CA1120300A - Method and device in beating apparatus for ligno-cellulose material - Google Patents
Method and device in beating apparatus for ligno-cellulose materialInfo
- Publication number
- CA1120300A CA1120300A CA000329632A CA329632A CA1120300A CA 1120300 A CA1120300 A CA 1120300A CA 000329632 A CA000329632 A CA 000329632A CA 329632 A CA329632 A CA 329632A CA 1120300 A CA1120300 A CA 1120300A
- Authority
- CA
- Canada
- Prior art keywords
- clearance
- gap
- grinding
- radiation
- discs
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000000034 method Methods 0.000 title claims abstract description 15
- 238000010009 beating Methods 0.000 title claims abstract description 11
- 239000000463 material Substances 0.000 title claims abstract description 9
- 229920002678 cellulose Polymers 0.000 title description 2
- 239000001913 cellulose Substances 0.000 title description 2
- 230000005855 radiation Effects 0.000 claims abstract description 35
- 239000007788 liquid Substances 0.000 claims abstract description 5
- 230000033001 locomotion Effects 0.000 claims description 14
- 229920000136 polysorbate Polymers 0.000 claims description 2
- 239000011324 bead Substances 0.000 claims 1
- ZZUFCTLCJUWOSV-UHFFFAOYSA-N furosemide Chemical compound C1=C(Cl)C(S(=O)(=O)N)=CC(C(O)=O)=C1NCC1=CC=CO1 ZZUFCTLCJUWOSV-UHFFFAOYSA-N 0.000 claims 1
- 230000005251 gamma ray Effects 0.000 claims 1
- 230000006835 compression Effects 0.000 description 3
- 238000007906 compression Methods 0.000 description 3
- 238000006073 displacement reaction Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 238000010408 sweeping Methods 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000001360 synchronised effect Effects 0.000 description 2
- 241000937413 Axia Species 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000008602 contraction Effects 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 235000021050 feed intake Nutrition 0.000 description 1
- 239000002657 fibrous material Substances 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000002045 lasting effect Effects 0.000 description 1
- 238000012806 monitoring device Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 125000006850 spacer group Chemical group 0.000 description 1
- 239000005418 vegetable material Substances 0.000 description 1
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
- D21D1/00—Methods of beating or refining; Beaters of the Hollander type
- D21D1/20—Methods of refining
- D21D1/30—Disc mills
Landscapes
- Crushing And Grinding (AREA)
- Analysing Materials By The Use Of Radiation (AREA)
- Disintegrating Or Milling (AREA)
- Paper (AREA)
Abstract
ABSTRACT
Method for use with beating apparatus equipped with axially adjustable grinding elements rotating relative to one another and preferably of disc type. The grinding elements are enclosed in a housing and between them is a gap or clearance through which the feed stock is passed while subjected to the pressure obtaining between the grinding elements. The width of this gap or clearance is adjusted while the mill is running by causing a beam of radiation, able to penetrate the feed stock and liquid in the clearance gap far more easily than the material of which the enclosing grinding apparatus is constructed, into the gap itself, the rays of this beam running parallel to the surface of the latter. The radiation beam is captured by a detector which measures the intensity of the rays reaching it as a measure of the width of the clearance gap.
Method for use with beating apparatus equipped with axially adjustable grinding elements rotating relative to one another and preferably of disc type. The grinding elements are enclosed in a housing and between them is a gap or clearance through which the feed stock is passed while subjected to the pressure obtaining between the grinding elements. The width of this gap or clearance is adjusted while the mill is running by causing a beam of radiation, able to penetrate the feed stock and liquid in the clearance gap far more easily than the material of which the enclosing grinding apparatus is constructed, into the gap itself, the rays of this beam running parallel to the surface of the latter. The radiation beam is captured by a detector which measures the intensity of the rays reaching it as a measure of the width of the clearance gap.
Description
llZ~ O
ROLF BERTIL REINHALL Our Ref.: Def 145 Method and devic _ beating apparatus for ligno-cellulose material The present invention is concerned with a method and device for use with beating apparatus equipped with axially adjustable grinding elements rotating relative to one another and preferably of disc type, enclosed in a housing and having a gap or clearance between them through which the feed stock is passed while subjected to the pressure obtaining between the grinding elements.
More precisely, the invention deals with a method and device permittingcontinuous gauging, monitoring and adjustrnent of the physical distance between the grinding discs rotating opposite one another in beating apparatus for fibrous or vegetable material. Beating apparatus of this type usually comprises grinding discs working in opposition to each other, grinding of the feed stock taking place in the gap between the discs, supported by a rotating machine part and a stator or by two machine parts or shafts rotating in opposite directions. The relative distance of the grinding elements, or clearance, is adjusted by moving the rotating machine part(s) or the stator-mounted grinding disc in an axial direction. Grinding mills of this type are also known as defi-brators or refiners, depending on the degree to which the feed stock is to be beaten to fibres or fibrils.
Methods are already known by which mechanical or electric instruments may be used to measure the clearance giYen by axial adjustment of the grinding elements.
A feature common to all these grinding methods is that they only measure the relative axial motion of the machine parts on which the grinding elements are mounted and not the true distance between the elements, d~
llZV3~}0 which may, in fact, vary from the distance 50 measured as a result of, for example, wear on the grinding elements, thermal expansion, or axial strain or compression in the machine part generated axially or by the forces arising in the grinding process. Departures from the width of clearance given as a measurement of the axial displacement of the ma-chine part display considerable variance.
