Automatic tool changer and tool change method

An automatic tool changer includes first and second tool change units that is driven respectively by a pair of servo motors and move along an arrangement direction of a plurality of tools installed on a tool installation unit, a torque detection unit that detects a torque of each of the pair of servo motors, and a control device that controls operations of the first and second tool change units. The control device fixes the first tool change unit at a reference position, and moves the second tool change unit toward the first tool change unit. The control device determines, based on a torque change of each servo motor, that a plurality of upper tools are brought together at the first tool change unit as a result of a movement of the second tool change unit.

TECHNICAL FIELD

The present disclosure relates to an automatic tool changer and a tool change method.

BACKGROUND ART

A press brake is a processing machine that performs bending of a material such as a sheet metal by using tools installed on tool installation units of upper and lower tales. Among press brakes, a press brake is known that is equipped with an automatic tool changer (also referred to as an ATC) for automatically performing tool change between a tool storage unit that stores the tools and a tool installation unit (see, for example, Patent Literatures 1 and 2).

Further, Patent Literature 3 discloses a bending machine provided with a back gauge for positioning a material. In Patent Literature 3, a technique is disclosed in which a side gauge attached to an abutment of the back gauge is moved and brought into contact with a punch or a die so that a position of the punch or the die is detected.

CITATION LIST

Patent Literature

SUMMARY

In some cases, when a tool placement by the automatic change fails due to a warning or a halfway termination, or when the tool is unclamped by an operation other than the automatic change, the tool position may be shifted. Since it is not possible to identify where the tool is located in the tool installation unit, there arises such a problem that the tool cannot be automatically stored by the automatic tool changer.

The present disclosure has been made in view of such circumstances, and an object of the present disclosure is to provide an automatic tool changer and a tool change method capable of recognizing a tool position even when the tool position is shifted.

According to a first aspect of one or more embodiments, an automatic tool changer for storing, in a tool storage unit, a plurality of tools installed side by side on a tool installation unit of a press brake is provided. The present automatic tool changer includes a pair of servo motors, first and second tool change units configured to be driven respectively by the pair of servo motors and move along an arrangement direction of the tools on the tool installation unit, a torque detection unit configured to detect a torque of each of the pair of servo motors, and a control device configured to control operations of the pair of the tool change units, in which the control device is configured to fix the first tool change unit at a predetermined reference position, move the second tool change unit toward the first tool change unit, and determine, based on a torque change of each of the servo motors detected by the torque detection unit, that the plurality of tools are brought together at the first tool change unit as a result of a movement of the second tool change unit.

Further, according to a second aspect of the one or more embodiments, a tool change method is provided by which a plurality of tools installed side by side on a tool installation unit of a press brake are stored in a tool storage unit. The present tool change method includes placing a fixing unit configured to regulate a movement of the tool at a reference position, moving the plurality of tools installed on the tool installation unit to one side along an arrangement direction of the tools on the tool installation unit, and bringing the plurality of tools together at the fixing unit.

According to the present disclosure, it is possible to recognize a tool position even when the tool position is shifted.

DESCRIPTION OF EMBODIMENT

Hereinafter, a press brake including an automatic tool changer according to an embodiment will be described. InFIG.1or2, a press brake1is a processing machine that performs bending of a material W such as a sheet metal by a pair of tools. The press brake1includes an upper table5U, a lower table5L, and automatic tool changers/tool movement regulators13U and13L.

The upper table5U is provided above left and right side frames3L and3R. The upper table5U is moved up and down by hydraulic cylinders7L and7R provided on the left and right. The lower table5L is provided below the side frames3L and3R in such a manner as to face the upper table5U in the vertical direction (Z-axis direction).

The upper table5U is provided with a tool installation unit/tool installation9U on which an upper tool P is installed. The tool installation unit9U extends in the left-right direction (X-axis direction). Depending on a layout of the tools to be used for the bending, a required number of tool stages in which one or more upper tools P are combined are installed side by side on the tool installation unit9U. When the press brake1is viewed from the front, the upper tools P installed on the tool installation unit9U are arranged side by side along the left-right direction.

