JPH04358825A - Manufacture of rubber roll - Google Patents

Abstract

PURPOSE:To provide a method for manufacture wherein a rubber roll with a high adhesive force between a core metal and a rubber roll part can be obtd. without occurrence of flash and decreasing in dimensional accuracy. CONSTITUTION:A cylindrical rubber roll raw material 5 wherein the inner diameter is the same length as, or a little larger than the outer diameter of a core metal and the outer diameter is a little smaller than the outer diameter of a rubber roll part 3, is molded by using a rubber contg. a foaming agent. This rubber roll raw material 5 is filled in a mild 6 for forming the outer peripheral face of the rubber roll part 3 and having a cavity face 6a with a diameter being equal to the outer diameter of a rubber roll part 3 and a round crosssection and the core metal 2 is inserted in a cylindrical hole of the rubber roll raw material 5 and the foaming agent in the rubber roll raw material 5 is expanded to obtain a rubber roll 1.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing rubber rolls used in printing machines, film processing machines, textile processing machines, plywood processing machines, office machines, ticket issuing machines, and the like.

0002

2. Description of the Related Art Rubber rolls are made by providing a cylindrical rubber roll portion on a core metal, and the press vulcanization method and the extrusion method are generally known as methods for manufacturing the rubber roll. In the former method, a core metal is placed between a pair of half-split molds, and the unvulcanized rubber material is placed above and below the core metal, and the unvulcanized rubber material is vulcanized by both molds. This is a method of obtaining rubber rolls by pressure vulcanization. In the latter method, a cylindrical rubber roll material is formed by extruding unvulcanized rubber through a die, and after this rubber roll material is vulcanized, a core metal is press-fitted into the cylindrical hole to obtain a rubber roll. .

0003

[Problem to be Solved by the Invention] In the case of the above-mentioned former method, when charging the unvulcanized rubber material into the mold, it is necessary to distribute the rubber material evenly over the entire circumference of the core metal. difficult. Therefore, when pressurized by the mold, uneven force acts on the core metal through the rubber material, causing the core metal to bend. Therefore,
When the product is taken out of the mold after vulcanization, the core bar is unbent, which may impair the dimensional accuracy of the resulting product. Further, for the above-mentioned pressure vulcanization, it is necessary to increase the amount of unvulcanized rubber material charged into the mold, but as a result, burrs are likely to occur and finishing processing (polishing) becomes troublesome.

On the other hand, in the latter case, in order to increase the adhesion between the rubber roll part and the core metal, it is necessary to make the outer diameter of the core metal slightly larger than the inner diameter of the rubber roll part. As a result, the compressive strain of the rubber roll portion when the core bar is press-fitted into the rubber roll portion increases, compressive stress remains in the product, and the dimensional accuracy (outer diameter) of the product also decreases. Therefore, it is necessary to separately apply annealing treatment to the product, and
Finishing of the product also becomes troublesome.

That is, an object of the present invention is to provide a manufacturing method capable of obtaining a rubber roll with high adhesion between the core bar and the rubber roll portion without causing the above-mentioned burrs or deterioration of dimensional accuracy. be.

[0006]

[Means for Solving the Problems] The present invention addresses these problems by employing a foaming method for manufacturing rubber rolls.

That is, a specific means for solving the above problem is a method for manufacturing a rubber roll in which a core metal is provided inside a cylindrical rubber roll portion, using a rubber material containing a foaming agent. A cylindrical rubber roll material is formed, the inner diameter of which is the same as or slightly larger than the outer diameter of the core metal, and the outer diameter of which is slightly smaller than the outer diameter of the rubber roll section. The mold is loaded into a mold having a cavity surface with a circular cross section whose diameter is equal to the outer diameter of the rubber roll material for forming the outer circumferential surface, and the core metal is passed through the cylindrical hole of the rubber roll material, and the state is as described above. The method is characterized in that the foaming agent for the rubber roll material is foamed.

[0008] The rubber materials used for forming the above rubber roll material include natural rubber, chloroprene rubber, styrene/butadiene rubber, ethylene/propylene rubber, butyl rubber, acrylic/nitrile/butadiene rubber, silicone rubber, urethane rubber, fluororubber, and halogenated rubber. Crosslinked rubber such as butyl rubber, chlorosulfonated polyethylene rubber, hydrogenated nitrile rubber, polyolefin type, polyester type,
It can be appropriately selected from thermoplastic elastomers such as polyether, polyamide, and polyurethane.

