The present invention relates to granulating machines.

Granulating machines are used in various industries to reduce solid material to a particulate form. Such machines generally comprise a rotor housed in a cutting chamber. The rotor has a plurality of fly blades and the cutting chamber is fitted with static blades. As the rotor rotates the fly blades interact in a cutting area with the static blades to produce a cutting action.

After a period of use the blades of the granulating machine become worn and blunt and it is necessary to sharpen them by grinding. In order to do this the blades have to be removed from the machine and transferred to a grinding station. After grinding the blades are replaced in the machine. The positioning of the static and fly blades and in particular the size of the gap between them during cutting is critical to obtaining an effective cutting action.

In known granulating machines the position of each of the static cutting blades is adjusted by a plurality of threaded bolts positioned at the rear of each blade. The bolts pass through holes in a supporting wall which are alternately threaded and unthreaded. The bolts which pass through the threaded holes abut the rear of the static blade and may be turned to "push" the blade towards the cutting area. The bolts which pass through unthreaded bores are threadedly engaged with holes in the rear of the blades and may be turned to enter further into the holes and effectively to "pull" the blade away from the cutting area. The bolts are adjusted as required along the length of the static blade to move it to the correct position. Feeler gauges are used to ensure the gap between static and fly blades is of the desired dimension. It will be appreciated that this method of adjusting the static blades is time consuming and tedious but requires a skilled operator.

The term granulating machine is used hereinafter in the description and claims to refer to any type of machine which employs a cutting action to reduce a solid object into smaller components.

It is an object of the present invention to obviate or mitigate the aforesaid disadvantages.

According to the present invention there is provided a granulating machine comprising a rotor with at least one first cutting blade, and at least one second cutting blade, the first and second cutting blades being designed to interact in a cutting area during rotation of the rotor to produce a cutting action characterised in that at least one of the cutting blades is adjustable by moving it towards the cutting area and in that pre-set elements are provided adjacent the adjustable cutting blade so that it can be moved to abut the pre-set element thereby setting it in a desired cutting position.

Preferably the pre-set element is positioned adjacent a cutting edge of the adjustable blade.

The pre-set element may comprise a bolt, the adjustable cutting blade being moved until its cutting edge abuts the head of said bolt.

Preferably the adjustable cutting blade extends beyond the cutting area and the pre-set elements are positioned outside the cutting area.

The pre-set elements may be adjustable to permit different positions of the adjustable cutting blade.

The adjustable cutting blade may be held in position by a plurality of releasable fixings and conveniently may have a plurality of corresponding slots by which the blade may move relative to the fixings when they are released.

The releasable fixings may comprise bolts.

Preferably the adjustable cutting blade is a static cutting blade which is fixed relative to the rotor during the cutting action.

A specific embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 is a sectioned side view of a granulating machine in accordance with the present invention;

Figure 2 is a sectioned side view of a rotor and cutting frame of the present invention;

Figure 3 is a plan view of a the cutting frame of figure 2; and Figure 4 is a side view of the cutting frame of figure 3.

Referring now to the drawings, the granulating machine comprises a cutting chamber generally indicated by arrow 10, a delivery chute 11 with opening 11a via which material to be cut is fed to the cutting chamber 10, a support frame generally indicated by arrow 12 and a motor 13 with drive belt 14.

Inside the cutting chamber 10 there is a rotor 15 mounted on a shaft 15a which is in turn rotatably mounted in bearings (not shown) on an associated cutting frame 16. The cutting frame 16 is constructed from four members 17,18,19,20 arranged in a rectangular frame configuration. Two spaced parallel beams 17,18 are interconnected at each end by two parallel plate members 19,20 to define a central rectangular space 21 which the rotor 15 occupies. The plates 19,20 are, for example, welded to a bottom surface of each beam 17,18. Adjacent the central space 21, at the inner edge of each plate member 19,20 there is an upstanding wall 22 with an arcuate recess 23. The height of each wall 22 is substantially the same as that of each beam 17,18 so that its top surface is substantially co-terminus with an upper surface of the beams 17,18.

The top surface of each beam 17,18 is fitted with a static cutting blade 24,24a arranged so that its cutting edge 25 projects into the central rectangular space 21.

Each static blade 24,24a is sandwiched between a mounting plate 26 and its corresponding beam 17,18 and is fixed there by bolts 27 which pass through fixing apertures in the mounting plate 26, the static blade 24,24a and the beam 17,18. The four apertures are equi-spaced along the length of the beam 17,18 and blade 24,24a assembly. The apertures in the mounting plates 26 are each through bores, whereas the apertures in the beams 17,18 are threaded blind bores 28. The

apertures in the blade 24,24a are in the form of elongate slots (shown in dotted line at 29) whose longitudinal axes extend across the width of each blade 24,24a.

At the upper edge of each upstanding wall 22 there is a bracket 30 fixed adjacent each end of the static cutting blades 24,24a. Each bracket 30 has a threaded aperture which receives a bolt 31 each of which has a head 32 designed to abut a part of the cutting edge 25 of the static blade 24,24a which extends outside the central space 21 beyond the upstanding walls 22. This part of the blade is not therefore employed in the cutting operation.

The brackets 30 are offset in height relative to one another to account for the fact that the cutting edge 25 of static blade 24 is defined on the lower surface of the blade whereas the cutting edge 25 of static blade 24a is defined on its upper surface.

The rotor 15 carries three equi-angularly spaced fly blades 33 and as it rotates a cutting edge of the fly blades 33 passes close to the cutting edge 25 of the static blades 24,24a to produce a scissor-like cutting action.

In use the bolts 31 are pre-set so that their heads 32 are at a predetermined offset position relative to the nearest edge of the beams 17,18. The offset between the bolt head 32 and the adjacent beam edge determines how far the cutting edge 25 of the static blade 24,24a extends into the central area 21. When a static blade 24,24a becomes worn it is removed by releasing fixing bolts 29 and withdrawing them from the static blade 24,24a and mounting plate 26. The cutting edge 25 of the static blade 24,24a is then re-ground at a grinding station and the blade 24,24a replaced between the mounting plate 26 and beam 17 or 18. The fixing bolts 27 are inserted in place but before they are tightened the rear edge of the cutting blade 24,24a is pushed until the cutting edge 25 abuts the pre-set bolt head 32 at each end of the blade 24,24a. Movement of the blade is possible by virtue of the elongate slots 29 which pass over the shanks of the fixing bolts 29. The static cutting blade 24,24a is now in the correct position for the selected cut and the fixing bolts 27 are tightened to hold it in place. It will be appreciated that the adjustment of the re- ground blade is much simplified, less time consuming and eliminates the need for a

skilled technician to set the blade after each re-grinding operation. Moreover, by having the static cutting blades extend beyond and the pre-set bolts positioned outside of the central space there is no need for the operator to access the cutting area.

It will be appreciated that numerous modifications to the design described above may be made without departing from the scope of the invention as defined in the appended claims. For example, the number of static or fly blades may be increased depending on the application or size of the machine. Furthermore, the pre-set bolts may be replaced by any functionally equivalent elements such as studs or pads.