JPH06190671A - Automatic tool exchange method and device therefor - Google Patents

Abstract

PURPOSE:To exchange tools at optimum speed according to the weight of tools by detecting the magnitude of a load required for the movement when a tool exchange arm is moved in the axial direction so as to draw out, and controlling the rotating speed in the succeeding process of the tool exchange arm according to the detected value. CONSTITUTION:The grippers of exchanging tools are provided on both end parts of a tool exchange arm 1. A rack 3 provided on the other end of a rotary and advancing/retreating shaft 2 of the arm 1 is threadedly engaged with a pinion 4 connected to the output shaft of a motor M1. Further a cylindrical spur gear 5 provided on the intermediate part of the shaft 2 is engaged with another pinion 6 connected to another motor M2. The respective motors M1, M2 are respectively controlled by means of respective servo parts 1, 2 connected to a machine control device MTC A containing an ATC arm speed control means B. When the arm 1 is moved in the axial direction so as to draw out, the magnitude of a load required for the movement is detected. Thereafter, the rotating speed of the arm 1 in the succeeding process is controlled according to the detected value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic tool changing method and device in a machine tool.

[0002]

2. Description of the Related Art In an automatic tool changer for a machine tool, the conventional tool changer (ATC) arm is equipped with a tool change operation sequence as shown in FIG. Indicates that the ATC arm is in the standby position. In (b), the arm in the standby position rotates 90 ° in the clockwise direction (CW), and the tool on the machine tool spindle and the tool on the pot in the standby position of the tool magazine are moved to the end portions on both sides of the arm ( Shown where it is gripped with a gripper). At that time, the spindle tool is unclamped and the arm is gripping the tool.

In (c), the arm moves forward (OUT) to grasp and pull out the tool on the spindle side and the tool on the pot side. The arm that has moved forward is shown to be rotated 180 ° while holding the replacement tool, and the positions of the tools on both sides are reversed. Arm rotation direction is tool change 1
Alternate clockwise (CW) and counterclockwise (CC
Rotate to W). Here, the centrifugal force due to the tool weight is applied to the gripper when the arm rotates, so the rotation speed of the arm has a certain constraint based on its structural strength and the size of the replacement tool weight.

In (d), the arm is moved backward (IN), the tools on both sides of the arm are inserted into the machine tool spindle and the pot of the tool magazine, and after the spindle side tool is clamped on the spindle, the arm is moved. After rotating 90 degrees counterclockwise (CCW) and returning to the standby position [the same position as in Fig. 4 (a)]
Is shown.

Of the operation sequence described above, FIG. 4 (c)
As mentioned earlier, while holding the replacement tool in the grippers on both ends of the arm, it suddenly moves in the axial direction and rotates 180 °, so centrifugal force and reaction force based on the inertial weight of the tool are Since it depends on the drive mechanism, in terms of strength or safe operation, the replacement operation speed of a constant value had to be determined according to the heaviest tool among the replacement tools. That is,
If the structure and operation of the tool changer or its drive mechanism are not matched with those of the heaviest tool among the changeable tools, a large centrifugal force may be applied during the rotating operation of the arm, and the tool may come off from the gripper. It is because there is a possibility that the drive device may be damaged due to an excessive force applied before and after the rotating operation of the arm and the forward / backward movement.

However, even in the case of a relatively light weight tool replacement operation, the tool replacement is performed at the same speed as the heavy tool replacement, so that the replacement efficiency is poor. In addition, since the equipment ratio of the replacement tool is generally large, the equipment ratio of the lightweight tool is large, so that the efficiency as a whole is lowered. In order to solve the above problems, there is an automatic tool change protection device disclosed in Japanese Utility Model Laid-Open No. 4-70440. This is because in an automatic tool changer that automatically performs tool change through a cam mechanism by a single electric motor, the operation reference speed of the automatic tool changer is set in advance, and the electric motor input during the tool change operation is set. The load condition is monitored by changing the current value and the tool change speed is changed. Then, the tool changer is driven at an optimum speed according to the weight of the tool, thereby preventing the mechanism of the tool changer from being damaged by the moment of inertia of the heavy tool.

This discloses a technique of changing the speed of the electric motor itself by monitoring the load state of the electric motor in a cam type tool changing device having a single electric motor. There is no disclosure regarding a speed control technique for a tool changing device that separately has a driving unit that reciprocates in a direction and a driving unit that rotates about an axis.

[0008]

SUMMARY OF THE INVENTION Therefore, the present invention solves the inconvenience inherent in the tool changing method in the conventional device described above, and determines the optimum speed according to the weight of the tool for the strength and performance of the device to determine the tool. (EN) A method and an apparatus for exchanging a tool, which aim to stabilize the operation of an automatic tool change, improve efficiency, and extend the service life of the apparatus.