[0009] Further, as the blowing agent contained in the above rubber material, azodicarbonamide, azobisisobutyronitrile, diazoaminobenzene, dinitrosopentamethylenetetramine, p-toluenesulfonyl hydrazide,
p,p'-oxybis(benzenesulfonylhydrazide) and the like can be preferably used.

In this case, it is desirable to set the amount of the foaming agent so that 0.5 to 50% by volume of the rubber roll portion obtained by foam molding becomes bubbles. That is, if the foaming amount is less than 0.5% by volume, the desired effect cannot be obtained, whereas if the foaming amount exceeds 50% by volume, the elastic modulus of the rubber roll portion becomes too low.

[0011] Further, reinforcing agents such as carbon black, and inorganic fillers such as silica, talc, and clay may be optionally selected and used.

[0012] Further, the rubber material may be blended with rubber extender oil, rubber chemicals, and rubber additives, if necessary. As the rubber extension oil, those appropriately selected from aromatic, naphthenic, paraffinic, etc. can be preferably used. Rubber chemicals and rubber additives include vulcanizing agents such as sulfur and peroxide, vulcanization accelerators such as zinc white and stearic acid, and vulcanizing agents such as sulfenamide, thiuram, thiazole, and guanidine. Sulfur accelerators, amine-based, phenol-based, sulfur-based, phosphorus-based anti-aging agents, or antioxidants, ultraviolet absorbers, ozone deterioration inhibitors, tackifiers,
It can be selected from plasticizers and the like depending on the purpose of use.

An effective means for increasing the rigidity and abrasion resistance of the rubber roll is to use a rubber material mixed with short fibers in addition to the foaming agent in the molding process of the rubber roll material. That's true.

[0014] As the short fibers, any of organic fibers such as nylon fibers, meta-aramid fibers and para-aramid fibers, and inorganic fibers such as carbon fibers can be used.

[0015] As short fibers, the fiber length L is 0.2 mm.
Above, the aspect ratio L/D between the fiber length L and the fiber diameter D
is preferably 20 or more. In this case, the orientation of the short fibers in the rubber roll material is such that the proportion of short fibers oriented in the circumferential direction of the roll is greater than the proportion of short fibers oriented in other directions (that is, the proportion of short fibers oriented mainly in the circumferential direction of the roll is ), an orientation in which the proportion of short fibers oriented in the roll axis direction is greater than the proportion of short fibers oriented in the other direction, or an orientation in which the proportion of short fibers oriented in the roll radial direction is oriented in the other direction. The orientation can be appropriately selected and adopted from among the orientations in which the proportion of the short fibers is higher than that of the short fibers.

Regarding the orientation of the short fibers, the rubber roll is
From the perspective of providing a stable coefficient of friction in both dry and wet conditions, and both at high and low temperatures, the proportion of short fibers oriented in the radial direction of the roll is higher than the proportion of short fibers oriented in other directions. Such an orientation can be preferably adopted. That is, in that case, after the rubber roll is molded, the surface thereof is polished to expose a portion of the short fibers, and this exposed portion is utilized for stabilizing the coefficient of friction.

Further, the length L of the short fibers is set to 0.2 mm or more because if it is shorter than 0.2 mm, the length of the short fibers exposed on the outer peripheral surface of the roll becomes too short after polishing.
This is because the stability of the coefficient of friction against water and oil is not achieved, and the short fibers tend to fall off from the rubber, resulting in poor wear resistance. On the other hand, the reason why the aspect ratio L/D is 20 or more is because if it is smaller than 20, the rigidity at room temperature and high temperature will be low, and the abrasion resistance will be poor.

The mixing ratio of short fibers to rubber is preferably 2 to 30% by volume of the total rubber. This is because if the amount does not exceed 2% by volume, the effect of short fiber mixing on the modulus of elasticity etc. will be small, and if it exceeds 30% by volume, it will be difficult to incorporate the short fibers into rubber.

[0019] In forming the rubber roll material, a rubber compound having a predetermined composition is kneaded using an open roll or an internal mixer. Then, this kneaded rubber is extruded using a die to obtain a cylindrical rubber roll material.

[0020] Furthermore, the mold used in manufacturing the rubber roll may be a cylindrical mold, or a semi-cylindrical mold obtained by cutting the mold in half. In either case, both ends of the cylinder are sealed to prevent rubber leakage. In addition, a mold release agent is applied to the cavity surface of the mold to improve the mold release properties of the molded product.
Alternatively, it is preferable to perform coating treatment with a non-adhesive coating material such as a fluororesin (for example, a tetrafluoride resin) in advance.

[0021]

[Function] In the above manufacturing method, since the inner diameter of the rubber roll material is formed to be the same as or slightly larger than the outer diameter of the core metal, the core metal can be easily inserted into the cylindrical hole of the rubber roll material. can be passed through without causing deformation. In addition, the outer diameter of the rubber roll material is slightly smaller than the outer diameter of the rubber roll portion of the product, and therefore smaller than the diameter of the cavity of the mold, so it is easy to load it into the mold, and the rubber roll material can be easily loaded into the mold. It does not cause food to come out of the mold.

When the foaming agent of the rubber roll material is foamed, the rubber roll material expands in volume and completely fills the gap between the core metal and the mold, and furthermore, the pressure caused by the foaming causes the outer periphery of the core metal to expand. It is pressed against the surface and the cavity surface of the mold. This increases the adhesion between the rubber roll portion and the core metal of the obtained molded product, and increases the dimensional accuracy of the outer circumferential surface of the rubber roll portion. Further, by uniformly mixing the foaming agent into the rubber material, the elastic modulus of the resulting rubber roll can be made uniform over the entire rubber roll. Furthermore, by controlling the blending amount or expansion ratio of the foaming agent, desired hardness can be imparted to the rubber roll portion.

[0023] Furthermore, when a rubber roll material is formed from a rubber material mixed with short fibers, the short fibers make it possible to increase the rigidity and wear resistance of the rubber roll.

[0024]

[Effects of the Invention] Therefore, according to the present invention, since the rubber roll portion is formed by foaming, the outer diameter of the rubber roll material loaded into the mold can be made smaller than the diameter of the cavity of the mold. This makes it easier to load the rubber roll material into the mold, and it also makes it possible to obtain a rubber roll with high adhesion between the core metal and the rubber roll without causing burrs or deteriorating dimensional accuracy. It becomes possible to simplify or omit finishing processing of the product.

Furthermore, when short fibers are mixed into the rubber material, the rigidity and abrasion resistance of the rubber roll can be increased, and the decrease in elastic modulus due to foaming can be compensated for.

[0026]

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings. Figure 1 shows a short fiber-containing rubber roll 1 as a molded product.
It is shown. This short fiber-containing rubber roll 1 has a rubber roll portion 3 fitted and fixed to a core metal 2, and short fibers 4 are oriented in the radial direction in the rubber roll portion 3. Further, a part of the short fibers 4 is exposed from the outer circumferential surface of the roll.

FIG. 2 shows a rubber roll material 5 for forming the rubber roll portion 3 of the rubber roll 1. As shown in FIG. This rubber roll material 5 is molded in an unvulcanized state using an unvulcanized rubber material containing a foaming agent and short fibers, and has an inner diameter slightly larger than the outer diameter of the core bar 2. Moreover, it has a cylindrical shape with an outer diameter slightly smaller than the outer diameter of the rubber roll portion 3.

In molding the rubber roll material 5,
A rubber compound having a predetermined composition is kneaded using an open roll or an internal mixer. Then, this kneaded rubber is extruded using a die to obtain the cylindrical rubber roll material 5. Therefore, according to this method, no parting line is generated in the rubber roll material 5.

FIG. 3 shows a mold 6 for molding the rubber roll 1. As shown in FIG. This mold 6 has a cylindrical shape and has a cavity surface 6a having a circular cross section and an inner diameter (diameter) equal to the outer diameter of the rubber roll portion 3 for forming the outer circumferential surface of the rubber roll portion 3. Then, the mold 6
Seal members 7, 7 for preventing leakage of rubber material from the mold 6 are fixed to both ends with set screws. The seal members 7, 7 each have a core metal hole 7a through which the core metal 2 passes.

In forming the rubber roll 1, the core metal 2 is passed through the cylindrical hole 5a of the rubber roll material 5, and in this state, it is loaded into the mold 6. Seal members 7, 7 are attached to both ends of the mold 6, and the rubber roll material 5 is heated through the mold 6 to vulcanize it and foam the foaming agent. As a result, the rubber roll material 5 causes volumetric expansion and completely fills the gap between the core metal 2 and the mold 6.
Furthermore, due to the pressure caused by the foaming, the outer peripheral surface of the core metal 2 and the mold 6
is pressed against the cavity surface 6a.

Thereafter, the seal members 7, 7 are removed from the mold 6, and the rubber roll 1, which is a molded product, is taken out from the mold 6.

Next, examples for clarifying the effects of the present invention will be described together with comparative examples. The composition of the rubber material in the example is as follows.

Chloroprene rubber 100 parts by weight Carbon black 30 parts by weight Oxidation
Zinc 5 parts by weight Magnesium oxide 4 parts Stearic acid 1 part by weight Blowing agent 0.5 parts by weight Meta-aramid fiber 10 parts by weight In the above formulation, the meta-aramid fiber has a diameter of 14 μm.
A Teijin Conex with a length of 3 mm and an aspect ratio of 214 was used. In addition, neoprene GS manufactured by Showa Denko DuPont was used as the chloroprene rubber, and azobisisobutyronitrile (AIBN) was used as the blowing agent.

[0034] Furthermore, the formulation of the rubber material of the comparative example is the same as that of the above-mentioned example, but without the foaming agent.

Then, in the above embodiment, the mold 6
The amount of rubber material charged is 70% by volume and 80% by volume, respectively.
, 90% by volume (in this case, the volume% is the ratio with the volume between the core metal 2 and the mold 6 being 100). At that time, the inner diameter of the rubber roll material is 8.5 mm, which is 0.5 mm larger than the outer diameter of the core metal.
And so. Then, the rubber roll material was loaded into a mold 6 together with a core metal, and vulcanization and foaming was performed. In addition, for the comparative example, a rubber plate was wound around a core metal so that the amount of the rubber material charged was 105% by volume, and the rubber plate was loaded into the mold 6 and vulcanized.

Then, the finished hardness, outer diameter runout, and burr thickness of each obtained rubber roll were measured. The results are shown in Table 1. Note that the outer diameter runout amount is the maximum amount of outer diameter runout when the rubber roll is rotated.

[0037]

[Table 1]

[0038] As is clear from Table 1, in the examples, the amount of outside diameter runout was smaller than in the comparative examples, and the amount of burrs generated was also smaller, indicating that finishing polishing was not necessary. On the other hand, in the case of the comparative example, the amount of vibration in the outer diameter is large and it cannot be put into practical use without finishing. Further, in the case of this comparative example, the orientation of the short fibers is disordered at the burr portion, resulting in non-uniform elastic modulus and friction coefficient. Furthermore, in the case of the examples, the finished hardness increases as the amount of rubber material charged increases, and it can be seen that the desired hardness or elastic modulus can be obtained by controlling the expansion ratio.

[Brief explanation of the drawing]

[Figure 1] A perspective view of a rubber roll containing short fibers with a portion cut away.

[Figure 2] A perspective view showing a part of the rubber roll material

[Fig. 3] A partially omitted cross-sectional view showing a mold and a rubber roll.

[Explanation of symbols]

1 Rubber roll containing short fibers 2 Core metal 3 Rubber roll part 4 Short fiber 5 Rubber roll material 6 Mold 6a Cavity surface 7 Seal member

Claims (2)

[Claims] [Claim 1] A method for manufacturing a rubber roll in which a core metal is provided inside a cylindrical rubber roll portion, using a rubber material containing a foaming agent, the inner diameter of which is the same as the outer diameter of the core metal, or the inner diameter of the core metal. A cylindrical rubber roll material having an outer diameter slightly larger than the outer diameter and slightly smaller than the outer diameter of the rubber roll portion is molded, and the rubber roll material is shaped into a cylindrical rubber roll material having a diameter as described above for forming the outer circumferential surface of the rubber roll portion. Loading it into a mold having a cavity surface with a circular cross section equal to the outer diameter of the rubber roll part, and passing the core metal through the cylindrical hole of the rubber roll material, and foaming the foaming agent of the rubber roll material in the above state. A method for manufacturing a rubber roll characterized by: Claim 2: In the process of forming the rubber roll material, a rubber material mixed with short fibers in addition to a foaming agent is used as claimed in Claim 1.
The method for manufacturing a rubber roll described in .