US3077640A - Method of forming a granite roll - Google Patents

Description

Feb. 19, 1963 E. OWEN 3,077,640

METHOD OF FORMING A GRANITE ROLL Filed June 15, 1960 2 Sheets-Sheet 1 INVENTOR: Em m Owen ATTYS.

Feb. 19, 1963 E. OWEN METHOD OF FORMING A GRANITE ROLL 2 Sheets-Sheet 2 Filed June 15, 1960 INVENTOR: Em yn Owen BY u/y W ATTYS.

3,677,640 METHGD 03F FURMENG A GRANITE ROLL Emlyn Owen, Bury, England, assignor to Walmsleys (Bury) Limited, Bury, England, a British company Filed June 15, 196i Ser. No. 36,281 Claims priority, appiication Great Britain Italy 7, 1%59 3 Claims. (Q1. 18-59) This invention concerns improvements in and relating to the method of forming a granite roll. More particularly it relates to the manufacture of granite press rolls for paper making machinery.

One object of the present invention is to provide a satisfactory substitute for natural granite, both for the manufacture of new press rolls and for the repair of existing rolls from natural granite.

Another object is the provision of a method for prefabricating paper making machine press rolls from synthetic granite, by shrinking individual sections onto a former.

According to the present invention, synthetic granite is made by cold casting under pressure of a setting mixture composed of natural granite particles and a synthetic resin cement. The granite is preferably mixed dry with acrylic resin powder and a setting liquid is introduced into the dry mixture. Thereafter the wet mixture is packed into a mould to which pressure is applied for a sufr'icient time to enable curing or hardening to take place. Also according to the present invention the peripheral surface of a paper making roll is cast in the cold by applying to a central core or roll former a setting mixture composed of natural granite particles and a synthetic resin cement, the mixture being compacted under pressure on to the core or former until curing or hardening has taken place.

This process may be adapted to build up a synthetic granite roll on a metal core or roll former by cold casting short annular sections of the synthetic granite around the metal progressively, a suitable adhesive or hinder being included between the successive sections. Alternatively the synthetic granite may be cold cast around an existing granite or synthetic granite roll for the purpose of increasing the roll diameter. Again, cracks or worn portions of a granite or synthetic granite roll may be repaired by cold casting therein or thereon synthetic granite according to the present invention.

According to the present invention, the process is performed by using an apparatus for cold casting a synthetic granite surface on paper making machinery rolls comprising a support wherein is locatable a central core or roll former, and an annular mould chamber movable along guide members extending from said support to define, with a core or roll former carried by said support, an annular space adapted to receive a setting mixture composed of natural granite particles and synthetic resin cement, a pressure-exerting member being provided on the said guide members and capable of entering said annular chamber for the purpose of compacting the setting mixture contained therein.

The invention will now be further described by way of example, with reference to the accompanying drawings, in which:

PEG. 1 shows a longitudinal section through an apparatus according to the present invention for cold casting the granite press rolls for paper making machinery, the section being taken along the line I-l of H6. 2;

FIG. 2 is an enlarged vertical cross section taken along the line ll-ll of FIG. 1, and FIG. 3 a general perspective view, partly broken away, illustrating the building up of a synthetic granite roll using the method of the present invention.

Referring to the drawings, a synthetic granite faced press roll for a paper making machine is built up on a steel or cast iron roll center or body 1%. As shown in FIGS. 1 and 2 of the drawings, the synthetic granite facing has not yet been applied to the roll body, but FIG. 3 shows several sections 26 of synthetic granite already applied to the roll body.

During application of the synthetic granite facing to the roll body 10, the latter is held in a vertical position by location of the backside journal 11 of the body in a stand 25 (see FIG. 3). A lug or eye 27 is provided at one end of the roll body iii) to facilitate lifting and lowering. At the lower end of the roll body it), when it is in its vertical position, a base plate 12 is arranged in abutting relationship to the main part of the body. Around its periphery base plate 12 carries a plurality of upstanding guide members in the form of threaded shafts 13 which extend along the whole length of the main part of the roll body 1t) in spaced relationship to the external periphery thereof. in the illustrated example three guide members 13 are shown. At their upper ends the guide members 13 are received in the topflange of a collar 14 which is held on to the top end face of the roll body 16 by means of studs 15 extending through the collar 14 and engaging in tapped bores 16 provided in the end face of the roll body it). Nuts 17 provided on guide members 13 and clamped down on to the end face of collar 14 hold the guide members 13 rigid in spaced relationship to the roll body it).