In large types of disc refiner, the axial forces generated between the yrinding elements during the grinding operation are often in the mag-nitude of 50 tons or more. Distortion and compression strains acting on the machine part supporting the grinding elements are often so great that the gap between these elements, the clearance, the size of which is selected with a view to achieving the desired degree of grinding, is widened too far.
In consequence, the clearance gap, which is set with the mill running unloaded and is measured in terms of the axial displacement of the machine element on which the grinding eleménts are mounted, must be readjusted by further axial displacement when subjected to operational loads, thus bringing the grinding elements closer to one another. If the axial load is particularly great, the degree of after-adjustment may then be greater than the distance, or clearance, between the grinding discs originally set with the machine running unloaded. Given this situation, should the supply of feed stock to be processed in the mill suddenly cease, the axial load acting on the discs will revert to the unloaded state, thus eliminating the axial distortion or compression which had first necessitated after-adjustment of the clearance gap. If the degree of adjustment of the gap from the no-load to the normally loaded state is greater than the gap itself, the grinding elements will be forced into direct mechanical contact with each other with disc destruction as the inevitable result. The same applies to the degree of thermal expansion or contraction occurring at start-up or stopping of the various types of mills should this be greater than the preset dis-tance between the grinding elements.
~lZ03~
In order to eliminate these inconveniences and, in ~ddition, to permit measurement of the wear occurring on the grinding element during oper-ation, this invention provides for the installation of an instrument capable of measuring the true distance between the grindiny elements at any given moment.
This is achieved in that the invention provides for the size of the clearance gap to be measured while the machine is running, this being made possible by means of a beam of radiation, able to penetrate the feed stock and liquid in the clearance gap far more easily than the material of which the enclosing grinding apparatus is constructed, emanating from a source of radiation into the gap itself, its rays running parallel to the surface of the gap, and afterwards captured by a receiving device or detector which registers the intensity of the rays reaching it as a measure of the width of the clearance gap. In one particularly important embodiment of the invention, the beam of radi-ation is closely defined by a channel or slot cut in an element capable of absorbing radiation, this element being given a reciprocating motion of predetermined speed in a path perpendicular to the plane of the clearance gap and mounted either before or after the clearance gap. By this means, the instrument is always able to provide exact readings no matter what the state of the clearance gap currently prevailing in the mill, even though this may be constantly changing as a result of, say, surface wear on the grinding elements. The invention also comprises an apparatus providing for the application of this method.
The invention will be described in greater detail in the paragraphs to follow, in which reference will be made to the appended drawings showing beating or refining apparatus featuring one rotating and one stationary grinding element.
Figure 1 shows a vertical section along the length of a beating apparatus.
Figure 2 shows in outline the details of the radiation source and the sensor or detector indicating radiation-intensity necessary for the design of a beating apparatus according to the principles of the invention.
11203~0 In the drawings the figure 10 is used to denote the supporting framework of the refiner in which a shaft 12 is mounted in two bearings, one of which is shown in Figure 1 and is there generally designated 14. The left-hand end of the shaft 12 is coupled to the shaft of the driving motor (not shown here), while the other end of the shaft 12 supports a grinding disc 22. Both the shaft 12 and the grinding disc 22 are ad-justable in an axial direction relative to a stationary grinding disc 24 mounted on a stator 76. The bearing 14 mounted by the grinding disc 22 is of the tapered roller type and runs in an inner race 28 mounted on the shaft and an outer, non-rotatable race 30. This bearing is able to take up both axial and radial loads. A spacer ring 34 is provided be-tween the inner race 28 and a shoulder 32 on the shaft 12. The bearing 14 is kept under constant axial pressure by means of a thrust bearing 36 of suitable tapered type, the inner race 38 of which is secured to the shaft 12 over an oil slinger 40 by means of a back nut 42. The outer race 44 of the bearing 36 bears against a prestressed, conical cup spring 46 and a casing 48 in contact with the non-rotating race 30 of the supporting bearing 14. The initial axial thrust exerted on this is commensurate with the tension of the spring 46, which may be as much as a few tons and which is at least as great as the axial component acting on the bearing 14 as a result of the weight of the rotating parts of the mill, any imbalances in construction, etc. In order to be able to resist radial thrust, the bearing 14 must also be subjected to axial thrust, and this the device described above is able to ensure even when the mill is not being used. The casing 48 is enclosed in an inner bearing housing 49, in which the stationary race 30 rests snugly, and which is axially displaceable together with the shaft 12 in an outer bearing housing 51.
A slide shoe 50 is here provided in order to eliminate the effects of the gap between the two bearing housings, 49 and 51, and bears upon the inner bearing housing 49 by means of pretensioned springs 52.
The rotating grinding disc 22 is secured by bolts 56 to a rotor 54. A
second grinding disc 58 may also be mounted inside the circumference of the grinding disc 22, this too being secured to the rotor 54 by means of bolts 60. The stationary grinding disc 24 is secured to the housing 64 enclosing the discs by mounting and adjustment devices 62 distributed -112~3~}0 around its circumference. These devices 62 comprise a mounting bolt 66 ~hich is threaded so as to be able to be screwed into the grinding disc 24 but which fits freely into a sleeve 68. The purpose of this sleeve, which is screwed into the housing 64, is to adjust the position of the grinding disc 24 relative to the housing.
