Patent Description:
Machine tools machine workpieces into predetermined shapes using tools. At this time, it is necessary to perform operations for attaching a workpiece to the machine tool, operations to attach a tool to a tool exchange device of the machine tool, and operations to unload the workpiece after machining is finished. At that time, production efficiency can be increased by performing attachment and unloading automatically, rather than manually, using robots or automated guided vehicles.

Patent Literature <NUM> discloses a production system which transports workpieces and tools, the system comprising a gantry loader having a hand storage area and several types of hands such as a workpiece hand and a tool hand, wherein the hand is exchanged depending on the target to be transported.

When a workpiece is machined by a machine tool, attachment and unloading of the workpiece are performed. Furthermore, since the tool provided in the tool exchange device of the machine tool becomes worn or broken by the machining, it is necessary to unload the unneeded tool to the outside of the machine tool, and insert a new tool into the tool exchange device of the machine tool. Though such operations are automatically performed using a robot in order to increase production efficiency, it is necessary to adapt to shape differences between the workpiece and the tool.

In the case in which workpieces and tools are transported, there is a method of exchanging the hand in accordance with the object to be transported, as in Patent Literature <NUM>. When exchanging the hand, a device for exchanging and exchanging time for exchanging are necessary.

The present invention has been completed in light of the circumstances described above, and aims to provide a machine tool system which can adapt to shape differences between workpieces and tools and which is constituted by a self-propelled robot which can efficiently perform transportation operations without requiring labor for exchanging the hand thereof.

The present invention provides a machine tool system for transporting tools and workpieces to a plurality of machine tools as defined in claim <NUM>.

As a result, even a self-propelled robot having a hand which is larger than a tool exchange groove formed in the tool holder and which cannot fit in the tool exchange groove can transport a tool holder from the tool storage to the tool magazine, which is in the tool exchange device of the machine tool. Furthermore, even a self-propelled robot having a hand which is smaller than a pallet exchange device groove formed in the pallet and which cannot fit in the pallet exchange device groove can transport a pallet from the workpiece storage to the pallet exchange device of the machine tool.

According to the present invention, since the tool holder adapter, the workpiece adapter, and the electrode holder can be gripped by hands having the same shape, tools, workpieces, and electrodes can be efficiently transported from storage to the machine tools with one type of self-propelled robot without exchanging the hand.

An embodiment of the present invention is shown in <FIG>. The present invention is directed to a machine tool system which transports tools T, workpieces W, and electrodes <NUM> between respective storages in which the tools T and workpieces W are accommodated and a plurality of machine tools <NUM> and electrical discharge machining devices <NUM> using a self-propelled robot <NUM>.

The machine tool <NUM> shown in <FIG> is a machining center in which a rotating tool T and a workpiece W are moved relative to each other with a feed axis to cut the workpiece W with the tool T. The machine tool <NUM> is constituted by a machining chamber <NUM>, a tool accommodation device <NUM>, and a pallet exchange device <NUM>. The machine tool <NUM> includes a spindle <NUM> which holds the tool T. The spindle <NUM> is rotatably supported in a spindle head <NUM>. The spindle head <NUM> can be moved in the X direction and Z direction by feed axes. The machine tool <NUM> includes a table <NUM> equipped with a chuck <NUM> which holds a pallet <NUM> on which a workpiece W is mounted. The table <NUM> can be moved in the Y direction by a feed axis. The tool T and the workpiece W are moved relative to each other by moving the spindle head <NUM> and the table <NUM> relative to each other. In the machine tool <NUM>, in order to automatically exchange the tool T held in the spindle <NUM>, each tool T, assembled with a tool holder <NUM>, is stored in the tool accommodation device <NUM>. The tool accommodation device <NUM> stores a plurality of tool holders <NUM>, and the tool T is exchanged when an unillustrated tool exchange device replaces the tool holder held by the spindle <NUM> with a tool holder <NUM> in the tool accommodation device <NUM>. The pallet exchange device <NUM> exchanges the pallet <NUM> held on the table <NUM> with another pallet <NUM>.

