GB2316646A - Process for production of rubber roll - Google Patents

Abstract

A process for producing a rubber roll comprises the steps of pouring a material having a flowability at a normal temperature and capable of being cured with time, e.g. concrete, into a mold comprising a tube member made of a rubber and at least one covering member mounted at at least one end of the tube member, and curing the material poured in the mold to form a core in the tube member. A mold for producing a rubber roll, which comprises a tube member made of a rubber and at least one covering member covering at least one end of the tube member, are provided. The rubber roll is used in copiers or printers, as a paper-feeding roll, conveying roll or platen roll.

Description

SPECIFICATION Title of the Invention Process for Producing a Rubber Roll Field of the Invention The present invention relates to a novel process for producing a rubber roll with a core made of a cement or a mortar, more particularly to a process for producing a rubber roll with a cement or mortar core, suitable for various rubber rolls such as a paper-feeding roll, conveying roll or platen roll, and further to the rubber roll used in copiers or printers.

Backqround of the Invention A platen roll used in dot printers is normally driven by a stepping motor. The platen roll conventionally used is a rubber roll made of an iron core and a rubber applied onto the core. Since this rubber roll is heavy and has a high moment of inertia, rotation of the rubber roll is hardly stopped at a predetermined position when driven by a stepping motor. Therefore, a backward force must be applied to the conventional rubber roll in order to stop the rotation of the roll at the predetermined position.

Recently, use of a rubber-coated core made of a cement or mortar for the platen roll has been studied. The specific gravity of the cement or mortar is generally 3 or less, which is about a half or less of that of iron, about 7.9.

Therefore, the rubber roll with a core made of a cement or a mortar is much lighter than that with a core made of iron.

For this reason, such a rubber roll can be stopped at a predetermined position under a smaller amount of backward force when driven by a stepping motor. Furthermore, since a cement or a mortar has a sound-damping property, noise generated from the type of printer in which a wire impacts against a printing surface of paper (often referred to as a "wire-dot printer') can advantageously be attenuated in printing.

Such a rubber roll has hitherto been produced by firstly preparing a cement or a mortar core and then covering the core with a rubber in a cylindrical form.

An example of prior art processes for producing a rubber roll with a core made of a cement or a mortar is shown in Fig. 9, in which numeral 1' denotes a rubber tube, and 10' a core made of a cement or a mortar. In the process shown in Fig. 9, the previously prepared core 10' is pressed into the rubber tube 1'.

The rubber roll is strictly required to has a smaller amount of deflection, that is, the core itself is also strictly required to has a smaller amount of deflection.

Therefore, a mold for producing the core must have a high degree of precision and hence it is highly expensive.

Cement or mortar needs a long period of time for cure.

For example, it takes about 2 hours until the cement is so cured at 700C that it may be pressed into a rubber tube.

When a great number of rubber rolls are to be produced by the above-mentioned process, a great number of molds for making the cores are needed. Therefore, the above-mentioned process is uneconomical for mass production of the rubber rolls.

A high pressure is required to press the core made of a cement or a mortar into a rubber tube, as well as the surface of the core must be wetted with an alcohol for providing good sliding between the core and the tube. Therefore, the above-mentioned process is poor in workability.

Summary of the Invention The object of the present invention is to provide a process for producing a rubber roll with a core made of a cement or a mortar, which process is excellent in that it does not require any specific core-making mold and is good in workability.

In order to achieve the object mentioned above7 there is provided a process for producing a rubber roll comprising the steps of: (a) pouring a material having flowability at a normal temperature and capable of being cured with the passage of time into a mold comprising a rubber tube member and at least one covering member at the ends of the tube; and (b) curing the material having been poured into the mold to form the core for the rubber roll.

The material having flowability at a normal temperature and capable of being cured with the passage of time used in the present invention may be selected from the group consisting of a cement, a mortar, a concrete, a light-weight concrete and an aerated concrete.

Brief Description of the Drawinqs Fig. 1 is a schematical view of an example of the process for producing a rubber roll in accordance with the present invention.

Fig. 2 is a schematical view of an example of the process for producing a rubber roll in accordance with the present invention, in which a curved tube member is straightened.

Fig. 3 is a schematical view of another example of the process in accordance with the present invention, in which a curved tube is straightened.

Fig. 4 is a schematical view of an example of the process for producing a rubber roll with a core having a metal axis at the center thereof.

Fig. 5 is a three-dimensionally analytical view of another example of a mold used in the process shown in Fig.

4, when the tube member is curved.

Fig. 6 is a three-dimensionally analytical view of a further example of a mold used in the process shown in fig.