A second stationary grinding disc 74 is secured by bolts 76 to the housing 64 within the circumference of the first 24. The adjacent sur-faces of the grinding discs here designated 22 and 24 are covered with a pattern of ribs and ridges, as in known practice, in order to facilitate the desired degree of shredding. The other two discs, designated 58 and 74, may serve as dischargers for the feed stock entering the housing 64 through an intake 78 and preferably also make some contribution to the grinding process.
The housing 64 is of rugged design in order to be able to withstand thesteam pressure prevailing therein and to hinder the grinding pressure from being transferred to the supporting framework 10 with a minimum of outward deflection. A stuffing box 80 is inserted between the shaft 12 and the housing 64. The housing 64 is horizontally divided in a plane above the stuffing box 80 and the wall of the feed intake 7~ and thus acquires an upper part or hat 82 secured to the rest of the housing by means of bolts, which allows it to be removed. With the upper part 82 removed, the grinding discs can be reached for inspection and adjust-ment, while at the same time an oval opening in the housing is revealed through which the discs can be removed for replacement. The housing 64 is provided with an extension 86 projecting upwards above the horizontal division and enclosed by the top part 82, which here serves an an abut-ment for the grinding disc 24.
Th~ grinding disc 22 is kept under pressure in a direction towards the disc denoted 24 by means of a servomotor, here generally designated 90.
This motor comprises a casing 92 rigidly secured to the supporting framework and a piston 94, both of which concentrically surround the shaft 12 with a small clearance between the two. The piston 94 is pro-vided with a central flange 96, this being axially movable inside a )3VO
chamber 98, the side walls 100 of which limit the extent to which the piston can move in the direction of the grinding disc 24. An inlet 102 and an outlet 104 suitable for a pressurized liquid, such as oil, are provided at each end of the chamber 98. The only seal between the piston 94 and the casing 92 enclosing it is therefore the suitably adjusted clearance.
An externally threaded sleeve 108 may be rigidly united with the end ofthe servomotor piston 94 closest to the bearing 14 by means of e.g.
keying 106. The pitch of the screw thread may be in the region of 5 mm.
An annular element 109 having an axial groove fitted with a pin 110 is threaded onto the sleeve 10~. Also threaded onto the sleeve 108 is a ring 1i2; and, axially removed from the latter, a plate 114 is mounted.
A number of bolts 115 distributed round the circumference pass freely through the ring 112 but are screwed into the plate 114 and an element 118 forming a lid to the bearing housing 49. These bolts compress springs 120 against the ring 112, thus eliminating the effects of the play between the components denoted 94 and 118. The annular element 109 presents a spherical surface to a ring 122 mounted in the lid 118. The combined pressure of the springs 120 is sufficient to overcome the re-sistance of the components united with the shaft 12 when this is dis-placed towards the left.
The piston 94 of the servomotor is rotatable and is turned by a trans-mission system which will be described in greater detail below. On the other hand, since the bearing housing 49 is stationary, when the piston rotates the annular element 109 will be moved axially and will carry the housing and hence the grinding disc along with it. The design of refi-ners of this type is given in greater detail in Swedish Patent no.
179 336.
~f an axia~ thrust is delivered from the shaft 12 to the stationary grinding disc 24, the shaft will be compressed within an area from the rotating grinding disc 22 to the bearing 14 taking up the axial pressure at the same time as that part of the supporting framework 10 and the grinding disc housing 64, which takes up the axial thrust or grinding ilZ0300 pressure between the grinding discs, is lengthened. The clearance, that is, the gap betwe~n the rotating 22 and the stationary 24 grinding discs, set to the desired distance with the mill running unloaded, is thereby increased. This increase is monitored by a measuring device constructed in accordance with the principles of the invention. Such device should preferably incorporate an isotope of cobalt 130 emitting ganlma rays, which should be mounted on a supporting shield 134 of lead thick enough to ensure that practically 100~ of the radiation emitted from the isotope 130 will be absorbed, and supported so as to be able to perform a reciprocating motion at right angles to the plane of the grinding surfaces. This motion is so directed that a slot 136 cut in the lead shield at right angles to the longitudinal direction of the machine and having a width in the region of 1/00 - 1/000 mm is made to sweep past that part of the housing of the grinding discs in which the gap between the discs is located. This movement is achieved by means of a synchronous motor 138 driving a double left and right-handed, self-reversing spindle 142 through a gearing system 140. This spindle trans-fers the desired motion to the lead shield 134 and the isotope 130 carried on it by means of a bolt 144 and supporting bracket 146.
The isotope thus sweeping past the grinding gap is enclosed in a casing148 of suitable size, also made of some material capable of absorbing radiation, and rigidly secured by bolts 150 to the outside of the housing 64 containing the grinding discs.
The thickness of the grinding disc housing is constant over the whole field 152 defined by the motion of the above-mentioned slot 136 and the sweep of the gamma rays.
That part of the radiation emitted by the isotope 130 and filtered by the lead shield 134 and the slot 136 cut in it penetrates the housing of the grinding discs in the area of uniform thickness 152 and, as a result of the axial sweeping motion it performs, will continue through and past the gap or clearance maintained between the grinding discs, 22 and 24.
