GB2198059A

GB2198059A - A machine setting method and apparatus

Info

Publication number: GB2198059A
Application number: GB08625211A
Authority: GB
Inventors: John Charles Greenwood Jagger; Roy George Page
Original assignee: Henry Simon Ltd
Current assignee: Simon Corrugating Machinery Ltd
Priority date: 1986-10-21
Filing date: 1986-10-21
Publication date: 1988-06-08
Anticipated expiration: 2006-10-21
Also published as: GB8625211D0; GB2198059B

Abstract

A method and an apparatus for setting a working gap between, for example, the grinding rolls of a cereal milling machine and comprising means (14,17,20) for driving a moving roll (11) towards a fixed roll (10), sensing means (22) for detecting the reducing distance between them and for transmitting a repeated signal to a control device which responds to the signal to stop the driving means once the signals remain constant with the rolls closed together. This establishes a zero or reference point from which the moveable roll (11) may be again moved away by motor (17) to establish a predetermined working gap. <IMAGE>

Description

A MACHINE SETTING METHOD AND APPARATUS This invention concerns a method of and apparatus for setting a working gap between a pair of co-operating machine parts, and is particularly, though not exclusively, concerned with the setting of the gap between the grinding rolls of a cereal milling machine.

In a conventional rollermill for cereal milling which includes at least one pair of co-operating grinding rolls arranged in close parallel relationship such that stock is ground or worked by passage between the rolls, it is essential for the correct working gap to be maintained irrespective of surface wear and changes in operating temperature. A skilled operator might adjust the rollermill gap setting manually using a handwheel provided at each end of the pair of rolls. The adjustment can be automated by replacing the handwheel with a motorised drive, but again, such an arrangement cannot compensate for changes in the gap which result from roll wear or changes in temperature, unless a skilled operator is employed to examine the milled material and operate the motorised drive accordingly.

An object of the present invention is provide a method of and apparatus for setting the working gap between a pair of co-operating machine parts such as the rolls of a rollermill, in a manner which will compensate for unexpected gap changes.

According to the present invention there is provided a method of setting a working gap between a pair of co-operating machine parts, comprising the steps of driving at least one of the parts towards the other, providing means sensing the reducing distance between them and producing a readable signal representative of said distance, feeding the signal to a control device and causing the latter to respond to the signal to change or discontinue drive to said at least one part once the signal remains constant with said parts closed together.

Further according to the invention there is provided apparatus for setting a working gap between a pair of co-operating machine parts, comprising means for driving at least one of the parts towards the other, means for sensing the reducing distance between them and for producing a readable signal representative of said distance, a control device to which said signal is fed and which responds to the signal to change or discontinue drive to said at least one part once the signal remains constant with said parts closed together.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Fig. 1 is schematic illustration as an end view of the operating parts of a rollermill incorporating the invention; and Fig. 2 is a circuit diagram.

The rollermill includes a fixed roll 10 and a movable roll 11, -the latter mounted on a cradle 12 pivotal at 13 by means of a pneumatic cylinder 14 which drives a lever 15 and link 16 attached to cradle 12.

A stepping motor 17 drives through a reduction gearbox 18 a toothed belt 19 which in turn drives a lead screw 20 which thus moves axially and serves as an adjustable stop for a fulcrum lever 21 against which link 16 bears.

A proximity detector 22 is fixed to the bearing housing of roll 10 and is directed on to the bearing housing of moving roll 11. Detector 22 produces an output signal proportional to the target distance.

In operation, with cylinder 14 extended to place the rolls under load in a grinding condition, fulcrum lever 21 is positioned hard against lead screw or stop 20 which is extended for the purposes of setting up the rolls such that there is a gap between the roll surfaces in the grinding condition.

To zero, or trim, the system, motor 17 is driven in a direction which via lead screw 20 and fulcrum lever 21 permits moving roll 11 to approach roll 10. As the roll moves the output signal from detector 22 changes.

This signal is fed to a controller 23 (see Fig. 2) which is adapted to compare the present signal with a signal from a time interval previous. The signals will show a difference whilst roll 11 continues to move, and in this condition motor 17 will continue to drive lead screw 20 permitting such movement. When the rolls touch with moving roll 11 fully loaded up against fixed roll 10 the next signal produced by detector 22 will be equal to the current one.

