GB2091128A

GB2091128A - Trituration machine, and cutting blades therefor

Info

Publication number: GB2091128A
Application number: GB8200149A
Authority: GB
Original assignee: SANT ANDREA NOVARA OFFICINE; SANT ANDREA NOVARA OFFICINE MECCANICHE E FONDERIE SpA
Current assignee: SANT ANDREA NOVARA OFFICINE; SANT ANDREA NOVARA OFFICINE MECCANICHE E FONDERIE SpA
Priority date: 1981-01-16
Filing date: 1982-01-05
Publication date: 1982-07-28
Also published as: DE3200372A1; FR2503582A1; IT8167048A0; IT1143275B

Abstract

A machine for triturating waste material, comprises a pair of counter- rotating shafts 3 carrying two sets of interdigitating cutting blades 6 Figure 5 of toothed disc configuration. The disc forming each cutting blade 6 is concave, so that the central zone of each disc face is spaced from the plane 12 Figure 3 containing the outer contour of said face. <IMAGE>

Description

SPECIFICATION Trituration machine, and cutting blades therefor This invention concerns machines for triturating waste material, comprising a pair of parallel shafts rotatably mounted in a support structure, means for rotating said two shafts in opposite directions, a plurality of toothed disc cutting blades coaxially located along each of said shafts, the blades of each shaft being disposed adjacently in pairs such that each pair of adjacent blades carried on one of the shafts is interposed between two adjacent pairs of adjacent blades carried on the other shaft, and a plurality of spacer rings mounted coaxially on said shafts and each disposed between two adjacent pairs of adjacent blades of each respective shaft.

In a known machine of this type the disc blades are mounted on each shaft by disposing them along the shaft with spacer rings interposed therebetween, and clamping the pack of blades and spacers thus obtained at its ends. Each shaft is of non-circular cross-section (for example it is hexagonal) and each blade has a central aperture shaped to fit the shaft, so that the blade rotates rigidly with the shaft. Each blade/spacer pack is clamped by means of a blade clamping ring mounted on the corresponding end of the shaft which supports the blades, the blade clamping ring being locked on the shaft (together with a roller bearing for rotatably supporting the end of the shaft) by a pair of threaded ring nuts screwed onto a threaded end portion of said shaft.The blade clamping ring is configured so as to provide a certain flexibility, to allow take-up of the axial movements of the blade pack which occur in operation when the material to be triturated enters between one cutting blade and the next, so forcing them to withdraw from each other. This design is not completely satisfactory as the deformation to which the blade clamping ring is subjected may be considerable, due to the fact that the movements of all the individual cutting blades are added together and the total transmissed to the blade clamping ring.

An object of the present invention is to provide a triturating machine in which each cutting blade is itself able to absorb movements caused by the wedging of triturated material entering between one cutting blade and the next.

According to the invention there is provided a machine for triturating waste material, comprising a support structure, a pair of parallel shafts rotatably supported by the support structure, means for rotating said shafts in opposite directions, a plurality of cutting blades of toothed disc configuration fixed coaxially along each of said shafts, the blades of each shaft being disposed adjacently in pairs in such manner that each pair of adjacent blades fixed on to one shaft is interposed between two adjacent pairs of adjacent blades fixed on the other shaft, and a plurality of spacer rings mounted coaxially on said shafts, each ring being disposed between two adjacent pairs of adjacent blades on each respective shaft, wherein the disc forming each cutting blade is concave and is located so that its concavity faces that of the cutting blade adjacent to it, such that the central zones of the two blades of each pair of adjacent blades are axially spaced-apart when undeformed.

Each cutting blade has sufficient flexibility to enable blade movements, caused by the entry of triturated material between one cutting blade and the next, to be taken up.

The disc forming each cutting blade may be forced by a spherical wall portion or by a cylindrical wall portion.

The present invention also provides a toothed disc cutting blade usable in triturating machines provided with two counter-rotating shafts carrying two sets of cutting blades spaced apart in pairs, wherein the disc forming said cutting blade is concave, such that the central zone of each disc face is spaced from the plane containing the outer contour of said face.

Further features and advantages of the invention will become apparent from the following description, made with reference to the accompanying drawings showing embodiments of the invention and in which Figure 1 is a sectional plan view of a triturating machine embodying the invention, Figure 2 is a front view of a cutting blade embodying the invention, Figure 3 is a sectional view drawn on the line Ill-Ill of Figure 2, and Figures 4 and 5 are a plan and perspective view respectively of details of the machine of Figure 1.

