Process for producing a hard roll

Details Process for producing a hard roll Process for producing a hard roll

1995-08-11

1998-05-19

Silbaugh, Jan H.

Plastic and nonmetallic article shaping or treating: processes

With severing, removing material from preform mechanically,...

264161, 264327, 264257, 264258, 264275, 264277, 264263, 492 50, 492 56, 2989524, 29895212, 298953, 2989532, B29C 3910, B29C 3938, B29C 3940, B21C 1300

Patent

active

057531650

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to a process for producing hard rolls for use in papermaking, fibers and various other industries, and more particularly to a process for producing hard rolls for use as elastic rolls including papermaking calender rolls, papermaking press rolls (inclusive of rolls substituted for papermaking stone rolls and rolls substituted for papermaking rubber rolls), fiber calender rolls, calender rolls for magnetic recording materials, etc.


BACKGROUND ART

For example, for calendering, paper, fibers, magnetic recording materials or like thin material is usually passed between a mirror-surfaced metal roll and an elastic roll opposed thereto at a predetermined temperature and high nip pressure and is made smooth and glossy over the surface by the application of pressure.
Already known as such a calender roll is a hard roll having a lower winding layer provided around a metal roll core by winding a fiber material impregnated with epoxy resin around the core outer periphery, and a covering layer of epoxy resin formed directly around the lower winding layer by cast molding (see, for example, Examined Japanese Patent Publication SHO 61-15807).
However, epoxy resin or like thermosetting resin generally undergoes marked reaction contraction and thermal shrinkage when curing, so that the following problem is encountered. The covering layer is likely to crack in its surface owing to the shrinkage during production. This phenomenon appears markedly in hard rolls having a large diameter and a large length, with the result that great difficulties are experienced in producing such hard rolls.
Accordingly, we previously proposed a process free of the foregoing problem for producing hard rolls (see Examined Japanese Patent Publication HEI 3-47359). The proposed process comprises forming a metal roll core having a fiber-reinforced lower winding layer, forming an outer layer hollow cylinder of predetermined size independently of the roll core by casting a thermosetting resin material into a specified mold and curing the material, then fitting the outer layer hollow cylinder around the metal roll core having the fiber-reinforced lower winding layer, casting an adhesive of low viscosity into an annular clearance formed between the cylinder and the winding layer and curing the adhesive to bond the cylinder to the winding layer with the adhesive.
The roll produced by the proposed process of course had excellent surface smoothness, high surface hardness and high heat resistance. Especially no crack developed in the surface of the outer layer cylinder of thermosetting synthetic resin during production or use. Moreover, the roll retained surface hardness which remained almost unchanged even when subjected to heat during use, had compression strength sufficient to withstand the high nip pressure to be applied by a metal roll and was satisfactorily usable at all times with high durability.
However, with the proposed process for producing hard rolls, the outer layer hollow cylinder having a predetermined size and cured was prepared independently of the metal roll core and thereafter bonded to the lower winding layer with an adhesive of low viscosity cast into the annular clearance between the cylinder and the layer, so that the process had the problem of including many steps and being low in production efficiency and therefore relatively high in production cost.
An object of the present invention, which has been accomplished in view of the above problems, is to provide a process for producing a hard roll free of cracking due to the reaction contraction and thermal shrinkage of thermosetting resin, the roll being usable without cracking in its surface and having high durability to remain almost unchanged in its surface hardness despite the influence of heat during use, the process being reduced in the number of steps and improved in production efficiency to consequently ensure a very low production cost.


DISCLOSURE OF THE INVENTION

The present invention provides a process for producing a hard

REFERENCES:
patent: 871554 (1907-11-01), Ayisworth
patent: 2505807 (1950-05-01), Stott
patent: 2518504 (1950-08-01), Stott
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patent: 3049762 (1962-08-01), Jackson
patent: 3555140 (1971-01-01), Argereu
patent: 4892696 (1990-01-01), Murakami et al.
patent: 5089201 (1992-02-01), Takahashi
patent: 5091027 (1992-02-01), Watanabe
patent: 5656176 (1997-08-01), Scott

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