Method of manufacturing rubber product

This method includes performing adhesion prevention treatment on uncrosslinked rubber powder, which is a material of the rubber product, to prevent mutual adhesion of the uncrosslinked rubber powder, and sequentially and repeatedly forming by supplying raw rubber powder, on which the adhesion prevention treatment has been performed, and irradiating the supplied portion with an electron beam to crosslink the irradiated portion, so that the crosslinked portions are stacked following a shape of the rubber product.

TECHNICAL FIELD

The present disclosure relates to a method of manufacturing a rubber product, and in particular to a method suitable for manufacturing rubber products that can flexibly respond to changes in the shape of the products.

The present application claims priority to Japanese Patent Application No. 2019-112262 filed on Jun. 17, 2019, the entire contents of which are incorporated herein by reference.

BACKGROUND

Known methods of manufacturing rubber products include a method of manufacturing a product by placing unvulcanized rubber in a mold that matches the shape of the product and vulcanizing the rubber by applying heat and pressure, as in Patent Literature (PTL) 1, and a method of placing unvulcanized rubber in a mold that is larger than the product, vulcanizing the rubber by applying heat and pressure, and then machining the rubber by cutting or the like to yield the shape of the product.

CITATION LIST

Patent Literature

SUMMARY

Technical Problem

However, in the method of using a mold that matches the shape of the product, the mold needs to be modified or made anew when a change in the shape of the product occurs for a reason such as a change in product specifications. The production costs and the time and effort for processing have thus been problematic. Furthermore, in a method of using a mold larger than the product, there has been room for improvement in the manufacturing accuracy, such as dimensional accuracy during machining, depending on the physical properties of the rubber.

It is an aim of the present disclosure to provide a method of manufacturing a rubber product that can flexibly respond to changes in the shape of a product and can achieve high manufacturing accuracy.

Solution to Problem

We carefully studied how to solve the aforementioned problem and concluded that a desired product shape can be obtained without using a mold by repeating a formation process of supplying material and treating the material according to the properties of the material, and then stacking following the shape of the desired product. After further investigating the aforementioned additive manufacturing, we discovered that the additive manufacturing can be applied to rubber products by performing appropriate treatment on the powder of uncrosslinked rubber to be used as a material and further crosslinking the powder of the uncrosslinked rubber, thereby completing the present disclosure.

We provide the following.

A method of manufacturing a rubber product according to the present disclosure includes:performing adhesion prevention treatment on uncrosslinked rubber powder, which is a material of the rubber product, to prevent mutual adhesion of the uncrosslinked rubber powder; andsequentially and repeatedly forming by supplying raw rubber powder, on which the adhesion prevention treatment has been performed, and irradiating the supplied portion with an electron beam to crosslink the irradiated portion, so that the crosslinked portion is stacked following a shape of the rubber product.

“Supplying raw rubber powder, on which the adhesion prevention treatment has been performed, and irradiating the sprayed portion with an electron beam” preferably refers to the raw rubber powder being supplied and the electron beam being irradiated simultaneously, but the cases of the supply of raw rubber powder preceding the irradiation with the electron beam and the irradiation with the electron beam preceding the supply of raw rubber powder are also included.

Advantageous Effect

According to the present disclosure, a method of manufacturing a rubber product that, without use of a mold, can flexibly respond to changes in the shape of a product and can achieve high manufacturing accuracy can be provided.

DETAILED DESCRIPTION

Methods of manufacturing rubber products according to embodiments of the present disclosure are described below.FIG.1is a flowchart illustrating an outline of a method of manufacturing a rubber product according to an embodiment of the present disclosure.

As illustrated inFIG.1, a method of manufacturing a rubber product according to an embodiment of the present disclosure includes performing adhesion prevention treatment on uncrosslinked rubber powder, which is a material of a rubber product, to prevent mutual adhesion of the uncrosslinked rubber powder (step S1), acquiring data on a plurality of thin pieces of a rubber product (step S2), and sequentially and repeatedly forming by supplying raw rubber powder, on which the adhesion prevention treatment has been performed, and irradiating the supplied portion with an electron beam to crosslink the irradiated portion, so that crosslinked portions are stacked following a shape of the rubber product (step S3), thereby manufacturing a rubber product.

