MACHINE TOOL, PROCESSING SYSTEM AND MANAGEMENT SYSTEM

A machine tool according to the present invention includes: a turret capable of holding a plurality of tools; a spindle that selectively holds one of the plurality of tools held by the turret; a control unit that controls the operation of the turret and the spindle in accordance with a control parameter; a weight acquisition unit that, every time one tool is attached to the turret, acquires a weight of the attached one tool; and a weight setting unit that sets the weight acquired by the weight acquisition unit or an index associated with said weight in the control unit in association with the attached one tool, wherein the control unit sets the control parameter on the basis of the weights of the individual tools, which are set by the weight setting unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on Japanese Patent Application No. 2019-045563, the contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a machine tool, a processing system and a management system.

BACKGROUND ART

In the related art, there is a known machine tool that includes a turret capable of holding a plurality of tools and that automatically exchanges tools between a spindle and the turret (for example, see Patent Literatures 1-3).

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Although the weights of tools held by a turret vary, control parameters of a machine tool are set regardless of the weights of the individual tools. For example, the moving speed of a spindle during exchange of tools between the turret and the spindle is the same regardless of the weight of the tool being held by the spindle.

An aspect of the present disclosure is a machine tool including: a turret capable of holding a plurality of tools; a spindle that selectively holds one of the plurality of tools held by the turret; a control unit that controls the operation of the turret and the spindle in accordance with a control parameter; a weight acquisition unit that, every time one tool is attached to the turret, acquires a weight of the attached one tool; and a weight setting unit that sets the weight acquired by the weight acquisition unit or an index associated with said weight in the control unit in association with the attached one tool, wherein the control unit sets the control parameter on the basis of the weights of the individual tools, which are set by the weight setting unit.

DESCRIPTION OF EMBODIMENT

A machine tool1according to one embodiment will be described below with reference to the drawings.

As shown inFIGS. 1 and 2, the machine tool1includes: a turret3that holds a plurality of tools2; a rotary motor (drive unit)4that rotates the turret3; a spindle5that selectively holds one of the plurality of tools2held by the turret3; and a control device6that controls the operation of the turret3and the spindle5.

The turret3is supported on an upper end portion of a column8extending vertically upward from a bed7. A table9, onto which a workpiece W is fixed, is mounted on the bed7. The spindle5is supported on a spindle mounting base10so as to be rotatable about a longitudinal axis of the spindle5, and the spindle mounting base10is supported on the column8, by means of a ball screw and a linear guide or the like, so as to be movable in the vertical direction. The bed7is provided with an X-axis feed motor (not shown) and a Y-axis feed motor (not shown) for moving the table9in horizontal directions. The column8is provided with a Z-axis feed motor19for moving the spindle mounting base10together with the spindle5in the vertical direction.

The machine tool1relatively moves the table9and the spindle5by means of the X-axis, Y-axis, and Z-axis feed motors, while rotating the spindle5about the longitudinal axis by means of a spindle motor (not shown). By doing so, the workpiece W and the rotating tool2are relatively moved, and thus, the workpiece W is processed by the rotating tool2.

The machine tool1has a function for automatically exchanging tools2between the turret3and the spindle5.

As shown inFIG. 3, the turret3includes a plurality of tool holders3athat are fixed to a peripheral edge portion of a circular rotary plate3b. The plurality of tool holders3aare arranged in a circumferential direction of the rotary plate3b, and each of the tool holders3acan hold one tool2. The individual tool holders3aare provided with identification information. The rotary motor4is, for example, a servomotor. The turret3is rotated about a central axis of the rotary plate3bby means of the rotary motor4, whereby one of the plurality of tool holders3ais selectively positioned at a prescribed tool exchange position. The machine tool1replaces the tool2held by the spindle5by exchanging the tools2between the tool holder3aat the tool exchange position and the spindle5.

The turret3is rotated by means of the rotary motor4, whereby one of the plurality of tool holders3ais selectively positioned at a prescribed tool attachment/removal position. The tool attachment/removal position is a position where a worker or a robot performs attachment of a tool2to a tool holder3aand removal of a tool2from a tool holder3a.

As shown inFIG. 4, the control device6includes: a control unit11that controls the operation of the turret3and the spindle5; a weight acquisition unit12that acquires the weights of the individual tools2held by the turret3; and a weight setting unit13that sets the weights of the individual tools2in the control unit11. The control unit11, the weight acquisition unit12, and the weight setting unit13each include a processor and a storage unit having a non-volatile storage, ROM, RAM, etc., and respectively execute processing, which will be described later, in accordance with programs stored in the storage units.

