FIELD OF THE INVENTION

This invention relates to a punch press in which pallets mounting the tooling are removable and replace¬ able by pallets mounting different tooling.

BACKGROUND AND SUMMARY OF THE INVENTION

It is known to provide punch presses in which the pallets mounting the tooling are removable, so that they may be replaced by other pallets mounting a different set of tooling which is appropriate for the particular jobs to be carried out on the punch press. Hitherto the change-over from one set of pallets to another, involving unlocking and removing the old pallets, then inserting, aligning and locking the new set, has been complex and time consuming. We have now devised an improved arrangement for locating and locking the pallets of a punch press, which enables a rapid change of pallets in simple manner.

In accordance with this invention, there is provided (in or for a punch press) a locating and' locking arrange- ment for tooling pallets, comprising a mounting arrange¬ ment for tooling pallets, comprising a mounting structure into which the pallets are slidable, and a locating _and locking pin which is extendable under force against an

inclined corner surface of each pallet to urge the pallet against locating abutments disposed along two adjacent sides of the pallet, to which sides said corner is opposite. Whilst the punch press is in use, each pallet is kept in position by keeping the locking pin extended under force. In order to change pallets, the locking pin is retracted, the pallet is slid out and replaced by the new pallet, and the locking pin is re-applied. Pre- ferably both pallets of the punch press (mounting the punches and the dies respectively) are slid out together, for example using a lifting truck having an appropriate adaptor to engage both pallets simultaneously: the truck then slides these pallets into an appropriate rack, then pic-ks up the newly required pair of pallets simultaneously from the same rack and slides these simultaneously into the punch press. Finally respective locking pins for the two pallets are extended to locate and lock the pallets in operative position. Preferably, in order to check that the pallets have been accurately located, a pair of machined pins are extended along fixed axes and through aligned bores in the two pallets. If these pins slide cleanly through the two pallets, this indicates that the pallets are both accurately positioned: the pins are then retracted to enable the punch press to be used.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of this invention will now be described by way of example only and with reference to the accompany- ing drawings, in which:

FIGURE 1 is a side elevational view of a punch press;

FIGURE 2 is a diagrammatic plan view of a pallet mounting structure in the punch press, with the actuating rams removed; and

FIGURE 3 is a front view of the arrangements shown in Figure 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The punch press which is shown comprises a generally C-shaped frame 10 with its upper and lower limbs respectively mounting pallets 12,14, which in turn respectively mount a plurality of punches 13 and a corresponding plurality of dies 15. These pallets are spaced apart, one above the other, by a small gap which receives the workpiece W: a carriage 5 is provided and mounts e.g. two workpiece clamps 6 for gripping the rear edge of the workpiece W and this carriage is movable along a horizontal beam 7 which is dis¬ posed transverse of the C-frame, this beam being movable along a horizontal axis perpendicular to itself (i.e. lengthwise of the press). These movements are controlled by a computer numerical control system and serve to position the workpiece accurately at successive required locations relative to the machine prior to actuation of a punch each time. In the example shown, the pallets are rectangular

(with their longer axes transverse to the press) and pro¬ vided with two rows of tooling (see ^" the two rows 18 of punches 13 in the pallet 12) extending along them. Rams 8 for actuating these punches are mounted to a carriage 9 which is movable lengthwise of the pallets (i.e. across the punch press) so as to position a ram over the punch which is required to be actuated. In the example shown, two rams 8 are mounted side-by-side on this carriage 9 _. one ram being relatively small and serving to actuate the punches in the row of smaller punches, and the other ram being relatively large and serving to actuate the punches in the row of larger punches.

A rectangular mounting structure 20 is provided for the upper pallet and another rectangular mounting structure 22 is provided for the lower pallet. The carriage 9

mounting the rams 8 is supported and guided along the upper structure 20. It will be seen that the two pallets 12,14 are slidable in a horizontal direction into their mounting structures from the front of the press. The front faces or edges of the apllets are provided with sockets 24 to receive respective prongs projecting from an adaptor to be carried by a pallet lifting truck, so that the adaptor can engage the two pallets simultaneously to remove them both together, then slide them into an appropriate rack. Then the truck can similarly engage the newly required pair of pallets, remove them from the rack and slide them into the mounting structures of the punch press. The truck may be manually operated or under remote control as in unmanned environments. _. The rear faces of the pallets are to locate against respective abutments 26 on the respective mounting struc¬ tures, and one end face of each pallet is to locate against abutments 28 on the respective mounting structure. When the adjacent rear and side faces of each pallet are urged against these abutments, the pallets are accurately positioned. The opposite front corner of each pallet is provided with an inclined surface 30: a locating and lock¬ ing pin 32 (Figure 2) is mounted along an axis normal to this surface and can be extended under hydraulic power from an actuator 33 to press against it. The pin 32 is retracted sufficiently, when the hydraulic pressure is relieved, to allow the pallet to be slid out or slid in, but when the hydraulic pressure is applied, the locating pin 32 extends, presses against the surface 30 on the pallet and urges the pallet against the rear and end abutments 26,28. Two such hydraulically-actuated pins are provided, one for each pallet.

The pallets are further formed with two aligned bores 34. Two machines pins 35 are provided to fit into these bores with close tolerance. These pins are extended by

actuators 35a_ along fixed vertical axes of the machine once the pallets have been inserted and locked in position: if these pins pass cleanly through the aligned bores 3*4, this indicates that the pallets are correctly and accurately positioned. These pins are then retracted from the aligned bores to enable use of the punch press.

In order to provide a further safeguard that the pallets will remain correctly in position during use of the press, pressure may be applied to the front edges of the pallets, at the opposite corner from the locking pins 32. In the example shown, for each pallet a roller 36 is mounted on an arm 38 which is swung into position around an axis 41 by an actuator 40 so that the roller is urged against the front face or edge of the pallet.