FIG.2illustrates a rubber product10, which is an example of a rubber product to be manufactured by the method of manufacturing a rubber product according to the present embodiment. As illustrated inFIG.2, the rubber product10can, for example, have a cylindrical shape.

Here, thin pieces refer to layers that are divided by cutting at numerous planes orthogonal to the axis along the stacking direction of the rubber product to be manufactured.

In the example of the rubber product10, when the Z-axis direction is the stacking direction (height), a plurality of sliced layers are formed by cutting the cylindrical three-dimensional shape at numerous planes orthogonal to the Z-axis direction. Each layer in the plurality of sliced layers illustrated inFIG.3is a thin piece of the rubber product10. The stacking direction in additive manufacturing of the rubber product10refers to the Z-axis direction inFIGS.2and3, but a suitable direction can be used as the stacking direction according to the shape, size, and the like of the rubber product to be manufactured.

Although the thin pieces L1to L3from the first layer to the third layer in the Z-axis direction of the rubber product10are illustrated inFIG.3, the rubber product10is actually converted into data on thin pieces L1to LN (N is a natural number) for the number of layers required to manufacture the rubber product10.

In this way, the shape of the rubber product10is converted into the data on a plurality of thin pieces, and the thin pieces are then stacked according to a manufacturing path based on this data to manufacture the rubber product10.

Each step is described in detail below.

In the adhesion prevention treatment step S1, uncrosslinked rubber powder, which is a material of the rubber product10, is treated to prevent mutual adhesion of the uncrosslinked rubber powder.

A material suitable for rubber products can be used as the material forming the uncrosslinked rubber powder in the present disclosure. Powders of polyisoprene rubber (IR), styrene-butadiene copolymer rubber (SBR), polybutadiene rubber (BR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), halogenated butyl rubber, acrylonitrile butadiene rubber (NBR), and other synthetic rubbers, in addition to natural rubber (NR), can be used as the rubber powder. Among these, powders of natural rubber (NR), styrene-butadiene copolymer rubber (SBR), and polybutadiene rubber (BR) are preferred. These rubber powders may be used alone, or a combination of two or more types thereof may be used.

The uncrosslinked rubber powder may also contain other materials other than natural rubber and synthetic rubber. As the other materials, fillers such as carbon black and silica, softeners, age resistors, zinc oxide, crosslinking accelerators, and the like may be selected as appropriate within a range not detrimental to the aim of the present disclosure. The other materials may be added not only by inclusion in the uncrosslinked rubber powder in advance but also after the treatment to prevent adhesion of the uncrosslinked rubber powder.

Furthermore, as an example of other materials, calcium oxide may be added. By the addition of calcium oxide into the uncrosslinked rubber powder, even when the rubber is heated to a temperature higher than the melting point during the crosslinking of the rubber, bubbles that might be generated in the rubber by heat can be suppressed, and cracks or tears can be prevented from occurring at the areas with bubbles.

The treatment on the uncrosslinked rubber powder to prevent mutual adhesion of the powder refers to the treatment for preventing the powder particles from adhering to each other and is suitably performed by coating the surface of the uncrosslinked rubber powder with an adhesion prevention agent. As the adhesion prevention agent, any of synthetic resin, talc, silica, calcium carbonate, calcium stearate, zinc stearate, carbon black, and the like, for example, or any combination thereof, can be used.