The control unit11controls the operation of the turret3, the spindle5, and the table9in accordance with control parameters by transmitting control commands to the spindle motor, the feed motors, and the rotary motor4, and causes processing of the workpiece W by the tool2and exchange of the tools2between the spindle5and the turret3to be executed. As will be described later, the control parameter for at least one of the turret3and the spindle5is set on the basis of the weights of the individual tools2, which are set by the weight setting unit13.

Every time one tool2is attached to any one of the tool holders3a, the control unit11, the weight acquisition unit12, and the weight setting unit13execute acquisition and setting of the weight of the attached tool2.

Specifically, the control unit11causes the turret3to rotate in a prescribed operating pattern by transmitting a control command to the rotary motor4. In the prescribed operating pattern, the turret3accelerates, at the start of rotation, to a prescribed rotational speed at a prescribed acceleration and decelerates, at the end of rotation, from the prescribed rotational speed at the prescribed acceleration.

The weight acquisition unit12estimates the weight of one tool2attached to a tool holder3aon the basis of a load on the rotary motor4while the turret3is rotating in the prescribed operating pattern. A method of estimating the weight will be described later.

The weight setting unit13stores the weight of the tool2, which is estimated by the weight acquisition unit12, in the storage unit of the control unit11in association with the identification information of the tool holder3a, thereby setting the weight of the tool2in the control unit11. Therefore, information about the weights of all tools2held by the turret3is accumulated in the control unit11. The weight of a tool2may be set in the control unit11in association with the identification information of said tool2. The identification information of a tool2is, for example, input to the control device6by a worker or is automatically acquired from a recording medium attached to the tool2.

The acquisition and setting of the weight are executed, for example, after attachment of a tool2to a tool holder3ais completed, in response to an instruction input to the control device6by a worker.

The weight setting unit13may set, instead of the weight, an index associated with the weight in the control unit11. For example, in a case in which the maximum allowable weight of a tool2that can be mounted on the turret3is 4 kg, the index is a numerical value indicating a weight class, i.e. “1”, “2”, “3”, or “4”. The “1” indicates a range of 1 kg or less, the “2” indicates a range of more than 1 kg and at most 2 kg, the “3” indicates a range of more than 2 kg and at most 3 kg, and the “4” indicates a range of more than 3 kg and at most 4 kg.

Next, the operation of the machine tool1, related to setting of the weight of a tool2, will be described with an example case where tools2are attached, one by one, to the turret3in which all of the tool holders3aare empty.

A first tool2is attached by a worker to a tool holder3aat the tool attachment/removal position. After attachment of the first tool2, acquisition and setting of the weight of the attached tool2to be measured are executed.

Specifically, the rotary motor4causes the turret3to rotate in the prescribed operating pattern. The weight acquisition unit12records load data indicating changes in the load on the rotary motor4during rotation of the turret3. For example, the weight acquisition unit12receives a current value of the rotary motor4from an ammeter connected to the rotary motor4, and records time series data of a load torque calculated from the current value as the load data.

Next, the weight acquisition unit12estimates the weight of the tool2to be measured by comparing the load data with reference data. The reference data is load data obtained when the turret3that holds only one tool2having a known reference weight is rotated in the prescribed operating pattern. The reference data is stored in advance, for example, in the storage unit of the weight acquisition unit12.FIG. 5shows reference data in a case in which the reference weight is 1 kg. A plurality of reference data sets for a plurality of reference weights may be stored.

FIG. 6shows load data obtained in a state in which one 1 kg tool2is held by the turret3. As shown inFIG. 6, load data equal to or substantially equal to the reference data is obtained in a case in which the weight of the tool2to be measured is equal to the reference weight.

As shown inFIG. 7, the load on the rotary motor4increases as the weight of the tool2held by the turret3increases.FIG. 7shows load data obtained with a 1.0 kg tool2and load data obtained with a 3.7 kg tool2. InFIG. 8, a portion of the load data inFIG. 7is enlarged. Therefore, the difference between the load data and the reference data corresponds to the difference between the weight of the tool2to be measured and the reference weight. The weight acquisition unit12estimates the weight of the tool2to be measured on the basis of the difference between the load data and the reference data.

After the weight of the tool2to be measured is estimated by the weight acquisition unit12, the weight setting unit13sets the estimated weight or index in the control unit11in association with the identification information of the tool holder3aholding the tool2to be measured.

As described above, setting of the weight of the first tool2is thus completed.

Next, another empty tool holder3ais positioned at the tool attachment/removal position by rotation of the turret3, and a second tool2is attached by the worker to the tool holder3aat the tool attachment/removal position. After attachment of the second tool2, acquisition and setting of the weight of the second tool2are executed in the same way as for the first tool2. The load data recorded at the second time by the weight acquisition unit12is load data based on the weights of the first and second tools2. The weight acquisition unit12estimates the weight of the second tool2on the basis of the difference between the first load data and the second load data. The weight acquisition unit12may estimate the weight of the second tool2on the basis of the difference between the reference data and the second load data, as well as the weight of the first tool2which is already estimated.