This is detected by the controller which them produces an output signal to stop motor 17. Thus the rolls are said to be trimmed.

From this position as a zero or reference, motor 17 can be energised in the reverse direction to drive fulcrum lever 21 a predetermined distance representative of the required working gap between the rolls. This gap will have been created from the zero reference established when the rolls were touching and is thus accurate irrespective of roll surface wear or changes in roll diameter created according to the operating temperature.

Fig. 2 shows the use of a position controller 24 receiving signals from controller 23 to effect predetermined movements of the stepping motor 17. The operation of trimming the rolls as has been described can be actuated by means of a switch 25 which initiates the zeroing or trimming sequence.

By providing a control loop at each end of a pair of rolls, individual but simultaneously referencing of the two ends can be made to ensure that the rolls are trimmed along their entire length.

The advantage of such a system in a rollermill is that it can be set up irrespective of the prevailing conditions by an unskilled operator since the system works by moving the rolls together under load in the absence of stock until relative motion ceases. Once this has been achieved the control system is reset to the established reference, and all variables such as temperature, roll wear, bearing clearance or movements within the machine are eliminated from the control loop. The rolls may be trimmed either when they are running or when they are stationary.

The mode and frequency of the trimming procedure may be determined according to requirements, but is likely to be carried out during and after a warm-up period after shut down, and at predetermined intervals, for example, hourly or twice daily, as is considered necessary.

Claims

1. A method of setting a working gap between a pair of co-operating machine parts comprising the steps of driving at least one of the parts towards the other, providing means sensing the reducing distance between them and producing a readable signal representative of said distance, feeding the signal to a control device and causing the latter to respond to the signal to change or discontinue drive to said at least one part once the signal remains constant with said parts closed together.

2. A method according to Claim 1, wherein said machine parts are initially placed apart, and after closing together to establish a zero or reference position are again driven apart by a predetermined distance according to the required working gap.

3. Apparatus for setting a working gap between a pair of co-operating machine parts, comprising means for driving at least one of the parts towards the other, means for sensing the reducing distance between them and for producing a readable signal representative of said distance, a control device to which said signal is fed and which responds to the signal to change or discontinue drive to said at least one part once the signal remains constant with said parts closed together.

4. Apparatus according to Claim 3, wherein said means for driving at least one of the parts towards the other includes a hydraulic or pneumatic cylinder and an electrically driven stepping motor, said control device producing no output signal to change or discontinue drive to said at least one part until consecutive signals received from said sensing means remain substantially constant, said stepping motor being reversible thus to drive said at least one part away from the other by a predetermined distance from a reference point established when the parts are closed together, to set the working gap.

5. Apparatus according to Claim 3 or Claim 4, wherein said co-operating machine parts are a pair of parallel grinding rolls of a cereal milling machine in which one roll is fixed and the other is movable towards and away from the fixed roll, there being a pneumatic cylinder adapted to move the movable roll relative to the fixed roll via a lever and link assembly connected to a cradle upon which the movable roll is mounted.

6. Apparatus according to Claim 5, wherein said lever and link assemble bears upon a lead screw rotationally driven by said stepping motor such that the pneumatic cylinder and the lead screw co-operate to determine the instantaneous position of the movable roll.

7. Apparatus according to Claim 6, wherein said stepping motor is drivingly connected to said lead screw through a reduction gear box.

8. Apparatus according to Claim 5, wherein said sensing means comprises a proximity detector fixed to a bearing housing of the fixed roll and directed onto the bearing housing of the moving roll thus to produce an output signal proportional to the target distance.

9. Apparatus according to any of Claims 3 to 8, and provided at each end of a pair of grinding rolls of a cereal milling machine such that individual but simultaneous referencing of the two ends can be made to ensure that the two ends are trimmed along their entire length.

10. Apparatus according to any one of Claims 3 to 9, including switch means adapted to initiate the setting up procedure automatically according to a predetermined sequence and frequency.

11. A method of setting a working gap between a pair of co-operating machine parts, substantially as hereinbefore described.

12. Apparatus for setting a working gap between a pair of co-operating machine parts, substantially as hereinbefore described, with reference to, and as illustrated in, the accompanying drawings.