US3506199A - Paper pulp refiner control system - Google Patents

Description

A ril 14, 1970 HAYWARD 3,506,199

PAPER PULP REFINER CONTROL SYSTEM Filed Jan. 18, 1968 2.Sheets-Sheet l r- \U H 70 65 4a 46 MAIN SUPPLY45 su ar TRANsbucER INVENTOR ti E:

FRANK HAYWAR D BY A Mw ATTORNEYS I United States Patent O 3,506,199 PAPER PULP REFINER CONTROL SYSTEM Frank Hayward, Romford, England, assignor to The Black 'Clawson Company, Hamilton, Ohio, a corporation of Ohio Filed Jan. 18, 1968, Ser. No. 698,931 Int. Cl. 1502c 7/14 US. Cl. 24137 9 Claims ABSTRACT OF THE DISCLOSURE A twin-disk refiner system incorporates an air motor drive for controlling refiner load by controlling the spacing between the refiner elements including a pneumatic control system for the refiner elements positioning motor which measures load on the main refiner drive motor and compares this with a refiner representing a desired refiner load, providing a system in which the increase in load is substantially linear with time.

BACKGROUND OF THE INVENTION This invention relates to the art of paper refining and more particularly to the control of disk or Jordan refiners, or the like, having mutually adjustable, relatively rotating elements between which the paper pulp passes under pressure, for refining the pulp. The refiner load is varied according to the distance between the rotating and stationary elements, and is adjustable in accordance with refining requirements. conventionally, the position of the elements is adjusted using a manually-controllable reversible electric motor, while monitoring the resulting refiner load.

SUMMARY OF THE INVENTION The invention of this application utilizes a fluid motor, and preferably an air motor, and makes particular use of the relatively wide range of speed and uniform torque characteristic of an air motor to provide an automatic, pneumatic, control system for regulating and maintaining the spacing of the rotating and fixed elements in a refiner. A bi-directional pneumatic control valve is positioned partially in accordance with the output of a transducer which is controlled by the load on the main refiner drive motor, preferably by sensing the current being applied to the motor. A reference signal corresponding to a predetermined or desired load setting is also applied to the control valve so that any deviations in refiner load from the desired load results in movement of the valve member to apply fluid pressure to the fluid motor controlling the spacing of the stationary and the rotating elements of the refiner in such a manner as to correct the refiner load and bring the valve member back to its predetermined balanced position. Since the control system of this invention directly monitors motor load and since the torque output of the fluid motor which adjusts the spacing of the rotating elements is substantially independent of speed, a control system is provided in which the load is controlled and changed in a substantially linear relation with time. Thus, when the rotatng elements are brought together during the initial start-up, the increase in load is substantially more linear with time as compared to prior systems in which the stationary and rotating elements are closed under manual control.

An electrical control system is provided in which safety interlocks and switches prevent damage to the refiner and which disable the automatic operation in the event of failure of drive current to the drive motor or in the event of failure of stock pressure. A timer is incorporated which automatically opens the refiner elements by a predetermined amount in the event of failure of stock pressure.

Reestablishment of stock pressure results in the refiner elements being again closed to bring the load back to a predetermined setting.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view, partially broken away, of a twin inlet, twin disk paper pulp refiner which is controlled by the system of this invention;

FIG. 2 is a schematic pneumatic diagram of the invention;

FIG. 3 is a transverse section through the bi-directional control valve; and

FIG. 4 is a wiring diagram of the electrical control system.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a typical paper pulp refiner is shown at 10 as including a mounting base 11 and a pulp refiner mechanism indicated generally at 12 having a pair of inlets 13 and 14 and a single outlet 15. The refiner 10 includes a centrally positioned rotating disk and a pair of oppositely positioned, axially sliding non-rotating disks 22 and 23. The rotating disk 20 is mounted for rotation on a drive shaft 25 and is driven by an electric motor 26.