The direction of the radiation is made parallel to the plane of the grinding disc surfaces by adjusting the position of the instrument 148 containing the isotope.
1~2~3(~0 A device fcr detecting radiation, preferably a Geiger-Muller counting tube 154 is located at a position on the grinding disc housing 64 di-ametrically opposed to the above, or at an angular distance from the radiation source such that the gamma rays emanating from the slot 136 must pass through the gap between the discs in order to reach the de-tector, which is enclosed in a container 156. This container enclosing the Geiger counter is also securely attached to the outside of the grinding disc housing, which here, too, is of uniform thickness at a place 158 opposite and perpendicular to the clearance between the discs.
The intensity of the radiation chosen is such that it is able to pene-trate the areas, 152 and 158, of the outer housing (machined to a uni-form, calibrated thickness), pass through the gap between the discs filled with feed stock and/or liquid, and then to give rise to a signal in the active part 160 of the Geiger counter.
As the gamma rays continue their reciprocating motion, as soon as they leave the open space (or clearance) between the grinding discs they encounter the grinding discs themselves, 22 and 24, and the feed stock, which instantly absorb the rays and prevent their continued passage towards the Geiger-MUller counting tube 154. Thanks to this arrangement, as long as the slot 136 cut in the lead shield 134 remains in the field defined by the grinding gap, an instantaneous signal can be received from the Geiger counter. This signal will cease abruptly as soon as the slot moves outside this area.
By calibrating the speed of the synchronous sweeping motion performed by the isotope to e.g. 1/00 or 1/000 mm per unit of time and measuring the time during which the Geiger counter is activated at every passage of the radiation beam leaving the slot 136 above and through the clearance between the grinding discs, a figure is obtained giving a direct reading of the true distance between the discs, 22 and 24, at any given moment.
Thus, if the slot is 1/00 mm in width and the isotope is moving at 10 mm per second, Geiger counter signals lasting 0.01 sec. indicate a clear-ance 0~1 mm wide.
The duration of the Geiger counter signal so measured thus provides a reading in direct proportion to the size of the clearance between the ilzv~ao discs; and the signal can therefore be used for both manual and auto-matic control and adjustment of this clearance between the grinding discs. By this means, the need for readjustment of the width of the gap between the grinding discs arising from the axial forces generated by the machine can be dealt with by continuously reading off the true distance between the two discs.
In automatic control of the disc clearance, the unit of time given as the period of the Geiger counter's signal is conveyed by conventional regulator technology to a monitoring device or meter 162, which, through the agency of a servomotor 164 and its associated transmission 166, maintains the clearance between the grinding discs at a constant, p~e-determined width by rotating the piston 94 with its threaded sleeve 108.
The invention is clearly not limited to the embodiment shown here but may be very widely varied within the framework of the basic idea on which it is founded, i.e. that the width of the grinding gap or clear-ance is measured by the use of rays penetrating the material and read off either in terms of the time needed for a beam of radiation to tra-verse the gap or as a simple measurement of the width of a field of radiation projected through the clearance between the grinding discs.
Instead of locating the fine slot 136 on the same side of the machine as the isotope it would also be feasible to locate it on the same side as the detector, the sensitive component of which, e.g. the Geiyer-Muller counting tube, would then be caused to perform a reciprocating motion past it.
It is important that the speed of the reciprocating element, such as the isotope, is kept constant for that part of its track during which the radiation beam is measuring the width of the clearance gap through the fine slot~
ROLF BERTIL REINHALL Our Ref.: Def 145 Method and devic _ beating apparatus for ligno-cellulose material The present invention is concerned with a method and device for use with beating apparatus equipped with axially adjustable grinding elements rotating relative to one another and preferably of disc type, enclosed in a housing and having a gap or clearance between them through which the feed stock is passed while subjected to the pressure obtaining between the grinding elements.
More precisely, the invention deals with a method and device permittingcontinuous gauging, monitoring and adjustrnent of the physical distance between the grinding discs rotating opposite one another in beating apparatus for fibrous or vegetable material. Beating apparatus of this type usually comprises grinding discs working in opposition to each other, grinding of the feed stock taking place in the gap between the discs, supported by a rotating machine part and a stator or by two machine parts or shafts rotating in opposite directions. The relative distance of the grinding elements, or clearance, is adjusted by moving the rotating machine part(s) or the stator-mounted grinding disc in an axial direction. Grinding mills of this type are also known as defi-brators or refiners, depending on the degree to which the feed stock is to be beaten to fibres or fibrils.
Methods are already known by which mechanical or electric instruments may be used to measure the clearance giYen by axial adjustment of the grinding elements.
A feature common to all these grinding methods is that they only measure the relative axial motion of the machine parts on which the grinding elements are mounted and not the true distance between the elements, d~
llZV3~}0 which may, in fact, vary from the distance 50 measured as a result of, for example, wear on the grinding elements, thermal expansion, or axial strain or compression in the machine part generated axially or by the forces arising in the grinding process. Departures from the width of clearance given as a measurement of the axial displacement of the ma-chine part display considerable variance.
In large types of disc refiner, the axial forces generated between the yrinding elements during the grinding operation are often in the mag-nitude of 50 tons or more. Distortion and compression strains acting on the machine part supporting the grinding elements are often so great that the gap between these elements, the clearance, the size of which is selected with a view to achieving the desired degree of grinding, is widened too far.