The electrical discharge machining device <NUM> is a die-sinking electrical discharge machining device which has a spindle which holds an electrode <NUM> and a table on which a workpiece W is mounted and which performs electrical discharge machining by moving the spindle and the table relative to each other with a feed axis, and applying a voltage between the electrode and the workpiece to generate an electrical discharge. The electrical discharge machining device <NUM> is constituted by a machining chamber <NUM>, an electrode accommodation device <NUM>, and a pallet exchange device <NUM>. Since the electrical discharge machining device <NUM> automatically exchanges the electrode held in the spindle, each electrode <NUM> is stored in the electrode accommodation device <NUM> assembled with an electrode holder <NUM>. The electrode accommodation device <NUM> exchanges electrodes by replacing the electrode holder <NUM> held in the spindle with an electrode holder <NUM> in the electrode accommodation device <NUM> by an unillustrated electrode exchange device. Furthermore, like the machine tool <NUM>, a pallet exchange device <NUM> is provided to exchange a pallet <NUM> held on the table and another pallet <NUM>.

The self-propelled robot <NUM> comprises an automated guided vehicle <NUM>, and a manipulator <NUM> having three or more degrees of freedom mounted on the automated guided vehicle <NUM>. A hand <NUM> is included on the tip of the manipulator <NUM>. A carriage <NUM> for temporary arrangement of articles to be transported is provided on an upper part of the automated guided vehicle <NUM> of the self-propelled robot <NUM>.

The hand <NUM> comprises two fingers, and an engagement portion for engaging with the shape of the fingers is formed in the object to be transported. In the present invention, the engagement portion is in the form of a groove formed in the outer circumference of the object to be carried. The fingers of the hand <NUM> are inserted into the groove-shaped engagement portion, and the two fingers are closed inwardly to grip the object to be transported. The fingers of the hand <NUM> match the groove shape, whereby the object can be reliably held without dropping.

A tool T used in the machine tool <NUM> of the present invention is attached to a tool holder <NUM> having a predetermined shape. The tool holder <NUM> is constituted by a taper part <NUM>, a flange part <NUM>, and a tip <NUM>. The shapes of the flange part <NUM> and the taper part <NUM> of the tool holder <NUM> are defined by standards. The taper part <NUM> of the tool holder <NUM> is used when the spindle <NUM> grips the tool holder <NUM>. A groove is formed in the flange part <NUM> of the tool holder <NUM>, and this groove is used when the tool holders <NUM> of the spindle <NUM> and the tool accommodation device <NUM> are exchanged by the automatic tool exchange device of the machine tool.

The tool holder adapter <NUM> is a tube-like article, has a flange <NUM> in an upper part thereof, and a groove-like engagement part <NUM> which engages with the fingers of the hand <NUM> is formed in the flange <NUM>. The tip side of the tool holder <NUM> can be inserted into the hole of the tube. <FIG> illustrates a state prior to insertion of the tool holder <NUM> into the tool holder adapter <NUM> and <FIG> illustrates a state in which the tool holder <NUM> has been inserted into the tool holder adapter <NUM>. Since the tip of the tool holder <NUM> may have any of various shapes, the tip is essentially not suitable as a portion to be gripped. However, by inserting the tool holder <NUM> into the tool holder adapter <NUM> and gripping the tool holder adapter <NUM> with the hand <NUM>, the tool holder <NUM> can be indirectly gripped.

A large number of reserve tool holders <NUM> are stored in the tool storage <NUM> inserted into tool holder adapters <NUM>. The self-propelled robot <NUM> grips the flange <NUM> of a tool holder adapter <NUM> with the hand <NUM> and transfers a tool holder <NUM> along with the tool holder adapter <NUM> between the carriage of the self-propelled robot <NUM> and the tool storage <NUM>.

