JP7262291B2 - Bearing device manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a cast product having a core material and a bearing device having a core material.

Castings are used in various forms, for example, as parts for vehicles, ships, aircraft, etc. (hereinafter referred to as vehicles, etc.) and as building materials. Needs improvement. As one measure for improving the strength of a cast product, there is a method of reinforcing the cast product by providing a core material for reinforcing the cast product. As a method for producing such a cast product, a method for producing a cast product by setting a core material in a mold and pouring a cast product forming material into the mold has been conventionally known in Patent Document 1 below. there is In the cast product manufactured by this cast product manufacturing method, the surface of the portion where the core material is set in the mold is formed from the core material, and the surface of the other portions is formed from the cast product forming material.

JP 2009-166051 A

Various vibrations and loads are applied to castings as parts of vehicles and the like. However, in the cast product manufactured by the conventional manufacturing method described in Patent Document 1, the surface of the portion where the core material is set in the mold is formed from the core material, and the surface of the other portion is formed from the cast product forming material. As formed, there is an interface between the core material and the casting forming material at the surface of the casting. There is a problem that a casting with material interfaces may be inferior in mechanical strength against vibration and load, compared to a casting with no material interface that is cast from a single material.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of manufacturing a cast product and a bearing device capable of improving the mechanical strength of the cast product.

A method for manufacturing a casting according to the present invention is a method for manufacturing a casting comprising a core material,
A step of placing the core material in the mold using an organic support material that supports the core material so as not to contact the mold;
and a step of melting and pouring a casting forming material for forming the casting into the mold in which the core material is arranged.

According to the casting manufacturing method of the present invention, the organic supporting material allows the core material to be arranged at a position inside the casting so as not to come into contact with the mold, that is, not to be exposed on the surface of the casting. When the casting material is poured into the mold, the organic support material that supports the core material is burned out by contact with the casting material because the casting material is in a molten high temperature state. Since the casting-forming material is poured into the mold, including the position where the burnt-out organic support material is installed, the casting can be embedded without the core material being exposed to the surface. A cast product having a core material is formed from a cast product forming material, which is a single material, on the surface thereof, and does not have an interface between the materials, so that the mechanical strength can be improved.

Here, in the method for manufacturing a casting, the organic support material may be a curable synthetic resin.

According to this, the curable synthetic resin has fluidity in a state before curing, and the core material can be easily fixed, and the core material can be easily supported by curing the curable synthetic resin. . In addition, since the hardening synthetic resin does not return to a fluid state due to the heat of the casting forming material, the hardening synthetic resin can support the core material until it is burned away.

Further, in the method for producing a casting, the organic support material is attached to the surface of the core material, and the organic support material is interposed so that the core material is arranged so as not to come into contact with the mold. can do.

According to this, the step of arranging the core material in the mold so as not to contact the mold includes arranging the core material to which the organic support material is adhered so as not to contact the mold without waiting for the organic support material to harden. Since it is sufficient to simply

Further, in the method for manufacturing a cast product, the core material may be a carbon steel plate, and the cast product forming material may be cast iron.

According to this, since the strength of the core material formed from carbon steel is greater than the strength of the cast product forming material formed from cast iron, the strength of the cast product can be increased.

Further, the bearing device according to the present invention includes a cylindrical bearing portion through which the shaft is inserted through the bearing, and a base portion having a bolt hole forming portion into which a bolt for fixing the bearing portion to the fixed portion is inserted. and a bracket that integrally connects the bearing portion and the pedestal portion,
A core member for reinforcing the bearing portion is embedded in the circumferential direction of the bearing portion without being exposed on the surface of the bearing portion.

According to the bearing device of the present invention, since the core member for reinforcing the bearing portion is embedded in the cylindrical bearing portion, the mechanical strength of the bearing portion, which is susceptible to vibration and load, can be improved.

Here, in the above bearing device, the bearing portion may be made of cast iron, and the core material may be made of carbon steel.