4, when the tube member is curved.

Fig. 7 is a three-dimensionally analytical view of a mold used in the process for producing the rubber roll in accordance with the present invention, in which the covering is retained as an end plate of the produced rubber roll.

Fig. 8 is a cross-sectional view of the mold shown in Fig. 7, one showing the mold which is filled with a cement and the other the mold which has the covering members cut off therefrom.

Fig. 9 is a schematical view of a conventional process for producing a rubber roll with a cement or mortar-made core.

Detailed Description of the Preferred Embodiments The rubber tube member is a cylindrical tube made of one of various rubbers, and constitutes at least one portion of the mold for making the rubber roll, together with the covering member. The mold is filled with a material which is flowable at a normal temperature and curable with time, such as a cement, and the material is then cured to form the core in the rubber tube member. The rubber tube is not separated from the core and the rubber tube forms a rubber body of the rubber roll.

Since the tube member constitutes one portion of the mold, it should preferably be self-sustaining and so rigid that it does not deform with the weight of the material being poured.

The tube member is preferably formed by, for example, extruding or injection molding a rubber in a cylindrical form, or curling up a rubber sheet in a tube form and adhering or fusing both the ends of the sheet, or extruding or injection molding a rubber in a cylindrical solid body and then boring the body along the axis thereof. Furthermore, the rubber tube member may comprise one rubber layer or at least two rubber layers laminated, between which may be provided a layer made of natural fibers such as cotton and jute fibers, synthetic fibers such as nylon fibers, polyester fibers, polypropylene fibers and polyethylene fibers, metal fibers such as stainless steel fibers and aluminum fibers, inorganic fibers such as glass fibers, ceramic fibers and carbon fibers, or a plastic film such as polyester film, polyamide film and polyurethane film.

The tube member may be made of a rubber generally used for the rubber roll. Such a rubber may be a synthetic diene rubber such as butadiene rubber, isoprene rubber, styrenebutadiene rubber, nitrile-butadiene rubber and chloroprene rubber, an olefin rubber such as butyl rubber, halogenated butyl rubber, acrylic rubber, ethylene-propylene rubber, ethylene-propylene-diene ternary copolymer rubber, chlorinated polyethylene, chlorosulfonated polyethylene and fluorinated rubber, a polyether rubber such as epicholorohydrin rubber, a natural rubber, a silicone rubber, a polysulfide rubber, an urethane rubber, and a styrene-butadiene block copolymer, styrene-isoprene block copolymer, styrenebutadiene block copolymer hydride, styrene-isoprene block copolymer hydride, a mixture of an ethylene-propylene rubber and polypropylene, a mixture of an ethylene-propylene rubber and polyethylene, and a thermoplastic rubber such as a thermoplastic urethane rubber, thermoplastic polyester rubber, thermoplastic polyester-polyamide rubber, thermoplastic polyamide rubber, thermoplastic vinyl chloride rubber and thermoplastic 1,2-butadiene rubber. Furthermore, fibers of at least one selected from the group consisting of silk, cotton, nylon, polypropylene, polyester and 1,2polybutadiene may be dispersed in the above-mentioned natural rubbers, diene rubbers or olefin rubber to form a fiber-reinforced rubber. The fiber-reinforced rubber may be made by treating the reinforcing fibers with a latex containing a resol and then mixing these fibers with the natural rubber, diene rubber or olefin rubber. Still further, a fine fiber-reinforced rubber made by melt kneading the natural rubber, the synthetic diene rubber or the olefin rubber with a polymer which is capable of forming a fiber such as a nylon or a polyethylene terephthalate and a binder such as a phenol-formaldehyde precondensate and then extrud ing the resultant mixture and extending it is preferably used as the material for the tube member.

The type of the covering member is not limited as far as it has such a structure that it is mounted so that it can close the ends of the tube and the fluid material filled up in the tube members does not leak out. For example, it may have such a structure that it has a projecting part capable of associating with the end opening of the tube, that it has a recess capable of associating with the projecting part of the tube, or that it can be applied to the end opening of the tube to close the end opening.

The covering member may have a hole through which the material capable of forming the core is poured into the mold. Further, the core may have a hole through which an axis is provided at the center of the core, thereby producing a rubber roll with a core having an axis at the center thereof. Still further, if the rubber tube is curved, then it must be straightened. In such a case, a pair of these covering members may be fixed to face each other, each having a plurality of holes provided therein, through each of which holes a rod is inserted so that the rubber tube can be straightened.

The covering member may be removed after the curable material was poured and cured to form the core, or may be retained as it is at the opposite ends of the roll.