An annular mould 18 (FIG. 1), having an inner diameter corresponding substantially to the desired outer diameter of the finished synthetic granite faced roll before machining thereof, has an outwardly directed flange 19, which is provided with clearance holes arranged for co-operation with the guide members 13, so that the mould 18 can slide along the guide members, and so that an annular chamber 2d for receiving the synthetic granite is defined between the outer periphery of the roll body 1d and the inner surface of the mould 18. The mould 18 is located in any desired position along guide members 13 by suitable adjustment of nuts 21 and lock nuts 22. FIG. 1 illustrates mould 18 in position for forming a first or initial section of synthetic granite facing, whereas FIG. 3 shows it positioned for forming an intermediate section.

Also engaging guide members 13 is a compacting member 23 which has an internal diameter which is only slightly greater than the external diameter of the roll body 1h, so that, as it is moved along guide members 13, it constitutes a close fit on the roll body (see P16. 1). That part of the compacting member 23 which is nearest to the mould 18 is of such a shape and size as to just fit within the annular chamber 29 defined between the mould 18 and the roll body 19, so that movement of the compacting member 23 along guide members 13 towards the mould 18 will cause consolidation or compaction of any material contained in the annular chamber 2%.

By use of the elements 18 to 23, the synthetic granite is built up around the periphery of the roll body 19 in individual sections as hereafter described. Bearing in mind that the roll is in a vertical position during this process, the compacting member 23 is withdrawn upwardly along guides 13 to enable the annular chamber it to be filled from the top with the synthetic granite mixture referred to in greater detail hereafter. During introduction of this mixture to the chamber 20, care is taken to ensure that no air spaces are left, i.e. the mixture may be tamped down. As soon as the chamber 2i; has been filled, the compacting member 23 is moved along guide members 13 until it comes into contact with the mixture. Thereafter, nuts 24- on guide members 13 are screwed down so that the annular portion of the compacting member 23 is forced into the annular chamber 24), thereby consolidating the synthetic granite mixture and placing it under considerable pressure. Levels 23 may be placed on theupper face of member 23 to ensure even tightening of nuts 24. The pressure exerted by member 23 is maintained for sufficient time to enable the synthetic granite mixture to harden or cure. Thereafter compacting member 23 is withdrawn along guide members 13 and y adjustment of nuts 21 and 22 the mould 18 is moved along the roll body to expose the newly formed portion 26 of synthetic granite covering and to define a fresh annular chamber 20 for reception of a further quantity of the synthetic granite mixture. The previously formed portion of synthetic granite facing constitutes a bottom for the next annular chamber20. Prior to introducing the synthetic granite mixture for the next section ofthe roll facing, an adhesive or joining solution is applied to the end face of the previously formed section. In this way a synthetic granite facing is progressively built up in sections 26 along the roll body 10.

In the production of a press roll having a length of 109" and a diameter ofapproximately 22", it was found convenient to build the roll in twenty individual sections 26. It has been found that a mould 18 of adepth of approximately 7" is suitable in constructing synthetic granite faced press rolls. This means that the original length of the annular chamberZt) is 7", but, assuming the full length of the chamberto be initially filled with synthetic granite mixture, after thecompacting member 23 has been forced down into that chamber, its length is reduced to approximately 6".

It will be appreciated that although the embodiment described refers to the compacting member as being tightened down manually, it is possible for the necessary pressure to be applied pneumatically or hydraulically.

In view of the fact that the sections are built up whilst the roll body 10 is in a vertical position, there is-no tendency for the mixture to spill out of the annular chamber 2%) after it has been introduced therein.

Conveniently the outer periphery of the metal roll body 10 is roughened or profiled to enable the synthetic granite more readily to key thereonto. On hardening or curing, synthetic granite tends to shrink slightly in the order of .0017" per inch and the facing therefore keys itself on to the body 16 during the hardening or curing action.

The profiling of the roller body 10 can be effected by circumferential or longitudinal machining to give a rough finish. Alternatively, the roller body may have grooving formed therealong or therearound.

