Automatic tool changer and machine tool

An automatic tool changer (ATC) serves as an ATC for automatically changing a tool attached to a lower tool rest of a machine tool. The ATC includes a robot arm and a movement mechanism unit moving the robot arm between inside and outside of a machining area. The robot arm has a base unit coupled to the movement mechanism unit, an arm unit pivotably coupled to the base unit, and a gripping unit provided in the arm unit and detachably gripping the tool. The arm unit is formed to extend in an arm shape from the base unit toward the gripping unit, and swings on a pivot axis as a fulcrum relative to the base unit. By such a configuration, an ATC implementing an automatic change of a tool by a simple and compact mechanism and a machine tool including such an ATC are provided.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to an automatic tool changer (ATC) and a machine tool.

Description of the Background Art

As to the conventional ATC, for example, Japanese Utility Model Laying-Open No. 60-117001 discloses a numerical-value controlling lathe equipped with an ATC, which aims at simplifying the operation of the ATC and shortening of the time required for changing a tool (PTD 1).

The numerical-value controlling lathe disclosed in PTD 1 includes an ATC for automatically changing a tool between a turret on a tool rest and a tool magazine. The ATC has a tool carrier that moves in the axial direction of a spindle and also in the direction orthogonal to the axial direction of the spindle while gripping the tool.

Furthermore, Japanese Patent Laying-Open No. 60-123243 discloses a machine tool equipped with a tool changer, which aims at providing cleaning means that allows easy cleaning on each guide plane when automatically changing a tool block in a linear reciprocating motion, and that has a simple structure but still reliably operates, and also allows further swift cleaning (PTD 2).

The machine tool disclosed in PTD 2 includes changing means for automatically changing a tool between a turret head on a tool rest and a tool magazine. The changing means has a gripper for gripping the tool, and is disposed so as to be capable of moving forward and backward between the turret head and the tool magazine.

Furthermore, Japanese Patent Laying-Open No. 06-238539 discloses a tool changer aiming at attaching/detaching a tool unit to/from a tool holder attached to a turret in parallel to the central axis line of the turret or at a right angle to this central axis line (PTD 3).

In the tool changer disclosed in PTD 3, near the turret, an X-Z stage is provided for holding a drive box so as to be movable in the directions at a right angle to and in parallel to the central axis line of the turret. A tool changing box having a tool hand for gripping the tool unit is swivelably provided in the drive box.

SUMMARY OF THE INVENTION

As disclosed in the above-described PTD 1 to PTD 3, various types of automatic tool changers (ATC) for automatically changing a tool attached to a tool rest (turret) of a machine tool are proposed. In such an ATC, it is required to implement an automatic change of a tool by a simple and compact mechanism in order to prevent an increase in size of the machine tool.

Accordingly, an object of the present invention is to solve the above-described problems, and to provide an ATC that implements an automatic change of a tool by a simple and compact mechanism, and a machine tool including such an ATC.

An ATC according to the present invention is provided as an ATC for automatically changing a tool attached to a tool rest of a machine tool. The ATC includes a robot arm and a movement mechanism unit moving the robot arm between inside and outside of a machining area. The robot arm has a base unit coupled to the movement mechanism unit, an arm unit pivotably coupled to the base unit, and a gripping unit provided in the arm unit and detachably gripping the tool. The arm unit is formed to extend in an arm shape from the base unit toward the gripping unit and swings on a pivot axis as a fulcrum relative to the base unit.

According to the ATC configured in this way, by moving the robot arm using the movement mechanism unit and by swinging the arm unit on the base unit as a fulcrum, the tool gripped by the gripping unit is moved and the attitude of this tool is changed. Accordingly, the tool can be automatically changed by a simple and compact mechanism.

Further preferably, the base unit is provided so as to be rotatable about a first rotation axis orthogonal to the pivot axis of the arm unit.

According to the ATC configured in this way, it becomes possible to increase the degree of freedom at the time when the tool gripped by the gripping unit is moved or when the attitude of the tool is changed.

Further preferably, the arm unit includes a first movable unit pivotably coupled to the base unit, a second movable unit pivotably coupled to the first movable unit, and a third movable unit pivotably coupled to the second movable unit and provided with the gripping unit. A first pivot axis between the base unit and the first movable unit, a second pivot axis between the first movable unit and the second movable unit, and a third pivot axis between the second movable unit and the third movable unit are arranged in parallel.

According to the ATC configured in this way, it becomes possible to increase the degree of freedom at the time when the tool gripped by the gripping unit is moved or when the attitude of the tool is changed.