A guide member11U extending in the left-right direction is provided on the rear side (back side in the Y-axis direction) of the upper table5U. The guide member11U is provided with the automatic tool changer13U. The automatic tool changer13U changes the upper tool P between a tool storage unit17U on the rear side of the upper table5U and the tool installation unit9U. Changing of the tool includes storing the upper tool P into the tool storage unit17U, taking out the upper tool P from the tool storage unit17U, installing the upper tool P on the tool installation unit9U, and taking out the upper tool P from the tool installation unit9U.

The automatic tool changer13U includes the left and right (a pair of) tool change units13UL and13UR. The respective tool change units13UL and13UR are configured to be movable in the left-right direction along the guide member11U. The pair of tool change units13UL and13UR are respectively driven by individual servo motors.

The tool change units13UL and13UR are each provided with a tool holding member (finger)15for holding the upper tool P by engaging with an engagement hole H provided in the tool (upper tool P). The tool holding member15is configured to be movable forward and backward in the front-rear direction (Y-axis direction) so as to engage with the engagement hole H and disengage from the engagement hole H.

When holding the upper tool P installed on the tool installation unit9U, the tool change units13UL and13UR are moved in the left-right direction so as to be positioned on the rear side of the upper tool P to be held. When the tool holding member15is switched to a forward movement state, the tool holding member15is inserted into the engagement hole H.

Further, the tool holding member15can cause the upper tool P to move in the left-right direction along the tool installation unit9U. Specifically, the tool holding member15is switched to the forward movement state when the upper tool P does not exist in front of the tool holding member15. When the tool change units13UL and13UR move in the left-right direction, the tool holding member15in the forward movement state abuts on an end portion of the upper tool P in the left-right direction. When the tool change units13UL and13UR continue to move in the left-right direction, an external force for moving the upper tool P is applied, which moves the upper tool P in the left-right direction.

Similar to the upper table5U, the lower table5L is provided with a tool installation unit9L as well on which a lower tool D is installed. The configuration of the tool installation unit9L is the same as that of the tool installation unit9U.

A guide member11L extending in the left-right direction is provided on the rear side (back side in the Y-axis direction) of the lower table5L, and the guide member11L is provided with an automatic tool changer13L. The automatic tool changer13L changes the lower tool D between a tool storage unit17L on the rear side of the lower table5L and the tool installation unit9L. This automatic tool changer13L includes a pair of tool change units13LL and13LR. The configuration of the automatic tool changer13L is the same as that of the automatic tool changer13U, and detailed description thereof will be omitted.

InFIG.3, a control device20controls operations of the automatic tool changers13U and13L. The control device20is mainly configured with a CPU, a ROM, a RAM, and an I/O interface. The control device20controls the operations of the automatic tool changers13U and13L when the CPU reads out various programs according to the processing contents from the ROM or the like, develops the various programs in the RAM, and executes the developed various programs.

The control device20supplies each servo motor25with a control command for controlling the servo motor25. Further, detection signals are supplied to the control device20from a torque detection unit27that detects a torque of each servo motor25and an encoder29that detects a rotation speed of the servo motor25, respectively. Note that the servo motor25, the torque detection unit27, and the encoder29are provided corresponding to the four tool change units13UL,13UR,13LL, and13LR, respectively, but only one set of configurations is representatively shown inFIG.3.

Further, a host device50is connected to the control device20. The host device50is, for example, an NC device that controls the press brake1, and the control device20can acquire necessary information from the host device50.

The control device20functionally has a calculation unit20a, a control unit20b, and a memory20c.

The calculation unit20amonitors the torque of the servo motor25based on the detection signal supplied from the torque detection unit27.