The material used for the covering member is not limited but may be a thermoplastic resin such as a polypropylene resin, polyethylene resin, ethylene-propylene copolymer resin, multi-purpose polystyrene resin, shock impact resistant polystyrene resin, styrene-a-styrene copolymer resin, polycarbonate resin, polyacetal resin, acrylic resin, acrylonitrile-styrene copolymer resin, acrylonitrile-butadienestyrene copolymer resin, polyamide resin, polytetrafluoroethylene resin, ethylene-tetrafluoroethylene copolymer resin, polyvinylidene fluoride resin, hard polyvinyl chloride resin, vinyl chloride-vinyl acetate copolymer resin, polysulfonic resin, polyether sulfonate resin, polyphenylene sulfide resin, polyetheretherketone resin, polyphenyleneether resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polyether-imide resin and polyamideimide resin, a polymer alloy comprising plural kinds of the above-mentioned resins, a cellulose resin such as cellulose acetate, cellulose butyrate, cellulose acetate butyrate, ethyl cellulose and benzyl cellulose, and a thermosetting resin such as an epoxy resin, phenol resin, hard polyurethane resin, urea resin, melamine resin and polyimide resin.

To these thermoplastic resin, polymer alloy and thermosetting resin may be added at least one selected from the group consisting of an inorganic filler of, for example, talc, glass beads, glass powder or calcium carbonate, glass long fibers, glass short fibers, carbon fibers, and ceramic fibers. Furthermore, glass fiber- or carbon fiber-reinforced resin is preferred.

As a material used for the covering member may be used a metal material such as stainless steel, carbon steel, free-cutting steel, copper, brass, bronze, aluminum bronze, beryllium bronze, nickel, nickel-copper alloys, nickelchromium alloys, pure titanium, titanium alloys, pure aluminum, aluminum alloys and magnesium alloys.

For the covering member may also be used a hard wood material such as ebony, rosewood, mahogany, boxwood, cherry or maple, and further also used various ceramics such as silica, alumina, SiAlON, zirconia, titania, silicon carbide, boron nitride and aluminum phosphate.

When synthetic resins such as thermoplastic resins, polymer alloys, cellulose resins and thermosetting resins are used as the material for the covering member, a forming method such as compression molding, transfer molding and injection molding may be used. When the metal or alloys are used as the material for the covering member, the covering member may be prepared by a working method such as pressing, machining and electric discharge machining. Further, when the ceramics are used as the material for the covering member, the covering member may be prepared by compacting, transfer molding or injection molding a raw material powder containing a binder and then sintering the molding. Still further, when the wood is used as the material for the covering member, the covering member may be prepared by cutting the wood with a wood processing lathe.

In the present invention, the material having a flowability at a normal temperature and capable of being cured with time may be a material such as a cement or mortar which is flowable at a normal temperature when poured into the mold comprising the covering member and the tube, and cured with time after the pouring. Since such a material is used for preparing the core of the rubber roll, it should preferably have a high uniformity, high hardness, high strength and good sound-absorbing qualities. The material having such properties as mentioned above may be not only the hydration-curing material such as cement, but also a cold cure resin curable by reacting a main material with a curing agent, such as an epoxy resin, two-pack urethane or unsaturated polyester resin, and an ultraviolet-curing resin such as an ultraviolet-curing acrylic resin.

The hydration-curing material may include a cement, a mortar, a concrete, gypsum, etc.

The cement includes, for example, a lime silicate cement, a lime aluminate cement, a lime aluminate silicate cement and a lime phosphate cement. The lime silicate cement includes Portland cement, a mixed cement which is a mixture of Portland cement and admixtures or additives and the like.

In the process of the invention, a cement, in particular Portland cement, and a concrete containing water and an aggregate such as small particle sands are preferable.

Among the concrete a light-weight concrete such as a mortar and a plaster is excellent in sound absorption. Thus a platen employing a rubber roll with the core of a light weight concrete can reduce the noise of printing.

The cold cure material may be a cold cure epoxy resin, two-pack polyurethane resin, one-pack polyurethane resin, unsaturated polyester resin, etc. These cold cure resins may be blended with an inorganic filler such as talc, calcium carbonate, carbon black, glass beads and glass particles; and inorganic fibers such as glass short fibers, glass long fibers, carbon short fibers, carbon long fibers and ceramic fibers. Furthermore, a reactive foaming agent or low boiling point organic solvent may be added to the cold cure resins, or air or nitrogen gas may be blown into the cold cure resins, and then the resins are poured into the mold in which the resins are cured and foamed.