In consequence, the clearance gap, which is set with the mill running unloaded and is measured in terms of the axial displacement of the machine element on which the grinding eleménts are mounted, must be readjusted by further axial displacement when subjected to operational loads, thus bringing the grinding elements closer to one another. If the axial load is particularly great, the degree of after-adjustment may then be greater than the distance, or clearance, between the grinding discs originally set with the machine running unloaded. Given this situation, should the supply of feed stock to be processed in the mill suddenly cease, the axial load acting on the discs will revert to the unloaded state, thus eliminating the axial distortion or compression which had first necessitated after-adjustment of the clearance gap. If the degree of adjustment of the gap from the no-load to the normally loaded state is greater than the gap itself, the grinding elements will be forced into direct mechanical contact with each other with disc destruction as the inevitable result. The same applies to the degree of thermal expansion or contraction occurring at start-up or stopping of the various types of mills should this be greater than the preset dis-tance between the grinding elements.
~lZ03~
In order to eliminate these inconveniences and, in ~ddition, to permit measurement of the wear occurring on the grinding element during oper-ation, this invention provides for the installation of an instrument capable of measuring the true distance between the grindiny elements at any given moment.
This is achieved in that the invention provides for the size of the clearance gap to be measured while the machine is running, this being made possible by means of a beam of radiation, able to penetrate the feed stock and liquid in the clearance gap far more easily than the material of which the enclosing grinding apparatus is constructed, emanating from a source of radiation into the gap itself, its rays running parallel to the surface of the gap, and afterwards captured by a receiving device or detector which registers the intensity of the rays reaching it as a measure of the width of the clearance gap. In one particularly important embodiment of the invention, the beam of radi-ation is closely defined by a channel or slot cut in an element capable of absorbing radiation, this element being given a reciprocating motion of predetermined speed in a path perpendicular to the plane of the clearance gap and mounted either before or after the clearance gap. By this means, the instrument is always able to provide exact readings no matter what the state of the clearance gap currently prevailing in the mill, even though this may be constantly changing as a result of, say, surface wear on the grinding elements. The invention also comprises an apparatus providing for the application of this method.
The invention will be described in greater detail in the paragraphs to follow, in which reference will be made to the appended drawings showing beating or refining apparatus featuring one rotating and one stationary grinding element.
Figure 1 shows a vertical section along the length of a beating apparatus.
Figure 2 shows in outline the details of the radiation source and the sensor or detector indicating radiation-intensity necessary for the design of a beating apparatus according to the principles of the invention.
11203~0 In the drawings the figure 10 is used to denote the supporting framework of the refiner in which a shaft 12 is mounted in two bearings, one of which is shown in Figure 1 and is there generally designated 14. The left-hand end of the shaft 12 is coupled to the shaft of the driving motor (not shown here), while the other end of the shaft 12 supports a grinding disc 22. Both the shaft 12 and the grinding disc 22 are ad-justable in an axial direction relative to a stationary grinding disc 24 mounted on a stator 76. The bearing 14 mounted by the grinding disc 22 is of the tapered roller type and runs in an inner race 28 mounted on the shaft and an outer, non-rotatable race 30. This bearing is able to take up both axial and radial loads. A spacer ring 34 is provided be-tween the inner race 28 and a shoulder 32 on the shaft 12. The bearing 14 is kept under constant axial pressure by means of a thrust bearing 36 of suitable tapered type, the inner race 38 of which is secured to the shaft 12 over an oil slinger 40 by means of a back nut 42. The outer race 44 of the bearing 36 bears against a prestressed, conical cup spring 46 and a casing 48 in contact with the non-rotating race 30 of the supporting bearing 14. The initial axial thrust exerted on this is commensurate with the tension of the spring 46, which may be as much as a few tons and which is at least as great as the axial component acting on the bearing 14 as a result of the weight of the rotating parts of the mill, any imbalances in construction, etc. In order to be able to resist radial thrust, the bearing 14 must also be subjected to axial thrust, and this the device described above is able to ensure even when the mill is not being used. The casing 48 is enclosed in an inner bearing housing 49, in which the stationary race 30 rests snugly, and which is axially displaceable together with the shaft 12 in an outer bearing housing 51.
A slide shoe 50 is here provided in order to eliminate the effects of the gap between the two bearing housings, 49 and 51, and bears upon the inner bearing housing 49 by means of pretensioned springs 52.
The rotating grinding disc 22 is secured by bolts 56 to a rotor 54. A
second grinding disc 58 may also be mounted inside the circumference of the grinding disc 22, this too being secured to the rotor 54 by means of bolts 60. The stationary grinding disc 24 is secured to the housing 64 enclosing the discs by mounting and adjustment devices 62 distributed -112~3~}0 around its circumference. These devices 62 comprise a mounting bolt 66 ~hich is threaded so as to be able to be screwed into the grinding disc 24 but which fits freely into a sleeve 68. The purpose of this sleeve, which is screwed into the housing 64, is to adjust the position of the grinding disc 24 relative to the housing.
A second stationary grinding disc 74 is secured by bolts 76 to the housing 64 within the circumference of the first 24. The adjacent sur-faces of the grinding discs here designated 22 and 24 are covered with a pattern of ribs and ridges, as in known practice, in order to facilitate the desired degree of shredding. The other two discs, designated 58 and 74, may serve as dischargers for the feed stock entering the housing 64 through an intake 78 and preferably also make some contribution to the grinding process.
