The present invention relates to a catching device for catching and holding a fish by the head. In the fish industry it is advantageous during some operations to hold a fish being processed by the head with a firm grip ensuring that the fish does not shift or move in relation to the gripping or catching device. It is an object of the present invention to provide a catching device that would provide such a firm grip. It is a further object to provide a catching device that will ensure that a caught fish head is aligned in the device.

It is a further object to provide a catching device that provides for detecting the position of a caught fish head.

This is achieved by means of a catching device for catching and holding a fish by the head, said device being characterised by a pair of jaws one of which is provided with a generally trough like skull guide for engaging and guiding the skull of the fish, the other jaw being provided with a jaw guide for engaging the lower jaw bone of the fish between the two flanks of said jaw bone, and means for opening and closing the pair of jaws. The trough shape of the skull guide generally conforms the shape of the skull of the fish to be caught and during the closing together of the pair of jaws the head of the fish is pressed by the jaw guide into the skull guide, whereby the head is longitudinally aligned with the skull guide. The jaw guide being pressed into the space between the two flanks of the lower jaw of the fish provides for a firm grip which prevents the fish from shifting.

The jaw provided with the skull guide is preferably fixed and the jaw provided with the jaw guide is preferably movable. This provides for accurate positio¬ ning of the head of the fish in relation to the catching device and an apparatus carrying the catching device e.g. a robot arm.

The fish engaging surfaces of the skull guide and the jaw guide are preferably smooth. This provides for the fish to slide into alignment with the skull guide during the closing of the pair of jaws.

I an embodiment suited for use in an automated pro¬ cessing system the catching device comprises sensor means for detecting the position of the head of a fish in the device. This provides for detecting the exact position of the head in relation to the device thereby making it possible to calculate required correction movements of e.g. a robot arm or other manipulator carrying the catching device needed to place the fish correct for further processesing. The sensor means preferably comprise means for sensing the snout of the fish or means for sensing the back of the head of the fish. Such sensor means provides for determining the longitudinal position of the fish head. The sensor means preferably also comprise means for sensing the two flanks of the lower jaw bone of the fish. Such sensor means provides for determining the angular position of the fish head in relation to its longitudinal axis. The invention will now be explained more detailled by way of example with reference to the accompanying drawings, in which

Fig. 1 shows a device according to the invention; Fig. 2 a section along the line II-II in Fig. 1; Fig. 3 a section along the line III-III in Fig. 1;

Figs. 4 and 5 show perspective views of two further embodiments of the jaw guide.

The catching device or gripper 1 comprises two jaws or fingers 2, 3, whereof the first finger 2 is fixed in relation to the major part of the gripper 1 and the second finger 3 is hinged to the fixed finger 2 by a joint 4 to rotate about an axis perpendicular to the plane of Fig. 1. It should be understood that the joint 4 may be placed in an other position than the one shown, thus providing an other centre of the relative movement between the two fingers 2, 3, or the two fingers may be moved translatoric in relation to each other. The hinged finger 3 is moved by a cylinder 5 with a piston rod 5a in order to open or close the gripper 1. On the fixed finger 2 is secured a skull guide 6 formed by a piece of sheet material bend into a trough like shape corresponding to the shape of the skull of a fish e.g. a cod to be caught by the gripper. By securing the skull guide 6 by means of releasable means such as screws the gripper may readily be adabted to other sorts of fish with another skull shape by changing the skull guide 6. Fig. 2 shows the profile of the skull guide 6 which may form part of a cylindrical or conical surface. Instead of sheet material the skull guide 6 may be made from bars.

The tip of the hinged finger 3 carries a jaw guide 7 hinged to the finger 3, the hinge axis 8 being parallel to the axis of the joint 4. The jaw guide 7 may as shown carry an alignment bar 9 which is seen more clearly in Fig. 3 as is the profile of the jaw guide 7 which in the shown embodiment is made from sheet material.

Figs. 4 and 5 show two other embodiments of the jaw guide 7. In these embodiments the jaw guide 7 comprises a relative narrow front part 18 for engaging the back

of the central part of the jaw bone of a fish and a wider part 19 for engagement with the soft part of the fish between the flanks of the jaw bone. The embodiment in Fig. 4 comprises a continous abutting surface 20 whereas this surface in the embodiment shown in Fig.5 is formed by two bars 21, 22.

In use the gripper 1 is placed with the skull guide 6 in contact with the skull of a fish 10 e.g. a cod, the hinged finger 3 being in its open position shown in full line in Fig. 1. Thereafter the hinged finger 3 is svung by means of the piston rod 5a to its closed position shown in dashed line in Fig. 1. During this movement the jaw guide 7 is pressed normally without breaking the skin into the space between the two flanks of the jaw bone. As the alignment bar 9 or the jaw guide 7 makes contact with the jaw bone of the fish a moment is applied about the hinge 8. This causes the jaw guide 7 to rotate. This rotation may cause the fish to slip in the gripper 1 until the rear edge of the foremost central part of the jaw bone makes contact with the tip of the jaw guide 7. The grasp thus obtained is a combination of location of the jaw guide 7 behind the jaw bone and a pressure grip between the upper and the lower side of the skull of the fish. The jaw guide 7's contact of the jaw bone flanks provides during the closing for a rotating and aligning or centralising effect on the fish. The same effect is provided for by the alignment bar 9. Once the hinged finger 3 is in its closed position a firm grip is provided without possibility of shifting under the influence of those forces that will normally be in question.

The gripper 1 may be used in an fish processing system. In that case it will be useful to know the exact position of a fish head caught by the gripper in order to be able to calculate corrections to be made to the

position of the gripper in order to place the fish head in a predetermined position. Such corrections could e.g. be made by means of a robot arm carrying the gripper. Therefore in one embodiment the gripper 1 or the system utilizing the gripper 1 is provided with sensor means for sensing the position of the fish head.

As a non-limiting example in Fig. 1 three different sensor means are shown which in practice may be used alone or in combination. A snout position sensor 11 comprises an abutment plate 12 mounted on a piston rod 13. As the fish head is positioned in the gripper 1 the abutment plate 12 and the piston rod 13 are pushed back a distance that provides a measure for the position of the snout. A traveling pick-up means 14 is moved forth and back by means of a cylinder 15 after the fish head has been caught and detects thereby the position of the back of the head which provides a sensible edge.

Finally a rotatable transverse abutment bar 16 mounted on an appropriate arm 17 may be brought into abutment on the lower jaw of a fish caught in the gripper 1 thereby providing a measure for the angel between the lower jaw of the fish and alignment bar 9 i.e. a measure for angular shift between the gripper 1 and the fish around the longitudinal axis. Although three mecanical sensors have been disclosed herein other kinds of sensors could be used e.g. ultra sonic sensors or light sensors.