If desired, it is possible to introduce reinforcement, such as steel hands of hoop iron, into the individual sections of the synthetic granite as they are applied to the roll body 10, this reinforcement being embedded in the synthetic granite so as to lie below the finished surface of synthetic granite.

After the completed roll has been built up in sections, it is then finished by turning with a tungsten carbide tool. The synthetic granite is given a constitution such that it has a slightly porous surface, such porosity being more or less essential to enable the paper to leave the roll without excessive adhesion.

Preferably in the mix for the synthetic granite there are eight-and-one-haif parts of granite dust to one part of resin by Weight. For instance, a suitable mix for the synthetic granite is as follows:

1 lb. of granite dust .12 lbs. of acrylic resin. (This is conveniently a powder in the form of polymerized methyl methacrylic acid, suitably prepared for the doughing and hardening characteristics required, the powder containing one of the components of a suitably selected redox system, to ensure the polymerisation of the monomer at ambient temperature) 89 cc. of cement, such as a cold setting methyl methacrylic, or a polymerized methyl methacrylic 22 cc. of a hardening substance, such as stabilized methacrylic acid.

For the 109 long and 22" diameter roll referred to above, it was found that the following amounts of synthetic granite mixture were required for each 7 section of facing (compacted to 6").

19 lb. 2 oz. of granite dust 21b. 4 oz. of acrylic resin 1710 cc. cement 428 cc. hardening substance.

With the synthetic granite mixture referred to above, it has been found that each section takes approximately 45 minutes to harden or cure, and at the end of that time it is possible to withdraw the compacting member 23 and move the mould 18 up in preparation for production of the next section.

A suitable jointing solution for application between successive sections ofthe synthetic granite facing is pro duced by mixing 21 grams of a paste, ofbenzoyl peroxide in phthalate plasticiser 50% paste, with cc. of-methyl methacrylic monomer catalized with dimethyl-para-toluidine.

To obtain the necessary porosity, it is desirable to ensure that the granite dust particles are of a suitable size. This may be achieved by using granite dust which conforms to a sieve test as follows:

It will be seen by reference to FIGS. 1 and 3 of the drawings that the top collar 14 extends the guide members 13 beyond the main part of the body 10, thereby enabling the compacting member 23 to be moved along the guide members 13 to a sufficient distance to enable the mould 18 to be located around the end (top) section of the roll body 10 and slightly protruding therefrom, thereby allowing compaction of the final section of synthetic granite to bring it into line with the end face of the roll.

Once the end section of synthetic granite has been applied and cured or hardened, then the elements 12 to 23 are removed and the roll is dressed with a tungsten carbide tool and finished with coarse and fine grinding wheels.

If desired, the outer peripheral ends of the roll body 10 may be undercut, for instance in the form of a dovetail, so that an additional keying of the synthetic granite surface to the roll body is achieved, over and above the shrinking-on of each section inherent in the curing or hardening of the synthetic granite.

It has previously been proposed to manufacture a roll wherein the active surface is formed by pieces of rock bound together with a rubber or rubber compound. Such a construction has proved unsatisfactory, by virtue of the Wide variation between the wearing properties of the rock and the rubber hinder, the latter tending to disintegrate much more rapidly than the rock with the result that the pieces of rock were loosened or evenseparated from the roll surface causing considerable damage to material passing over the roll. The present invention provides, for the first time, a synthetic granite wherein the resinous binding material exhibits wearing properties commensurate with that of the granite particles which are embedded therein. Moreover, by providing the granite constituent of the substance in dust form rather than in particulate, discrete or lumpy pieces, the tendency for uneven wear with a synthetic granite facing according to the present invention is further reduced.

A major advantage of the synthetic granite facing of the present invention is that the porosity of the roll surface can be adjusted as previously mentioned, and this of course is not possible with natural granite rolls. Neither can it be obtained when a rubber bin-ding agent is employed, as the rubber, being impervious to moisture, produces a surface on the roll which has an uneven porosity.

By building up a roll surface of synthetic granite in individual sections according to the present invention, any tendency for the roll to crack or fracture along its length is greatly reduced. Certainly any fault is localized, inasmuch as development of a crack or fracture is arrested on reaching the boundary of any individual section. In view of the above, a paper making machine roll according to the present invention is better able to withstand or absorb stresses than is a roll provided with a one-piece facing.

