Abstract: The present invention relates to a workpiece pallet changer which changes a work pallet fitted on a pallet positioning device on the table of a machine tool. The changer comprises a moveable pallet mounting assembly disposed at plural locations along the peripheral surface of a rotatable frame, each of which engages a work pallet to permit transfer of the work pallet between the pallet mounting assembly located on the surface of the rotatable frame and the pallet positioning device, while simultaneously allowing chips fall automatically from the work pallet as it rotates downward.

Abstract: The present invention relates to a device for pushing and pulling an accessory instrument of a manufacturing plant, such as a clamp for a metallic mould, by means of a chain driven by a hydraulic actuator having a vertical cylinder. One end of the chain is supported by a case which houses the chain. The chain is driven by one of more sprockets engaging the chain at and rotatably supported by a movable part of the cylinder.

Abstract: An improved pneumatic-hydraulic driving device for the knockout mechanism associated with the slide of a press-machine wherein the device serves to actuate the knockout mechanism in a controlled manner to provide cushioning motion during punching of the work, and knocking out motion after punching to permit removal of the punched work by a transfer machine, with the device being particularly useful in the fabrication of printed circuit plates wherein the device serves to decrease cycle-time of fabrication and increase quantity of production.

Abstract: A work-clamp pallet of the exchangeable type for facilitating changing of works and intended for use with a machine tool of either the vertical or horizontal type with its base block provided with a plurality of hydraulic clamping devices and also with a special shut-off valve for shutting down its oil path. It is so arranged that its oil path may be shut down after supplying the hydraulic clamping devices with a set level of hydraulic pressure. This hydraulic pressure is maintained for a long time without any supplementary feeding of hydraulic pressure for the clamping devices to be kept in the clamping condition. When this work-clamp pallet is used, it is possible to change workpieces on the work-clamp pallet at a work-changing station outside the work table of the machine tool. The work-clamp pallet with workpieces clamped in position can then be transferred onto the machine tool to carry out the machining operations.

Abstract: A retracting clamp suited for clamping a die or a workpiece, a die of an injection molding machine in particular, is disclosed, wherein a hydraulic cylinder is provided in the rear part of a clamp housing, a clamp block is carried slidably by a gently tapered underside of the front part of its piston rod, and the clamp block is urged forward by a spring so as to drive it for clamping at its extruded position and, when clamping is over, the clamp block is retracted to its retracted position and a piston is urged toward the clamping position as necessary by a spring, and the position of the clamp block is detectable by means of limit switches.

Abstract: A slide wedge clamp for clamping workpieces to a mounting face such as the work table of a machine tool. A work-engaging member is secured to the mounting face by a fixing bolt set perpendicular thereto. By screwing up a clamping bolt set downward through a clamping block with its rearward and downward facing driven wedge face in contact with its forward and upward facing driving counterpart wedge face on the work-engaging member, the clamping block is driven forward and downward for clamping. By providing a raised workpiece-carrying portion on the forward end side of the clamping block, it is possible to clamp workpieces in a raised state.

Abstract: A device for exchanging dies for a machine using dies is disclosed, wherein a pair of carriage cars are adapted to be movable in front of a die mounting space between a stationary plate and a movable plate of the machine to which the dies are clamped, transfer means for exchanging the dies between the die mounting space and the carriage car are provided, a main unit of a push-pull device is provided in front of the carriage car independently thereof so that the dies can be changed by this push-pull device between the carriage car and the die mounting space.

Abstract: A work-clamping unit includes a base plate in which hydraulic cylinders are totally embedded, each cylinder including a piston vertically movable beneath the top surface of the base plate, the piston being adapted to carry a clamping member detachably connected thereto so as to transmit a clamping force from the piston to the clamping member, the base plate additionally including an oil path for feeding hydraulic pressure to each of the cylinders.

Abstract: An overload protector for mechanical press comprises a cylinder chamber formed in the mechanical actuating chain of the press, and filled with incompressible fluid; a safety valve which relieves the fluid from the chamber when the chain receives an overload, and which includes a relief route containing a pilot valve part and main valve part in series. The pilot valve part is arranged to close the route at the outlet of the passage penetrating the valve member of the main valve part therethrough, and to be opened by the pressure of the fluid when above the setting pressure for relief. The valve member of the main valve part is arranged to be moved for opening the route by the difference between the pressures acting thereon from both sides connected by the passage when the pilot valve part is opened.

Abstract: A pressure fluid engine of single acting cylinder type has a directional control valve and a master valve with a spool and two valve seats. The spool is formed on a piston rod extending from a piston in the cylinder, the rod passing through a cylindrical disc of the directional control valve. One of the valve seats is provided in the disc to unseal the pilot operating fluid when it cooperates with the spool at a dead point. Another valve seat for the spool is provided in one of the valve chambers of the directional control valve to unseal the pilot operating fluid when it cooperates with the spool at the other dead point. The directional control valve is actuated by means of directional control of a pilot operating fluid with the master valve, in order to reverse the direction of the piston when the piston reaches one of the dead points.