The control unit20bcontrols the servo motor25to control the position of each of the tool change units13UL,13UR,13LL, and13LR. In this position control, the control unit20bcan recognize the position of each of the tool change units13LL,13LR,13UL, and13UR in the left-right direction based on the detection signal supplied from the encoder29. Further, in addition to the position control, the control unit20balso controls a forward and backward operation of the tool holding member15carried by each of the tool change units13UL,13UR,13LL, and13LR, and a movement of each of the tool change units13UL,13UR,13LL, and13LR required for tool change.

The memory20cstores various information. The memory20cstores information on a torque threshold value for determining a torque change of each servo motor25. The memory20cstores information on a reference position.

The memory20cstores a tool ID for identifying each tool (the upper tool P and the lower tool D) owned by the press brake1, and storage information indicating correspondence with a storage position in the tool storage units17U and17L.

Hereinafter, a tool change procedure by the automatic tool changers13U and13L will be described with reference toFIGS.4to6. This tool change procedure is a procedure for storing, into the tool storage unit17U or17L, the upper tool P or the lower tool D in an unclamped state on the tool installation unit9U or9L, and the tool change procedure is carried out by the control device20.

Note that in the following description, an operation of the automatic tool changer13U corresponding to the upper table5U will be described, but an operation of the automatic tool changer13L corresponding to the lower table5L is also the same. Further, of the pair of tool change units13UL and13UR, one tool change unit13UL located on the left side ofFIG.1is referred to as a first tool change unit13UL, and the other tool change unit13UR located on the right side ofFIG.1is referred to as a second tool change unit13UR. It is assumed that a plurality of upper tools, for example, four upper tools P1to P4are installed on the tool installation unit9U.

In performing this procedure, as shown inFIG.1, the control unit20barranges the pair of tool change units13UL and13UR at initial positions. The left end portion of the guide member11U is the initial position of the first tool change unit13UL, and the right end portion of the guide member11U is the initial position of the second tool change unit13UR. In a state in which the first tool change unit13UL and the second tool change unit13UR are arranged at the initial positions thereof, the four upper tools P1to P4exist between the first tool change unit13UL and the second tool change unit13UR.

First, in step S10, the control unit20bstarts moving the first tool change unit13UL and the second tool change unit13UR. Specifically, the control unit20bcontrols the servo motor25for driving the first tool change unit13UL so that the first tool change unit13UL is moved toward the right side, that is, toward the second tool change unit13UR (FIG.5A). Similarly, the control unit20bcontrols the servo motor25for driving the second tool change unit13UR so that the second tool change unit13UR is moved toward the left side, that is, toward the first tool change unit13UL (FIG.5A).

In step S11, the calculation unit20astarts torque detection of the servo motors25based on the detection signal supplied from the torque detection unit27. The torque detection is performed on each of the servo motor25for driving the first tool change unit13UL and the servo motor25for driving the second tool change unit13UR.

Here, inFIG.6, “Tq1” indicates a torque of the servo motor25for the first tool change unit13UL, and “Tq2” indicates a torque of the servo motor25for the second tool change unit13UR. InFIG.6, “t1” is a time at which movement of the first tool change unit13UL and the second tool change unit13UR are started.

In step S12, the control unit20boutputs a stop command to the servo motor25for the first tool change unit13UL so that the first tool change unit13UL is stopped and fixed at a reference position Pst (FIG.5B, a time t2inFIG.6). The reference position Pst is set in advance to the right side of the initial position of the first tool change unit13UL, that is, a predetermined position closer to the second tool change unit13UR. The control unit20brefers to the position of the first tool change unit13UL specified by the encoder29, and determines whether or not the first tool change unit13UL has reached the reference position Pst.

