Gripping device

A gripping device and process comprising: PA1 first and second matable jaw members; PA1 a cylinder adapted to reciprocate vertically; PA1 connecting the first jaw member to the cylinder such that, in operation, the cylinder and connection urge the first jaw member to open and close the jaws; PA1 maintaining the second jaw member in a fixed position relative to the cylinder; PA1 a fixed table positioned beneath the jaw members, provided with at least one transverse groove; PA1 transporting a product downstream on the fixed table to locate it with its upstream or downstream edge overlying the transverse groove; PA1 advancing the cylinder downwardly with the jaws in the open position to enable the lower end of the second jaw member to contact the product at its upstream or downstream end above the groove causing the product to tilt in the groove; PA1 activating the cylinder to close the jaws to grip the tilted product at its upper end; PA1 retracting the cylinder upwardly with the closed jaws gripping the product; and PA1 deactivating the cylinder to open the jaws to release the product.

The present invention relates to a gripping device, more particularly for 
picking up frozen food products and releasing them. 
Existing picking units comprising vacuum suction cups are not fully 
reliable for picking up products with an uneven or grooved surface nor for 
products which can let air through owing to the presence of slits or holes 
therein. In addition, rapid movements transverse to the suction force 
cause a hazard. 
We have now invented a gripping device which avoids the above-mentioned 
difficulties. 
Accordingly, the present invention provides a gripping device comprising: 
first and second matable jaw members; 
a cylinder adapted to reciprocate vertically; 
means connecting the first jaw member to the cylinder such that, in 
operation, the cylinder and connecting means urge the first jaw member to 
open and close the jaws; 
means for maintaining the second jaw member in a fixed position relative to 
the cylinder; 
a fixed table positioned beneath the jaw members, provided with at least 
one transverse groove; means for transporting a product downstream on the 
fixed table to locate it with its upstream or downstream edge overlying 
the transverse groove; 
means for advancing the cylinder downwardly with the jaws in the open 
position to enable the lower end of the second jaw member to contact the 
product at its upstream or downstream end above the groove causing the 
product to tilt in the groove; 
means for activating the cylinder to close the jaws to grip the tilted 
product at its upper end; 
means for retracting the cylinder upwardly with the closed jaws gripping 
the product; and 
means for deactivating the cylinder to open the jaws to release the 
product. 
The means connecting the first jaw member to the cylinder may be a pivot 
positioned between the ends of the first jaw member so that the part of 
the first jaw member above the pivot is impelled by the cylinder piston. 
The means for maintaining the second jaw member in the fixed position 
relative to the cylinder may be any suitable conventional fixing means and 
conveniently includes a plate connected to the cylinder. 
The fixed table positioned beneath the jaw members is preferably provided 
with a plurality of consecutive spaced transverse grooves. Desirably the 
grooves are spaced from one another by a distance corresponding 
substantially to the length of each product so that the upstream and 
downstream edges of successive products transported on the table overlie 
the grooves. 
The means for reciprocating the cylinder may be, for example, an electric 
motor or a pneumatic cylinder. Advantageously, there are a plurality of 
cylinders. The means for activating and deactivating the cylinder to close 
and open the jaws may conveniently be a pneumatic valve. Advantageously, 
the second jaw member is connected to the first jaw member below the pivot 
by a spring. 
The transverse grooves are preferably provided with upstream and downstream 
planar walls the inside surfaces of which are at an acute angle to the 
surface of the table e.g. from 20.degree. to 70.degree. and especially 
from 30.degree. to 60.degree.. This enables the part of the tilted product 
in the groove to rest firmly against the surface of a wall of the groove. 
Advantageously, the gripping parts of the jaw members are positioned at an 
angle suitable for gripping the tilted product in the transverse groove. 
Conveniently, the cylinder is also adapted to reciprocate horizontally from 
an upwardly retracted position above the table with the closed jaws 
gripping the products to a position above a means for receiving the 
product, at which position the jaws open to release the product onto the 
receiving means, and then back to the upwardly retracted position above 
the table. 
The present invention also provides a process for gripping a product 
comprising positioning a device having: 
first and second matable jaw members; 
a cylinder adapted to reciprocate vertically; 
means connecting the first Jaw member to the cylinder such that, in 
operation, the cylinder and connecting means urge the first jaw member to 
open and close the jaws; 
means for maintaining the second jaw member in a fixed position relative to 
the cylinder; and 
means for activating and deactivating the cylinder for closing and opening 
the jaws above a fixed table provided with at least one transverse groove; 
transporting a product on the fixed table to locate it beneath the jaw 
members with its upstream or downstream edge overlying the transverse 
groove; 
advancing the cylinder downwardly with the jaws in the open position to 
enable the lower end of the second jaw member to contact the product at 
its upstream or downstream end above the groove causing the product to 
tilt in the groove; 
activating the cylinder to close the jaws to grip the tilted product at its 
upper end; 
retracting the cylinder upwardly with the closed jaws gripping the product; 
and 
deactivating the cylinder to open the jaws to release the product from the 
jaws. 
The gripping device of the present invention is especially suitable for 
gripping resilient food products, such as frozen sawn fish pieces formed 
from a frozen fish block which has travelled beneath a saw. One advantage 
of the device of the present invention when gripping frozen sawn fish 
pieces is that the adjoining individual sawn pieces, which are often stuck 
together, can be broken apart by the action of the second jaw member 
contacting the end of the fish piece and pushing that end into a 
transverse groove. 
The means for receiving the product may be, for instance, a pickup or 
distribution conveyor for transporting the product to a packing machine 
e.g. directly to the pockets of a Multivac machine.

