The present invention relates to a locking device for a transfer feeder employed in a transfer press.

A transfer feeder employed in the conventional transfer press is constructed to have a pair of transfer bars which are movable in two-dimensional or three-dimensional directions, and to clamp a work by means of a finger provided in opposition to these transfer bars for transporting the work.

On the other hand, the transfer bars are adapted to be driven in feeding direction, lifting direction and clamping direction by means of a cam driven to rotate by a driving force taken-off by a power take off of the transfer press. A clutch, a brake and so forth are provided in the power take off for controlling transmission and blocking of the driving power.

In the above-mentioned conventional transfer feeder, when maintenance or repairing of the driving section in the feeder, an engineer enters within the feeder to perform maintenance or repair by stopping motion of the feeder side by a brake in a press main body side when the clutch of the power take off is engaged and by stopping motion of the feeder by means of a brake of the power take off when the clutch of the power take off is released.

However, since the brake of the press main body and the brake of the power take off employ friction plates, it is possible to cause unexpected movement of the transfer bars so forth due to slip of the friction plates due to weight of the transfer bars or so forth. Therefore, in the prior art, it cannot ensure safety of maintenance and repair.

The present invention is to solve the above-mentioned problems. Therefore, it is an object of the present invention to provide a locking device for a transfer feeder which can certainly lock transfer bars at desired positions so that the transfer bars and their driving portions will never initiate motion unexpectedly.

In order to accomplish the above-mentioned object, there is provided, in accordance with the first aspect of the invention, a locking device for a transfer feeder of a transfer press, which transfer feeder includes a pair of transfer bars driven in two or three dimensional directions, which comprises engaging means provided in a drive mechanism of the transfer bar, locking means provided at a plurality of stationary portions of a press main body for engaging with the engaging means, and driving means for driving the locking means.

In order to accomplish the above-mentioned object, there is provided, in accordance with the second aspect of the invention, and in the locking device according to the above-mentioned first aspect of the invention, the engaging means comprises a plurality of engaging plates fixed on a feed carrier and equalizer bar provided in lift/clamping mechanism and having a plurality of engaging holes formed in alignment in the longitudinal direction with a regular interval, and the locking means comprises a plurality of locking pins provided at plurality of portions of the press main body respectively in opposition to the engaging plates and movable in axial and lateral directions by means of the driving means to engage with one of a plurality of the engaging holes.

In order to accomplish the above-mentioned object, there is provided, in accordance with the third aspect of the invention, and in the locking device according to the above-mentioned second aspect of the invention, each of the engaging plates has dogs at predetermined positions corresponding to each engaging holes, and engagement and release of the locking pin relative to the engaging holes is controlled by detecting one of the dogs by means of a detector.

In order to accomplish the above-mentioned object, there is provided, in accordance with the fourth aspect of the invention, and in the locking device according to the above-mentioned first aspect of the invention, the engaging means comprises a engaging plate secured on the press main body in upright fashion and having a plurality of engaging holes formed in alignment in a feed direction of a feed carrier with a regular interval, an engaging portion having a plurality of recessed grooves formed in the a clamping drive lever in alignment in the longitudinal direction thereof with a regular interval and an engaging portion having a plurality of recessed grooves formed in a lifting drive lever in alignment in the longitudinal direction thereof with a regular interval, and the locking means comprises a plurality of locking cylinders secured on the feed carrier and two portions of the press main body respectively in opposition to the engaging plate and two engaging portions to engage with respective one of engaging holes and recessed groove.

In order to accomplish the above-mentioned object, there is provided, in accordance with the fifth aspect of the invention, and in the locking device according to the above-mentioned fourth aspect of the invention, the locking cylinder is placed at locking position by a biasing means and at an unlocking position by a hydraulic pressure.

