US3554453A - Method of shredding fibrous pulp - Google Patents

Method of shredding fibrous pulp Download PDF

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Publication number
US3554453A
US3554453A US647088A US3554453DA US3554453A US 3554453 A US3554453 A US 3554453A US 647088 A US647088 A US 647088A US 3554453D A US3554453D A US 3554453DA US 3554453 A US3554453 A US 3554453A
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US
United States
Prior art keywords
shredding
roller
engagement
tooth
nodules
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Expired - Lifetime
Application number
US647088A
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English (en)
Inventor
Allan Thale
Olav B Hovstad
Lennart Ivnas
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
GEA Process Engineering AS
Fiskeby AB
Original Assignee
Niro Atomizer AS
Fiskeby AB
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Publication date
Application filed by Niro Atomizer AS, Fiskeby AB filed Critical Niro Atomizer AS
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    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21B—FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT
    • D21B1/00—Fibrous raw materials or their mechanical treatment
    • D21B1/04—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres
    • D21B1/06—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres by dry methods
    • D21B1/066—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres by dry methods the raw material being pulp sheets

Definitions

  • a shredding or fluffing machine for fibrous material such as groundwood comprising a toothed holding member and a shredding roller with teeth engaging the axial space between the teeth of the holding member with a depth of engagement less than half of the length of the shredding roller, preferably near zero, and a method for operating the machine with a peripheral speed of the shredding roller exceeding 20 m./sec.
  • This invention relates to the operation of a machine for shredding fiber goods such as groundwood, sulfate, sulfite or semichemical pulp, w; are the pulp in the shape of a compressed web or flat pieces is passed in between a roller, designated a shredding roller, and a toothed holding or retaining member, where the shredding roller consists of a plurality of toothed discs clamped together with interposed spacing discs of greater thickness and smaller diameter than said toothed discs, or another shape of roller provided with similar toothing, whereas the holding or retaining member consists of a toothed comb with teeth engaging the spaces between said toothed discs or similar toothing'of said shredding roller,
  • Such machines are by way of example, used in conjunction with the treatment of fibrous material for the manufacture of paper. Particularly in this case it is to the highest possible degree of importance, to avoid the formation of small fiber bundles, the so-called knots or nodules (in the following the term nodules will be used) in the material, since the nodules will appear as spots or so-called fish eyes" in the finished paper.
  • nodules are due to many different reasons, both mechanical as well as chemical, and before as well as after the shredding process, and various methods have been provided'for reducing the effect of the various causes, or for wholly or partially removing said causes, aswell as for removing or dissolving nodules already formed. Since it is not possible with any certainty, to observe the nodules until the paper is finished, it is difficult to safely judge the individual causes for the formation of nodules, or the effects of the measures taken with a view to avoiding such formation.
  • nodules already formed may to some extent be broken down. Observations made in conjunction with the development of this invention seem, however, to indicate that this is not correct, or, at any rate, that this is not the primary effect of the shredding on the number of nodules, since it rather seems to be a fact that the shredding process may be a veryess ential reason for the formation of nodules.
  • this invention has for its purpose to provide an arrangement in a machine of the type here concerned, where the risk of nodules being formed during the shredding process is essentially reduced.
  • this purpose is achieved by the fact that the depth of engagement between the toothings of the shredding roller and those of the holding member is not more than half the length of the shredding roller teeth.
  • the depth of engagement- is less than one'third of the depth of engagement of the shredding roller. preferably near, or equal to zero.
  • This is especially advantageous in connection with the pulps, which, as experience shows, are difficult to shred, such as e.g. sulfite pulp, where it is normally regarded as absolutely necessary to carry out the shredding process as a two step or multistep operation, bl ll where. in spite of all, the shredding or fiuffing has not imparted such properties to the particles as to make it possible to maintain the formation of nodules at a sufficiently low level.
  • the length of tooth of the holding member is at least twice the depth of engagement, preferably about three times the depth of engagement or more. lf so, the engagement with the holding member will, as is the case with the shredding roller, only be a fraction of the length of tooth which, not at least in connection with a stationary holding member, may be of importance.
  • tooth shapes other than those normally used for such shredders it may be advantageous to use tooth shapes other than those normally used for such shredders, and thus, it may, according to the invention, be advantageous that the teeth, at any rate, those of the shredding roller, have such shape that, viewed in the direction of movement, the leading tooth flank is, reckoned from the tip of the tooth, forwardly inclined with respect to radius through the tip.