Further preferably, the second movable unit is provided to extend in an arm shape in an axial direction of a second rotation axis orthogonal to the second pivot axis and to be rotatable about the second rotation axis. The third movable unit is provided to extend in an arm shape in an axial direction of a third rotation axis orthogonal to the third pivot axis and to be rotatable about the third rotation axis.

According to the ATC configured in this way, it becomes possible to increase the degree of freedom at the time when the tool gripped by the gripping unit is moved or when the attitude of the tool is changed.

A machine tool according to the present invention includes: the ATC described in any of the above; and a tool rest disposed within a machining area and equipped with a tool automatically changed by the ATC.

According to the machine tool configured in this way, the ATC is configured by a simple and compact mechanism, so that the machine tool can be decreased in size.

Further preferably, the tool is inserted from one direction into the tool rest when the tool is attached to the tool rest. The movement mechanism unit moves the robot arm in a direction parallel to an insertion direction of the tool into the tool rest.

According to the machine tool configured in this way, when the tool is attached to the tool rest, the movement mechanism unit moves the robot arm, so that the tool can be inserted into the tool rest.

Further preferably, the machine tool further includes a headstock provided within the machining area and rotating a workpiece. A pivot axis of the arm unit is orthogonal to a rotation axis of the workpiece in the headstock.

According to the machine tool configured in this way, the ATC can be configured in a compact manner particularly in the direction orthogonal to the rotation axis of the workpiece. Thereby, excellent accessibility for an operator to a headstock can be achieved at the time when the machine tool is used.

As described above, according to the present invention, it becomes possible to provide: an ATC that implements an automatic change of a tool by a simple and compact mechanism; and a machine tool including such an ATC.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be hereinafter described with reference to the accompanying drawings. In the drawings referred in the following, the same or corresponding components are designated by the same reference characters.

First Embodiment

FIG. 1is a front view showing a machine tool in the first embodiment of the present invention.FIG. 1is a perspective view of a cover body exhibiting an external appearance of the machine tool, which shows the inside of the machine tool.

Referring toFIG. 1, a machine tool100serves as a composite processing machine having a turning function using a fixed tool and a milling function using a rotating tool. First, the entire structure of machine tool100will be hereinafter described. Machine tool100includes a bed141, a first headstock111, a second headstock116, a tool spindle121, and a lower tool rest131.

Bed141serves as a base member for supporting first headstock111, second headstock116, tool spindle121, and lower tool rest131, and is placed on an installation surface of a factory or the like.

First headstock111and second headstock116are disposed to face each other in the Z-axis direction extending in the horizontal direction. First headstock111and second headstock116have a spindle112and a spindle117, respectively, for rotating a workpiece during the turning process using a fixed tool. Spindle112is provided so as to be rotatable about a central axis201parallel to the Z-axis while spindle117is provided so as to be rotatable about a central axis202parallel to the Z-axis. Spindle112and spindle117each are provided with a chuck mechanism for detachably holding a workpiece.

A tool spindle (upper tool rest)121rotates the rotating tool during milling processing using the rotating tool. Tool spindle121is provided so as to be rotatable about a central axis203parallel to the X-axis extending in the vertical direction. Tool spindle121is provided with a clamping mechanism for detachably holding the rotating tool.

Tool spindle121is supported on bed141by a column and the like (not shown). Tool spindle121is provided so as to be movable in the X-axis direction, in the Y-axis direction extending in the horizontal direction and orthogonal to the Z-axis direction, and in the Z-axis direction by various types of feed mechanisms, guide mechanisms, servo motors, and the like provided in the column and the like. The machining position by the rotating tool attached to tool spindle121is moved in a three-dimensional manner. Tool spindle121is provided so as to be also swivelable about a central axis parallel to the Y-axis.

Lower tool rest131is equipped with a plurality of fixed tools for a turning process. Lower tool rest131, which has a so-called turret type, is equipped with a plurality of fixed tools in a radial manner, and serves to perform swivel indexing.

More specifically, lower tool rest131has a swivel unit132. Swivel unit132is provided so as to be swivelable about a central axis204parallel to the Z-axis. At each of positions (10 positions in the present embodiment) disposed at intervals in the circumferential direction about central axis204, tool holders for holding the fixed tools is attached. Swivel unit132swivels about central axis204, thereby causing the fixed tools held by the tool holders to move in the circumferential direction, so that the fixed tools used for the turning process is indexed.

Lower tool rest131is supported on bed141by a saddle and the like that is not shown. Lower tool rest131is disposed so as to be movable in the X-axis direction and in the Z-axis direction by various types of feed mechanisms, guide mechanisms, servo motors and the like provided in the saddle and the like.