While the means for coating the surface of the uncrosslinked rubber powder with the adhesion prevention agent is not particularly limited, a powdered adhesion prevention agent having a diameter smaller than that of the uncrosslinked rubber powder can be stirred and mixed with the uncrosslinked rubber powder to coat the surface of the uncrosslinked rubber powder, for example. The surface of the uncrosslinked rubber powder may also be coated by applying a dissolved solution or an aqueous dispersion of the adhesion prevention agent to the surface of the uncrosslinked rubber powder. When a dissolved solution or aqueous dispersion of the adhesion prevention agent is used, a coating layer of uniform thickness can easily be formed on the surface of the uncrosslinked rubber powder, but a step of drying the uncrosslinked rubber powder is required after the application. A powdered adhesion prevention agent is preferably used to prevent an increase in the number of production steps.

The adhesion prevention treatment step may be a step included in the preparation of the uncrosslinked rubber powder that becomes the material of the rubber product10or may be a separate step performed after the preparation of the uncrosslinked rubber powder.

According to the adhesion prevention treatment step, mutual adhesion of the uncrosslinked rubber powder can be prevented. That is, lumps are not formed due to mutual adhesion of the uncrosslinked rubber powder. This facilitates handling of the uncrosslinked rubber powder. In particular, when the uncrosslinked rubber powder is stored or applied to the additive manufacturing apparatus100described below, the manufacturing accuracy of the rubber product can be improved, and the uncrosslinked rubber powder can be easily stored and supplied.

The average diameter of the uncrosslinked rubber powder (raw rubber powder) to which the adhesion prevention treatment is applied is preferably from 1 μm to 500 μm. By the average diameter being 1 μm or more, floating during storage and other times can be suppressed, and the mutual adhesion of the raw rubber powder can more effectively be suppressed. By the average diameter being 500 μm or less, the manufacturing accuracy of the rubber product can be further improved.

In the below steps from the thin piece data acquisition step onwards, the raw rubber powder is used to manufacture the rubber product10. The manufacturing apparatus is not particularly limited as long as the method of manufacturing a rubber product according to the present disclosure can be implemented, but an additive manufacturing apparatus100with the following form can, for example, be used.

FIG.4is a perspective view schematically illustrating the configuration of the additive manufacturing apparatus100. The stacking direction is hereinafter designated the Z-axis direction, and two orthogonal directions in any plane orthogonal to the Z-axis direction are designated the X-axis and the Y-axis.

As illustrated inFIG.4, the additive manufacturing apparatus100includes a manufacturing table110, a powder supply nozzle120, and electron beam irradiation means130.

The manufacturing table110includes a manufacturing table body111for manufacturing a rubber product. A surface111ais arranged on the top surface of the manufacturing table body111. The manufacturing table110has a rectangular plate-like shape in the illustrated example but may have a circular cylinder shape, polygonal cylinder shape, or the like.

The manufacturing table110may be supported by a support112. The support112can variably support the position. The support112can adjust the position of the manufacturing table110in some or all of the XYZ-axis directions. For example, a piston member using hydraulic or pneumatic pressure, or a ball screw, can be provided as means of adjusting the position of the manufacturing table110in the Z-axis direction. For example, a guide member that guides in the XY-axis direction or a rotating member that rotates the manufacturing table110about a point in plan view can be provided as means for adjusting the position of the manufacturing table110in the XY-axis direction.

The manufacturing table110can also be supported immovably.

In the additive manufacturing apparatus100, the powder supply nozzle120is arranged at a distance in the Z-axis direction with respect to the surface111a. Although any powder supply nozzle120can be used, the powder supply nozzle120in the illustrated example includes a powder housing121and a powder discharger122.

In the powder supply nozzle120, the powder housing121can house the raw rubber powder inside. In the illustrated example, the powder housing121is a space divided into a cylindrical shape, but the shape is not particularly limited. The powder housing121may be configured to allow direct filling of the raw rubber powder into the powder housing121, or to receive, via a tube or the like, raw rubber powder that was filled into another housing (not illustrated).

The powder discharger122includes a powder discharge passage122athat is connected to the powder housing121and a powder discharge port122bthat opens to the outside from the powder discharge passage122a. The powder discharger122can supply the raw rubber powder in the powder housing121through the powder discharge passage122ato the outside from the powder discharge port122b.

