The present invention relates to a band saw for use among others for cutting ribs of porkers, to be more specific carcases, but having capabilities for other sawings.

In connection with rationalization and attempts to reduce the human physical stress within the slaughter¬ house industry research has been made to develop machines for cutting ribs and the like of carcases. Thus a circular saw has been developed for this rib sawing, but the saw has the disadvantage that a subsequent fine cutting of the bones is needed.

The present invention provides a compact and handy saw, first of all being efficient by allowing the cutting to be performed in one single operation, such that one person can carry out the hard physical labour of three to four persons.

The invention is characterized in that an endless saw blade is only guided around a single larger wheel in contrast to ordinary band saws, e.g. known from the wood working industry, which have two or several wheels, around which the saw blade is guided, tensioned and driven.

By the saw according to the invention the exceeding wheels of the known band saws have been replaced by two arms having hard metal lining as abutment for the saw blade. The sawing takes places between the two arms. In the free area, where the sawing takes place, the blade can be adjusted to different curvatures according to the shape of the object. The main principle of the saw is the manner in which the power transfer and the rotation of the saw blade takes place. The power transfer takes place by the blade being urged against the edge of a

rotating wheel, on a part of the circumference by means of a toothed belt or other form of belt. This belt is guided by a number of pulleys arranged such that the blade is forced against the intended part of the circum¬ ference of the driven wheel. Cleaning is essential among others within the slaughterhouse industry and it appears that the use of a toothed belt reduces cleaning. Also, the saw is open downwardly, such that saw dust and the like is not stuck in the saw. Furthermore the saw is gyro suspended and counterbalanced, such that the opera¬ tor only should turn the saw following the bones, and should not lift, turn nor rotate the saw.

An embodiment of the saw according to the invention particularly designed for cutting ribs of porkers' car¬ cases shall be described in the following with reference to the accompanying drawing. On the drawing is shown:

Fig. 1 a schematically perspective view of the saw seen from the front and with the removal of a cover shield, covering the rotating parts, and

Fig. 2 a schematically perspective view, showing the saw as seen from the rear.

A driven wheel 2 is mounted directly on an electric motor 4. A band saw blade 6 is overlaying a part of the periphery of the driven wheel, and is guided by two arms 8 having hard metal plates, and the outer ends of the arms being curved towards each other. The outer ends of the arms can be adjusted, such that the blade in the free area between these can be adjusted to different curvatures.

The blade is forced against the driven wheel by a toothed belt 10, the toothed side of which is in contact with the blade. As indicated the band is overlaying the upper part of the driven wheel and follows the blade

outside the driven wheel at a distance in the downward direction until two fixed turning pulleys 12, about which the toothed belt is inverted and is now having the toothed side outwardly and further in the upward direc¬ tion around a tension pulley 14. Accordingly the blade is supported by the toothed belt on the majority of the length of the free distance between the driven wheel and the arms. The toothed belt can be tightened by the ten¬ sion pulley 14, which can be displaced vertically by a compressed air cylinder 16, at the rear side of the base plate 18. The saw is suspended counterbalanced in a yoke 20. The entire saw can be tilted about bearings 22 at the ends of the yoke. Furthermore the entire saw be rotated about the bearings 24 in cooperation with the ring 26.

The apparatus is safeguarded thereby that the toothed belt is slackened when air pressure is taken off the cylinder 16, which activates the tension pulley 14. When the toothed belt is slackened the blade looses contact with the driven wheel and accordingly stands still. The cover or shield covering the main parts of the rotating parts is equipped with contacts disconnect¬ ing the power supply to the electric motor when the shield is incorrectly placed. The two handles 28 for manoeuvring the saw are having contacts such that the saw can only be operated when both contacts are acti¬ vated. They can either be air switches for the tension pulley 16 or switches for the electric motor 4.

As the saw is retracted during a cutting operation the blade has a tendency to be drawn out of the arms which is countered by a roller 30 at the end of an arm 32, which can be brought into a position in front of the blade. At the rear side of the base plate 18 the arm is connected to the bearing of the tension pulley 14 by a rod 34, such that the roller 30 is swung away from the blade when the toothed belt 10 is slackened, and the

blade can be replaced.

The invention provides an extremely efficient saw especially for cutting carcases easing the otherwise hard physical work. The saw is easy to operate as it is suspended counterbalanced, the suspension at the same time allowing the saw to be rotated and tilted to almost any position. Also the curvature of the blade can be adapted to the objects to be cut.