In the present embodiment, lower tool rest131incorporates a motor for rotating the rotating tool. The rotating force from the motor is transmitted to the rotating tool held by the tool holder, so that the rotating tool can be used in lower tool rest131.

Then, the structure of an automatic tool changer (ATC)10included in machine tool100will be hereinafter described.

Machine tool100has an ATC10and a tool stocker151. ATC10serves to automatically change a tool attached to lower tool rest131. Tool stocker151is provided as a tool housing unit for housing a replacement tool to be attached to lower tool rest131.

Machine tool100has a tool holder (for ATC)136. Tool holder136is attached to lower tool rest131(swivel unit132). Tool holder136incorporates a clamping mechanism for detachably holding the tool. ATC10automatically replaces the tool held by tool holder136among a plurality of tools attached to lower tool rest131with a tool housed in tool stocker151. When the tool is attached to lower tool rest131, the tool is inserted from the direction parallel to the Z-axis into tool holder136.

Although not shown inFIG. 1, machine tool100includes, around first headstock111, an ATC for automatically changing the tool attached to tool spindle121and a tool magazine housing replacement tools to be attached to tool spindle121.

Machine tool100has a side cover142. Side cover142is provided on the opposite side of first headstock111across second headstock116. Side cover142provides a separation between the inside and the outside of machining area200. Side cover142is provided with a shutter143that can be opened and closed. Tool stocker151is provided outside the machining area.

ATC10has a robot arm31and a movement mechanism unit21. Robot arm31is provided so as to be capable of gripping the tool. Movement mechanism unit21moves robot arm31between the inside and the outside of machining area200. Movement mechanism unit21moves robot arm31in a range of a tool changing position31A within the machining area, a standby position31B outside the machining area, and a stocker position31C outside the machining area.

Movement mechanism unit21has a base member23, a linear guide22, a rack and pinion25, a servo motor (not shown), and a support pillar24as a mechanism for causing robot arm31to linearly reciprocate.

Base member23is made of a plate material, and has robot arm31and the servo motor attached thereto. Linear guide22and rack and pinion25are placed by support pillar24at a certain height from the installation surface of machine tool100. Linear guide22is provided as a guide mechanism for guiding base member23in the direction parallel to the Z-axis. Rack and pinion25converts the rotation output from the servo motor into linear motion, thereby moving base member23in the Z-axis direction.

During processing of the workpiece, robot arm31stands by at standby position31B without gripping the tool. When processing of the workpiece is completed and replacement of the tool attached to lower tool rest131is required, shutter143is brought into an open state. Robot arm31moves into the machining area through an opening appearing in side cover142, and reaches tool changing position31A. Robot arm31grips the tool held by tool holder136. Tool holder136releases clamping of the tool at the timing when the tool is gripped by robot arm31. Robot arm31gripping the tool moves from tool changing position31A to stocker position31C (conveyance of the tool). Robot arm31returns the tool removed from lower tool rest131back to tool stocker151.

Robot arm31grips a replacement tool prepared in tool stocker151, and moves from stocker position31C to tool changing position31A (conveyance of the tool). Robot arm31inserts a new tool into tool holder136. Tool holder136clamps the tool at the timing when the tool is inserted by robot arm31. Robot arm31moves from tool changing position31A to standby position31B, and shutter143is brought into a closed state. Then, replacement of the tool by ATC10is completed.

FIG. 2is a perspective view showing a robot arm inFIG. 1.FIG. 3is a side view showing an end portion of the robot arm inFIG. 2.

Referring toFIGS. 1 to 3, the structure of robot arm31will then be described in detail. Robot arm31has a base unit32, an arm unit33, and a gripping unit36.

Base unit32is coupled to movement mechanism unit21. Base unit32is shaped to protrude from movement mechanism unit21vertically in the downward direction. Arm unit33is coupled to base unit32so as to be pivotable about a pivot axis211. InFIG. 2, pivot axis211extends in the direction parallel to the Y-axis. Gripping unit36is provided in arm unit33. Gripping unit36detachably grips a tool. Gripping unit36is of a single-arm type capable of gripping one tool at a time.

Arm unit33is formed to extend in an arm shape from base unit32toward gripping unit36. Arm unit33has one end and the other end provided with base unit32and gripping unit36, respectively. Arm unit33is formed to extend in an arm shape in a plane orthogonal to pivot axis211. Arm unit33swings on pivot axis211as a fulcrum as shown by an arrow221inFIG. 2. In accordance with swinging motion of arm unit33, the position of the tool gripped by gripping unit36is changed in a plane orthogonal to pivot axis211.

Arm unit33is formed of a first movable unit33L, a second movable unit33M, and a third movable unit33N.