I claim:

1. The method of forming a granite roll for a paper making machine using an annular mold shorter than the roll comprising the steps of forming a first annular ring of a mixture of granite particles and synthetic resin cement within the mold around a core, said ring being of a length less than the core and holding the mixture to a cylindrical shape and compacting it axially, permitting the first ring to set to a sufiicient hardness to support an axial force of compacting a second ring thereagainst, applying "a joining material to an end face of the ring, thereafter moving the mold axially and forming a second annular ring of a mixture of granite particles and synthetic resin cement around the core against the end of the first ring with said joining material therebetween, and similarly forming successive annular rings along said core each with a layer of joining material joining it to a previous ring to complete -a roll.

2. The method of forming a granite roll for a paper making machine using an annular mold shorter than the roll comprising steps of dry mixing natural granite particles with an acrylic resin powder to form a mixture, forming a first annular ring of said mixture within the mold around the core, said ring being of a length less than the core, and holding the mixture to a cylindrical shape compacting it axially, permitting the first ring to set to a suflicient hardness to support an axial force of compacting a second ring thereagainst, applying a joining material to the end face of the ring, thereafter moving the mold axially and forming a second ring of said mixture against the end of the first ring with said joining material therebetween, and similarly forming successive annular rings of the mixture along said core each with a layer of joining material joining it to the previous ring to complete a roll.

,3. The method of forming a granite roll for a paper making machine using an annular mold shorter than the roll comprising the steps of forming a first annular ring of a mixture of granite particles and synthetic resin cement within the mold around a core, said ring being of a length less than the core and holding the mixture to a cylindrical shape and cold casting the mixture under pressure permitting the first ring to set to a sufiicient hardness to support an axial force of compacting a second ring thereagainst, applying a joining material of an adhesive substance to an end face of the ring after said ring has set, thereafter moving the ring axially forming a second annular ring of a mixture of granite particles and synthetic resin cement around the core against the end of the first ring with said joining material therebetween, and similarly forming successive annular rings along said core each with a layer of joining material joining it to a previous ring to complete a roll.

References Cited in the file of this patent UNITED STATES PATENTS Re.17,740 Martin July 22, 1930 226,013 Allen Mar. 30, 1880 228,034 Detr-ick Nov. 6, 1883 1,074,983 Sborowitz Oct. 7, 1913 1,624,904 Claus Apr. 12, 1927 1,787,890 Woodward Jan. 6, 1931 2,110,143 Ball et a1 Mar. 8, 1938 2,605,533 Hirsh Aug. 5, 1952 2,883,703 Frank Apr. 28, 1958 2,983,990 Stevenson et al. May 16, 196 1

Claims (1)

1. THE METHOD OF FORMING A GRANITE ROLL FOR A PAPER MAKING MACHINE USING AN ANNULAR MOLD SHORTER THAN THE ROLL COMPRISING THE STEPS OF FORMING A FIRST ANNULAR RING OF A MIXTURE OF GRANITE PARTICLES AND SYNTHETIC RESIN CEMENT WITHIN THE MOLD AROUND A CORE, SAID RING BEING OF A LENGTH LESS THAN THE CORE AND HOLDING THE MIXTURE TO A CYLINDRICAL SHAPE AND COMPACTING IT AXIALLY, PERMITTING THE FIRST RING TO SET TO SUFFICIENT HARDNESS TO SUPPORT AN AXIAL FORCE OF COMPACTING A SECOND RING THEREAGAINST, APPLYING A JOINING MATERIAL TO AN END FACE OF THE RING, THEREAFTER MOVING THE MOLD AXIALLY AND FORMING A SECOND ANNULAR RING OF A MIXTURE OF GRANITE PARTICLES AND SYNTHETIC RESIN CEMENT AROUND THE CORE AGAINST THE END OF THE FIRST RING WITH SAID JOINING MATERIAL THEREBETWEEN, AND SIMILARILY FORMING SUCCESSIVE ANNULAR RINGS ALONG SAID CORE EACH WITH A LAYER OF JOINING MATERIAL JOINING IT TO A PREVIOUS RING TO COMPLETE A ROLL.

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