On the other hand, the second tool change unit13UR continues to move toward the first tool change unit13UL (FIG.5C). When the second tool change unit13UR continues to move, the second tool change unit13UR abuts on the upper tool P4located on the far right side. The upper tool P4is pushed by the second tool change unit13UR, which causes the upper tool P4to be moved toward the first tool change unit13UL. By repeating this operation, the upper tool P3, the upper tool P2, and the upper tool P1are pushed one after another by the second tool change unit13UR. Finally, the four upper tools P1to P4are moved to the first tool change unit13UL in a state of being in close contact with each other.

Further, in the present embodiment, the first tool change unit13UL is fixed at the reference position Pst. Therefore, when the four upper tools P1to P4moved by the second tool change unit13UR abut on the first tool change unit13UL, a large torque change also occurs in the servo motor25for the first tool change unit13UL (a time t4inFIG.6).

The torque threshold value Tth is for identifying an excessive torque generated in each servo motor25when the upper tools P1to P4are brought together at the first tool change unit13UL. An optimum value obtained through experiments and simulations is set to the torque threshold value Tth, which is stored in the memory20c.

In other words, in step S13, the calculation unit20acompares the torques Tq1and Tq2from the respective servo motors25with the torque threshold value Tth, so as to determine whether or not the four upper tools P1to P4are brought together at the first tool change unit13UL as a result of a movement of the second tool change unit13UR. If a positive determination is made in step S13, that is, if the torques Tq1and Tq2of the respective servo motors25are larger than the torque threshold value Tth, a positive determination is made in step S13and the process proceeds to step S14. On the other hand, if a negative determination is made in step S13, that is, if the torques Tq1and Tq2of both or one of the servo motors25are equal to or less than the torque threshold value Tth, a negative determination is made in step S13and the process returns to step S13.

In step S14, the control unit20boutputs a stop command to the servo motor25for the second tool change unit13UR so that the second tool change unit13UR is stopped. This processing in the step S14is executed by the positive determination in step S13, that is, a determination that the four upper tools P1to P4are brought together at the first tool change unit13UL as a result of the movement of the second tool change unit13UR.

In some cases, even if the stop command is output to the servo motor25, the servo motor25may not stop immediately and thus the second tool change unit13UR may advance by inertia. This results in a state in which the four upper tools P1to P4are pushed together by the second tool change unit13UR. In this case, vibrations of the upper tools P1to P4may be transmitted to the servo motor25and regarded as an abnormality of the servo motor25. In addition, there is a possibility that an end position Peg, which will be described later, cannot be recognized correctly.

Therefore, in step S15, the control unit20bperforms a correction operation, specifically, an operation of causing the second tool change unit13UR to travel in the reverse direction by a predetermined amount. Specifically, the control unit20bcalculates, based on the moving speed of the second tool change unit13UR and the weights of the upper tools P1to P4, an amount of inertia movement in which the second tool change unit13UR moves by inertia after the stop command. Then, the control unit20bcontrols the servo motor25so as to cause the second tool change unit13UR to travel in the reverse direction by the amount of inertia movement. Note that this correction operation may be performed when the first tool change unit13UL is stopped.

In step S16, the control unit20brefers to the detection signal from the encoder29and specifies a stop position of the second tool change unit13UR. Then, the control unit20bspecifies the end position Peg of the four upper tools P1to P4based on the stop position of the second tool change unit13UR (FIG.5D). The end position Peg corresponds to a boundary surface between the upper tool P4located closest to the second tool change unit13UR and the second tool change unit13UR.

In step S17, the calculation unit20adetermines any excess or deficiency of the tool with respect to the upper tools P1to P4that have been brought together. If any of the upper tools P1to P4is manually removed, a difference is produced between the length from the reference position Pst to the end position Peg and the total sum of the divided lengths of the upper tools P1to P4that should be on the tool installation unit9U.

Then, the calculation unit20aacquires layout information from, for example, the host device50. This layout information defines a layout of the tools to be used for the bending, and indicates information of the upper tools that should be on the tool installation unit9U. The layout information includes information on the tool ID, a divided length, an installation position, and the like.