First movable unit33L is coupled to base unit32so as to be pivotable about pivot axis211(the first pivot axis). First movable unit33L is formed to extend from base unit32in an arm shape in the direction orthogonal to pivot axis211. First movable unit33L swings on pivot axis211as a fulcrum as shown by an arrow221inFIG. 2.

Second movable unit33M is coupled to first movable unit33L so as to be pivotable about pivot axis212(the second pivot axis). Pivot axis212extends in the direction parallel to pivot axis211. Second movable unit33M is coupled to the end of first movable unit33L that extends from base unit32in an arm shape. Second movable unit33M extends from first movable unit33L in an arm shape in the direction orthogonal to pivot axis212. Second movable unit33M swings on pivot axis212as a fulcrum as shown by an arrow222inFIG. 2.

Third movable unit33N is coupled to second movable unit33M so as to be pivotable about pivot axis213(the third pivot axis). Pivot axis213extends in the direction parallel to pivot axis211and pivot axis212. Third movable unit33N is coupled to the end of second movable unit33M that extends from first movable unit33L in an arm shape. Third movable unit33N extends from second movable unit33M in an arm shape in the direction orthogonal to pivot axis213. Third movable unit33N swings on pivot axis213as a fulcrum as shown by an arrow223inFIG. 2.

Base unit32is provided so as to be rotatable about rotation axis214(the first rotation axis) as shown by an arrow224inFIG. 2. Rotation axis214extends in the direction orthogonal to pivot axis211. Rotation axis214extends in the vertical direction.

Second movable unit33M extends in an arm shape in the axial direction of a rotation axis215(the second rotation axis). Second movable unit33M is provided so as to be rotatable about rotation axis215as shown by an arrow225inFIG. 2. Rotation axis215extends in the direction orthogonal to pivot axis212. Third movable unit33N extends in an arm shape in the axial direction of rotation axis216(the third rotation axis). Third movable unit33N is provided so as to be rotatable about rotation axis216as shown by an arrow226inFIG. 2. Rotation axis216extends in the direction orthogonal to pivot axis213.

By such a configuration, robot arm31is provided as a robot arm capable of controlling six axes (pivot axes211to213and rotation axes214to216) independently from each other.

Gripping unit36is provided along an imaginary extension line of rotation axis216along which third movable unit33N extends in an arm shape. Gripping unit36has a coupling portion37and a claw portion38. Claw portion38is formed in a claw shape that can be engaged with a tool. Claw portion38is provided on the outer circumference of the axis extended from rotation axis216. Coupling portion37is provided as a coupling mechanism for coupling claw portion38to arm unit33(third movable unit33N).

FIGS. 4 to 8each are a side view illustrating movement of the robot arm at the time when automatically changing the tool attached to the lower tool rest in the machine tool inFIG. 1.

Referring toFIGS. 1 and 4, at the time when automatically changing a tool150attached to lower tool rest131, robot arm31is moved in the Z-axis direction by movement mechanism unit21so as to be moved from standby position31B into the machining area.

When robot arm31is moved from standby position31B into the machining area, arm unit33is in a folded state. Specifically, the state of arm unit33is controlled such that first movable unit33L extends in the obliquely upward direction from base unit32, second movable unit33M extends in the obliquely downward direction from first movable unit33L, and third movable unit33N extends in the obliquely upward direction from second movable unit33M.

Referring toFIGS. 1, 5, and 6, while robot arm31is further moved in the Z-axis direction by movement mechanism unit21, arm unit33is swung such that gripping unit36comes closer to tool150held by tool holder136.

In the present embodiment, arm unit33(first movable unit33L) is swung on pivot axis211as a fulcrum, to thereby move gripping unit36to the same height as that of tool150held by tool holder136. At this time, arm unit33is placed in an attitude such that rotation axis216of third movable unit33N extends in the direction parallel to the Z-axis. Tool150held by tool holder136is positioned along an imaginary extension line of rotation axis216of third movable unit33N.

Third movable unit33N is rotated about rotation axis216, thereby adjusting the position of claw portion38of gripping unit36to that of tool150held by tool holder136. The position of claw portion38that is different depending on the tool may be grasped by robot arm31reading data stored in a chip having a record of a tool ID and provided in the tool.

Referring toFIGS. 1 and 7, robot arm31is further moved in the Z-axis direction by movement mechanism unit21while maintaining the attitude of arm unit33. Tool150held by tool holder136is gripped by gripping unit36.

Referring toFIGS. 1 and 8, robot arm31is moved in the opposite direction along the Z-axis direction by movement mechanism unit21while maintaining the attitude of arm unit33. Thereby, tool150is separated from lower tool rest131.