With the present invention having the above-mentioned respective features, since the locking device for mechanically locking the drive mechanisms for driving the transfer bars in feeding, lifting and clamping directions, even when engineer performs maintenance or repair by entering into the transfer feeder, the transfer bars or its driving portions will never move unexpectedly due to their own weight or so forth to ensure safety in maintenance and repairing operations.

In addition, since it is constructed that the locking pin detecting the engaging hole in the engaging plate enters into the detected engaging hole, lock can be certainly established even when the transfer bars are stored at any desired position.

The above-mentioned and other objects, aspects and advantages of the present invention will become clear to those skilled in the art from the discussion described and illustrated in connection with the accompanying drawings which illustrate preferred embodiments meeting with the principle of the invention.

• Fig. 1 is a perspective view of in the vicinity of a feed driving mechanism, in which the preferred embodiment of the present invention is employed;
• Fig. 2 is an enlarged perspective view of the preferred embodiment of the present invention;
• Fig. 3 is schematic illustration showing overall construction of a lock system of a transfer feeder employing another embodiment of the present invention;
• Fig. 4 is a schematic plan view of a lock cylinder employed in the embodiments of the invention and elements in the vicinity thereof; and
• Fig. 5 is a section of the lock cylinder to be employed in the embodiment of the invention.

The preferred embodiments of the present invention will be discussed herebelow in connection with the accompanied drawings.

At first, discussion will be given for the first embodiment of the present invention with reference to Figs. 1 and 2.

In Fig. 1, the reference numeral 1 denotes a main body of a transfer press, which includes a moving bolster 2. A pair of transfer bars 4 of a transfer feeder 3 are provided above the moving bolster 2.

The transfer bars 4 are provided in parallel relationship orienting in parallel to the transfer direction of not shown works. The transfer bars 4 are adapted to be driven in three-dimensional directions of feeding direction, lifting direction and clamping direction by a driving force taken off by a not shown power take off provided in the main body of the press 1. A locking device 7 according to the present invention, is provided in the vicinity of a feed carrier 5a of a feed drive mechanism 5 or an equalizer bar 6 provided in a lift and clamp mechanisms (both being not shown).

As shown in Fig. 2, the locking device 7 has an engaging plate 8 fixedly secured on the feed carrier 5a or the equalizer bar 6.

The engaging plate 8 is formed with a plurality of engaging holes 8a aligned in the longitudinal direction with a regular interval and dogs 8b at the positions corresponding to the engaging holes 8a. The dogs 8b are adapted to be detected by means of a detector 9, such as a proximity switch, movable along the engaging plate 8.

The detector 9 is mounted on a sliding member 7b movably supported on a base 7a of the locking device 7 via a bracket 10. A thread shaft 12 which is rotatingly driven by a feeding motor 11 is engaged with the lower portion of the sliding member 7b so that the sliding member 7b is driven to move along the engaging plate 8 by means of the feeding motor 11.

The sliding member 7b carries a locking pin 13 in opposition to the engaging plate 8, which lock pin 13 has a tip end entering into the engaging hole 8a of the engaging plate 8 to lock the engaging plate 8.

The locking pin 13 is normally biased toward the engaging plate 8 by means of a compression spring 14 so as to establish locking for the engaging plate by the effect of the compression spring 14. The rear end of the locking pin 13 is connected to a hydraulic cylinder 15 so as to unlock the engaging plate in response to a hydraulic pressure supplied from a pressurized fluid source 18 via an electromagnetic valve 16 and a piping 17.

It should be noted that, in the drawings, the reference numeral 19 denotes a detector for detecting locking and unlocking states of the locking pin 13.

Next, discussion will be given for operation. Upon maintenance or repair of the transfer feeder 3, once the transfer feeder 3 is stopped, the sliding member 7b is driven by revolution of the feeding motor 11 to move along the engaging plate 8.

Since the detector 9 is provided on the sliding member 7b, the detector 9 detects the dogs 8b of the engaging plate 8. In response to a signal from the detector 9, an electromagnetic valve 16 is switched from a communicating position 16a to a drain position 16b so that a work fluid in the hydraulic cylinder is drained.