For the ultraviolet-curing resin are preferably used compositions comprising a monomer such as a methacrylate, a prepolymer such as a polyesteracrylate, epoxy acrylate, urethane acrylate, alkyd resin acrylate and silicone resin acrylate, and ultraviolet-polymerization initiators incorporated therein.

In the present invention, the hydration-curing material is preferable for the material having a flowability at a normal temperature and capable of being cured with time. A concrete having a specific gravity of 3 or less is preferable among the hydration-curing material.

A rubber roll employing a concrete having a specific gravity of 3 or less is light in weight per se. When the rubber roll is driven by a stepping motor, the load of the stepping motor can be reduced due to a small moment of inertia of the rubber roll.

In accordance with the present invention, the rubber roll may be produced by, for example, the following steps: (a) putting one covering member in each of both ends of the tube member to form the mold, one of the covering members having an opening through which the core-forming material is poured into the mold, (b) allowing the mold to stand upright with the covering member having the opening being at the top, (c) pouring the core-forming material into the mold through the opening, (d) leaving the mold to stand, in which the core-forming material is cured to form the core, (e) removing the covering member or members after the coreforming material was cured, and finishing the covering member-removed end(s) by a machine such as a lathe, so that it or they are flat.

These steps may be modified within the spirit of the present invention, and are modified, for example, as follows: A covering member is put into only one end of a tube member. Then, the tube member is allowed to stand upright on the end with the covering member put therein. A material having flowability at a normal temperature and capable of being cured with time is poured into the tube member. When the tube member is filled with the material, the remaining end of the tube member is closed by another covering member.

The tube member is left to stand, thereby curing the poured material to form the core.

Furthermore, a covering member having a hole through which a metal axis passes may be used to produce the rubber roll with the metal axis through the center of the core.

Still further, in the case where the tube member is curved, two covering members with a plurality of holes through which the rods are inserted may be used, the rods being inserted through all the holes of the covering members facing each other, and fixed, thereby straightening the curved tube member.

Alternatively, the curved tube member may be straightened by tightly placing a straight cylinder member of a highly rigid material outside the tube member. The highly rigid herein used means that there occurs little curving of the cylinder member when the curved tube member is placed in the cylinder member, and there is little deformation of the cylinder member due to the weight of the material poured into the tube member.

The highly rigid material used for the cylinder member includes various synthetic resins and metal materials.

The synthetic resins may be a thermoplastic resin such as polypropylene resin, polyethylene resin, ethylene-propylene copolymer, multi-purpose polystyrene, shock impact resistant polystyrene, styrene-a-styrene copolymer, polycarbonate, polyacetal, acrylic resin, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, polyamide resin, polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride, hard polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polysulfonate resin, polyether sulfonate resin, polyphenylene sulfide resin, polyetherether ketone resin, polyphenylene ether resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polyether imide resin and polyamide imide resin, and a polymer alloy comprising a plurality of the above-mentioned thermoplastic resins, a cellulose resin such as cellulose acetate, cellulose butyrate, cellulose acetate butyrate, ethyl cellulose and benzyl cellulose, a thermosetting resin such as an epoxy resin, phenol resin, hard polyurethane resin, urea resin, melamine resin and polyimide resin. Into these thermoplastic resins, polymer alloys and thermosetting resins may be incorporated at least one selected from the group consisting of inorganic fillers such as talc, glass beads, glass powder and calcium carbonate, long glass fibers, short glass fibers, carbon fibers, and ceramic fibers. Glass fiber-reinforced resins and carbon fiber-reinforced resins are also preferably incorporated.

For the metal material may be used stainless steel, carbon steel, cutting steel, copper, brass, bronze, aluminum bronze, beryllium bronze, nickel, nickel-copper alloys, nickel-chromium alloys, pure titanium, titanium alloys, pure aluminum alloys and magnesium alloys.

The cylinder member is not limited in thickness, but should preferably be thicker in view of the rigidity, more preferably 1 mm or more. The cylinder member may be comprised of two or more parts divided in a longitudinal direction.

After the core was formed, the covering members may be removed from the rubber roll, or the covering members may be retained as the end plate. When the covering members are retained as they are at the ends of the rubber roll, they may be cut with a bite and finished to have so parallel and flat surfaces as possible. In particular, when a rubber roll with a core made of a hydration-curing material such as a cement or mortar is directly machined with a bite, the bite and the core both are broken with ease, and the end faces are hardly finished. To the contrary, the covering member is made of the above-mentioned various thermosetting resins, polymer alloys, cellulose resins, thermoplastic resins, metal materials and hard wood materials and, hence, it can easily be machined to form the covering member a highly flat surface. Therefore, the rubber roll with a core made of a cement or mortar should preferably have the covering members retained in the tube member, by machining them to be end plates.