[0009]

In order to achieve the above-mentioned object, the present invention has the respective constituents described below. (1) In an automatic tool changing method in which a tool changing arm is used to perform tool changing by reciprocating movement in the axial direction and rotating operation about its rotation axis, the tool changing arm holding the tool is moved in the axial direction. When the tool is pulled out from the machine tool spindle or the tool magazine, the magnitude of the load required for axial movement of the tool changing arm is detected, and the speed of the rotating operation in the next step of the tool changing arm is controlled according to the detected value. The automatic tool changing method.

(2) A tool exchanging arm having a gripper for gripping a tool, a first drive means for reciprocating the tool exchanging arm in the axial direction thereof, and an operation of the first drive means. Second drive means for rotating the tool exchanging arm around its rotation axis, and the tool exchanging arm holding the tool is moved along its axial direction to move the tool from the machine tool spindle or the tool magazine. Load detection means for detecting the magnitude of the load of the first drive means at the time of pulling out, and control means for controlling the speed of the rotation operation in the next step of the tool changing arm based on the detection value of the detection means. An automatic tool changer consisting of and.

[0011]

[Action]

(1) As shown in FIGS. 4B and 4C, the tool exchanging arm advances (OUT) in the rotation axis direction while holding the exchanging tool by the grippers at both ends. (2) In the above operation, the first driving means of the arm is
A load is required to move the entire mass of the arm member to which the inertial weight of the exchange tool held by the arm is added. In particular, at the start of the operation, the influence of the tool weight (mass) significantly appears on the first driving means of the arm. (3) The load applied to the first driving means of the arm is detected.

(4) By inputting the detected value into the control means,
When these are moved / stopped by the exchanging device / driving means, a control command of an appropriate speed suitable for the mechanical strength and characteristics of the exchanging device is output. (5) The second drive means of the arm is controlled so that the subsequent tool exchange operation, that is, the rotation operation of the tool exchange arm is performed at the appropriate speed commanded by the control means. By doing so, it is possible to shorten the tool change time of the lightweight tools, which statistically occupies the majority, without considering the load on the device during the heavy tool change. Further, the tool change efficiency can be improved without externally providing a special accessory to the tool changer.

[0013]

EXAMPLES Examples of the present invention will be described below with reference to the drawings. However, some of the members constituting the examples are within the technical level known in the art at the time of the application. ,
Considering that a person skilled in the art can arbitrarily change the design, it should be understood that the gist of the present invention is limited based on only the configuration of the present embodiment without showing any special reason. Absent.

FIG. 1 is a block diagram of a first embodiment of the method and apparatus of the present invention, in which the tool changer is driven by a servomotor. In the figure, the tool exchanging arm 1 is provided with grippers for exchanging tools at both ends of the arm. 2 indicates a rotation axis and forward / backward axis of the arm,
At the other end, a rack 3 that meshes with a pinion 4 that is connected to the output shaft of the electric motor M ₁ is provided via a joint, and the left direction along the axis of the rotary shaft 2 is forward (OUT) and the right direction. Is the rear (IN) (see also FIG. 4).

The cylindrical spur gear 5 mounted on the rotary shaft 2 has a length in the generatrix direction which is substantially the same as the forward / backward stroke of the arm 1, and the cylindrical spur gear 5 and an electric motor M ₂ meshing with the gear 5 are provided. The pinion 6 connected to the output shaft is provided so as not to break the interlocking relationship regardless of the front-back position of the arm 1 in the rotation axis direction. The electric motors M ₁ and M ₂ are respectively a servo section (1) and a servo section (2) connected to a machine control device MTC including “ATC arm speed control means”.
Controlled by. Further, as shown in the figure, the MTC issues commands such as a tool change No., spindle ON / OFF, cutting fluid ON / OFF, and is connected to an NC device including an NC program.

FIG. 2 is an operation sequence diagram of the above-mentioned "ATC arm speed control means". In step S1, the "tool change signal" is received from the NC device and the electric motor M is received.
Command ₂ to "rotate arm 90 °". As a result, the arm 1 is moved through the electric motor M ₂ , the pinion 6 and the cylindrical spur gear 5.
Rotates (CW), and the replacement tool is gripped by both grippers of the arm [see FIG. 4 (b)]. Next, in S2,
Actuates the motor M ₁ and output through the servo unit (1) command for "arms forward", the pinion 4, the replacement tool in company arm 1 through the rack 3 to try to advance (OUT) [4 ( See c)].

In this case, in S3, the magnitude of the inertial weight of the exchange tool gripped by the arm is deeply related to the rising drive load of the forward movement of the arm 1, for example, the current value of the electric motor M _1. The weight of the tool held by the arm 1 at that time can be detected by detecting the current value of the electric motor M ₁ during the rise of OUT. S4
In, the lightness judgment of the weight of the replacement tool is performed based on the detected value, and thereby the arm operation speed of the next step is
Depending on the weight of the tool, the appropriate speed is determined based on the mechanical strength and characteristics of the existing replacement device and drive device. According to a predetermined function or table determined in advance, the control is performed fast for a light change tool and slow for a heavy change tool. For this speed control,
The upper limit speed and the lower limit speed may be set.