According to this, since the tensile strength of the core material made of carbon steel is greater than the tensile strength of the bearing portion made of cast iron, it is possible to improve the mechanical strength of the bearing portion, which is susceptible to vibration and load. can.

According to the method for manufacturing a cast product of the present invention, the core material can be arranged at a position to be embedded inside the cast product, and the cast product including the core material can be embedded without the core material being exposed on the surface. can be assumed. For this reason, the cast product of the present invention is formed from the cast product forming material, which is a single material, on the surface thereof, and does not have an interface between the materials, so that the mechanical strength can be improved.

1 is a front view of a bearing device manufactured by a casting manufacturing method according to an embodiment of the present invention; FIG. FIG. 2 is a sectional view taken along line II-II of FIG. 1; FIG. 2 is a cross-sectional view of a mold used in the method for manufacturing a cast product according to an embodiment of the present invention, and is a cross-sectional view of the mold corresponding to the position of the III-III line of the bearing device in FIG. 1; FIG. 4 is an image diagram of pouring a casting forming material into the mold of FIG. 3 ;

Hereinafter, a method for manufacturing a cast product according to an embodiment of the present invention will be described with reference to the drawings. In the embodiment, as shown in FIGS. 1 and 2, a bearing device is a casting in which a shaft (not shown) for a vehicle or the like is fixed to the side of the vehicle or the like via an annular bearing (not shown). 1 manufacturing method will be described as an example. Of course, the castings of the present invention are not limited to bearing devices, and include parts for vehicles such as gears, wheels, engine blocks, transmission cases and brake discs, processing tools such as machining centers, lathes and drills, pots and pans. It can be applied to all kinds of castings, such as daily necessities such as cutlery, seismic reinforcement beam members, seismic damper members, and building materials such as handles.

In the method of manufacturing the bearing device 1 as a casting according to the embodiment, the mold 5 shown in FIG. and a bracket 2 integrally connecting the base portion 25 with the bearing device 1 by casting. A core member 3 for reinforcing the bearing portion 4 is embedded in the outer wall portion 22 of the bearing portion 4 in the circumferential direction.

The bearing device 1 as a cast product of the embodiment is composed of cast iron as a casting forming material 8 that forms the bearing portion 4, the pedestal portion 25, and the bracket 2, and the bearing portion 4 of the bearing device 1 in terms of strength. and a carbon steel plate as a supplementary core material 3 . Cast iron is made by melting cast iron as a raw material, pouring it into a mold 5 described later, and cooling and solidifying in the mold 5.

The cast iron of the cast product forming material 8 contains 2.5 to 4.5% by mass of carbon, and the carbon steel plate of the core material 3 contains 0.7 to 1.5% by mass of carbon. . Due to the difference in the properties of iron due to the difference in carbon content, the core material 3 of the carbon steel plate has higher tensile strength and elongation than the casting forming material 8 (cast iron), so it can supplement the bearing part 4 in terms of strength. can. Further, the melting point of the carbon steel plate of the core material 3 is 1400° C. or higher, and the core material 3 is not melted by being covered with molten cast iron (1300 to 1380° C.). The specific gravity of cast iron and the carbon steel plate are substantially the same, and the coefficient of thermal expansion of cast iron and the coefficient of thermal expansion of the carbon steel plate are substantially the same. Spherical graphite cast iron FCD400 (JIS G 5502: 2001) is used for the casting forming material 8 (cast iron) forming the bearing portion 4, the pedestal portion 25 and the bracket 2, and the core material 3 (carbon steel plate) is Carbon tool steel SK85 (JIS G 4401:2009) was used.

As the organic support material 7 for fixing the core material 3, a two-liquid mixing reaction type epoxy resin adhesive of a reaction curing type synthetic resin was used. The two-liquid mixing reaction type epoxy resin adhesive is composed of a mixture of epoxy resin as a main agent and polyamide as a curing agent. can be fixed in time. Epoxy resin adhesives can be cured in a shorter time by being heated. The organic support material 7 made of epoxy resin adhesive burns and burns out at about 500° C., which is lower than the melting point of cast iron. As the two-liquid mixing reaction type epoxy resin adhesive as the organic support material 7, a two-liquid mixing reaction type epoxy adhesive Cemedine 1500 (manufactured by Cemedine Co., Ltd.) was used.