  • the leading tooth flank is, reckoned from the tip of the tooth, forwardly inclined with respect to radius through the tip.
  • the distance between a tooth of the shredding roller and one of the holding member is 1.5 to 10 mm, preferably 1.5 to 5 mm., as in conjunction with a small distance of about 1.5 mm.
  • a low depth of engagement is used, preferably a depth of engagement equal to or near zero. This distance is of importance for the efficiency of the shredding as well as for the formation of nodules, as a small distance furthers the formation of nodules as well as the efficiency.
  • the low depth of engagement used in the invention it is possible without any risk to go down to quite a small distance and so obtain a very effective shredding, and still keep the nodule number low.
  • the method of operating the machine is further characterized in that the shredding roller is rotated at a peripheral speed exceeding 20 m./sec.
  • the holding member may be a rotary holding roller
  • its peripheral speed is in this connection normally of no importance, as in machines of the type here concerned, the speed must, for practical reasons correspond to the rate of feed of material and, consequently, normally lies at a value of less than l mJsec.
  • the shredding roller When rotating the holding roller at an essentially higher speed, it will also be necessary to rotate the shredding roller at a correspondingly higher peripheral speed, since it is the difference in speed that is the deciding factor.
  • the rotation of the shredding roller at the relatively high peripheral speed in conjunction with the low depth of engagement, increases the efficiency of the shredding process without the high speed causing any essential increase in the formation of nodules, or requiring high driving power.
  • the shredding roller is rotated at a peripheral speed of to 50 m./sec.
  • FIG. 1 shows schematically a machine of the type dealt with in the invention.
  • FIG. 2 shows a cross section through line ll-ll in FIG. 1 shown purely schematically.
  • FIG. 3 is a side view, partially in axial section, of a shredding roller for an embodiment of the machine according to the invention.
  • FIG. 4 is a tooth disc for the shredding roller shown in FIG. 3.
  • FIG. 5 is an enlarged and schematical detail for describing the tooth dimensions for the machine according to the invention.
  • FIGS. 6 and 7 are sectional views of another embodiment of the machine with the FIG. 6 view taken along line 6-6, of FIG. 7.
  • FIG. 1 and 2 shows a shredding machine highly schematically, consisting of a housing 1, having an inlet passage 2, through which the fiber goods are fed between a toothed holding or retaining member, which in the FIG. is shown in the form of a so-called holding roller 3, and a toothed roller, a socalled fluffing roller 4, disposed in said housing. The fluffs fall down below the rollers and are removed from the housing through a discharge opening 5.
  • a motor 20 is connected through an endless belt 21, a variable speed drive 22 and a clutch 23 to a shaft 24.
  • the rotation of shaft 24 is transferred by an irreversible worm gear 25, a shaft 26 and over a clutch 27 to an axle 28 on which the holding roller 3 is mounted.
  • the axle is supported by bearings 30 and 30'.
  • a motor 31 is connected through an endless belt 32 to an axle 33 of the shredding roller 4.
  • the axle is supported by bearings 35 and 35'.
  • All the bearings 30, 30 nd 35, 35- are mounted on brackets 36 and 37 which are fixed in the housing 1.
  • the shredding roller 4 for an embodiment of the shredding machine according to the invention is shown in FIG. 3.
  • This shredding roller consists of a drum 7 mounted on a shaft 6, on which drum provision has been made for toothed annular discs 8 and spacing rings 9 alternately arranged and clamped together by means of end flanges 10 secured to the ends of drum 7 by bolts 11.
  • Holding roller 3 may be correspondingly designed, and, in the machine, the two rollers should be mounted parallel to each other, with a certain engagement between the toothed annular discs which, consequently, should be axially displaced with respect to each other, so that the teeth of the two rollers engage each others spaces.
  • FIG. 3 shows some of the two toothings 12 which, e.g. may be toothed annular discs of a holding roller not otherwise shown, said annular discs engaging the spaces between corresponding annular discs 8 of the shredding roller shown. If the holding or retaining member is in the shape of a stationary comb, such comb may be made in a similar way.
  • FIG. 4 shows part of an annular disc 8 for the shredding roller shown in FIG. 3.
  • This annular disc 8 is at its circumference provided with teeth 13, and for closer explaining the tooth shape used in the embodiment of the invention shown,
  • an arrow indicates the direction of rotation of the annular disc in the shredding machine.
  • the leading flank 14 of a tooth 13 is. reckoned from the tip 15, of the tooth, forwardly inclined with respect to the radius R through the tip 15 of the tooth.
  • the tooth shape differs materially from the tooth shapes normally used in such machines of which a typical shape is indicated in dotted lines, the leading flank 16 of which, viewed in the direction of rotation, is rearwardly inclined with respect to radius through the tip 17 of the tooth.