Referring to the drawings, a pneumatic mini-cylinder 10 adapted to 
reciprocate vertically and horizontally is provided with a piston 11 and a 
plate 12 with an extending arm 13. Connected to the plate 12 is a fixed 
jaw member 14 with a gripping portion 15 and connected to the extending 
arm 13 by means of a pivot 16 is a jaw member 17, 17a with a gripping 
portion 18, 18a, and an upper portion 19, 19a, contacting the piston 11. 
(17a, 18a and 19a depict the open jaw position by the broken lines in FIG. 
1). 
The jaws are connected by extension spring 20. A fixed table 21 is provided 
with transverse grooves 22 positioned beneath the gripping portion 15 of 
the fixed jaw member 14 having an angled downstream wall 23 and an 
upstream wall 24. Sawn frozen fish pieces 25 travel on the table 21. A 
conveyor 26 leading to a Multivac packing machine is shown in FIG. 5. 
In operation, fish blocks (not shown) are sawn into fish pieces 25 which 
travel to the left in the drawings on the grooved table 21 until the 
upstream and downstream edges of the fish pieces 25 are positioned to 
overlie the transverse grooves 22 on the table 21. As the leading fish 
piece 25 passes beneath the jaw members 14, 17, the cylinder 10 is in the 
raised position and the jaw members are in the open position as depicted 
by the broken lines 17a, 18a, 19a in FIG. 1 and the piston 11 is in the 
retracted position. 
The cylinder 10 descends together with the jaw members 14, 17 and the lower 
end of the gripping portion 15 of the fixed jaw 14 contacts the upstream 
end of the fish piece 25 and pushes it downwards into the transverse 
groove 22 causing the fish piece to tilt at an angle equivalent to that of 
the downstream wall 23 while it is held in that position by the gripping 
portion 15. A pneumatic valve (not shown) activates the piston 11 to urge 
the upper part 19a of the jaw member 17a so that it pivots about the pivot 
16 so that the gripping portion moves from position 18a to position 18 
causing the jaws to close so that the tilted fish piece 25 is gripped by 
the gripping portions 15, 18. 
The cylinder 10 ascends together with the closed jaws gripping the tilted 
fish piece 25 and then travels horizontally to a position above the 
conveyor 26 whereupon the piston 11 retracts causing jaw member 17 to open 
by pivoting about the pivot 16 and to release the fish piece on to the 
conveyor 26. The cylinder 10 with the jaws open then returns horizontally 
to a position above the table 21 whereupon the process is repeated. 
The vertical and horizontally reciprocating movements of the cylinder may 
be controlled by an electric motor or a pneumatic cylinder and the whole 
operation may be synchronised by a computer.