Controller for rivetting machine

A controller of a rivetting machine having a hydraulic cylinder, and a motor and a hydraulic power source connected to said hydraulic cylinder, the cylinder including a piston shaft, a spindle extending through and journaled to said piston shaft and driven by said motor, a rivet head forming tool secured to the bottom end of said spindle, and a forming shaft supported by said rivet head forming tool, whereby said spindle is lowerable by said hydraulic cylinder to cause abutting contact between the bottom end face of said forming shaft and the top end face of a work rivet and at the same time said spindle is rotatable by said motor to form a rivet head on the work rivet with said forming shaft, said controller comprising:

• a linear encoder in operative association with said piston shaft so as to detect the axial position of said piston shaft;
• an electric/hydraulic servo valve provided in a hydraulic circuit between said hydraulic power source and said hydraulic cylinder so as to control the flow of hydraulic fluid to and from said hydraulic cylinder, said hydraulic circuit including a hydraulic line extending to said hydraulic cylinder;
• a pressure sensor operatively connected to said hydraulic line so as to sense the pressure of hydraulic fluid in said hydraulic line;
• and
• a control unit programmable to receive machining data for rivets to be worked by the riveting machine, said control unit being operatively connected to said linear encoder so as to receive the output of said linear encoder, said control unit being operatively connected to said hydraulic cylinder via at least said electric/hydraulic servo valve so as to control said hydraulic cylinder by controlling the position of said electric/hydraulic servo valve based on the machining data and the output of said linear encoder, and said control unit also being operatively connected to said pressure sensor so as to monitor the pressure in said hydraulic line and effect a control of said electric/hydraulic servo valve, based on said monitoring of the pressure in said hydraulic line during an extension of said piston shaft, which causes said piston shaft to retract when said piston shaft has moved a predetermined stroke without the pressure in said hydraulic line having increased thereby detecting that a rivet is not disposed in a position to be worked by said forming shaft.

A controller of a rivetting machine having a hydraulic cylinder, and a motor and a hydraulic power source connected to said hydraulic cylinder, the cylinder including a piston shaft, a spindle extending through and journaled to said piston shaft and driven by said motor, a rivet head forming tool secured to the bottom end of said spindle, and a forming shaft supported by said rivet head forming tool, whereby said spindle is lowerable by said hydraulic cylinder to cause abutting contact between the bottom end face of said forming shaft and the top end face of a work rivet and at the same time said spindle is rotatable by said motor to form a rivet head on the work rivet with said forming shaft, said controller comprising:

• a linear encoder in operative association with said piston shaft so as to detect the axial position of said piston shaft;
• an electric/hydraulic servo valve provided in a hydraulic circuit between said hydraulic power source and said hydraulic cylinder so as to control the flow of hydraulic fluid to and from said hydraulic cylinder, said hydraulic circuit including a hydraulic line extending to said hydraulic cylinder;
• an electromagnetic pressure control valve operatively hydraulically connected in said hydraulic line so as to control the pressure of hydraulic fluid flowing therethrough to said cylinder;
• a pressure sensor operatively connected to said hydraulic line so as to sense the pressure of hydraulic fluid in said hydraulic line;
• and
• a control unit programmable to receive machine data for rivets to be worked by the riveting machine, said control unit being operatively connected to said linear encoder so as to receive the output of said linear encoder, said control unit being operatively connected to said hydraulic cylinder via at least said electric/hydraulic servo valve so as to control said hydraulic cylinder by controlling the position of said electric/hydraulic servo valve based on the machining data and the output of said linear encoder, said control unit being operatively connected to said electromagnetic pressure control valve to regulate the pressure of hydraulic fluid flowing through said hydraulic line based on the machining data for a rivet to be worked, and said control unit also being operatively connected to said pressure sensor so as to monitor the pressure in said hydraulic line and effect a control of said electric/hydraulic servo valve, based on said monitoring of the pressure in said hydraulic line during an extension of said piston shaft, which causes said piston shaft to retract when said piston shaft has moved a predetermined stroke without the pressure in said hydraulic line having increased thereby detecting that a rivet is not disposed in a position to be worked by said forming shaft.

A rivetting machine comprising:

• a hydraulic cylinder;
• a motor and a hydraulic power source connected to said hydraulic cylinder;
• the cylinder including a piston shaft, a spindle extending through and journaled to said piston shaft and driven by said motor, a rivet head forming tool detachably secured to the bottom end of said spindle, and a forming shaft supported by said rivet head forming tool, whereby said spindle is lowerable by said hydraulic cylinder to cause abutting contact between the bottom end face of said forming shaft and the top end face of a work rivet and at the same time said spindle is rotatable by said motor to form a rivet head on the work rivet with said forming shaft;
• a press jig detachably securable to the bottom end of said spindle in place of said rivet head forming tool whereby the press jig when secured to the bottom end of said spindle can press-fit rivets into holes formed in a sheet when said piston shaft is extended;
• and a controller including
• a linear encoder in operative association with said piston shaft so as to detect the axial position of said piston shaft,
• an electric/hydraulic servo valve provided in a hydraulic circuit between said hydraulic power source and said hydraulic cylinder so as to control the flow of hydraulic fluid to and from said hydraulic cylinder, said hydraulic circuit including a hydraulic line extending to said hydraulic cylinder,
• a pressure sensor operatively connected to said hydraulic line so as to sense the pressure of hydraulic fluid in said hydraulic line, and
• a control unit programmable to receive machining data for rivets to be worked by the riveting machine, said control unit being operatively connected to said linear encoder so as to receive the output of said linear encoder, said control unit being operatively connected to said hydraulic cylinder via at least said electric/hydraulic servo valve so as to control said hydraulic cylinder by controlling the position of said electric/hydraulic servo valve based on the machining data and the output of said linear encoder, and said control unit also being operatively connected to said pressure sensor so as to monitor the pressure in said hydraulic line and effect a control of said hydraulic circuit, while the pressure in said hydraulic line is monitored, which selectively operates said hydraulic cylinder in a rivet head forming mode when said rivet head forming tool is secured to the bottom end of said spindle and a press-fitting mode when the press jig is secured to the bottom end of said spindle.