  • the trailing flank 18, viewed in the direction of rotation of tooth 13, is in the embodiment shown symmetrical with the leading flank 14 with respect to radius through the tip of the tooth, but its shape is of less importance and has primarily been chosen with a view to obtaining both the required strength and the required length of tooth d.
  • annular disc 8 At the internal circumference of annular disc 8, there are a number of rectangular notches 9 which in combination with similarly shaped keys and keyways in drum 7, serve to prevent the annular discs from rotating with respect to the drum.
  • the tooth shape of holding member 3 may be chosen rather arbitrarily, and it will, therefore, if the member is in the shape of a roller, for productional reasons be advantageous to use toothed annular discs for this roller of the same shape and dimensions as those used for shredding roller 4.
  • FIG. 5 shows the engagement between the toothed annular discs of the shredding roller and toothings 12 of the holding member.
  • the length of tooth of the shredding roller is designated by d, whereas the depth of engagement of the two toothings is designated by i, and the free space between the successive toothings of the holding member 3 and the shredding roller 4 is designated by a.
  • the depth of engagement 1 is, according to the invention not more than half the length of tooth d, and is in FIG. 4 shown in the order of about one third d, whereas, according to the invention it may be as low as zero.
  • distance a must be sufficiently large to prevent the toothings from getting jammed in the material, but as a consequence of the low depth of engagement, the distance a may, according to the invention, be of a very low order.
  • the distance a is preferably chosen to be between 3 and 5 mm., but it may be still lower, for example, as low as 1.5 mm., but if so, the depth of engagement should be near zero.
  • the depth of engagement with respect to the length of tooth of the holding member is, as a rule, less critical, but most often this length of tooth may advantageously be so chosen as to maintain the depth of engagement to the length of tooth ratio within the same limits as those applying to the shredding roller.
  • toothed annular discs it would, for example, be possible to use relatively soft steel, which is adequately surface-hardened, for example, case hardened. If so, it is posible without any difficulty, to obtain the required wear properties as well as the required tensile strength of the teeth.
  • a tooth length d of about 15 mm.
  • a thickness of 2 to 3 mm. could suitably be used, and with spacing rings 9 of 10 mm., the distance a will be 3.5 to 4 mm., which in many cases will give a particularly excellent result.
  • Shredding roller 4 is driven by driving means not shown. If the holding member is also a rotary roller, a single drive motor may be used for the two rollers, but as the shredder, according to the invention most often will use a shredding roller rotating at a very considerable speed,'whereas, the holding roller is to rotate at a relatively low speed, it will often be advantageous, with a view to avoiding too high ratios, to use a separate drive motors for the two rollers.
  • a rotary holder When a rotary holder is used, its peripheral speed should, as a rule, correspond to the rate of feed of the material. If, for example, the material is fed to the machine in the shape of a con-. tinuous web, e.g. delivered from a dehydration press, the rate of feed will normally lie about 0.5 mjsec. lf this roller rotates too fast, such continuous web will be torn apart so that the operation of the machine will become irregular.
  • the object of the holding roller is substantially to maintain the material pressed against shredding roller 4, and to advance said material between the rollers at an appropriate speed.
  • the shredding roller 4 has to be driven at a higher speed and, consequently, a certain moment of rotation is transferred to the holding roller, tending to cause it to rotate at a higher speed than desired. Consequently, measures have to be taken to ensure the desired speed of rotation of the holding roller, which, for example, can be done by the roller being driven through an irreversible worm gear, which will brake the roller towards torques outside the worm.
  • shredding roller 4 is preferably driven at a speed of 25 to 30 m./sec. If this speed is reduced to a value essentially lower than 20 m./sec., for example, lower than m./sec., the efficiency of the shredding process is considerably reduced, whereas, a speed essentially above 50 m./sec., must be regarded as inexpediently high, because the reduction of the nodule number resulting from an increase of the speed within the range stated in connection with this infiber goods for other purposes, because by means of this machine, one obtains, in addition to the reduced formation of nodules, an essentially increased efficiency of the Shredding process and less power consumption, both of which factors are, as a matter of fact, of independent significance, and are, therefore, also of importance in such case where the formation of nodules is of less importance.
  • a method of shredding fibrous articles such as groundwood, and compressed webs and flat pieces of sullite and semichemical pulp, comprising passing said fibrous articles between a shredding roller rotating at a peripheral speed exceeding 20 meters per second and a holding roller rotating at a peripheral speed of from 0 meters per second to the rate of feed of said'fibrous articles while subjecting same to the action of a plurality of laterally spaced interdigitating toothed discs carried by said rollers, the depth of engagement between the teeth of the discs of the shredding roller and those of the holding roller being not more than half the length of the teeth of the shredding roller.

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  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Wood Science & Technology (AREA)
  • Mechanical Engineering (AREA)
  • Crushing And Pulverization Processes (AREA)
US647088A 1966-06-20 1967-06-19 Method of shredding fibrous pulp Expired - Lifetime US3554453A (en)

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SE08396/66A SE338914B (fr) 1966-06-20 1966-06-20

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3658613A (en) * 1970-06-17 1972-04-25 Personal Products Co Absorbent products from wet cross-linked wood pulpboard and methods of making the same
US3964716A (en) * 1970-09-03 1976-06-22 Mccorkle Alfred S Wood processing unit for reducing air pollution
US4683814A (en) * 1984-02-28 1987-08-04 Revere Copper And Brass Incorporated Apparatus and processes for compressing and/or biodigesting material
US20050067121A1 (en) * 2003-09-29 2005-03-31 Dezutter Ramon C. Pulp flaker
US20080045762A1 (en) * 2004-09-10 2008-02-21 Iogen Energy Corporation Process for Producing a Pretreated Feedstock

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US93668A (en) * 1869-08-17 Improved bone-black equalizer
US221744A (en) * 1879-11-18 Improvement in oatmeal-machines
FR461899A (fr) * 1912-11-09 1914-01-13 Jean Bosc Appareil de concassage pour anthracite, charbon et autres matières analogues
US1233514A (en) * 1915-10-28 1917-07-17 William H Scott Shredding-machine for paper-stock.
US2236969A (en) * 1938-09-06 1941-04-01 Einar I Flateboe Paper shredder
US2306665A (en) * 1941-03-19 1942-12-29 American Electro Metal Corp Method of preparing ferritic iron powder for manufacturing shaped iron bodies
US2464774A (en) * 1946-04-22 1949-03-15 Pennsylvania Crusher Co Single roll crusher with opposed toothed-apron feed
US2745454A (en) * 1951-06-16 1956-05-15 Parnell W Fuelling Chopping device for harvesting machine
US3396914A (en) * 1966-03-15 1968-08-13 Centriblast Corp Machine for disintegrating paper and other waste materials

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US93668A (en) * 1869-08-17 Improved bone-black equalizer
US221744A (en) * 1879-11-18 Improvement in oatmeal-machines
FR461899A (fr) * 1912-11-09 1914-01-13 Jean Bosc Appareil de concassage pour anthracite, charbon et autres matières analogues
US1233514A (en) * 1915-10-28 1917-07-17 William H Scott Shredding-machine for paper-stock.
US2236969A (en) * 1938-09-06 1941-04-01 Einar I Flateboe Paper shredder
US2306665A (en) * 1941-03-19 1942-12-29 American Electro Metal Corp Method of preparing ferritic iron powder for manufacturing shaped iron bodies
US2464774A (en) * 1946-04-22 1949-03-15 Pennsylvania Crusher Co Single roll crusher with opposed toothed-apron feed
US2745454A (en) * 1951-06-16 1956-05-15 Parnell W Fuelling Chopping device for harvesting machine
US3396914A (en) * 1966-03-15 1968-08-13 Centriblast Corp Machine for disintegrating paper and other waste materials

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3658613A (en) * 1970-06-17 1972-04-25 Personal Products Co Absorbent products from wet cross-linked wood pulpboard and methods of making the same
US3964716A (en) * 1970-09-03 1976-06-22 Mccorkle Alfred S Wood processing unit for reducing air pollution
US4683814A (en) * 1984-02-28 1987-08-04 Revere Copper And Brass Incorporated Apparatus and processes for compressing and/or biodigesting material
US20050067121A1 (en) * 2003-09-29 2005-03-31 Dezutter Ramon C. Pulp flaker
US7291244B2 (en) 2003-09-29 2007-11-06 Weyerhaeuser Company Pulp flaker
US20080001011A1 (en) * 2003-09-29 2008-01-03 Weyerhaeuser Co. Pulp flaker
US20080045762A1 (en) * 2004-09-10 2008-02-21 Iogen Energy Corporation Process for Producing a Pretreated Feedstock
US7709042B2 (en) 2004-09-10 2010-05-04 Iogen Energy Corporation Process for producing a pretreated feedstock
US20100190226A1 (en) * 2004-09-10 2010-07-29 Iogen Energy Corporation Process for producing a pretreated feestock
US8252568B2 (en) 2004-09-10 2012-08-28 Iogen Energy Corporation Process for producing a pretreated feestock

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Publication number Publication date
SE338914B (fr) 1971-09-20
FI45248B (fr) 1971-12-31
FI45248C (fi) 1972-04-10

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