The housing 64 is of rugged design in order to be able to withstand thesteam pressure prevailing therein and to hinder the grinding pressure from being transferred to the supporting framework 10 with a minimum of outward deflection. A stuffing box 80 is inserted between the shaft 12 and the housing 64. The housing 64 is horizontally divided in a plane above the stuffing box 80 and the wall of the feed intake 7~ and thus acquires an upper part or hat 82 secured to the rest of the housing by means of bolts, which allows it to be removed. With the upper part 82 removed, the grinding discs can be reached for inspection and adjust-ment, while at the same time an oval opening in the housing is revealed through which the discs can be removed for replacement. The housing 64 is provided with an extension 86 projecting upwards above the horizontal division and enclosed by the top part 82, which here serves an an abut-ment for the grinding disc 24.
Th~ grinding disc 22 is kept under pressure in a direction towards the disc denoted 24 by means of a servomotor, here generally designated 90.
This motor comprises a casing 92 rigidly secured to the supporting framework and a piston 94, both of which concentrically surround the shaft 12 with a small clearance between the two. The piston 94 is pro-vided with a central flange 96, this being axially movable inside a )3VO
chamber 98, the side walls 100 of which limit the extent to which the piston can move in the direction of the grinding disc 24. An inlet 102 and an outlet 104 suitable for a pressurized liquid, such as oil, are provided at each end of the chamber 98. The only seal between the piston 94 and the casing 92 enclosing it is therefore the suitably adjusted clearance.
An externally threaded sleeve 108 may be rigidly united with the end ofthe servomotor piston 94 closest to the bearing 14 by means of e.g.
keying 106. The pitch of the screw thread may be in the region of 5 mm.
An annular element 109 having an axial groove fitted with a pin 110 is threaded onto the sleeve 10~. Also threaded onto the sleeve 108 is a ring 1i2; and, axially removed from the latter, a plate 114 is mounted.
A number of bolts 115 distributed round the circumference pass freely through the ring 112 but are screwed into the plate 114 and an element 118 forming a lid to the bearing housing 49. These bolts compress springs 120 against the ring 112, thus eliminating the effects of the play between the components denoted 94 and 118. The annular element 109 presents a spherical surface to a ring 122 mounted in the lid 118. The combined pressure of the springs 120 is sufficient to overcome the re-sistance of the components united with the shaft 12 when this is dis-placed towards the left.
The piston 94 of the servomotor is rotatable and is turned by a trans-mission system which will be described in greater detail below. On the other hand, since the bearing housing 49 is stationary, when the piston rotates the annular element 109 will be moved axially and will carry the housing and hence the grinding disc along with it. The design of refi-ners of this type is given in greater detail in Swedish Patent no.
179 336.
~f an axia~ thrust is delivered from the shaft 12 to the stationary grinding disc 24, the shaft will be compressed within an area from the rotating grinding disc 22 to the bearing 14 taking up the axial pressure at the same time as that part of the supporting framework 10 and the grinding disc housing 64, which takes up the axial thrust or grinding ilZ0300 pressure between the grinding discs, is lengthened. The clearance, that is, the gap betwe~n the rotating 22 and the stationary 24 grinding discs, set to the desired distance with the mill running unloaded, is thereby increased. This increase is monitored by a measuring device constructed in accordance with the principles of the invention. Such device should preferably incorporate an isotope of cobalt 130 emitting ganlma rays, which should be mounted on a supporting shield 134 of lead thick enough to ensure that practically 100~ of the radiation emitted from the isotope 130 will be absorbed, and supported so as to be able to perform a reciprocating motion at right angles to the plane of the grinding surfaces. This motion is so directed that a slot 136 cut in the lead shield at right angles to the longitudinal direction of the machine and having a width in the region of 1/00 - 1/000 mm is made to sweep past that part of the housing of the grinding discs in which the gap between the discs is located. This movement is achieved by means of a synchronous motor 138 driving a double left and right-handed, self-reversing spindle 142 through a gearing system 140. This spindle trans-fers the desired motion to the lead shield 134 and the isotope 130 carried on it by means of a bolt 144 and supporting bracket 146.
The isotope thus sweeping past the grinding gap is enclosed in a casing148 of suitable size, also made of some material capable of absorbing radiation, and rigidly secured by bolts 150 to the outside of the housing 64 containing the grinding discs.
The thickness of the grinding disc housing is constant over the whole field 152 defined by the motion of the above-mentioned slot 136 and the sweep of the gamma rays.
That part of the radiation emitted by the isotope 130 and filtered by the lead shield 134 and the slot 136 cut in it penetrates the housing of the grinding discs in the area of uniform thickness 152 and, as a result of the axial sweeping motion it performs, will continue through and past the gap or clearance maintained between the grinding discs, 22 and 24.
The direction of the radiation is made parallel to the plane of the grinding disc surfaces by adjusting the position of the instrument 148 containing the isotope.
1~2~3(~0 A device fcr detecting radiation, preferably a Geiger-Muller counting tube 154 is located at a position on the grinding disc housing 64 di-ametrically opposed to the above, or at an angular distance from the radiation source such that the gamma rays emanating from the slot 136 must pass through the gap between the discs in order to reach the de-tector, which is enclosed in a container 156. This container enclosing the Geiger counter is also securely attached to the outside of the grinding disc housing, which here, too, is of uniform thickness at a place 158 opposite and perpendicular to the clearance between the discs.