The refiner load is controlled by regulating the spacing between the axially fixed rotating disk 20 in the axially slidable non-rotating disks 22 and 23. For this purpose, each of the disks 22 and 23 is supported on pairs of transversely extending arms 28 and 29 which have their opposite ends mounted on threaded bars 30 and 31. The portions of the torsion bars 30 and 31 supporting the disk 22 are threaded oppositely of those portions supporting the disk 23, so that rotation of the rods 30 and 31 brings the arms and the supported disks either toward or away from the rotating disk 20. Means for regulating the position of the non-rotating elements of the refiner includes a pair of worm and wheel transmission units 32, one for each of the bars 30, 31 and connected together by a common shaft 33.

The twin inlet, twin disk refined shown in FIG. 1 is typical of the refiners to which the present control system may be applied. It is within the scope of the invention to apply the present control system to any paper pulp refiner in which the spacing of relatively fixed and movable refiner elements can be accurately controlled, and accordingly the invention can be applied, for example, to a conical or Jordan refiner, or to the disk type as shown in the US. Patent of Baxter 2,986,434, issued May 30, 1961.

The present invention utilizes a proportional fluid control system for controlling the refiner load. For this purpose, a fluid motor, preferably an air motor illustrated generally at 35 in FIG. 1, is connected in driving relation to the shaft 33. A fluid motor has particular advantage for use in the present invention in that it is easily controllable and it has relatively uniform torgue output over a wide range of speeds. An example of a suitable such motor is the model R.M. 100 of The Globe Pneumatic Engineering Company Limited, Ashton Road, Romford, Essex, England.

The diagram of the preferred pneumatic control system for the motor 35 is shown in FIG. 2. Means forming a signal proportional to load on the motor 26 includes a phase winding pick-up transformer which forms an electric signal proportional to refiner load. The signal from the transformer 40 is applied through a rectifier 41 to an electric-to-air transducer 44, which provides a pneumatic signal which is proportional to the electric input signal. The suitable transducer for this purpose may be type 01TG331 of Taylor Instruments Companies, Gunnels, Wood Road, Stevenage, Hertfordshire, England.

The control system includes means forming a common 30111'68 45 of air pressure, which may have a pressure of -120 p.s.i.g. The source is shown in FIG. 2 as being applied through a lubricator 46 to the center inlet of a )i-directional solenoid control-load valve 48 for the manu= 11 control of the air motor 35. The valve 48 is of the mid- )ias type which normally blocks both of the inlet A and 'eturn B to the air motor, but which may be positioned n either of two moved positions for applying air under Jressure from the source 45 to one of the motor inlets k or B while exhausting the other inlet into the atmosahere, to effect manual control of the air motor for rota- ;ion in either direction for opening or closing the space Jetween the sliding elements 22 and 23 and the rotating :lement 20.

When the automatic control mode is selected, the output of the transducer 44 is applied to a pneumatic ampliier which provides a three-to-one amplification in air gressure as compared to the output of the transducer. The iir input to the transducer 44 is preferably a regulated Z0 p.s.i. as provided by a pressure regulator 49 connected to the air line.

The signal amplifier 50 may be the model 66 of Assoziated Electrical Industries Limited, P.O. Box 1, Harlow, Essex, England. The output from the amplifier 50 is ac- :ordingly an air signal which varies directly proportional to load on the refiner drive motor 26. The output from the amplifier is applied on a line 52 to one end of a balanced, )i-dlI'CCtlOIlal, differential pressure responsive control valve 55 for the motor 35, which valve is described in greater detail in connection with FIG. 3.

A reference signal proportional to a manually selected load comprises a manually controllable pressure regulator valve 56 connected to receive air under pressure from the source 45. A gauge 57 on the output side of the regulator valve 46 is calibrated directly in values of refiner load and may be observed during the setting of the manually settable regulator valve 56. The output of the valve 56 is applied on a line 58 to the opposite end of the motor control valve 55.

Air for operating the motor in the automatic mode is applied through a solenoid-controlled mid-open valve 60 and through a restrictor 62 to the main air inlet port 65 (FIG. 3) of the valve 55. Exhaust air from the motor is also controlled by the valve 60 through a non-return valve 58 which is connected to a common exhaust port (FIG. 5) of the control valve 55.

Referring to FIG. 3, the cross-sectional details of the :ontrol valve 35 are shown as including cylindrical housing defining the valve inlet and outlet ports. The musing accordingly defines the centrally positioned air inlet port 65 and a pair of transversely spaced air outlet ports 82a and 82b. The ports 82a and 82b are connected to the respective motor ports A and B as identified in FIG. 2. Laterally spaced exhaust ports 86 and 87 are positioned outwardly of the motor ports 82a and 82b and are connected exteriorly of the valve to form the common valve exhaust 70.

The housing is fitted with a ported metering sleeve 90 which is formed of hardened steel and which, in turn, receives a hardened steel spool 92. The sleeve 90 is formed with metering ports communicating with the inlet and outlet and exhaust ports, described above, and cooperates with the lands and passageways formed on the spool 92 to control the flow of fluid pressure from the main air inlet port 65 selectively to the outlet ports 82a and 82b. The spool 92 is formed with a close sliding fit with the inner surface of the ported sleeve 90 and in effect forms an air tight seal with the cooperating land regions. The spool 90 is of the balanced construction defining a central pair of land surfaces 95 which control the air flow at the inlet port 65. ransversely of the central land surfaces, the spool is formed with a pair of regions 96 of reduced diameter relatively formed passageways 96a and 965 which communicate respectively with the outlets 82a and 8212.

In the balanced position of the valve as shown in FIG. 3, the passageways 96a and 96b defined in the spool 92 each uncover a portion of the exhaust ports 86 and 87, while the central lands 95 block the inlet port 65. In this condition, both motor inlets A and B are vented to the exhaust manifold. If the spool is shifted to the left, for example, the inlet port 65 will be connected by the spool passageway 96a to the outlet 82a to drive the motor in a direction to open or increase the spacing between the rotating elements, while motor inlet B will continue to be connected to the exhaust manifold. The opposite condition is obtained when the spool is shifted to the right from its central position, causing the motor to be driven in the opposite direction.

The control valve 35 further includes constant mechanical bias means in the form of a control spring 100 which is received over a mandrel 102 supported on a thrust plate 103 at one end of the housing 80. The thrust plate is, in turn, held in place by an end cap 105 which forms a fluid tight seal with the adjacent end of the housing 80. The control spring 100 forms the means by which the re sponse of the control valve 55 may be matched to the ap plied control pressures.

The opposite end of the housing 80 is closed by a closure plate and an end cap 112 constructed similarly to the cap 105. Means for admitting control air from the regulator 56 to one end of the spool 92 includes an inlet 115 which opens into the interior of the housing at the end of the spool remote from the control spring 100. The inlet 115 is thus connected to the line 58 and applies the control air under a predetermined pressure to one end of the spool 92 which tends to shift the spool to the right as viewed in FIG. 3 by compressing the control spring 100. Movement of the spool to the right applies air to the motor inlet B driving the disks toward a closed position.

The signal on line 52 proportional to refiner load is applied to the valve 55 through a port 116 formed on the end of the housing adjacent the control spring 100 and admits the variable fluid pressure from the signal amplifier 50 into the interior of the housing where it acts upon the opposite end of the spool 92 tending to shift the spool to the left as viewed in FIG. 3. Movement of the spool to the left applies air to the motor inlet A driving the disks to the open position.

The electrical control system for the invention is shown in FIG. 4. Limit switches LS1 and LS2 are provided for defining the overall extent of manual movement of the refiner disks 22 and 23 between the closed and open positions. Thus limit switch LS1 is suitably mounted on the refiner 10 to define the extent to which the disks 22 and 23 can be closed when no stock pressure is available. Limit switch LS1 is formed with normally closed contacts LSIB in series with solenoid SV2 of valve 48 to disable the operation of this valve to prevent further manual operation toward the closed position once this limit switch has been tripped.

Limit switch LS2 has its contacts positioned in series with solenoid SV1 to interrupt the manual openin of the disks when the disks have been opened a predetermined maximum amount to prevent mechanical damage to the disks. This fully opened condition is usually obtained only when repairing or inspecting the refiner.

An interlock is provided to ensure that the main drive motor 26 must be running before the disks can be closed up either manually or automatically. For this purpose, there is provided a motor control relay MC having its normally closed contacts MC1 connected to energize the solenoid SV1 to open the disks in the event that the motor control relay becomes unenergized, such as by failure of the power supply to the motor. Also, the normally open contacts MC2 of the motor control relay must be closed, signaling the proper operation of the motor 26, before either manual or automatic control may be efiected.

Means for selecting between manual or automatic control includes a two-position rotary switch 120 which, in the hand or manual position, applies power to a threeposition rotary manual control switch 122. The switch 122 permits manual selection between a central off-position and opposite open and close positions, and provides the means by which an operator may selectively operate the solenoids SV1 and SV2 of the manual control valve 48 to operate the motor 35.

The control system also includes means for opening the disks a predetermined amount and preventing automatic operation in the event of failure of stock pressure at the inlet side of the refiner. For this purpose, a normally open stock pressure switch 125 is provided in controlling relation to a control relay R1. The switch 125 will close when the stock pressure has raised an acceptable amount, thereby energizing relay R1 and closing contacts R1/3 in series with solenoid SV3, permitting the operation of selector valve 60 when the control switch 120 is moved to' the automatic position. Relay contacts R1/1 are in parallel with limit switch contacts LSlB to permit closing of the disks beyond the minimum position permitted by limit switch LS1 only as long as there is sufficient stock pressure for proper operation.

In the event of failure of stock pressure, the opening of the switch 125 deenergizes the relay R1 thus opening contacts R1/4v to a timer 130 which has change-over contacts T1 and T2. The contacts T1 are then closed by the timer 130 for a predetermined short period of time to energize the solenoid SV1 and open the plates, after which the timer opens its contacts T1 and closes contacts T2 energizing an amber warning light 132 indicating to the operator that there has been a loss of stock pressure and that the disks have been partially open to prevent damage to the disks. Reestablishment of stock pressure, while the system is in the automatic mode, will cause the relay R1 to be energized and automatic load selection to be reestablished.

The operation of the invention is largely self-evident from the preceding description. In initially starting up the system, it is assumed that there is a suitable source of air pressure at the source 45 and that the manual selector 56 has been properly adjusted to a desired value as indicated by the gauge 57. The refiner motor 26 may then be started, energizing the motor control relay MC, and the switch 120 moved to the hand position. The switch 122 is then moved to the close position energizing solenoid SV2 of the manual control valve 48 applying air to motor inlet B. Exhaust air is returned to the valve 48 and is exhausted to atmosphere. The air motor is then driven in a direction to close the spacing between the plates. The alternate exhaust through the control valve 55 is blocked by the valve 60.

After the plates have been closed a predetermined amount, the limit switch LS1 is activated and deenergizes solenoid SV2. At the same time, the contacts LSlA are closed energizing a green lamp 135 indicating to the operator that the refiner is ready for stock. Low stock pressure or the absence of stock pressure is indicated by the red lamp 136 in series with relay contacts Rl/S.

Stock may then be admitted to the refiner inlets 13 and 14 and when the stock pressure reaches a predetermined minimum, the stock pressure switch 125 is closed, energizing relay R1. The red lamp 136 is then extinguished and the timer 130 is armed by the closing of contacts R1/ 4. The system may now be switched to automatic control by the selection of the auto position of switch 120. In this position, the control valve 60 is shifted to the automatic position by the operation of solenoid SV3, providing an exhaust to atmosphere of exhaust air from the valve 55 and further providing for the application of the source 45 to the control valve inlet 65.

Assuming that the load setting is intially in excess of the variable output from the transducer 44 and the signal amplifier 50, the spool 92 of the valve 55 will be shifted to the right against the control spring 101} and will cause the motor 35 to operate in such a direction as to close the spacing of the disks in the refiner. As the current in the main drive motor 26 begins to rise, as indicated by the pickup transformer 40 and as applied to the transducer 44, the output of the transducer rises correspondingly. The spool 92 is gradually moved back to a more neutral position and the, air motor 35 slows down. Eventually, the forces applied to either side of the spool 92 are equal and no further movement of the refiner disks will take place unless there is a disturbance in the refiner load. Increase in load will open the disks until the transducer outlet again balances, and conversely, a decrease in load will close the disks again until the output is balanced. The initial movement of the refiner disks to the closed position and thereafter the movement in response to the automatic control provided by this invention is one which the time required for movement is substantially proportional to the change in refiner loading. Adjustments to load can be made while runnnig, by adjusting the variable load regulator 56 as required.

It is accordingly seen that this invention provides an automatic control system using the principles of fluid control for paper pulp refiners. The pneumatic control system uses components which are relatively low in cost, and high in reliability and provide a system in which the refiner load can be accurately and automatically controlled over a wide range of operating conditions.

What is claimed is:

1. A reversible automatic control system for a pulp refiner in which relatively movable refiner elements are spaced automatically in accordance with refiner load comprising a reversible fluid-driven motor connected to control the spacing of said refiner elements, a source of fluid under pressure, means forming a fluid signal corresponding to refiner load, load setting means connected to said source forming a fluid signal corresponding to desired refiner load, and a motor control valve having a valve member movable between a neutral position'and opposite displaced positions, means applying said source to said valve, port means in said valve for applying fluid pressure from said source to said fluid motor to drive said fluid motor in either direction depending upon direction of movement of said valve member from said neutral position, means applying fluid pressure from said load setting means and said fluid signal representing said refiner load to said valve member to control the displacement of said valve member from said neutral position in ac cordance with the effective difference in magnitude of the output of said signals.

2. The system of claim 1 in which said refiner is driven by an electric motor and in which said means forming a fluid signal corresponding to refiner load includes means responsive to motor drive current forming an electric signal of refiner motor load and an electric-to-fluid pressure transducer receiving said electric signal and forming said fluid pressure signal.

3. The system of claim 1 in which said fluid motor has relatively constant torque output over its range of operating speeds.

4. A reversible automatic control system for a motor driven pulp refiner in which axially movable refiner elements are positioned automatically in accordance with drive motor load, comprising a reversible fluid-driven motor connected to control the spacing of said refiner elements, a source of fluid under pressure, means forming a signal corresponding to drive motor load, a bidirectional diiferential pressure operated fluid control valve connected to said source and in fluid controlling relation to said motor and having a housing and a valve member in said housing movable between a neutral position in which fluid pressure is blocked from said motor and a first displaced position in which said source is 7 i applied to drive said motor in one direction to close said elements and an oppositely-displaced second position in which said motor is driven to increase element spacing, adjustable load means connected to apply a fluid bias pressure to said valve urging said valve member toward said first position, a control spring in said housing resisting the force of said load means and tending to move said valve member toward said second position, and transducer means connected to receive said drive motor load signal and to form a variable fluid pressure signal proportional to said motor load and connected to apply said fluid pressure signal as an opposite bias to said valve member in force-assisting relation to said control spring to urge said valve member toward its said second position.

5. The control system of claim 4 further comprising a manual control means eifective to disconnect said control valve, and including a two-position mid-bias valve connected to said source and to said fluid motor providing an alternate source of energizing fluid to said fluid motor.

6. The control system of claim 5 further including switch means responsive to the loss in stock pressure, and timer means controlled by said stock pressure switch and connected to operate said manual control valve to open said elements by a predetermined amount upon the loss of stock pressure.

7. The control system of claim 6 further comprising limit switch means defining a predetermined closed position of said elements when no stock pressure is present,

and control means by-passing said limit switch means upon the occurence of stock pressure at said refiner.

8. The control system of claim 4 in which said fluiddriven motor is an air motor.

9. The system of claim 4 in which said refiner is driven by an electric motor, and said motor signal forming means includes a pick-up transformer responsive to motor drive current and a current rectifier connected to apply the signal output therefrom to said transducer.

References Cited UNITED STATES PATENTS Re. 24,185 7/1956- Staege 24l37 X 2,887,277 5/1959 Sakata 241-37 3,212,721 10/1965 Asplund 24l--37 3,302,893 .2/1967 Feder 24137 3,309,031 3/ 1967 McMahon 24137 LESTER M. SWINGLE, Primary Examiner D. G. KELLY, Assistant Examiner

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