The process for producing the rubber roll in accordance with the present invention will be illustrated below with reference to the drawings.

Fig. 1 is a schematical view of one example of the process for producing the rubber roll in accordance with the present invention. In Fig. 1, numeral 100 represents a rubber roll. Numeral 1 represents a tube member made of a rubber, numeral 2 a covering member, and numeral 3 an opening provided in the covering member, through which a coreforming material such as a cement is poured into the tube member. Numeral 10 represents a core of the rubber roll 100. Numeral 11 represents a projection corresponding to the opening 3. Numeral 20 represents a mold for forming the core 10. Numeral 21 represents a recess formed in the covering member 2.

In the example shown in Fig. 1, covering member 2 acts as a cover for the end of tube member 1. Covering member 2 has a recess 21 formed therein. The end of tube member 1 is inserted in the recess 21. One of two covering members 2 has an opening 3 at the center of recess 21, i.e., on the axis of covering member 2.

Fig. 1 includes a three-dimensionally analytical view of the structure of mold 20. As shown in Fig. 1, the ends of tube member are inserted in recesses 21 to form mold 20.

A cement is poured in mold 20 at opening 3, as shown in Fig. 1 with arrow A near the center thereof, thereby filling the mold with the cement. Thereafter, the cement is cured to form core 10.

Covering members 2 are removed from tube member 1 filled with the cured cement, as shown in Fig. 1. The ends of core 10 and tube member 1 are finished by machining to have a flat face, thus forming rubber roll 100. The rubber roll 100 is not removed, and acts as a rubber cover for the core. The side of tube member 1 may also be finished by polishing as desired.

Projection 11 may be removed as desired, when both the ends of the core 10 and tube member 1 are finished to have flat faces parallel to each other. In the example of Fig.

1, the projection is retained.

Fig. 2 is a schematical view of an example in which a curved tube member 1 is straightened. In Fig. 2, numeral 100 represents a rubber roll. Numeral 1 represents a tube member made of rubber, numeral 2 a covering member, numeral 3 an opening provided at the covering member 2, through which a cement is poured, numeral 4 a rod for fixing the covering members 2 facing each other, numeral 5 a hole provided in covering members 2, through which the rod 4 is inserted, numeral 10 a core of the rubber roll 100, numeral 11 a projection to be engaged with opening 3, numeral 20 a mold for forming core 10, and numeral 21 a recess provided in covering member 2.

Each of the covering members 2 shown in Fig. 2 has a recess 21 formed therein in the same manner as shown in Fig.

1. The ends of tube member 1 are inserted in recesses 21.

Each of the covering members 2 is provided with four holes 5 around the recess 21. The rod 4 is inserted in each of the holes 5, followed by covering both the ends of tube member 1 with covering members 2, so that the covering members face each other, and fixing the covering members, so that tube member 1 is straightened.

Fig. 2 includes a three-dimensionally analytical view of the structure of mold 20.

A cement is poured through opening 3 in mold 20, as shown in Fig. 2 with arrow A, thus filling the mold with the cement. The cement is cured as it is to form core 10.

Covering members 2 are removed from tube member 1 filled with the cured cement, as shown in Fig. 2. The ends of core 10 and tube member 1 are finished by machining to have a flat face, thus forming rubber roll 100. The rubber roll 100 is not removed, and acts as a rubber cover for the core 10. The side of tube member 1 may also be finished by polishing as desired.

Projection 11 may be removed when both the ends of the core 10 and tube member 1 are finished to have flat faces parallel to each other. In the example of Fig. 2, the projection is retained.

Fig. 3 is a schematical view of another example in which a curved tube member 1 is straightened. In Fig. 3, numeral 100 represents a rubber roll. Numeral 1 represents a tube member made of rubber, numeral 2 a covering member, numeral 3 an opening provided at the covering member 2, through which a cement is poured, numeral 6 a cylindrical member for covering the tube member 1, numeral 10 a core of rubber roll, numeral 11 a projection to be engaged with opening 3, numeral 20 a mold for forming core 10, and numeral 21 a recess provided in covering member 2.