The intensity of the radiation chosen is such that it is able to pene-trate the areas, 152 and 158, of the outer housing (machined to a uni-form, calibrated thickness), pass through the gap between the discs filled with feed stock and/or liquid, and then to give rise to a signal in the active part 160 of the Geiger counter.
As the gamma rays continue their reciprocating motion, as soon as they leave the open space (or clearance) between the grinding discs they encounter the grinding discs themselves, 22 and 24, and the feed stock, which instantly absorb the rays and prevent their continued passage towards the Geiger-MUller counting tube 154. Thanks to this arrangement, as long as the slot 136 cut in the lead shield 134 remains in the field defined by the grinding gap, an instantaneous signal can be received from the Geiger counter. This signal will cease abruptly as soon as the slot moves outside this area.
By calibrating the speed of the synchronous sweeping motion performed by the isotope to e.g. 1/00 or 1/000 mm per unit of time and measuring the time during which the Geiger counter is activated at every passage of the radiation beam leaving the slot 136 above and through the clearance between the grinding discs, a figure is obtained giving a direct reading of the true distance between the discs, 22 and 24, at any given moment.
Thus, if the slot is 1/00 mm in width and the isotope is moving at 10 mm per second, Geiger counter signals lasting 0.01 sec. indicate a clear-ance 0~1 mm wide.
The duration of the Geiger counter signal so measured thus provides a reading in direct proportion to the size of the clearance between the ilzv~ao discs; and the signal can therefore be used for both manual and auto-matic control and adjustment of this clearance between the grinding discs. By this means, the need for readjustment of the width of the gap between the grinding discs arising from the axial forces generated by the machine can be dealt with by continuously reading off the true distance between the two discs.
In automatic control of the disc clearance, the unit of time given as the period of the Geiger counter's signal is conveyed by conventional regulator technology to a monitoring device or meter 162, which, through the agency of a servomotor 164 and its associated transmission 166, maintains the clearance between the grinding discs at a constant, p~e-determined width by rotating the piston 94 with its threaded sleeve 108.
The invention is clearly not limited to the embodiment shown here but may be very widely varied within the framework of the basic idea on which it is founded, i.e. that the width of the grinding gap or clear-ance is measured by the use of rays penetrating the material and read off either in terms of the time needed for a beam of radiation to tra-verse the gap or as a simple measurement of the width of a field of radiation projected through the clearance between the grinding discs.
Instead of locating the fine slot 136 on the same side of the machine as the isotope it would also be feasible to locate it on the same side as the detector, the sensitive component of which, e.g. the Geiyer-Muller counting tube, would then be caused to perform a reciprocating motion past it.
It is important that the speed of the reciprocating element, such as the isotope, is kept constant for that part of its track during which the radiation beam is measuring the width of the clearance gap through the fine slot~
Claims (10)
PROPERTY OR PRIVILEGE IS CLAIMED AS DEFINED AS FOLLOWS:
1. Method for use with beating apparatus equipped with axially adjustable grinding elements rotating relative to one another and preferably of disc type, enclosed in a housing and having a gap or clearance between them through which the feed stock is passed while subjected to the pressure obtaining between the grinding elements, characterized in that the size of the clearance gap is measured while the machine is running, this being made possible by means of a beam of radiation, able to penetrate the feed stock and liquid in the clearance gap far more easily than the material of which the enclosing grinding apparatus is constructed, emanating from a source of radiation into the gap itself, its rays running parallel to the surface of the gap, and afterwards captured by a receiving device or detector which registers the intensity of the rays reach-ing it as a measure of the width of the clearance gap.
2. Method of Claim 1, characterized in that the bead of radi-ation is emitted from the radiation source through the grinding gap and passes to the detector located on another, preferably op-posite, side of the gap between the discs.
3. Method of Claims 1 and 2, characterized in that the radi-ation beam is closely defined by a channel or slot cut in an el-ement capable of absorbing radiation, this element being given a recipracating motion of predetermined speed in a path perpendicu-lar to the plane of the clearance gap and mounted either before or after the clearance gap.
4. Method of Claim 2, characterized in that the radiation source or detector, respectively, is so arranged as to be carried with the element as it performs its reciprocating motion.
5. Device for use with beating apparatus for implementation of the method described in Claim 1, such apparatus being equipped with axially adjustable grinding elements rotating relative to one another and preferably of disc type, enclosed in a housing and having a gap or clearance between them through which the feed stock is passed while subjected to the pressure obtaining between the grinding elements, in which an instrument, preferably a Gei-ger-Muller counting tube, is so devised as to measure the position of the grinding elements relative to one another, characterized in that the instrument comprises a source of radiation so devised as to emit a beam running parallel to the plane of the clearance between the grinding discs, the nature of this beam being such that it is essentially only able to penetrate the gap and its con-tents and is thus to a large degree absorbed by the material of which the grinding discs are made, and that a detector sensitive to radiation is located in the path of the beam passing the gap and is so designed as to give a signal of an intensity proportion-ate to the width of the clearance.
6. Device of Claim 5, characterized in that the source of radi-ation and the detector are both mounted outside the clearance be-tween the grinding discs and preferably outside the housing of the latter.
