In a case where a vacant space exists on only one side in a holder area of a stocker positioned at an exchange position, a first upper tool exchange unit is first moved in the left-right direction, and located in the vicinity of the vacant space. Next, the first upper tool exchange unit is moved forward and thereafter moved to the left, so that a tool retention member of the first upper tool exchange unit is brought into contact with one side surface of a tool. Then, under the contact state, the first upper tool exchange unit is moved to the right until the other side surface of the tool abuts on a stopper.

On a back side of a table, moving bodies are provided being movable in a left-right direction. A bending system includes moving actuators to cause the moving bodies to move in the left-right direction relative to the table and position detectors to detect positions of the moving bodies in the left-right direction. The moving bodies are provided with hole detectors to detect the engagement holes of tools fitted to a tool holder. The bending system includes a hole position acquisition unit to acquire positions of the engagement holes of the tools in the left-right direction, based on positions of the moving bodies in the left-right direction at the time of the engagement holes of the tools being detected.

A bending system includes a tool storage, first and second tool exchange units each having a tool retention member, and a control device. When misalignment of tools held by a tool holder of a press brake occurs or is estimated to occur, the control device is configured to (1) move the first tool exchange unit to one side in a lateral direction to a position corresponding to one end of a regular arrangement position at which the tool retention member of the first tool exchange unit contacts with the tools and (2) move the second tool exchange unit to another side in the lateral direction to a position corresponding to another end of the regular arrangement position at which the tool retention member of the second tool exchange unit contacts with the tools.

In an installing method for installing divided upper tools to upper tool holders disposed to be spaced at an appropriate interval in a left-right direction in a lower portion of an upper table of a press brake, by using a tool changer, a round bar-shaped finger provided in the tool changer is engaged in a circular engagement hole provided at a central portion in the lateral direction of each divided upper tool. The divided upper tool is temporarily positioned in a gap between an upper tool holder to which the divided upper tool is to be installed, and an adjacent upper tool holder. The temporarily positioned divided upper tool is moved in the left-right direction to be installed to the upper tool holder to which the divided upper tool is to be installed.