Abstract: A caulking machine has a column with a table for placing a work piece having rivet shanks passing therethrough, a cylinder vertically movably mounted on the column, a piston shaft fixedly mounted in the cylinder so as to be movable together with the cylinder, a spindle rotatably mounted in the piston shaft, and a rivet head forming tool having a forming shaft and mounted to the bottom end of the spindle. The forming shaft is adapted to be pressed against the rivet shank in the work piece by operating the cylinder, and can be rotated by a motor via the spindle to form a rivet head on the rivet shank. The machine has a rotation detector for determining whether a rivet head is being formed or the machine is idling by measuring the rotation of the forming shaft. If it is determined that the machine is idling, a display device can be activated and the operation of the machine can be stopped.

Abstract: A rivetting machine has a hydraulic cylinder connected with a hydraulic power source, the cylinder including a piston shaft, a motor-driven spindle extending through and journaled to the piston shaft, and a rivet head forming tool secured to the bottom end of the spindle and carrying a forming shaft. A controller of the machine has a linear encoder for detecting the axial position of the piston shaft, an electric hydraulic servo valve provided in a hydraulic circuit between the hydraulic power source and the hydraulic cylinder, a machining data input unit for inputting machining data of the work rivet into a programmable control unit. The control unit receives the output of the linear encoder and the input machining data and controlling the hydraulic cylinder via the electric/hydraulic servo valve based on the machining data and the output of the encoder.

Abstract: A device for changing the stroke of a caulking machine having a table on which is placed an article having a plurality of rivet shanks, and a rivet head forming tool. The table is adapted to be moved back and forth and right and left to bring the rivet shanks into the position right under the rivet head forming tool one after another. The rivet head forming tool is driven by a motor and moved up and down by a cylinder to form a rivet head at the top of each rivet shank. The device for changing stroke has a plate member movable up and down together with the rivet head forming tool and stopper pins having their top ends secured to the plate member. An annular plate is mounted outside a rotary shaft of the rivet head forming tool so as to be freely rotatable at a predetermined position. A plurality of pins having lengths corresponding to the lengths of the rivet shanks of the article are secured at equal intervals to the annular plate to extend upright.

Abstract: A stroke control device having a servomotor, a hydraulic cylinder having a piston, a ball-thread mechanism coupling the servomotor with the piston, and a hydraulic circuit including pressure control valves for driving the hydraulic cylinder. Further it has a numerical control unit for driving the servomotor based on the numerical input data representative of the movement and moving speed of the piston, for detecting signals representative of the load on the servomotor and for producing control signals to control the pressure control valves in the hydraulic circuit in response to the load signals to move the piston so that the load on the servomotor will approach zero.