The calculation unit20acalculates the total sum of the divided lengths of the four upper tools P1to P4based on the layout information. When the length from the reference position Pst to the end position Peg coincides with the total sum of the divided lengths of the upper tools P1to P4, the calculation unit20adetermines that there is no excess or deficiency of the tool. On the other hand, if the length from the reference position Pst to the end position Peg does not coincide with the total sum of the divided lengths of the upper tools P1to P4, the calculation unit20adetermines that there is some excess or deficiency of the tool.

In step S18, the calculation unit20aacquires tool information. The tool information is information on the four upper tools P1to P4that have been brought together, in which the tool ID is associated with an arrangement order of the tool from the end position Peg for each of the four upper tools P1to P4. The calculation unit20acan acquire the tool information based on information generated by a user from the four upper tools P1to P4that have been brought together. The calculation unit20acan acquire the information generated by the user via, for example, the host device50. Further, when a device/acquirer capable of automatically acquiring the tool ID and the arrangement order of the tool from the end position Peg is provided for each of the four upper tools P1to P4that have been brought together, the tool information can be acquired through this device/acquirer. Further, if there is no excess or deficiency of the tool, the calculation unit20acan also acquire the tool information from the layout information described above.

In step S19, the calculation unit20aacquires the storage information from the memory20c.

In step S20, the calculation unit20acontrols one or both of the tool change units13UL and13UR and executes a storage operation of picking up the four upper tools P1to P4, which have been brought together, in order starting with the upper tool closest to the end position Peg so as to be stored in the tool storage positions.

Specifically, the calculation unit20aspecifies, based on the tool information and the storage information, the tool storage positions in which the four upper tools P1to P4are stored, respectively. The tool storage position is specified with reference to the tool ID.

The calculation unit20adetermines the upper tools P1to P4to be stored according to the arrangement order of the upper tools P1to P4from the end position Peg. The first one to be stored is the upper tool P4at the end position Peg, followed by the upper tools P3, the upper tool P2, and the upper tool P1. These upper tools P1to P3are to be stored in this order.

In this case, the calculation unit20acan specify, based on the end position Peg and the divided lengths of the upper tools P1to P4, the end position of the upper tools P1to P4to be stored (the boundary positions with the adjacent tools). For example, the end position of the upper tool P4is the above-mentioned end position Peg, and the end position of the upper tool P3is a position shifted to the left by the divided length of the upper tool P4from the above-mentioned end position Peg. The end position of the upper tool P2is a position shifted to the left by the divided lengths of the upper tools P4and P3from the above-mentioned end position Peg, and the end position of the upper tool P1is a position shifted to the left by the divided lengths of the upper tools P4, P3, and P2from the above-mentioned end position Peg.

Further, the engagement holes H for holding the upper tools P1to P4are provided at the centers of the upper tools P1to P4in the left-right direction. Therefore, the calculation unit20aspecifies, based on the end position of the upper tools P1to P4to be stored and the divided lengths of the tools, holding positions at which the upper tools P1to P4to be stored are held by the tool change units13UR and13UL.

Then, the control unit20bcontrols the tool change units13UR and13UL based on the holding positions thereof, and removes the upper tools P1to P4to be stored from the tool installation unit9U. Then, the control unit20bcontrols the tool change units13UR and13UL to store the upper tools P1to P4in the tool storage positions of the tool storage unit17U.

When such storage operations are performed on all of the four upper tools P1to P4, the series of procedures are completed.

As described above, the automatic tool changer13U according to the present embodiment includes the pair of servo motors25, the first and second tool change units13UL and13UR configured to be driven respectively by the pair of servo motors25and move along the arrangement direction of the tools of the tool installation unit9U, a torque detection unit27configured to detect a torque of each of the pair of servo motors25, and a control device20configured to control the operations of the first and second tool change units13UL and13UR. Then, the control device20fixes the first tool change unit13UL at the predetermined reference position Pst, moves the second tool change unit13UR toward the first tool change unit13UL, and determines, based on the torque change of each servo motor25detected by the torque detection unit27, that the plurality of upper tools P1to P4are brought together at the first tool change unit13UL as a result of the movement of the second tool change unit13UR.

