This invention concerns the blade assembly of a crusher. It particularly concerns such a crusher, which is used for crushing various kinds of waste materials, in order to compact them into a small volume and a suitable shape for possible further use, such as burning. Often there is a particular requirement for the crushed material to be homogenous. Generally such crushers include a rotating rotor and blades in it, which carry out the crushing in conjunction with corespondingly shaped grooves in a stationary counter-component.

There are numerous different crushers known in the field, which are based on a rotating rotor and the blades in it, which crush the material by passing over a counter-blade in the stationary part of the crusher.

There are many known solutions, the effectiveness of which is claimed to be based on the specific shape of the blades. Another type of claimed improvements in crushers concerns the arrangement by means of which the blades are attached to the surface of a rotating drum. One method of attaching the blades to the drum is to set them in a sequential arrangement round the circumference of the drum, another method is to set the blades in a spiral arrangement in relation to the length of the drum. And in some solutions a V-shaped arrangement of the blades is used. There are very many different methods.

The attachment of the blades to the drum is carried out in many state of the art devices by welding attachment lugs to the drum and securing the blade to such a lug by means of a bolted connection. The attachment lugs can be situated in grooves in the drum. An attachment of this kind often leads to a poor result in terms of dimensional accuracy. Welding is often quite an inaccurate means of attachment and may cause warping or other faults in the drum, due to the high

temperatures used.

There is also a crusher on the market, the blades of which are attached to a long base plate. The base plate is then secured to a recess in the surface of the drum by means of two bolts in such a way that the length of the base plate lies in line with the axis of the drum. This solution provides a better result dimensionally than the welded solution described above, but almost completely neglects the fact that the blades are subject to extreme stresses, especially impact stresses. The breaking of the attachment bolts seems to be frequent in such a solution.

There are also numerous special blade solutions known for various purposes, in which the blade assembly is secured in place by means of a wedge attached to the frame by a bolt. These assemblies usually have long blades, for operation in chipping devices.

Because crushers are used to crush very different kinds of material, from paper to steel rims, and because the material is usually mixed, the blades are subject to extreme stress. Even a small gap, which always arises even in a tight but otherwise unsupported bolted joint, will in time cause the joint to loosen and finally break. In crusher operation, the joints are extremely important.

The intention of this invention is to create a crusher blade assembly, in which the stresses on the blade, including impact, do not cause the attachment of the blade to loosen. The intention is also to create such a blade assembly, in which, the above notwithstanding, the blades can easily be changed and in which the assembly is, despite everything, sufficiently simple. Yet another intention is to create a blade assembly in which the adjustment of the blades in the drum is very precise and, because of this, it is possible to make the tolerances between the blades and the stationary counter-blades very small, in which case the final result of

the crushing is good. A further intention of the invention is to make the blade assembly as package-like as possible so that it is as easy and simple as possible to handle.

The aforementioned and other advantages and benefits of this invention are achieved by means of a blade assembly, the characteristics of which are created in the manner described as being characteristic in the accompanying Claims.

In what follows, the invention is described in greater detail by reference to the accompanyiung drawings, in which;

Figure 1 is a transverse cross-section of the drum at one of the blades,

Figure 2 is a cross-section of Figure 1 , turned through ninety degrees, showing the situation when the cutting blade is travelling straight towards the viewer.

In general it is possible to say that the blades of the crusher are attached to the drum in machined grooves, which correspond in size to the parts located in them. From the point of view of this invention, there is no significance as to what order or pattern the blades are located on the drum. The choreography of the arrangement is selected in accordance with the specific operating purpose.

The crusher always includes, as usual, a counter-blade, in which case crushing takes place between the blades located on the drum and the counter-blade, as the blades travel with a small tolerance through the grooves corresponding to the blades of the counter-blade.

Figure 1 shows an embodiment of a crusher blade assembly in accordance with the invention, in partial cross-section.

Thus in this case it is assumed that drum 1 is cylindrical and has a smooth surface. On the other hand it is also possible if desired to use a drum that is multi-angled in

cross section. Drums can also be suitably grooved or otherwise machined if desired ^" .