Next, another empty tool holder3ais positioned at the tool attachment/removal position by rotation of the turret3, and a third tool2is attached by the worker to the tool holder3aat the tool attachment/removal position. After attachment of the third tool2, acquisition and setting of the weight of the third tool2are executed in the same way as for the first tool2. The weight acquisition unit12estimates the weight of the third tool2on the basis of the difference between the second load data and the third load data.

Thereafter attachment of a tool2to an empty tool holder3a, and acquisition and setting of the weight of the tool2are repeated.

After the weights of all the tools2held by the turret3are set, the control unit11sets a control parameter for at least one of the turret3and the spindle5on the basis of the weights of the individual tools2, which are set by the weight setting unit13, and executes processing of the workpiece W and exchange of the tools2.

An example of the control parameter is the speed at which the spindle5is vertically moved by means of the Z-axis feed motor19during tool exchange. When the tools2are exchanged between the turret3and the spindle5, the spindle mounting base10and the spindle5are vertically moved with respect to the turret3by means of the Z-axis feed motor19. The control unit11sets the moving speed of the spindle5and the spindle mounting base10such that the moving speed of the spindle5becomes higher as the tool2held by the spindle5becomes lighter. By doing so, it is possible to reduce the time required for the tool exchange.

Another example of the control parameter is the speed at which the turret3is rotated by means of the rotary motor4. The inertia of the tool2becomes larger as the tool2becomes heavier and as the rotation of the turret3becomes faster. The control unit11sets the rotational speed of the turret3such that the rotational speed becomes lower as the maximum weight among the weights of the tools2held by the turret3becomes larger. By doing so, it is possible to prevent a heavy tool2from being detached from the tool holder3adue to inertia and falling from the turret3or being damaged.

As described above, every time one tool2is attached to the turret3, the machine tool1automatically acquires and sets the weight of the attached tool2, and sets control parameters in accordance with the weights of the individual tools2. Therefore, even in a case in which tools2having various weights are held by the turret3, it is possible to set appropriate control parameters in accordance with the weights of the individual tools2. Because a decision by a worker is not required for setting the weights and the control parameters, even in a case in which an inexperienced worker attaches a tool2to the turret3, it is possible to set appropriate control parameters in accordance with the weight of the tool2and to prevent the occurrence of a problem such as the tool2falling off.

Although the case where a tool2is attached to the turret3in which all of the tool holders3aare empty has been described in the abovementioned embodiment, the weight of a tool2newly attached to the turret3may be acquired and set after any one of the plurality of tools2held by the turret3is replaced therewith.

The machine tool1may further include a notification unit14that notifies a worker in a case in which the weight of a tool2, which is acquired by the weight acquisition unit12, exceeds a prescribed allowable value. The notification unit14is, for example, a display that displays an alarm indication or an alarm device that issues an alarm sound.

With this configuration, the worker can recognize that the weight of the tool2attached to the tool holder3aexceeds the allowable value, on the basis of the output of the notification unit14. Thus, it is possible to prevent the machine tool1from using a tool2having a weight exceeding the allowable value. In order to prevent the machine tool1from operating in a state in which a tool2having a weight exceeding the allowable value is held by the turret3, the control unit11may prohibit the operation of the turret3, the spindle5, the table9, etc. in the case in which a tool2having a weight exceeding the allowable value is attached to a tool holder3a.

In the abovementioned embodiment, the control device6may include a learning unit that learns the relationship between the load on the rotary motor4and the weight estimated from the load by the weight acquisition unit12.

For example, the load data and the weight of a tool2, which is calculated from the load data, are accumulated in the storage unit of the control unit11. The control unit11serving as the learning unit learns the relationship between the accumulated load data and weight on the basis of a learning program stored in the storage unit. The weight acquisition unit12estimates the weight a tool2by using a learning result of the learning unit. By doing so, it is possible to enhance the precision for estimating the weight by the weight acquisition unit12.

Although the weight acquisition unit12estimates the weight of a tool2on the basis of the load on the rotary motor4in the abovementioned embodiment, alternatively, as shown inFIG. 9, the weight acquisition unit12may receive the weight of a tool2attached to a tool holder3aor information about the weight from an external device16.

An example of the external device16is a gravimeter that measures the weight of a tool2. For example, the gravimeter is disposed outside the machine tool1and is connected to the control device6so as to be able to communicate therewith. The worker measures the weight of a tool2by using the gravimeter, and subsequently attaches the tool2to a tool holder3a. The measurement of the weight of a tool2by means of the gravimeter may be performed by a robot that attaches/removes a tool2to/from the turret3. The weight of the tool2is transmitted to the weight acquisition unit12from the gravimeter.