7. Device of Claim 6, characterized in that the source of radi-ation and the detector are mounted on diametrically opposite sides of the discoid grinding elements.
8. Device of Claim 5, characterized in that the source of radi-ation comprises an isotope emitting gamma ray and enclosed in a container secured to a wall made of some material capable of ab-sorbing radiation, in which is cut a fine channel or slot so form-ed as to allow the passage of the beam of radiation and direct it along a course parallel to the clearance between the grinding discs.
9. Device of Claim 8, characterized in that, by means of a driving mechanism, the container is able to perform a motion rel-ative to the housing in a plane perpendicular to that of the clearance between the grinding discs at a predetermined speed so causing the radiation beam emitted from the isotope to travel backwards and forwards past the clearance between the grinding discs.
10. Device of Claim 5, characterized in that those parts of the housing traversed by the beam of radiation are of constant thick-ness and define a plane perpendicular to that of the beam of radi-ation and the clearance between the grinding discs.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE7807231A SE419411B (en) | 1978-06-26 | 1978-06-26 | SET AND DEVICE FOR LIGNOCELLULOUS MATERIAL MALAWARE |
| SE7807231-1 | 1978-06-26 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1120300A true CA1120300A (en) | 1982-03-23 |
Family
ID=20335316
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000329632A Expired CA1120300A (en) | 1978-06-26 | 1979-06-13 | Method and device in beating apparatus for ligno-cellulose material |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS553896A (en) |
| BR (1) | BR7904009A (en) |
| CA (1) | CA1120300A (en) |
| DE (1) | DE2923507A1 (en) |
| FI (1) | FI62367C (en) |
| SE (1) | SE419411B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4688726A (en) * | 1986-03-03 | 1987-08-25 | Champion International Corporation | Method and apparatus for controlling a particle refining process |
| SE463396B (en) * | 1987-09-29 | 1990-11-19 | Sunds Defibrator Ind Ab | SET AND DEVICE INDICATING THE AXIAL TOUCH LAYER FOR MALYTOR ON TWO RELATIVE RELATIVELY TO ANOTHER ROTABLE MILL DISCS IN A DISC REFINERY |
| US12196307B2 (en) | 2020-07-01 | 2025-01-14 | Sew-Eurodrive Gmbh & Co. Kg | Gear unit having a shaft, a first bearing, a housing part, and a cover |
| DE102020122645A1 (en) * | 2020-08-31 | 2022-03-03 | Voith Patent Gmbh | Control of a fiber treatment device |
-
1978
- 1978-06-26 SE SE7807231A patent/SE419411B/en unknown
-
1979
- 1979-06-09 DE DE19792923507 patent/DE2923507A1/en not_active Withdrawn
- 1979-06-13 CA CA000329632A patent/CA1120300A/en not_active Expired
- 1979-06-14 JP JP7408679A patent/JPS553896A/en active Pending
- 1979-06-18 FI FI791933A patent/FI62367C/en not_active IP Right Cessation
- 1979-06-25 BR BR7904009A patent/BR7904009A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| BR7904009A (en) | 1980-03-11 |
| FI62367B (en) | 1982-08-31 |
| FI62367C (en) | 1982-12-10 |
| SE419411B (en) | 1981-08-03 |
| JPS553896A (en) | 1980-01-11 |
| FI791933A7 (en) | 1979-12-27 |
| SE7807231L (en) | 1979-12-27 |
| DE2923507A1 (en) | 1980-01-17 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| FI128873B (en) | Arrangement and method for adjusting blade gap in refiner | |
| US4519304A (en) | Device for controlling and monitoring the thickness of a chocolate film delivered by chocolate refiners | |
| CA1120300A (en) | Method and device in beating apparatus for ligno-cellulose material | |
| GB2177197A (en) | Mechanical face seal | |
| FI75052C (en) | Radiation based inspection system for a material manufacturing device as well as a method using radiation meters. | |
| US4370835A (en) | Working pressure control mechanism | |
| WO2007094711A1 (en) | A method and a device for controlling the alignment between refining surfaces | |
| US2743874A (en) | Disk type grinding apparatus for fibrous materials | |
| US4680843A (en) | Apparatus for rotating the shells of rolls in calenders or the like | |
| US2931586A (en) | Grinding device for the breaking down of wood fibres | |
| US4202505A (en) | Refiner | |
| US4936518A (en) | Apparatus for crushing or grinding of fibrous material, in particular drum refiner | |
| US3684200A (en) | Grinding apparatus | |
| US2964250A (en) | Grinding apparatus for fibrous materials | |
| US3709274A (en) | Method and apparatus for regulating output in tobacco cutting machines | |
| US3827644A (en) | Grinding apparatus | |
| US11034050B2 (en) | Device for reducing the size of feed material and method for operating a size reduction device of this type | |
| US3032282A (en) | Grinding apparatus for fibrous material | |
| FI82392C (en) | Disc grinder | |
| US3586250A (en) | Adjustable noncoaxial disc refiner | |
| FI82394B (en) | Combined hydrostatic/hydrodynamic bearing system for a milling unit | |
| US4669382A (en) | Ink dosage adjusting device for ink zone supply in a printing machine | |
| US4129036A (en) | Alignment indicator for roller-type support | |
| CA1045434A (en) | Disk refiner | |
| US5145121A (en) | Apparatus for crushing or grinding of fibrous material, in particular drum refiner |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |