GB2117342A

GB2117342A - Control circuit for accelerating a conveyor

Info

Publication number: GB2117342A
Application number: GB08306654A
Authority: GB
Inventors: Joe Carey
Original assignee: Danepak Ltd
Current assignee: Pilgrims Pride Ltd
Priority date: 1982-03-27
Filing date: 1983-03-10
Publication date: 1983-10-12
Also published as: GB2117342B; GB8306654D0

Abstract

A conveyor 11 includes an electric motor 18 arranged to drive the conveyor, control means including electronic braking means operable to brake the motor and further including a first electronic circuit for supplying electric current to the motor for driving the motor at a constant rate and a second electronic circuit for accelerating and decelerating the motor from and back to said constant rate, and actuation means for actuating said second circuit. The conveyor is periodically accelerated to separate groups of articles e.g. bacon slices deposited on the conveyor. <IMAGE>

Description

SPECIFICATION Jump conveyor The present invention relates to a jump conveyor which is controlled electronically.

In our U.K. Patent 1546195 we described a jump conveyor which is driven by a hydraulic motor and includes a hydraulic circuit which controls the motor to move the conveyor at a constant feed rateireferred to as the normal mode) and at predetermined intervals temporarily accelerate the conveyor (raferred to as the jump mode). The conveyor is primarily intended for use with a food slicing machine so that during the normal mode of the conveyor the food is sliced to form a shingle which is taken away from the slicer, the jump mode serving to separate the shingle into groups containing a plurality of slices.

Hydraulic circuitry has several drawbacks in that it is expensive, bulky and difficult to maintain in a hygenic condition.

An additional drawback in the use of hydraulics for driving a jump conveyor for providing separation of shingle is that it is difficult to provide fine adjustments in control for varying rates of acceleration/deceleration ofthe conveyor in the jump mode. This is particularly important in the slicing of bacon since different types of bacon cut require different rates of acceleration/deceleration.

If either the rate of acceleration or deceleration is too harsh there is a danger that the separated groups of slices could slip on the conveyor and accumulate together.

It is a general aim of the present invention to provide a jump conveyor which overcomes, or substantially reduces the above drawbacks.

According to one aspect of the present invention there is provided a jump conveyor including an electric motor arranged to drive the conveyor belt of the conveyor, control means including electronic braking means operable to brake the motor and further including a first electronic circuit for supplying electric current to the motor for driving the motor at a constant rate and a second electronic circuit for accelerating and decelerating the motor from and back to said constant rate, and actuation means for actuating said second circuit.When the conveyor is to be used for producing slices of a food product, the actuation means is preferably controlled by sensing means which either count or weigh the number of slices being produced and after a predetermined number predetermined or collective weight have been sensed the sensing means operates the actuation means to actuate the second circuit.

Various aspects of the present invention are hereinafter described with reference to the accompanying drawings, in which: Figure 1 is a graph schematically illustrating normal running and jump modes of a jump conveyor according to the present invention; Figure 2 is a schematic illustration of a jump conveyor according to the present invention shown in combination with a food slicing machine; Figure 3 is an electronic circuit diagram showing the motor and control circuitry according to the present invention.

Referring initially to Figure 2 there is shown a jump conveyor 10 including a conveyor belt 11 made up of a plurality of side by side continuous strips 11 a which wrap around a drive roller 12 and a freely rotatabie roller 14. Rollers 1 2 and 14 are mounted on a frame 1 6. Roller 12 is directly driven by an electric motor 18, i.e. the drive connection between the motor and roller 1 2 is such that the roller is positively driven at all times by the motor so that the motor can accelerate or decelerate the roller.

The slicing machine is the same as that described in our U.K. Patent 1 546195 and reference should be made thereto for a description of the slicing machine and the operation of slicing bacon for producing portioned shingle.

The electric motor 1 8 and control circuit 30 (Figure 3) are arrangedto move the conveyor at a constant rate which can be varied between predetermined limits to give control as to the extent of overlap between adjacent slices in the shingle. The slicing machine referred to includes a revolving blade which on each revolution produces a single slice. The jump mode of the conveyor has to be completed during one revolution of the blade. Accordingly the arrangement is such that the motor accelerates and then decelerates during the time taken for one revolution of the blade. The control circuit is arranged so that the degree of acceleration and deceleration may be varied.The jump and normal running modes of the conveyor are schematically illustrated in Figure 1, the time period T being the time taken for one revolution of the blade of the slicing machine.

In order to achieve the desired operating characteristics, the motor 1 8 is a direct current motor which includes an electronic brake, a suitable motor of this type being a G19M4 as supplied by Printed Motors Limited. The electronic brake is operated by a tachometer 35 (Figure 3).

The motor 1 8 is controlled by a control circuit 36 which includes a chopper type 4 quadrant control unit 37 as supplied by Ashe Controls Ltd.

The circuit 36 also includes a relay 39 which normally connects the control circuit to the motor 18 for providing the normal running mode. The relay is operated by a sensing means which preferably counts the number of revolutions of the slicing blade as described in our U.K. Patent 1546195. When a predetermined number of revolutions have been counted, the relay is operated by a switching pulse to connect the motor to a pulse circuit which includes storage capacitors which during the normal running mode have been charged. Alternatively, the sensing means may be arranged to weigh the slices being produced and then operate the relay when a predetermined collective weight of the slices has been sensed. On operation of the relay the capacitors discharge through the motor creating a rapid acceleration. The capacitors also discharge through a potentiometer 40 which serves as a control for the speed of the conveyor during the jump mode. The relay returns to its normal mode after termination of the switching pulse. The length of the switching pulse is adjustable to provide a variable jump period.

A potentiometer 45 is provided which serves to provide a variable control of the current supplied to the motor during the normal running mode for control of the speed of the conveyor.

Claims

1. A jump conveyor including an electric motor arranged to drive the conveyor belt of the conveyor, control means including electronic braking means operable to brake the motor and further including a first electronic circuit for supplying electric current to the motor for driving the motor at a constant rate and a second electronic circuit for accelerating and decelerating the motor from and back to said constant rate, and actuation means for actuating said second circuit.

2. Ajump conveyor according to Claim 1 arranged to operate in conjunction with a food slicer for producing slices of food, the actuation means being controlled by sensing means which count the number of slices being produced and after a predetermined number of slices have been counted operate the actuation means to actuate the second circuit.

3. A jump conveyor according to Claim 1 arranged to operate in conjunction with a food slicer for producing slices of food, the actuation means being controlled by sensing means which weigh the number of slices being produced and after a predetermined collective weight of slices is produced operates the actuation means to actuate the second circuit.

4. A jump conveyor according to Claim 1,2 or 3 wherein the motor positively drives the conveyor, the electronic brake being arranged to act upon the motor for decelerating the conveyor.

5. A jump conveyor according to Claim 4 wherein the motor is a direct current motor.

6. A jump conveyor according to Claim 5 wherein the first control circuit includes a relay which is normally switched for supplying a constant current to the motor, the sensing means being arranged to actuate the relay to connect the motor to a storage capacitor which discharge through, the motor to provide an acceleration in motor speed.

7. A jump conveyor according to Claim 6 wherein a potentiometer is provided and arranged to be connected on actuation of the relay so that the capacitor discharges through both the potentiometer and motor.

8. A jump conveyor according to Claim 7 wherein a sensing means is provided for sensing the speed of the motor when accelerating and which is arranged to operate the electronic brake when the speed reaches a predetermined maximum.

9. A jump conveyor substantially as described with reference to and as illustrated in the accompanying drawings.