The covering members 2 shown in Fig. 3 act as a cover for the ends of tube member 1, like the covering member 2 shown in Fig. 1. The covering members 2 each are provided with recesses 21 at the center thereof. The ends of the tube member 1 are inserted in these recesses 21. One of the covering members has an opening 3 provided therein at the center of the recess 21, i.e., on the axis of the covering member. Cylindrical member 6 is highly rigid and straight, and has approximately the same inner diameter as the outer diameter of the tube member 1, so that cylindrical member 6 can tightly cover tube member 1. The longitudinal length of cylindrical member 6 is shorter than that of tube member 1 by the total length of the portions of tube member 1 which are inserted in the respective recesses 21.

As illustrated in a three-dimensionally analytical view included in Fig. 3, each of the ends of tube member 1 is inserted in recess 21 to form mold 20. The cylindrical member allows the curved tube member to be straightened.

Then, mold 20 is filled with a cement by pouring the cement through the opening 3 as shown in Fig. 3 with arrow A at the middle position therein. The cement is cured to form core 10.

Covering members 2 are removed from tube member 1 filled with the cured cement, as shown in Fig. 3. The ends of core 10 and tube member 1 are finished by machining to have a flat face, thus forming rubber roll 100. The rubber roll 100 has the tube member retained, which acts as a rubber cover for the core. The side of tube member 1 may also be finished by polishing as desired.

Projection 11 may be removed as desired, when both the ends of the core 10 and tube member 1 are finished to have flat faces parallel to each other. In the example of Fig.

3, the projection is retained.

Fig. 4 is a schematical view showing an example of the process for producing a rubber roll with a metal axis at the center of core 10. In Fig. 4, numeral 100 represents a rubber roll. Numeral 1 represents a tube member made of rubber, numeral 2 a covering member, numeral 7 the metal axis, numeral 8 a hole in which the metal axis is inserted, numeral 10 a core of the rubber roll 100, and 20 a mold.

Numeral 21 represents a recess formed in the covering member 2.

The covering members 2 shown in Fig. 4 are covers for the ends of the tube member 1. A recess 21 is provided at the center of the covering member 2. The end of the tube member 1 is inserted in the recess 21. Hole 8 in which the metal axis 7 is inserted is provided at the center of recess 21, i.e., in the axis of the covering member.

Fig. 4 includes a three-dimensionally analytical view of the structure of mold 20. As shown in Fig. 4, one of the ends of tube member 1 is covered with covering members, numeral 4 rods for fixing the covering members facing each other, numeral 5 holes in which the rods 4 are inserted, numeral 7 a metal axis being through the center of the core 10, numeral 8 a hole through which the metal axis 7 is inserted, numeral 20 a mold, and numeral 21 a recess provided at the covering member 2, with which the tube member 1 is engaged.

In the mold 20 shown in Fig. 5, the covering members 2 act as a cover for the ends of then tube member. The covering members 2 have recesses 21 with which the ends of the tube member 1 are to be engaged. Hole 8 through which metal axis 7 is inserted is provided at the center of each of the recesses 21, i.e., in the taxis of the covering member. Four holes 5 through which the rods are inserted respectively are provided in each of the covering members around the hole 8.

When a rubber roll is to be produced with the mold 20, the following process may be taken.

Firstly, the mold 20 is formed by inserting one of the ends of tube member 1 into the recess 21 of the covering member 2. In this case, metal axis 7 is inserted through hole 8 provided in covering member 2. Rods 4 are inserted through holes 5, respectively.

Then, tube member 1 is allowed to stand upright with the bottom end covered by the covering member and the top end not covered. A cement is poured into the tube member at the top end thereof, thus filling the mold 20 with the cement. Thereafter, the top end is covered by the other covering member 2. The other end of the metal axis 7 is inserted through hole 8 provided in the other covering member 2. The other ends of the rods 4 are inserted through holes 5, respectively. The top end of the tube member 1 is inserted into the recess 21 of this covering member 2. The cement is cured to form core 10.

Covering members 2 are removed with axis 7 retained after the curing of the cement. Core 10 and tube member 1 are finished at both the end faces by machining, thus form ing rubber roll 100. Rubber roll 100 has tube member retained, which acts as a rubber cover for the core 10. The side of the tube member may be finished by polishing as desired, after the formation of core 10.

Fig. 6 is a three-dimensionally analytical view of a still further example of mold 20, in which tube member 1 is curved in the example shown in Fig. 4. In Fig. 6, numeral 1 represents a tube member made of rubber, numeral 2 covering members, numeral 6 a cylindrical member for covering the tube member 1, numeral 7 a metal axis through the center of the core 10, numeral 8 a hole through which the metal axis 7 is inserted, numeral 20 a mold, and numeral 21 a recess provided at the covering member 2, with which the tube member 1 is engaged.