Atriturating machine 1 is shown in Figure 1 to comprise a support structure 2 rotatably supporting the ends of two parallel shafts 3. The shafts 3 each have a cross-section in the shape of a regular hexagon (c.f. Figures 4, 5), and their axes are disposed in the same horizontal plane. An electric motor (not shown) rotates the shaft 3 shown at the top of Figure 1, by way of a gear transmission. On this shaft there is keyed a gear wheel 4 which engages a gear wheel 5 of greater diameter, keyed in its turn on to the other shaft 3. The electric motor therefore rotates the two parallel shafts 3 in opposite directions and at different angular speeds.Each shaft 3 is provided with a plurality of cutting blades 6 of toothed disc configuration disposed adjacently in pairs, and a plurality of spacer rings 7 each interposed between two adjacent pairs of adjacent cutting blades. Each blade 6 has a central bore 6a (see Figure 2) the shape of which corresponds to that of the cross-section of each shaft 3. In this manner, when mounted on the shaft 3, each blade 6 is carried in rotation rigidly with the shaft 3. In addition, each blade 6 has a cutting tooth 6b. The two blades 6 of each pair of adjacent blades have their teeth 6b in diametrically opposite zones.

Each pack of cutting blades 6 and spacer rings 7 associated with each shaft 3 is clamped at the end of shaft 3 distant from the gear wheels 4, 5 by a blade clamping ring 8 kept in position (together with a roller bearing 9) by a pair of threaded ring nuts 10 screwed on to a threaded portion of the end of each shaft 3.

The disc forming each cutting blade is concave.

The effect of this concavity is that the central zone of the disc face, indicated at 11 in Figure 3, is spaced from the plane, indicated at 12, containing the outer contour of said face.

In Figure 3, the proportions of the disc forming the cutting blade 12 have been exaggerated for clarity. In reality, the degree of concavity of each cutting blade is much less. For example, with a cutting blade of the type illustrated in Figure 2 having a radius R of 110 mm, the distance indicated by A in Figure 3 is about 0.15 mm. For this reason the concavity of the cutting blades 6 is not visible in the section shown in Figure 1. Each cutting blade 6 is mounted on the corresponding shaft 3 such that its concavity faces that of the blade adjacent to it.

By virtue of its concavity, each cutting blade 6 has a certain flexibility, so that it can deform, during machine operation, if material to be triturated become wedged between two blades of the same shaft which are separated by a spacer ring. In this way neither blade is compelled to move axially to provide space for the material wedged between the blades, as happens in machines of known type. It follows that the blade clamping ring 8, which is relatively flexible, is not compelled, by deforming, to take-up all the possible axial movements of the cutting blades of each blade pack, as is the case with known machines.

The disc forming each cutting blade can correspond to a spherical or cylindrical wall portion.

Obviously, within the principle of the invention, the constructional details and forms of execution may widely vary with respect to that described and illustrated by way of example only, without departing from the scope of the invention.

Claims

1. A machine for triturating waste material, comprising: a support structure, a pair of paraliel shafts rotatably supported by the support structure, means for rotating said shafts in opposite directions, a plurality of cutting blades of toothed disc configuration fixed coaxially along each of said shafts, the blades of each shaft being disposed adjacently in pairs in such manner that each pair of adjacent blades fixed on to one shaft is interposed between two adjacent pairs of adjacent blades fixed on the other shaft, and a plurality of spacer rings mounted coaxially on said shafts, each ring being disposed between two adjacent pairs of adjacent blades on each respective shaft, wherein the disc forming each cutting blade is concave and is located so that its concavity faces that of the cutting blade adjacent to it, such that the central zones of the two blades of each pair of adjacent blades are axially spaced-apart when undeformed.

2. A machine as claimed in Claim 1, wherein the disc forming each cutting blade corresponds sub stantially to a spherical wall portion.

3. A machine as claimed in Claim 1, wherein the disc forming each cutting blade corresponds substantiallyto a cylindrical wall portion.

4. Atoothed disc cutting blade usable intriturating machines provided with two counter-rotating shafts carrying two sets of cutting blades spaced apart in pairs, wherein the disc forming said cutting blade is concave, such that the central zone of each disc face is spaced from the plane containing the outer contour of said face.

5. A cutting blade as claimed in Claim 4, wherein the disc forming said blade corresponds to a spherical wall portion.

6. A cutting blade as claimed in Claim 4, wherein the disc forming said blade corresponds to a cylindrical wall portion.

8. A machine for triturating waste material substantially as herein described with reference to the accompanying drawings.

9. A toothed disc cutting blade according to Claim 4 and substantially as herein described with reference to the accompanying drawings.