GB1569375A - Shredding machine - Google Patents

Description

(54) SHREDDING MACHINE (71) We, DRESSER EUROPE S.A., a limited liability company incorporated in Belgium, of Boulevard du Souverain, 191-197 (13-3)1160 Brussels, Belgium, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:: This invention relates to shredding machines for the reduction by a shearing action of solid waste material particularly bulky refuse, tyres and other tough rubber itcms, tat cans, tin plate, iron scrap and other similar materiaL According to the present invention, there is prided a shredding machine incorporating two parallel shredding rotors each comprising a shaft and mounted thereon a plurality of spaced cutter discs which project into the gaps defined by the cumer discs on the other shaft and a drive for driving the rotors in contrarotation, wherein the drive comprises an electric motor for each shaft and a power supply unit capable of controlling the eoergisation of the motors to vary the speed of the rotors independently.

Preferably the motors are d.c. motors and the power supply unit is a rectifier device.

The device may be a thyristor power supply unit.

In order that the invention may be more fully understood, one embodiment thereof will now be described, by way of example, with reference to the accompanying drawings in which Figure 1 is a plan view of the machine, Figure 2 is a sectional side view through one of the rotor shafts, Figure 3 is a cross-sectional view of the machine, and Figure 4 is a diagrammatic view of the drive employed for the rotors.

Referring now to Figures 1, 2 and 3 the machine comprises a carrier frame 1 mounted on a support frame 2. The carrier frame 1 carries two spaced parallel rotor shafts 3 and 4 mounted in bearings 5. On each shaft are positioned a plurality of cutter discs 6 having in each case three cutting edges and being spaced by spacers 7 and these discs project into the gaps defined by the discs on the other shaft. One end of each shaft extends beyond the carrier frame to a coupling 8 (for shaft 3) or 9 (for shaft 4) by means of which a drive is connected to the particular shaft.

Combs 11 forming part of upper comb assemblies I la and lower comb assemblies 1 ib mounted respectively on the upper and lower carrier frame parts, project into the gaps between the cutting discs on each shaft on the outside of each rotor assembly.

Turning now to Figure 4, each shaft is provided with a respective d.c. driving motor 12 (for shaft 3) and 13 (for shaft 4), the drive in each case being taken through a first flexible coupling 14, 15, a gear box 16, 17 and one of the above referred to couplings 8, 9. The motors are supplied froml a rectifier power supply 18 comprising in the arrangement described thyristors. The arrangement is such that the two rotors each comprising a shaft and series of cutter discs thereon are, in normal operation of the machine, driven in contra-rotation with the cutting edges of the cutting discs moving towards one another at the top of the machine. Furthermore the supply unit 18 provides independent speed and optionally torque control for the two rotors by means of voltage and/or current control.

In operation of the machine, the two rotors are driven at the desired speeds set by means of the unit 18 and material fed into the machine in known manner will be shredded by a shearing action of the cooperating cutting discs.

In order to guard against stalling of the motors due to the presence of particularly tough or irreducible material between the rotors, the supply unit incorporates detectors operative to detect heavy overload or stalling conditions, to operate the motors and hence the rotors in reverse for a short predetermined time and then to restore normal operation.

If desired the detectors and associated control gear may incorporate a shut-down device to switch-off the machine after the rotors have been reversed a predetermined number of times.

For the purpose of "overload reversal" (as has just been described), the motors will be current controlled and the control fully regenerative to facilitate rapid reversal of the motors during frequent reversal of the machine.

It should be noted that the above described drive employing individually controlled motors for the two rotor shafts enables the most efficient operating rotor speed to be selected for the particular material being disposed of and enables these speeds to be readily adjusted on site to satisfy changing operating conditions. Furthermore the drive is quite quiet, involves little in the way of maintenance compared with hydraulic drives, for example, and has the further advantage that the power consumed at any instant is directly related to the load created by the feed material at that time.

WHAT WE CLAIM IS:- 1. A shredding machine incorporating two parallel shredding rotors each comprising a shaft and inounted thereon a plurality of spaced cutter discs which project into the gaps defined by the cutter discs on the other shaft and a device for driving the rotors in contra-rotation, wherein the drive comprises an electric motor for each shaft and a power supply unit capable of controlling the energisation of the motors to vary the speed of the rotors independently.

2. A shredding machine as claimed in claim 1, wherein the power supply unit also provides independent torque control for the two rotors.

3. A shredding machine as claimed in claim 1 or 2, wherein the motors are d.c. motors and the power supply unit is a rectifier device.

4. A shredding machine as claimed in claim 3, wherein the device is a thyristor device.

5. A shredding machine as claimed in any one of claims 1 to 4, wherein the supply unit incorporates detectors operative to detect heavy overload or stalling conditions, to operate the motors and hence the rotors in reverse for a short predetermined time and then to restore normal operation.

6. A shredding machine as claimed in claim 5, wherein the unit incorporates a shut-down device to switch-off the machine after the rotors have been reversed a predetermined number of times.

7. A shredding machine substantially as hereinbefore described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. switch-off the machine after the rotors have been reversed a predetermined number of times. For the purpose of "overload reversal" (as has just been described), the motors will be current controlled and the control fully regenerative to facilitate rapid reversal of the motors during frequent reversal of the machine. It should be noted that the above described drive employing individually controlled motors for the two rotor shafts enables the most efficient operating rotor speed to be selected for the particular material being disposed of and enables these speeds to be readily adjusted on site to satisfy changing operating conditions. Furthermore the drive is quite quiet, involves little in the way of maintenance compared with hydraulic drives, for example, and has the further advantage that the power consumed at any instant is directly related to the load created by the feed material at that time. WHAT WE CLAIM IS:-

1. A shredding machine incorporating two parallel shredding rotors each comprising a shaft and inounted thereon a plurality of spaced cutter discs which project into the gaps defined by the cutter discs on the other shaft and a device for driving the rotors in contra-rotation, wherein the drive comprises an electric motor for each shaft and a power supply unit capable of controlling the energisation of the motors to vary the speed of the rotors independently.

2. A shredding machine as claimed in claim 1, wherein the power supply unit also provides independent torque control for the two rotors.

3. A shredding machine as claimed in claim 1 or 2, wherein the motors are d.c. motors and the power supply unit is a rectifier device.

4. A shredding machine as claimed in claim 3, wherein the device is a thyristor device.

5. A shredding machine as claimed in any one of claims 1 to 4, wherein the supply unit incorporates detectors operative to detect heavy overload or stalling conditions, to operate the motors and hence the rotors in reverse for a short predetermined time and then to restore normal operation.

6. A shredding machine as claimed in claim 5, wherein the unit incorporates a shut-down device to switch-off the machine after the rotors have been reversed a predetermined number of times.

7. A shredding machine substantially as hereinbefore described with reference to the accompanying drawings.