A fastener driving apparatus in which the fastener driving means in the form of a piston and piston rod construction is mounted within a cylinder which is movable from a first position into a second position by fluid pressure in the reservoir of the apparatus, while the fastener driving means is maintained in a fastener receiving position. Movement of the cylinder from the first position to the second position establishes a negative pressure beneath the driving piston and/or a pressure equal to reservoir pressure or greater than reservoir pressure above the driving piston so that when the fastener driving means is released it will move from the fastener receiving position into a fastener driven position under differential pressure conditions which are greater than reservoir pressure above the piston and atmospheric pressure below the piston. The apparatus is actuated by a work contacting member and a trigger member through an interlock means which effects movement of an actuating valve into an actuating position in response (1) to the simultaneous movement of the work contacting and trigger members into their operative positions, (2) to the movement of the work contacting member into its operative position when the trigger member is in its operative position or (3) to the movement of the trigger member into its operative position when the work contacting member is in its operative position. The interlock means comprises an elongated interlock member having a transversely extending slot formed in the central portion thereof through which a pivot pin carried by the housing is disposed, one end of the interlock member having a lost motion connection with the work contacting member and the other end of the interlock member having a lost motion connection with the trigger, the interlock member including an actuating valve engaging portion intermediate the ends thereof.
A safety mechanism particularly suited for smaller fastener driving or applying tools includes a mechanical latch carried on the nosepiece structure of the tool with a part of the latch disposed within the drive track immediately below the end of the driver blade. The latch is coupled to a workpiece engaging member which retracts the latch to permit driver blade movement when the tool is placed adjacent a workpiece. If the tool is operated before being placed against a workpiece, the driver blade engages and locks the latch in latching position so that it cannot be retracted or released by thereafter placing the tool against the workpiece. The illustrated embodiments include both positive and indirect cam type couplings between the latch and the workpiece engaging member as well as pivoting and sliding latches.
A method and device for keeping metal mold in a clamped state characterized in that the mold-halves of the metal mold are respectively coupled to a plurality of hydraulic cylinders and pistons, the mold-halves are forced to close so that the displacement of the pistons causes a hydraulic fluid to flow from one space to the other in the hydraulic cylinders and also to an accumulator through a control valve, and upon the completion of the closure, shifting the control valve to another position so that the remaining fluid in the above mentioned one space is further evacuated to another accumulator at a low pressure with the simultaneous communication maintained between the other space of the hydraulic cylinders and the first accumulator, whereby a pressure difference is created between the two spaces separated by the pistons, and the mold-halves are thereby clamped.
A pneumatic fastener driving tool includes a main valve operable to cause compressed air to be alternately introduced into and discharged from the upper piston chamber, a first passage leading the compressed air into the main valve chamber, a repeat valve disposed in the first passage for opening and closing the same, and a second passage extending between the lower piston chamber and a repeat valve chamber in which the repeat valve is reciprocably received. With this construction, the repeat valve is reciprocally movable in response to a change of pressure in the lower piston chamber to cause the main valve to reciprocate, thereby reciprocating the piston repeatedly. Since the reciprocating fastener driving movement of the piston is directly related to the reciprocating movement of the repeat valve, the fastener driving work can be achieved reliably without causing any operational failure such as a non-load striking.
A pot shaped housing insert (6) is arranged in a driving apparatus for fastener elements, such as nails, between a pot shaped main body (2) and the driving cylinder (12). In such a driving apparatus the excess driving energy is taken up by an impact buffer (11) made of elastic material. The housing insert (6) is made of a synthetic material having a high inner damping, so that the excess driving energy and thus the impact noise are dissipated to a large extent already in the housing insert (6). Thus, the operator is not exposed to any unnecessary nuisance and the housing (1) may be manufactured more easily in an economical manner at lesser expense.
A pneumatically operated fastener driving device includes a pilot pressure operated main valve movable from a normally closed position into an opened position allowing a supply of air under pressure to be communicated with a piston chamber to initiate and effect the movement of a piston and fastener driving element through a fastener drive stroke. A first passage structure communicates a pilot pressure chamber and an exhaust port. A secondary valve member is mounted with respect to the first passage structure so as to be movable between an opened position permitting communication between the pilot pressure chamber and the exhaust port and a closed position preventing such communication. A second passage structure communicates the piston chamber with the secondary valve member. An operative cycle is initiated upon exhausting pilot pressure in the pilot pressure chamber causing the main valve to move to its opened position thereby initiating the fastener drive stroke. A build-up of pressure over the drive piston in the piston chamber communicates with the secondary valve member moving it to its closed position thereby preventing communication between the pilot pressure chamber and the exhaust port and causing the main valve to move to its closed position. The secondary valve member is constructed and arranged to move in response to changes in air pressure over the drive piston occurring in the piston chamber to cause the main valve to reciprocate thereby causing the drive piston to move through repeated operating cycles as long as the trigger member is in its operative position.