Although the process of removing tool150attached to lower tool rest131has been described, robot arm31operates similarly also in the case where a replacement tool is attached to lower tool rest131.

Referring toFIG. 1, at the time when changing the tool at stocker position31C, six axes (pivot axes211to213and rotation axes214to216) of robot arm31are controlled, so that gripping unit36is positioned appropriately or the attitude thereof is changed relative to the tool prepared in tool stocker151.

In ATC10in the present embodiment, since an automatic change of the tool attached to lower tool rest131is carried out by robot arm31capable of moving on the inside and the outside of machining area200, ATC10can be configured by a simple and compact mechanism. Accordingly, an increase in size of machine tool100can be prevented.

Furthermore, in the present embodiment, when the tool attached to lower tool rest131is attached and detached, arm unit33of robot arm31swings on pivot axis211as a fulcrum in the machining area (seeFIGS. 4 to 8). Since pivot axis211extends in the direction orthogonal to central axes201and202(Y-axis direction) serving as the rotation axis of the workpiece in first headstock111and second headstock116, robot arm31can be housed in a compact space particularly in the Y-axis direction. Consequently, excellent accessibility for an operator to a workpiece can be achieved.

The structure of ATC10in the first embodiment of the present invention as described above will be hereinafter summarized. ATC10in the present embodiment is provided as an ATC for automatically changing a tool attached to lower tool rest131as a tool rest of machine tool100. ATC10includes robot arm31and movement mechanism unit21that moves robot arm31between the inside and the outside of machining area200. Robot arm31has base unit32coupled to movement mechanism unit21, arm unit33pivotably coupled to base unit32, and gripping unit36provided in arm unit33and detachably gripping a tool. Arm unit33is formed to extend in an arm shape from base unit32toward gripping unit36, and swings on pivot axis211as a fulcrum relative to base unit32.

According to ATC10in the first embodiment of the present invention configured in this way, the tool attached to lower tool rest131can be automatically changed by a simple and compact mechanism.

In the present embodiment, by moving robot arm31in the Z-axis direction using movement mechanism unit21and by swinging arm unit33(first movable unit33L) in robot arm31, the tool attached to lower tool rest131is attached and detached, but the present embodiment is not limited to such a configuration. For example, starting from the attitude of robot arm31shown inFIG. 6, first movable unit33L, second movable unit33M, and third movable unit33N may be swung on pivot axis211, pivot axis212, and pivot axis213, respectively, each as a fulcrum, to thereby move gripping unit36in the Z-axis direction while being maintained at the height in the X-axis direction.

Insertion and removal of the tool into and from tool holder136can be done if robot arm31has one swing axis. The tool gripped by gripping unit36approaches tool holder136while drawing a path of a circular arc in accordance with the swinging motion of robot arm31. When robot arm31has one swing axis, a mechanism capable of changing the height of the placing table of the tool may be provided in tool stocker151in order to allow tool replacement in tool stocker151.

Furthermore, although an explanation has been given in the present embodiment with regard to the case where the present invention is applied to a composite processing machine having a turning function and a milling function, the present invention is applicable to a machine tool as long as it includes a tool rest for which a tool can be automatically changed.

Second Embodiment

FIG. 9is a side view showing an end portion of a robot arm according to an ATC in the second embodiment of the present invention. The ATC in the present embodiment basically has a similar structure as compared with ATC10in the first embodiment. The description of the identical structure will not be hereinafter repeated.

Referring toFIG. 9, in the present embodiment, gripping unit36is of a double-arm type that is capable of gripping two tools at a time.

More specifically, robot arm31has gripping units36P and36Q, and a support plate39. Support plate39is provided along an imaginary extension line of rotation axis216along which third movable unit33N extends in an arm shape. Gripping units36P and36Q are provided on both sides across support plate39.

Gripping units36P and36Q each has a gripping unit36that includes a coupling portion37and a claw portion38. Coupling portion37is provided as a coupling mechanism for coupling claw portion38of each gripping unit to support plate39. When third movable unit33N rotates about rotation axis216, the positions of gripping unit36P and gripping unit36Q are reversed.

According to such a configuration, robot arm31is moved toward the tool changing position within the machining area in the state where one of gripping unit36P and gripping unit36Q grips a replacement tool. Thereby, removal of the tool held by tool holder136and attachment of the replacement tool to tool holder136can be simultaneously performed.

According to the ATC in the second embodiment of the present invention configured in this way, the functions and effects described in the first embodiment can be similarly achieved.

The present invention is mainly applied to a machine tool provided with an ATC.