The powder supply nozzle120may be configured to supply the raw rubber powder to the outside by spraying. For example, inert gas ejection means can be provided at or around the powder discharge port122b, and an inert gas such as argon gas, nitrogen gas, or helium gas can be discharged from the powder discharge port122btogether with the raw rubber powder, so that the raw rubber powder is supplied by being sprayed onto the surface111aof the manufacturing table110.

The powder supply nozzle120may include a support mechanism123(not illustrated). The support mechanism123supports the powder supply nozzle120and can adjust the position thereof in the XYZ-axis direction.

Furthermore, the powder supply nozzle120can adjust the supply amount, supply rate, supply diameter, and the like of the raw rubber powder.

Two powder supply nozzles120are depicted inFIG.4, but one, or three or more, may be provided.

In the additive manufacturing apparatus100, the electron beam irradiation means130is arranged at a distance in the Z-axis direction with respect to the surface111a. Although any electron beam irradiation means130can be used, at least one electron beam source131and an electron beam adjusting means132are preferably used.

The electron beam source131can be a thermal electron emission type electron gun. More specifically, for example, thermal electrons are generated by heating a cathode formed by tungsten, LaB6, CeB6, or the like, and an electron beam is generated by accelerating the thermal electrons.

The electron beam adjusting means132can, for example, include a magnetic field generator132aand a focus controller132b. Using the magnetic force of a permanent magnet, an electromagnet, or the like, the magnetic field generator132acan adjust the convergence, deflection, and the like of the electron beam generated by the electron beam source131. The focus controller132bcan also adjust the focus of the electron beam at the irradiation target using an optical lens, an electromagnetic lens, or the like. Although one electron beam source131is depicted in the illustrated example, a plurality of electron beam sources131may be included, each of which may be controlled under different irradiation conditions.

The electron beam irradiation means130may include a support mechanism133(not illustrated). The support mechanism133may immovably support the electron beam irradiation means130, or may support the electron beam irradiation means130while being capable of adjusting the position of the powder supply nozzle120in the XYZ-axis directions.

By being housed in a chamber (not illustrated) or the like, the additive manufacturing apparatus100can be used in a near-vacuum environment during operation of the electron beam irradiation means130.

Furthermore, the additive manufacturing apparatus100can be connected over a network to a control device200. The control device200includes a hardware processor, such as a central processing unit, and includes a thin piece data acquisition interface201and a manufacturing controller202.

The thin piece data acquisition interface201can acquire the data on the thin pieces necessary for manufacturing the rubber product10.

The manufacturing controller202can control the additive manufacturing by providing instructions and information, via a network, to each component of the additive manufacturing apparatus100based on the data on the thin pieces. That is, the manufacturing controller202can control the operations of the manufacturing table110, the powder supply nozzle120, the electron beam irradiation means130, and the like, which configure the additive manufacturing apparatus100.

Each of the steps from the thin piece data acquisition process S2onwards in the method of manufacturing a rubber product according to the present embodiment will be described below in detail with an example using the additive manufacturing apparatus100.

In the thin piece data acquisition step S2, the thin piece data on the rubber product10, which is necessary for manufacturing the rubber product10, is acquired by the thin piece data acquisition interface201of the control device200.

The thin piece data can, for example, be acquired by converting three-dimensional manufacturing data on the rubber product10. More specifically, the thin piece data acquisition interface201acquires the three-dimensional manufacturing data from an apparatus such as another computer that is connected to the control device200or that can transmit information to the control device200. Here, the three-dimensional manufacturing data for manufacturing the rubber product10is, for example, three-dimensional manufacturing data designed by three-dimensional CAD, or three-dimensional manufacturing data captured by a three-dimensional scanner, digitizer, or the like. The three-dimensional manufacturing data may be converted into Standard Triangulated Language (STL) format, in which the surface of the three-dimensional rubber product10is represented as a collection of triangles. This three-dimensional manufacturing data on the rubber product10is acquired by the thin piece data acquisition interface201and converted into data on thin pieces L1to LN (N is a natural number). The thin piece data refers to the data on the thin pieces L1to LN and may include data on a manufacturing path based on the data on the thin pieces L1to LN.

Three-dimensional manufacturing data may also be converted to thin piece data by an apparatus such as another computer that is connected to the control device200or is capable of transmitting information to the control device200, and the thin piece data may then be acquired by the thin piece data acquisition interface201.

[Raw Rubber Powder Supply and Electron Beam Irradiation]

Step S3and onwards, after the thin film data acquisition, will be described with reference toFIGS.5A to5F. InFIG.5Aand subsequent figures, the control device200is omitted.

After the thin piece data acquisition, forming is carried out by supplying raw rubber powder, on which the adhesion prevention treatment has been performed, and irradiating the supplied portion with an electron beam to crosslink the irradiated portion, and the forming is sequentially repeated so that the crosslinked portions are stacked following the shape of the rubber product.

FIG.5Ais a diagram illustrating the forming of the starting portion LM1, which is the first portion to be formed in the layer M1corresponding to the thin piece L1. The position of the starting portion LM1can be determined according to the manufacturing path based on the data on the thin piece L1.

As illustrated inFIG.5A, raw rubber powder, on which the adhesion prevention treatment has been performed, is supplied to the surface111aof the manufacturing table110. The means for supplying the raw rubber powder on which the adhesion prevention treatment has been performed is not particularly limited. For example, the powder supply nozzle120can be used. The powder housing121is filled with the raw rubber powder, and the powder supply nozzle120can supply the raw rubber powder through the powder discharge passage122aof the powder discharger122to the outside from the powder discharge port122b.

The powder supply nozzle120can also use an inert gas to adjust the supply rate and the like of the raw rubber powder from the powder discharge port122b. For example, an inert gas such as argon gas, nitrogen gas, or helium gas can be discharged from the powder discharge port122btogether with the raw rubber powder, so that the raw rubber powder is supplied by being sprayed onto the surface111aof the manufacturing table110.

The position at which the raw rubber powder is supplied by the powder supply nozzle120is the position at which the starting portion LM1should be formed and can be adjusted by the support mechanism123of the powder supply nozzle120.

Furthermore, according to the shape and thickness of the starting portion LM1, the supply amount, supply rate, and supply diameter of the raw rubber powder can be adjusted by the powder supply nozzle120.

The thickness t1of the starting portion LM1, which is a thickness corresponding to the thin piece L1, can be adjusted according to the irradiation conditions of the electron beam described below, the average particle size of the raw rubber powder, and the like, but is preferably 500 μm or less for uniform crosslinking over the thickness direction.

In the illustrated example, two powder supply nozzles120are used to supply the raw rubber powder, but one, or three or more, powder supply nozzles120may be used. In the case in which a plurality of powder supply nozzles120is used, each powder supply nozzle120may be filled with a different type of raw rubber powder, and some of the powder supply nozzles120may be filled with a material other than raw rubber powder. If each powder supply nozzle120is filled with a different type of raw rubber powder, the type of the raw rubber powder can be changed during the manufacturing process according to the manufacturing conditions of the rubber product10, so that rubber products using a plurality of different raw rubber powders can easily be manufactured. Also, by simultaneously supplying a plurality of raw rubber powders or a raw rubber powder and other materials from a plurality of powder supply nozzles120, the materials can be mixed on the surface111aof the manufacturing table110without needing to be mixed in the powder supply nozzles.

Formation is carried out by the above-described supply of the raw rubber powder, along with irradiation of the supplied portion of the raw rubber powder with an electron beam to crosslink the irradiated portion. The electron beam irradiation means is not particularly limited, but the electron beam irradiation means130, for example, can be used. The electron beam generated by the electron beam source131of the electron beam irradiation means130is converged and deflected by the magnetic field generator132ato irradiate the position where the starting portion LM1is to be formed. The irradiation position of the electron beam may be adjusted by adjusting the position of the manufacturing table110with the support112so that the position where the starting portion LM1is to be formed is irradiated by the electron beam. Alternatively, the irradiation position may be adjusted by the magnetic field generator132a, or by adjusting the position of the electron beam irradiation means130with the support mechanism133. The focus controller132benables adjustment of the position where the electron beam achieves just focus, i.e., the focus.

When the position on the surface111aof the manufacturing table110where the raw rubber powder is supplied, which is also position where the starting portion LM1is to be formed, is irradiated with the electron beam, the rubber molecules of the raw rubber powder are provided with energy by high-speed electrons. The high-speed electrons cleave the molecular bonds, which generates radicals, and the radicals react between molecular chains to form a three-dimensional structure, yielding a crosslinking reaction.

According to the electron beam crosslinking means, the location to be crosslinked can be changed by controlling the position where the electron beam is irradiated, thus eliminating the need to prepare a mold and other such hassle, and enabling a flexible response to changes in product shape. Furthermore, a high manufacturing accuracy can be achieved. Rubber products with complex shapes that are difficult to remove from a mold, or that cannot be manufactured with a mold, can also be manufactured.

The irradiation conditions of the electron beam can be controlled by the control device200based on the thin piece data on the rubber product10that is to be manufactured. The specific irradiation conditions of the electron beam can be adjusted appropriately according to factors such as the shape and thickness of the starting portion LM1and the average diameter of the raw rubber powder. For example, the following irradiation conditions can be used.

For example, the focusing of the electron beam is preferably set to achieve just focus on the surface of the supplied portion (the surface of the starting portion LM1) to generate a sufficient crosslinking reaction in the rubber.

Although the temperature at the time of electron beam irradiation is not particularly limited, the supply of the raw rubber powder and the irradiation with the electron beam are preferably performed in a temperature environment lower than the melting point of the rubber. According to the above configuration, the crosslinking reaction can be produced at a lower temperature than with means for vulcanizing rubber by heating. Bubbles that might be generated in the rubber by heating can therefore be suppressed, and cracks or tears can be prevented from occurring at the areas with bubbles.

Furthermore, the electron beam irradiation is preferably performed in a high vacuum environment to prevent deactivation of the radicals by oxygen. For example, when the additive manufacturing apparatus100is housed in a chamber or the like, a high vacuum is created in the chamber.

As described above, the crosslinked portion can be formed as the starting portion LM1by supplying the raw rubber powder and irradiating the supplied portion with an electron beam.

FIG.5Bis a perspective view schematically illustrating a state in which the layer M1corresponding to the thin piece L1has been manufactured.FIG.5Cis a cross-sectional view schematically illustrating a state in which the layer M1corresponding to the thin piece L1has been manufactured and schematically illustrates a cross-section along line II-II ofFIG.5B. By sequentially repeating the supply of the raw rubber powder and the irradiation of the supplied portion with the electron beam while adjusting the supply position of the raw rubber powder and the irradiation position of the electron beam according to the data on the manufacturing path based on the thin piece data, a ring-shaped layer M1corresponding to the thin piece L1can be manufactured as in the illustrated example.

FIG.5Dis a diagram illustrating the treatment after the layer M1corresponding to the thin piece L1has been manufactured. After the layer M1is manufactured, the supply position of the raw rubber powder and the irradiation position of the electron beam in the Z-axis direction are adjusted to manufacture the layer M2corresponding to the next thin piece L2to be stacked on the thin piece L1. In the illustrated example, the supply position of the raw rubber powder and the irradiation position of the electron beam are adjusted by lowering the manufacturing table110by the thickness of the layer M1. Adjustment is not limited to the adjusting means in the illustrated example, and the supply position of the raw rubber powder and the irradiation position of the electron beam may be adjusted by raising the positions of the powder supply nozzle120and the electron beam irradiation means130in the Z-axis direction by the thickness of the layer M1.

FIG.5Eis a diagram illustrating the manufacturing of the next layer M2corresponding to the next thin piece L2. As illustrated inFIG.5E, raw rubber powder is supplied by the powder supply nozzle120onto the surface of the layer M1.

The supply position, supply amount, supply rate, and supply diameter of the raw rubber powder by the powder supply nozzle120can be adjusted appropriately in the same manner as the formation of the starting portion LM1in the layer M1.

Formation is carried out by the above-described supply of the raw rubber powder, along with irradiation of the supplied portion of the raw rubber powder with an electron beam on the surface of the layer M1to crosslink the irradiated portion.

The irradiation conditions of the electron beam may be the same as the irradiation conditions at the time of formation of the starting portion LM1in the layer M1, or may be different.

For example, in the first layer M1, the focusing of the electron beam may be controlled so that the electron beam achieves just focus on the surface of the supplied portion, and in the second layer M2, a plurality of electron beam supply sources may be used and the electron beams controlled to achieve just focus on the surface of the supplied portion and on the boundary with the adjacent layer M1immediately below the layer M2. According to the above configuration, the supplied portion in the layer M2can be sufficiently crosslinked, and the crosslinked portions of the adjacent layers M1and M2can be bonded together.

The focusing of the electron beam can be controlled so that the focusing is always the same, or the focusing can be changed.

Although the temperature at the time of electron beam irradiation is not particularly limited during manufacturing of the layer M2either, the crosslinking is preferably performed in a temperature environment lower than the melting point of the rubber, as during the manufacturing of the layer M1. According to the above configuration, the manufacturing accuracy can be further enhanced, and deterioration of the rubber product due to heating can be prevented.

InFIG.5F, the formatting of the crosslinked portion is repeated, and the layers M1to M8are stacked. After manufacturing of the layer M2as described above, in order to manufacture the layer M3corresponding to the next thin piece L3to be stacked on the thin piece L2, formation is repeated by adjusting the supply position of the raw rubber powder and the irradiation position of the electron beam in the Z-axis direction, supplying the raw rubber powder onto the surface of the layer manufactured immediately before, and irradiating the supplied portion with the electron beam to crosslink the irradiated portion, so that the crosslinked portions are stacked following the shape of the rubber product10to manufacture the rubber product10.

The method of manufacturing a rubber product including each of the above steps can flexibly respond to changes in the shape of the product and achieve high manufacturing accuracy. Furthermore, since the raw material rubber powder is supplied following the shape of the rubber product10, there is no need to process the uncrosslinked raw material rubber powder, and even if uncrosslinked raw material rubber powder remains, only a small amount remains. The work time can thus be shortened.

Another example of the rubber product is a rubber product11having a shape such that a cylindrical hollow11ais formed inside a cylinder, as illustrated inFIG.6. According to the method for manufacturing a rubber product including the above steps S1to S3, the rubber product11having a hollow11acan be manufactured. Furthermore, according to the above method of manufacturing, since the raw rubber powder is supplied following the shape of the rubber product11, nearly no uncrosslinked raw rubber powder remains in the hollow11a. A hollow rubber product can therefore easily be manufactured without processing uncrosslinked raw rubber powder.

Another example of the rubber product is a rubber product12having a shape such that the entire outer circumference is curved, and a hollow is formed inside, as illustrated inFIG.7. According to the method for manufacturing a rubber product including the above steps S1to S3, the rubber product12having a hollow can be manufactured. Furthermore, according to the above method of manufacturing, since the raw rubber powder is supplied following the shape of the rubber product12, nearly no uncrosslinked raw rubber powder remains in the hollow. A hollow rubber product can therefore easily be manufactured.

INDUSTRIAL APPLICABILITY

The method of manufacturing a rubber product of the present disclosure can be suitably applied to the manufacturing of rubber products such as anti-vibration rubber, seismic isolation rubber, tires, and tire treads.

REFERENCE SIGNS LIST