The pallet <NUM> used in the machine tool <NUM> and the electrical discharge machining device <NUM> of the present invention will be described. A groove <NUM> is formed in the outer circumference of the pallet <NUM>, and the groove <NUM> is used for a pallet exchange device to grip the pallet <NUM> when a pallet <NUM> on the table is exchanged. Since a workpiece W is loaded onto the pallet <NUM>, the outer circumference of the pallet <NUM> is made larger as compared to the tool holder <NUM>. Since the outer circumference of the pallet <NUM> is large, it cannot be gripped with a hand <NUM> having the same size as the hand <NUM> of the self-propelled robot <NUM> used to transport the tool holder <NUM>. Thus, conventionally, it was necessary to prepare self-propelled robots having different hand sizes for the transportation of the tool holder <NUM> and the workpiece W, or to perform an operation to exchange the hand itself.

A workpiece adapter <NUM> will be described with reference to <FIG>. The workpiece adapter <NUM> is formed on top of the pallet <NUM>. A pull stud <NUM> which is used for connection with a chuck <NUM> is formed below the pallet <NUM>. The upper surface of the workpiece adapter <NUM> serves as an attachment part <NUM> for attachment of the workpiece W. The workpiece adapter <NUM> is formed smaller than the outer shape of the pallet <NUM>. A groove-like engagement part <NUM> for engaging with the fingers of the hand <NUM> is formed in the outer circumference of the workpiece adapter <NUM>. As a result, gripping can be performed with the hand <NUM> of the self-propelled robot <NUM> without exchanging the hand <NUM>.

In the workpiece storage <NUM>, each unmachined workpiece W is affixed to a pallet <NUM> via a workpiece adapter <NUM>. The self-propelled robot <NUM> can move a workpiece W along with a pallet <NUM> onto the carriage <NUM> of the self-propelled robot <NUM> by gripping the workpiece adapter <NUM> with the hand <NUM>. Furthermore, after machining, the self-propelled robot <NUM> collects the machined workpiece W along with the pallet <NUM> and the workpiece adapter <NUM> from the machine tool <NUM> or electrical discharge machining device <NUM>, and transports them to the workpiece storage <NUM>.

Next, an electrode holder <NUM> will be described with reference to <FIG>. A groove-like engagement part <NUM> which is used when an electrode exchange device holds the electrode holder <NUM> is formed in the outer circumference of the electrode holder <NUM>. A pull stud <NUM> which is used for connection with the spindle is formed on the top of the electrode holder <NUM>. This engagement part <NUM> of the electrode holder <NUM> has the same shape as the engagement portion for the hand of the self-propelled robot <NUM>. As a result, the electrode holder <NUM> can also be gripped with the hand <NUM> of the self-propelled robot <NUM>. An electrode holder <NUM> can be transported by the self-propelled robot <NUM> between the electrode accommodation device <NUM> of the electrical discharge machining device <NUM> and an electrode storage <NUM>.

A large number of reserve electrode holders <NUM> are stored in the electrode storage <NUM>. The self-propelled robot <NUM> directly grips the engagement part <NUM> of the electrode holder <NUM> with the hand <NUM>, and moves the electrode holder <NUM> between the carriage <NUM> of the self-propelled robot <NUM> and the electrode storage <NUM>.

Due to the above structure, the self-propelled robot <NUM>, which receives a transport command from a central controller which manages the entire machine tool system, transports workpieces W between the machine tool <NUM> or electrical discharge machining device <NUM> and the workpiece storage <NUM>. The self-propelled robot <NUM> grips the workpiece adapter <NUM> with the hand <NUM>, whereby the workpiece W can be moved along with the pallet <NUM> onto the carriage <NUM> of the self-propelled robot <NUM>. Thereafter, the self-propelled robot <NUM> travels to the vicinity of the destination pallet exchange device <NUM>, grips the workpiece adapter <NUM> with the hand <NUM>, and places the workpiece W on the carriage <NUM> at the destination.