In the mold 20 shown in Fig. 6, the covering members 2 act as a cover for the ends of the tube member 1. The covering members 2 each have recesses 21 with which the respective ends of the tube member 1 are to be engaged.

Hole 8 through which metal axis 7 is inserted is provided at the center of each of the recesses 21, i.e., in the axis of the covering member. Cylindrical member 6 is highly rigid and straight, and has approximately the same inner diameter as the outer diameter of the tube member 1, so that cylindrical member 6 can tightly cover tube member 1. The longitudinal length of cylindrical member 6 is shorter than that of tube member 1 by the total length of the portions of tube member 1 which are inserted in the respective recesses 21.

When a rubber roll is to be produced with the mold 20, the following process may be taken.

First, the mold 20 is formed by inserting one of the ends of tube member 1 into the recess 21 of the covering member 2. In this case, metal axis 7 is inserted through hole 8 provided in covering member 2. Tube member 1 is covered by cylindrical member 6.

Then, tube member 1 is allowed to stand upright with the bottom end covered by the covering member and the top end not covered. A cement is poured into the tube member 1 at the top end thereof, thus filling the mold 20 with the cement. Thereafter, the top end is covered by the other covering member 2. The cement is cured to form core 10.

Covering members 2 are removed with axis 7 retained after the curing of the cement. Further, cylindrical member 6 is removed. Core 10 and tube member 1 are finished at both the end faces by machining, thus forming rubber roll 100. Rubber roll 100 has tube member 1 retained, which acts as a rubber cover for the core 10. The side of the tube member 1 may be finished by polishing as desired, after the formation of core 10.

Fig. 7 is a three-dimensionally analytical view of an example of the mold 20 by which the covering members are retained as end plates in the finished rubber roll.

In Fig. 7, numerals 1, 2, 7, 8 and 20 represent the same things as shown in Figs. 1-6. Further, numeral 22 represents a part of covering member 2 having a smaller outer diameter than that of tube member 1 and being inserted in the end of the tube member, and numeral 23 a part of covering member 2 having approximately the same outer diameter as that of the tube member 1.

Fig. 8 is a cross-sectional view of mold 20 shown in Fig. 7 and filled with cement, and covering member 2 as machined.

In Fig. 8, numerals 1, 2, 7, 8, 20, 22 and 23 represent the same things as shown in Fig. 7.

Fig. 8 includes a view of mold 20 filled with cement.

As seen in Fig. 8, the part 22 of covering member 2, i.e., a projection which has such a shape that it projects at one end of covering member 2 and can be inserted in the end of tube member 1. The part 22 alone is inserted in the end of tube member 1. Mold 20 in such a condition as mentioned above is filled with a cement, which is then cured. After curing of the cement, the part 23 of covering member is machined without removing both tube member 1 and covering member 2, thus forming rubber roll 100. In Fig. 8, the machined part surrounded with a two-dot chain line was removed. In an example shown in Fig. 8, lower part, the whole of part 23 is removed, but the whole is not always required to be removed.

In the process for producing the rubber roll in accordance with the present invention, the rubber-made tube member itself acts as a mold for forming the core at the time of forming the rubber roll and as a cover on the core at the time when the rubber roll was completed. Therefore, the process of the present invention is different from prior art processes in which the core previously formed is pressed into the rubber cover. Thus, the process of the present invention does not require to press the core into the rubber cover, and hence is good in workability and efficiency of workability.

Claims (5)

What is claimed is:

1. A process for producing a rubber roll, which comprises the steps of pouring a material having a flowability at a normal temperature and capable of being cured with time into a mold comprising a tube member made of a rubber and at least one covering member mounted at at least one end of the tube member, and curing the material having been poured in the mold to form a core in the tube member.

2. A process according to claim 1, wherein the material is selected from the group consisting of a cement, a mortar, a concrete, a light-weight concrete and an aerated concrete.

3. A process according to claim 1, wherein the covering member has a recess provided therein, into which the end is inserted.

4. A process for producing a rubber roll which comprises: preparing a tube member made of a rubber having a first end and a second end; making a first covering member and a second covering member, the second covering member having a through opening; putting a first and a second covering members in the first and second ends respectively to make a mold; allowing the mold stand upright on the first covering member with the second covering member being up; pouring a core-forming material having a flowability at a normal temperature and capable of being cured with time into the mold through the through opening; and leaving the mold to stand to cure the core-forming material.

5. A process according to anyone of the preceding claims, wherein the coreforming material is selected from the group consisting of a cement, a mortar, a concrete, a light-weight concrete, an aerated concrete and a gypsum.

