Field of the invention

This invention concerns improvements in or relating to bending machines, in particular machines for bending lengths of material such as rods, tubes or wires. For convenience reference will hereinafter be made to "wire", which expression is intended to include any such elongate material.

Background to the invention

Bending machines are known in which the wire to be bent is inserted laterally into a bank of bending heads in each of which at least one length of wire is retained by a device such as a ball catch. This insertion operation is usually manually performed by the machine operator; and it has been found, particularly where a long length of wire is to be bent, that difficulties are frequently experienced by the operator in correctly inserting the wire.

Summary of the invention

According to the present invention there is provided a wire bending machine comprising a bending head having a slot for receiving at least one length of wire and a retaining device movable into a retention position so as to close the open end of the slot, so that during bending the wire is retained in the slot.

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By this means the wire can more rapidly be set up in the bending head and is also more positively located in the slot.

Where the bending head is movable relative to the remainder of the machine in a direction along the length of the wire (before bending), the retaining device may form part of the bending head.

Advantageously the retaining device comprises a pivotal lever movable by a ram into a forward position, and a hold-back device engages with a central part of the lever to cause pivoting of the lever into a retention position, in which it is substantially perpendicular to the slot in the bending head.

Brief description of the drawings

An example of the invention will now be described, with reference to the accompanying drawings, in which:

Figure 1 is a side view of a bending machine embodying the invention; and

Figure 2 is a detail of the head of the bending machine.

Detailed description

Referring first to Figure 1 there is shown the general outline of a wire bending machine. A coil of wire is fed from a decoiling unit 2, to a straightening unit 4 comprising two sets of opposed rollers, one set having rollers rotatable about horizontal axes while the other set has rollers rotatable about vertical axes.

To the right of the straightening unit the wire is fed to a cropping or shearing unit 6. The severed length of wire is now held by three transfer units, and to the right of the transfer unit is an end trimmer adapted to trim the leading end of the wire.

Beneath the transfer unit are mounted two banks 12 of bending heads. Each bank 12 comprising four bending heads slidable under computer control along a horizontal slide. Between the two banks of bending heads is a rotatable clamp 14.

Referring now to Figure 2 , there is shown one bending head 16 rotatable about a horizontal axis and formed with a slot 18 in which a plurality of wires 20, in this case three wires, are receivable.

Inboard of the bending head 16, to the right as viewed in Figure 2, is a hydraulic cylinder or ram 22 mounted from a frame 24 of the bending head on which the bending head is individually slidable, as above-mentioned.

Projecting from the cylinder 22 is an actuating rod 26 slidable in a journal bearing 28 forming part of the frame 24.

Fixedly mounted on the rod 26 between the cylinder 22 and the journal bearing 28 is a block 30 in which is slidably carried a smaller rod 32, also slidable in the bearing 28. Pinned to the rod 32 is a further block 34 through which the actuating rod 26 is slidable, a compression spring 36 being located around the rod 26 between the blocks 30 and 34, to urge the block 34 into a forward position.

At the front end of the block 34 is an abutment 38 which on forward movement of the rod 26 abuts with an adjustable screw 40 secured to the bearing 28.

Pinned to the forward end of the smaller rod 32 is an end block 41 through which the forward end of the actuating rod 26 is also slidable.

Pivoted about the forward end of the actuating rod 26 is a finger or lever 42 to the middle of which is also pivoted a link 44 pivotal about the end block 41.

The operation of the device will now be described.

Starting with the actuating rod 26 in its withdrawn position, as shown in solid lines, the hydraulic cylinder 22 is actuated, causing the actuating rod 26 and the smaller rod 32 to extend forwards, ie to the left as viewed in Figure 2. Both rods continue to be extended until the abutment 38 meets the screw 40, which arrests movement of the smaller rod 32. During further movement of the rod 26 against the pressure of the compression spring 36, the block 30 slides along the smaller rod 32 until the block 30 meets the abutment block 34. During this movement the right hand pivot of the link 44 is stationary so that the outward movement of the rod 26 causes clockwise rotation of the lever 42 until it is in an upright position, as shown chain dotted. In this position the free end of the lever 42 is positioned adjacent the slot 18 in the bending head so that it pushes the wire 20 into the slot and retains it therein.

It will be appreciated that the device described enables

the wires to be more easily set up in the bending heads, and additionally retains the wires in the slots in a more positive manner.