The blade assembly in accordance with the invention is located in a recess machined in the surface of drum 1 in such a way that the combined dimensions of the components located in the recess correspond essentially precisely to the dimensions of the recess.

According to the invention, body component 2 is located in the recess, and is thus essentially the same width as the recess (viewed along the line of the cross section) and the drilled hole 3 is at the location of the hole 5 drilled in drum 1 in such a way that the component can be bolted using a bolt 4 set in hole 3 and running in the internal thread of hole 5.

The figure also shows a horizontally drilled hole 6 in the body section 2, the internal thread of which is intended to receive a bolt, which secures the cutting blade piece 7 to the body component, or it is also possible to push into the drilled hole a pin that guides the blade piece 7 into place.

The front wall of body component 2 is essentially at right- angles to the line of its base, but if necessary it may also be at an angle, if it is wished to adjust the angle of the blade piece 7 to the material being cut. However, adjustment can also be made by making the blade piece 7 thicker on one side than on the opposite side.

The rear wall of the body component 2 is sloping. A wedge¬ like component 8, which comes behind body component 2 in the recess in drum 1, can be attached by screwing a bolt 9, which goes through the hole in component 8, into the internal thread in the drilled hole 10 in the body component 2.

Figure 2 shows how blade piece 7 is attached by means of a

bolt through hole 6 in the centre into the internal thread of a corresponding hole in the body component. On the other hand, due to the attachment arrangement described later, blade 7 can be secured in place at this stage using only pin 6 (Figure 2), which sets blade piece 7 in place, but does not tighten it. Tightening proper takes place with the aid of wedge 8. Blade 7 is supported securely on the surfaces that correspond to the shape of the blade in the body component 2 itself.

Even though the figures show, by way of example, the blade having a shape that is essentially a square standing on one corner, the invention is certainly not limited to this embodiment, it being possible to shape the blade as desired, if necessary. If a blade of another shape i.s used, the supporting surfaces must correspondingly follow the shape of that blade.

The rotation of blade 7 around the axis formed by an attachment bolt or pin can certainly be realized in many other ways, one of which is the location of the lower edge of blade 7 in a groove (not shown) made in drum 7. However, it is also possible to use a securing arrangement between the blade 7 and the body component 2 (pins, a groove-lug arrangement, or similar).

A blade assembly in accordance with the invention is put into operating condition as follows. The blade piece 7 proper is attached to the body component 2 by means of a bolts in such a way that its side surfaces are supported by the surfaces of the body component 2. Wedge piece 8 is loosely attached to the body component by means of a bolt 9 (or, for example, by means of two bolts). The blade is now a package ready for installation, which can be dropped into the corresponding recess in the drum 1. After this, bolt 4 is set into its hole 3 and it is screwed relatively tightly into place.

The two final measures are the tightening of wedge piece 8 by means of bolt 9 and the final tightening of bolt 4. The blade assembly is now secured in place in a manner that is completely without gaps and stable. If however, damage should occur, the blade assembly can be removed very easily and a new one installed.

It is also simple to change the blade piece 7 or alter its cutting angle, because it is easy to remove the blade in its entirety for this change/alteration. A blade assembly 7 that has been removed can also be easily set in a vice for repair or replacement.

A special extractor has been developed for the removal of the blade assembly, by means of which wedge 8 is detached through the opening in the drilled hole 3 in the body component 2, in such a way that part of the extractor pulls the wedge 8 through the opening.

Another arrangement that helps detachment is one in which, after the detachment of bolt 4, a special screw is screwed into the internal thread of hole 3 and being supported on the base of hole 5 in the rotor makes it possible to push out the entire assembly.

It is also naturally possible to use a solution, in which components 2 and 7 are in one piece. The construction and blade changing, etc. are then even simpler. For practical reasons, the choice of materials and other details will probably favour a non-integrated construction.

One great advantage of the invention is also the fact that only a single hole is made in drum 1 for the attachment of the entire blade assembly. Thus there is only one point in the drum where a flaw can develop, whereas there are several in known assemblies.

In an assembly in accordance with the invention it is

extremely unlikely that a defect would extend to the rotor itself. In state of the art devices, defects often demand the replacement of the entire large rotor, which is very expensive.