5. A process according to claim 4, wherein the first covering member has a first recess provided therein, the second covering member has a second recess provided therein, the first and second ends are respectively inserted in the first and second recesses, and the second covering member has the through opening in the second recess.

6. A process according to claim 5, further comprising: making first holes in the first covering member around the first recess, and making second holes in the second covering member around the second recess, the second holes being the same number as the first holes and each of the second holes confronting with each of the first holes; rods are inserted through the first and the second holes respectively so as to fix the first and the second covering members, thereby straightening the tube member, at the same time as putting the first and the second covering members on the first and second-ends respectively; after the cure of the core-forming material, removing the first covering member, the second covering member and the rods; and finishing the first and the second ends.

7. A process according to claim 4, further comprising: preparing a cylindrical member which is highly rigid; after making the mold and before performing the pouring step, tightly covering the tube member with cylindrical member, thereby straightening the tube member; and after the cure of the core-forming material, removing the cylindrical member.

8. A process according to claim 7, wherein the length of the cylindrical member is shorter than that of the tube member by the total length of the parts of the tube member which are inserted in the first and second recesses.

9. A process according to claim 4, further comprising: removing the first and the second covering members after the cure of the core-forming material; and finishing the first and the second ends.

10. A process according to claim 4, further comprising: finishing the first and the second covering members after the cure of the core-forming material.

11. A process according to claim 7, further comprising: removing the first and the second covering members after the cure of the core-forming material; and finishing the first and the second ends.

12. A process according to claim 7, further comprising: finishing the first and the second covering members after the cure of the core-forming material.

13. A process according to claim 4, wherein the coreforming material is selected from the group consisting of a cement, a mortar, a concrete, a light-weight concrete and an aerated concrete.

14. A process for producing a rubber roll which comprises: prepare a tube member made of rubber a having a first end and a second end; making a first covering member having a first recess provided therein and making a second covering member having a second recess provided therein; making a first hole in a center of the first recess and making a second hole in a center of the second recess; putting the first covering member on the first end so that the first end is engaged with the first recess to make a mold, and inserting a metal axis into the first hole; allowing the mold stand upright on the first covering member with the second end being up; pouring a core-forming material having a flowability at a normal temperature and capable of being cured with time into the mold through the second end; putting the second covering member on the second end so that the second end is engaged with the second recess and that the metal axis passes through the second hole; and leaving the mold to stand to cure the core-forming material.

15. A process according to claim 14, further comprising: removing the first and the second covering members after the cure of the core-forming material with the metal axis retained in the core; and finishing the first and the second ends.

16. A process according to claim 14, further comprising: finishing the first and the second covering members after the cure of the core-forming material.

17. A process according to claim 14, wherein the coreforming material is selected from the group consisting of a cement, a mortar, a concrete, a light-weight concrete and an aerated concrete.

18. A process for producing a rubber roll, substantially as described herein with reference to the accompanying drawings.

Amendments to the claims have been filed as follows 1. A process for producing a rubber roll which comprises: preparing a tube member made of a rubber having a first end and a second end; making a first covering member having a first recess provided therein, and a second covering member having a second recess provided therein; making first and second axis holes in centres of the first and second recesses respectively; putting the first covering member on the first end so that the first end is engaged with the first recess to make a mold with inserting a metal axis in the first axis hole through the tube member; allowing the mold to stand upright on the first covering member with the second end being up; pouring a core-forming material having a flowability at a normal temperature and capable of being cured with time into the mold from the second end to form a core; putting the second covering member on the second end so that the second end is engaged with the second recess with inserting the metal axis in the second axis hole; leaving the mold to stand to cure the core-forming material; and finishing the first and second covering members after the cure of the core-forming material.

2. A process according to claim 1, further comprising: making first holes in the first covering member around the first recess, and making second holes in the second covering member around the second recess, the second holes being the same number as the first holes and each of the second holes confronting with each of the first holes; rods are inserted through the first and the second holes respectively so as to fix the first and second covering members, thereby straightening the tube member, at the same time as putting the first and second covering members on the first and second ends respectively; and after the cure of the core-forming material, removing the rods.

3. A process according to claim 1, further comprising: preparing a cylindrical member which is highly rigid; after making the mold and before performing the pouring step, tightly covering the tube member with the cylindrical member, thereby straightening the tube member; and after the cure of the core-forming material, removing the cylindrical member.

4. A process according to claim 3, wherein the length of the cylindrical member is shorter than that of the tube member by the total length of the parts of the tube member which are inserted in the first and second recesses.