Regarding the transportation of a tool holder <NUM>, like the case of the workpiece W, the self-propelled robot <NUM>, which receives a transportation command from the central controller, transports the tool holder <NUM> between the machine tool <NUM> and the tool storage <NUM>. The self-propelled robot <NUM> grips the tool holder adapter <NUM> with the hand <NUM>, whereby the tool holder <NUM> is moved along with the tool holder adapter <NUM> onto the carriage <NUM> of the self-propelled robot <NUM>. Thereafter, the self-propelled robot <NUM> travels to the vicinity of the tool accommodation device <NUM> of the destination machine tool, grips the tool holder adapter <NUM> with the hand <NUM>, and places the tool holder <NUM> on the carriage <NUM> along with the tool holder adapter <NUM> at the destination.

The machine tool <NUM> and the electrical discharge machining device <NUM> perform machining while automatically exchanging the tool holder <NUM>, pallet <NUM>, and electrode holder <NUM> on the spindle or table of the machine tool <NUM> or the electrical discharge machining device <NUM> with a tool holder <NUM>, pallet <NUM>, or electrode holder <NUM> in the tool accommodation device <NUM>, pallet exchange device <NUM>, or electrode accommodation device <NUM> in accordance with independently executed commands described in a machining program.

According to the present invention, there is proposed a machine tool system which can perform transportation between the machine tool <NUM> and the electrical discharge machining device <NUM> and the tool storage <NUM>, the workpiece storage <NUM>, and the electrode storage <NUM> with a single self-propelled robot <NUM> having a single type of hand <NUM>, and which can adapt without performing an operation to exchange the hand. The present invention is effective even when there is a plurality of self-propelled robots <NUM>. For example, when many tool holders <NUM> are transported, a greater number of self-propelled robots <NUM> can be assigned to the transportation of tool holders <NUM>, and if the transportation of workpieces W increases, the number of self-propelled robots <NUM> assigned to the transportation of workpieces W can be easily increased, whereby operations with less waste can be carried out.

Claim 1:
A machine tool system for transporting tools (T) and workpieces (W) to a plurality of machine tools (<NUM>, <NUM>), the system comprising:
a plurality of machine tools (<NUM>, <NUM>), wherein at least one of the plurality of machine tools (<NUM>, <NUM>) has a pallet chuck (<NUM>) for engagement with a pallet (<NUM>),
a plurality of tool holders (<NUM>) each configured for holding a tool (T),
a self-propelled robot (<NUM>) having a hand (<NUM>) comprising two fingers for engagement with a predetermined shape,
a plurality of tool holder adapters (<NUM>) each having a hole for accommodating one of the respective tool holders (<NUM>) and a flange (<NUM>) having formed therein a first groove-like engagement part (<NUM>) for engagement with the fingers of the hand (<NUM>),
a tool storage (<NUM>) for storing the plurality of tool holder adapters (<NUM>),
a plurality of pallets (<NUM>) configured to engage with the at least one pallet chuck (<NUM>);
a plurality of workpiece adapters (<NUM>) each including an attachment part (<NUM>) to which a workpiece (W) can be attached and a second groove-like engagement part (<NUM>) for engagement with the fingers of the hand (<NUM>), said second groove-like engagement part (<NUM>) being formed in an outer circumference of the workpiece adapter (<NUM>) between the pallet (<NUM>) and the attachment part (<NUM>), and
a workpiece storage (<NUM>) in which the plurality of pallets (<NUM>) to which workpieces (W) are mounted are stored in a state in which each workpiece (W) is attached to a respective one of the attachment parts (<NUM>),
wherein the system is configured such that, when one of the plurality of tool holders (<NUM>) is transported from the tool storage (<NUM>) to one of the plurality of machine tools (<NUM>), the self-propelled robot (<NUM>) transports the tool (T) by gripping the first groove-like engagement part (<NUM>) of the tool holder adapter (<NUM>), and
wherein the system is configured such that, when one of the respective workpieces (W) is transported from the workpiece storage (<NUM>) to one of the plurality of machine tools (<NUM>, <NUM>), the self-propelled robot (<NUM>) transports the workpiece (W) by gripping the second groove-like engagement part (<NUM>) of the workpiece adapter (<NUM>).