According to this configuration, by sandwiching the plurality of upper tools P1to P4between the first tool change unit13UL and the second tool change unit13UR, the upper tools P1to P4can be brought together at the first tool change unit13UL. Further, since the first tool change unit13UL is fixed at the reference position Pst, it is possible to accurately determine that the plurality of upper tools P1to P4are brought together at the first tool change unit13UL by paying attention to the torque change of each servo motor25. In this manner, even if the tool position is shifted and the position thereof cannot be recognized correctly, it is possible to recognize the positions of the plurality of upper tools P1to P4by putting the plurality of upper tools P1to P4together with respect to the first tool change unit13UL that is at the reference position Pst.

Further, in the present embodiment, the control device20specifies the end position Peg of the plurality of upper tools P1to P4that have been brought together based on the torque change of each servo motor25detected by the torque detection unit27and the position of the second tool change unit13UR.

According to this configuration, since the end position Pegs of the plurality of upper tools P1to P4can be specified, the positions of the plurality of upper tools P1to P4can be recognized between the reference position Pst and the end position Pegs.

Further, in the present embodiment, the control device20determines excess or deficiency of the tool based on the layout information of the tools to be installed on the tool installation unit9U and the length from the reference position Pst to the end position Peg.

According to this configuration, even if any of the upper tools P1to P4is manually removed, this fact can be appropriately determined. As a result, the statuses of the upper tools P1to P4installed on the tool installation unit9U can be appropriately grasped.

Further, in the present embodiment, the control device20acquires the tool information in which the tool ID for identifying the tool is associated with the arrangement order of the tool from the end position Peg for each of the plurality upper tools P1to P4that have been brought together. Similarly, the control device20acquires the storage information in which the tool ID is associated with the tool storage position in the tool storage unit17U. Then, the control device20specifies, based on the tool information and the storage information, the tool storage position for each of the plurality of upper tools P1to P4that have been brought together.

According to this configuration, the tool storage position can be specified for each of the plurality of upper tools P1to P4that have been brought together. Thereby, the upper tools P1to P4can be stored into the tool storage unit17U.

Further, in the present embodiment, the control device20controls one or both of the pair of tool change units13UL and13UR and executes the storage operation of picking up the upper tools P1to P4in order starting with the upper tool closest to the end position Peg so as to be stored in the tool storage positions.

According to this configuration, the plurality of upper tools P1to P4can be automatically stored by using the pair of tool change units13UL and13UR.

Further, in the present embodiment, the control device20determines the upper tools P1to P4to be stored according to the arrangement order of the upper tools P1to P4from the end position Peg, and specifies the holding positions at which the tools are held by the tool change units13UL and13UR based on the end position of the upper tools P1to P4to be stored and the divided lengths of the tools. Further, the control device20picks up, from the tool installation unit9U, the tools to be stored based on the holding positions thereof so as to be stored in the tool storage positions.

According to this configuration, the upper tools P1to P4can be appropriately held. Thereby, the upper tools P1to P4on the tool installation unit9U can be reliably picked up and stored in the tool storage positions.

Further, in the present embodiment, the control device20determines that the plurality of upper tools P1to P4are brought together when the torque Tq2of the servo motor25for driving the second tool change unit13UR is equal to or higher than the torque threshold value Tth.

When the plurality of upper tools P1to P4are brought together at the fixed first tool change unit13UL, the movement of the second tool change unit13UR is forcibly regulated. In this case, the servo motor25for driving the second tool change unit13UR becomes overloaded, and a large torque change is generated. By comparing the torque Tq2of the servo motor25with the torque threshold value Tth, the torque change can be specified. As a result, it can be appropriately determined that the plurality of upper tools P1to P4are brought together.