Another example of the external device16is a robot that attaches/removes a tool2to/from the turret3. For example, the robot is provided with: an articulated robot arm; a hand that is connected to the distal end of the robot arm; and a force sensor that detects a load acting on the hand. The robot detects a load acting on the hand, in other words, the weight of a tool2by means of the force sensor, in a state in which the tool2is gripped by the hand, and transmits the detected weight of the tool2to the weight acquisition unit12. Another embodiment of the present disclosure may be a processing system including the machine tool1and such a robot as described above.

Another example of the external device16is a control device of another machine tool that is connected to the control device6. The weight acquisition unit12receives the weight of a tool, which is stored in the control device of the other machine tool, together with the identification information of the tool from the control device of the other machine tool. The control device6may transmit, to the control device of the other machine tool, the weight of a tool2together with the identification information thereof. Thus, by sharing the information about the weight of a tool2between a plurality of machine tools, the control devices of the individual machine tools can efficiently collect the information about the weights of various tools2.

Although setting of the weight of a tool2in the control unit11is executed in the control device6of the machine tool1in the abovementioned embodiment, alternatively, a control device different from the control device6may set the weight of a tool2in the control unit11.FIGS. 10 to 12show other embodiments.

In another embodiment shown inFIG. 10, the machine tool1is connected to the external device16via another control device17different from the control device6. The other control device17is, for example, a microcomputer that is disposed inside or outside the machine tool1. The weight acquisition unit12and the weight setting unit13are provided in the other control device17. The other control device17acquires the information about the weight of a tool2from the external device16, and sets the weight of the tool2in the control unit11of the control device6. Thus, the connection between the external device16and the machine tool1is relayed by the other control device17, and this makes it possible to simplify the wiring.

The other control device17may be connected to a power supply18different from a power supply of the machine tool1. With this configuration, it is possible to enhance the maintenance workability of the machine tool1. For example, even when the power supply of the machine tool1is turned off, the worker can check, with the other control device17, the weight of a tool2held by the turret3.

FIG. 11shows a management system100according to another embodiment. The management system100includes a plurality of machine tools1A,1B,1C. A control device6A of one machine tool1A is connected to control devices6B,6C of other machine tools1B,1C and monitors the other machine tools1B,1C. The control device6A includes the weight acquisition unit12and the weight setting unit13, and sets the weight of a tool2in respective control units11of the control devices6A,6B,6C. By doing so, it is possible to set control parameters in accordance with the weights of the individual tools2held by the turret3also in the machine tools1B,1C that do not include the weight acquisition unit12and the weight setting unit13.

FIG. 12shows a management system200according to another embodiment. The management system200includes a plurality of machine tools1A,1B,1C and a host control system (control device)20. In the management system200, control devices6A,6B,6C and the external device16are edge devices, and the host control system20is connected to the control devices6A,6B,6C of the plurality of machine tools1A,1B,1C and the external device16. The host control system20includes the weight acquisition unit12and the weight setting unit13, and sets the weight of a tool2in respective control units11of the control devices6A,6B,6C. By doing so, with one host control system20, it is possible to set control parameters of the plurality of machine tools1A,1B,1C in accordance with the weights of the individual tools2held by the turret3.

The host control system20is, for example, a computer connected to the control devices6A,6B,6C by wires or a computer or the like disposed within the same site as the control devices6A,6B,6C. The host control system20is sometimes referred to as a fog computer. The host control system20may be a production management system, a delivery management system, a robot management system, a department management system or the like. The host control system20includes: a control unit having a processor or the like; a display device; a storage unit having a non-volatile storage, ROM, RAM, etc.; an input device which is a keyboard, a touch panel, an operation panel or the like; and so forth.

In the management systems100,200inFIGS. 11 and 12, the information about the loads on rotary motors4and the estimated weights of the tools2in the plurality of machine tools1A,1B,1C is aggregated in the common control device6A or20. This configuration is advantageous in that it is possible to enhance the learning efficiency in a case in which the control devices6A,20have a learning function similar to that of the aforementioned learning unit of the control device6.

In the management systems100,200inFIGS. 11 and 12, the plurality of control devices6A,6B,6C may each have a learning function. In this case, for example, the host control system20may transmit, as learning data, the aggregated information about the loads on the rotary motors4and the estimated weights of the tools2to the individual control devices6A,6B,6C.

A plurality of host control systems20may be connected to another host control system. The other host control system is, for example, a cloud server connected to the plurality of host control systems20via a wired or wireless communication network. In this case, the other host control system may set the weight of a tool2in the control units11of the machine tools1A,1B,1C serving as edge devices. The other host control system may have a learning function.

REFERENCE SIGNS LIST