By this, the locking pin 13 is projected in the direction toward the engaging plate 8 by the action of the compression spring 14 and thus inserted into the engaging hole 8a at the corresponding position to the detected dog 8b. Therefore, the feed carrier 5a or the equalizer bar 6 of the lifting and clamping mechanisms fixed to the engaging plate 8 can be mechanically locked. Therefore, unexpected movement of the transfer bars due to its own weight during maintenance or repairing operation can be certainly prevented.

Next, the second embodiment of the present invention will be discussed in connection with Figs. 3 to 5.

As can be clear from Fig. 3, by a power take off 25 mounted thereon, a press main body 21 takes off the driving force for rotatingly driving a cam shaft 26 by the taken off driving force.

A feeding cam 26a, a clamping cam 26b and a lifting cam 26c are provided on the cam shaft 26. A feed carrier 7 is driven by the feeding cam 6a. A clamping drive lever 8 is driven by the clamping cam 6b. A lifting drive lever 9 is driven by the lifting cam 6c. The transfer bars 4 are driven in a three-dimensional directions, i.e. feeding and returning direction, clamping and unclamping direction and lifting and lowering direction, by the feed carrier 7, the clamping drive lever 8 and the lifting drive lever 9.

Locking devices 10, according to the present invention, are respectively provided in the vicinity of the feed carrier 7, the clamping drive lever 8 and the lifting drive lever 9.

The locking device 10 provided for the feed carrier 7 has locking cylinders 11 arranged at both sides of the feed carrier 7. A piston rod 11a projected from the locking cylinder 11 is adapted to insert the tip end portion thereof into an engaging hole 12a of an engaging plate 12 provided on the upright side 1a of the press main body 1 for locking the feed carrier.

On the other hand, the locking devices 10 provided in the vicinity of the clamping drive lever 8 and the lifting drive lever 9 have locking cylinders 11 which are constructed to engage the tip ends of the piston rods 11b to a plurality of recess form engaging portions 8a and 9a respectively aligned in the longitudinal directions of the clamping drive lever 8 and the lifting drive lever 9.

The locking cylinders 11 are mounted on a stationary portion, such as a bed of the press main body 1 by means of brackets 10a. As shown in Figs. 3 and 4, the interior space of the lock cylinder 11 is divided into a pressure chamber 11₁ and a spring chamber 11₂ by the piston 11a. A hydraulic pressure is supplied to the pressure chamber 11₁ from a pressurized fluid source 13 via an electromagnetic valve 14. On the other hand, a compression spring 11c for biasing the piston 11a in the locking direction is housed within the spring chamber 11₂.

An actuation rod 11c provided on the piston 11a to project toward the spring chamber 11₂ externally extends from the cylinder 11. A dog 15 is carried on the tip end of the actuation rod. A lock detector 16 comprising a proximity switch is adapted to detect the dog 15.

Next, operation of the foregoing embodiment will be discussed. Upon maintenance or repair of the transfer feeder 3, once the transfer feeder 3 is stopped, the hydraulic pressure supplied to respective of the pressure chambers 11₁ if the locking cylinders 11 are drained by switching respective electromagnetic valves 14 from communicating position s 14a to drain positions 14b. By this, the piston rods 11b maintained at the retracted position by the hydraulic pressure project toward the engaging plate 12, the clamping drive lever 8 and the lifting drive lever 9. As a result, tip ends of respective piston rods 11b enters into the engaging portions 12a, 8a and 9a to lock the feed carrier 7, the clamping drive lever 8 and the lifting drive lever 9.

Since the motion of the transfer bars 4 in the feeding and returning direction, the clamping and unclamping direction and lifting and lowering direction is restricted, unexpected motion of the transfer bars 4 due to their own weight can be certainly prevented.