Further, in the present embodiment, the control device20determines that the plurality of upper tools P1to P4are brought together when not only the torque Tq2of the servo motor25for driving the second tool change unit13UR but also the torque Tq of the servo motor25for driving the first tool change unit13UL are equal to or higher than the torque threshold value Tth.

When the plurality of upper tools P1to P4are brought together at the fixed first tool change unit13UL, a force from the second tool change unit13UR that pushes these upper tools P1to P4also acts on the first tool change unit13UL. In this case, a large torque change is also generated in the servo motor25for driving the first tool change unit13UL. Therefore, by using the torques Tq1and Tq2of both of the servo motors25, it is possible to reliably determine the state in which the plurality of upper tools P1to P4are brought together.

Further, in the present embodiment, the control device20outputs the stop command for stopping the second tool change unit13UR when the plurality of upper tools P1to P4are brought together at the first tool change unit13UL. Further, the control device20calculates the amount of inertia movement in which the second tool change unit13UR moves by inertia after the stop command is output based on the moving speed of the second tool change unit13UR and the weights of the plurality of upper tools P1to P4. Then, the control device20causes the second tool change unit13UR to travel in the reverse direction based on the amount of inertia movement.

Even if the second tool change unit13UR is stopped, the stop position may be shifted due to inertia. This results in a state in which the plurality of upper tools P1to P4are pushed by the second tool change unit13UR, vibrations and the like of the tools may be regarded as an abnormality of the servo motor25. In this respect, it is possible to cause the second tool change unit13UR to travel in the reverse direction, and to return the second tool change unit13UR to an original stop position.

In addition, since the state in which the second tool change unit13UR is at the position at which the tools remain pushed can be eliminated, the position shift of the second tool change unit13UR can be suppressed. Thereby, the automatic tool change can be performed appropriately.

Further, the tool change method according to an embodiment is a method of storing, in the tool storage unit17U, the plurality of tools installed side by side on the tool installation unit9U of the press brake1. In this tool change method, the fixing unit for regulating the movement of the upper tools P1to P4is provided at the reference position Pst of the tool installation unit9U, and the plurality of upper tools P1to P4installed on the tool installation unit9U are moved to one side along the arrangement direction of the tools, so that the plurality of upper tools P1to P4are brought together at the fixing unit.

According to this method, by bringing the plurality of upper tools P1to P4together at the fixing unit, the plurality of upper tools P1to P4can be put together with respect to the reference position Pst. In a state before being brought together, it is not possible to specify where the plurality of upper tools P1to P4are located in the tool installation unit9U. However, by putting the plurality of upper tools P1to P4together with respect to the reference position Pst, it is possible to recognize the positions of the plurality of upper tools P1to P4.

Note that in the above-described embodiment, the upper tools P1to P4are brought together by using the pair of tool change units13UL and13UR. However, the tool change method according to the present embodiment may be a method of manually moving and putting together the upper tools P1to P4with respect to the reference position Pst. Furthermore, in the above-described embodiment, the first tool change unit13UL is used as the fixing unit. However, in the tool change method according to the present embodiment, any object other than the first tool change unit13UL may be used as long as the object regulates the movement of the upper tools P1to P4.

Further, in the tool change method according to the present embodiment, the tool change units13UL and13UR that automatically perform tool change store, in the tool storage unit17U, the plurality of upper tools P1to P4that have been brought together.

According to this configuration, since the positions of the plurality of upper tools P1to P4can be recognized, it is possible to automatically store, into the tool storage unit17U, the plurality of upper tools P1to P4by the tool change units13UL and13UR.

In the above description, the embodiments have been described mainly for the automatic tool changer13U corresponding to the upper table5U, but the same applies to the automatic tool changer13L corresponding to the lower table5L.

The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.

The disclosure of the present application is related to the subject matter described in Japanese Patent Application No. 2019-087387 filed on May 7, 2019, all of which are incorporated herein by reference.