In S5, a command of "arm 180 ° swing" is output together with the determined proper operating speed through the servo section (2), and the proper speed is provided through the electric motor M ₂ , the pinion 6 and the cylindrical spur gear 5. The arm 1 is controlled so as to turn (CW). Therefore, regardless of the weight of the replacement tool, the members constituting the replacement device and drive device are not overloaded during operation, so there is no risk of accidents and the service life of the device is reduced. In addition to being able to extend the tool, the tool is changed at the maximum allowable speed. That is, when the weight of the exchange tool is light, the arm can be swung at a correspondingly high speed, so that there is no possibility that the tool exchange operation becomes inefficient. In S6, the arm after it has finished 180 ° turning (CW), the command "Arm Retract" and output via servo unit (1) actuates the motor M _1, the spindle-side tool to the spindle, also pot The side tool is attached to the pot [see FIG. 4 (c)].

FIG. 3 is a block diagram of the second embodiment of the present invention, showing the case where the ATC arm member is driven by a hydraulic mechanism. In the figure, members designated by the same reference numerals as those in FIG. 1 have the same structure and members as those described in the first embodiment. Further, the configurations and functions of the machine control device MTC, the "ATC arm speed control means" and the NC device are basically the same as those described in the first embodiment. In the double-acting hydraulic cylinder 7, one end of its piston rod is connected to the rotary shaft 2 of the arm 1 via a joint, and the ATC arm 1 is moved forward (OUT) or backward (I) depending on its operation.
N) (see FIGS. 4C and 4D).

The rack 8 meshing with the cylindrical spur gear 2 is driven by a double-acting hydraulic cylinder 9, and the arm 1 is alternately passed through the cylindrical spur gear 2 as shown in FIG. CW), turn counterclockwise (CCW). Each end of the hydraulic cylinders 7 and 8 has a fluid supply pipe,
The arm 1 communicates with the hydraulic power source 11 via the flow rate control device 10 operated by a command from the "TC arm speed control means".
Are operated in the order of the steps shown in FIG. As shown in FIGS. 4 (b) to 4 (c), the flow velocity sensor 12 for detecting the flow velocity of pressure oil on the piston advance side of the hydraulic cylinder 7 is
The valve of the flow control device 10 is opened to supply pressure oil to the cylinder 7 to advance the arm 1 while holding the exchange tool, and at the time of rising thereof, the flow velocity influenced or related to the inertial weight of the exchange tool gripped by the arm is detected. .

The detected flow velocity at the time of rising is "AT
Based on the flow similar to the sequence diagram shown in FIG. 2 which is input to the "C arm speed control means", a control command is issued to the flow rate control device 10 so that the arm operation of the subsequent process is performed at an appropriate speed according to the detected value. Output. The operation of this embodiment is almost the same as that described in the first embodiment, and the description thereof will be omitted.

[0022]

EFFECTS OF THE INVENTION Since the present invention is as described above, (1) statistically, the tool exchange time of a lightweight tool having a large equipment ratio is shortened without considering the load on the device when exchanging a heavy tool. can do. (2) The exchange speed can be controlled without installing a special new device. (3) As a result, the processing efficiency is improved. (4) It is possible to eliminate the failure of the tool changer and extend the service life. And so on, it is possible to obtain actions and effects that cannot be expected from conventional devices.

[Brief description of drawings]

FIG. 1 is a block diagram of a first embodiment of the present invention.

FIG. 2 is an AT in a machine control device MTC which constitutes the present invention.
The operation | movement sequence diagram of C arm speed control means is shown.

FIG. 3 is a block diagram of a second embodiment of the present invention.

FIG. 4 shows an operation / sequence of tool exchange.

[Explanation of symbols]

 1 Tool changing arm 2 Arm rotating shaft 3 Rack 4 Pinion 5 Cylindrical spur gear 6 Pinion 7 Double-acting hydraulic cylinder 8 Rack 9 Double-acting hydraulic cylinder 10 Flow control device 11 Hydraulic power source 12 Flow velocity sensor.

Claims (2)

[Claims] 1. An automatic tool exchanging method in which a tool exchanging arm is used to perform tool exchanging by reciprocating movement in the axial direction and rotational movement around its rotation axis, wherein the tool exchanging arm holding the tool is moved in the axial direction. When the tool is moved and the tool is pulled out from the machine tool spindle or tool magazine, the magnitude of the load required to move the tool changing arm in the axial direction is detected, and the speed of the rotating operation in the next step of the tool changing arm is detected according to the detected value. An automatic tool changing method characterized by controlling the. 2. A tool exchanging arm having a gripper for gripping a tool, a first drive means for reciprocating the tool exchanging arm in an axial direction thereof, and an operation of the first drive means. Second drive means for rotating the tool changing arm around its rotation axis, and moving the tool changing arm holding the tool along its axial direction to pull out the tool from the machine tool spindle or tool magazine. Load detecting means for detecting the magnitude of the load of the first driving means at this time, and control means for controlling the speed of the rotating operation in the next step of the tool exchanging arm based on the detection value of the detecting means. An automatic tool changer characterized by comprising: