency converter sends an alarm message, the frequency converter controls the cutter motor to stop running.

10. The control method as claimed in claim 8, wherein the tool holder position detector sends the first detection signal to the upper controller and the frequency converter simultaneously.

11. The control method according to claim 7, wherein the automatic tool changer includes a signal wheel and a detecting switch, the signal wheel changes the rotation angle with the rotation of the tool changing arm, the detecting switch detects the rotation angle of the signal wheel and generates a third detecting signal; the control method also comprises the following steps:

when the upper controller receives the third detection signal, it outputs a second command to the frequency converter;

when the frequency converter receives the second command, a second control signal is correspondingly output to the tool changing motor so as to control the tool changing arm to rotate.

12. The control method according to claim 11, further comprising the steps of:

when the frequency converter receives the second command, whether the third detection signal is received or not is judged, if the third detection signal is received, the tool changing motor is controlled to operate at a third speed, and if the third detection signal is not received, the tool changing motor is controlled to operate at a fourth speed, wherein the third speed is higher than the fourth speed.

Images