As the mold 5, a formwork corresponding to the shape of the bearing device 1 was used. As shown in FIGS. 3 and 4, the mold 5 includes a sprue 62 into which the molten cast product forming material 8 is poured, a runner 63 through which the cast product forming material 8 flows, and a mold portion 6 in which the bearing device 1 is molded. , and has a shape that can be separated into an upper mold 51 and a lower mold 52 for demolding. The casting mold 5 has a mold portion 6 formed so that the up-down direction of the bearing device 1 (FIG. 1) is horizontal and the front-rear direction of the bearing device 1 (FIG. 2) is vertical. 3 and 4 are cross-sectional views of the mold corresponding to the position III-III shown in FIG. Although not shown, a mold portion for molding the bracket 2 and the pedestal portion 25 is provided on the front side of the drawing.

A method for manufacturing a casting according to the embodiment will be described below. The method for manufacturing a cast product according to the embodiment includes the steps of fixing the core material 3 to the mold 5 using the organic support material 7 so as not to contact the mold 5, and melting and pouring the cast product forming material 8 into the mold 5. and

In the process of fixing the core material 3 to the mold 5 so as not to contact the mold 5, first, the front end and the rear end of the core material 3 processed into a cylindrical shape (the upper end and the lower end when fixing to the mold 5 ), the epoxy resin adhesive of the organic support material 7 was adhered according to the shape of the outer wall mold portion 65 for molding the bearing portion 4, respectively, and cured. Prior to bonding, the epoxy resin adhesive was prepared by mixing the epoxy resin as the main agent and the polyamide as the curing agent, and the core material 3 was processed into a cylindrical shape and heated (preheated). Curing of the epoxy resin adhesive can be accelerated by preheating the core material 3 . Next, in the mold 5 of FIG. 3 corresponding to the position inside the wall of the outer wall portion 22 of the cylindrical bearing portion 4 of the bearing device 1 (FIG. 1), a cylindrical shape for molding the bearing portion 4 was hollowed out. The core material 3 provided with the epoxy resin adhesive of the organic support material 7 was arranged and fixed in the outer wall mold part 65 . Since the epoxy resin adhesive of the organic support material 7 is provided at the front and rear ends of the core material 3 (upper and lower ends when fixed to the mold 5), the gap between the core material 3 and the mold 5 is reduced. The core material 3 is fixed to the mold 5 so that the core material 3 does not come into contact with the mold 5 .

In the step of melting and pouring the cast product forming material 8 into the mold 5, as shown in FIGS. Cast iron as material 8 is poured. At this time, the cast iron is filled from the lower side (rear side of the bearing device) of the mold 5 toward the upper side (front side). Since the cast iron filled from the lower side of the mold 5 burns and vaporizes the organic support material 7 on the lower side, the cast iron also flows into the portion filled with the organic support material 7 . By pouring cast iron one after another, the inside of the mold 5 is filled with cast iron from the lower side, and finally the upper side of the mold 5 is filled. The cast iron is also filled in the mold part 6 for molding the bracket 2 and the base part 25 . The filled cast iron burns and evaporates the organic support material 7 on the upper side, and the cast iron also flows into the part filled with the organic support material 7 . At this time, the core material 3 is not fixed to the organic support material 7, but since the specific gravity of cast iron and the specific gravity of the carbon steel plate are substantially the same, the core material 3 is not fixed to the cylindrical bearing portion of the bearing device 1. There is no movement (deviation) from the center of 4. Since the melting point of the core material 3 is higher than that of cast iron, the core material 3 does not melt. In addition, since the core material 3 is preheated, the cast product forming material 8 poured into the mold 5 is prevented from being rapidly cooled due to contact with the core material 3, and the cast product forming material 8 is The whole is uniformly cooled, the occurrence of distortion is suppressed, and the strength of the casting can be increased.

By solidifying the cast product forming material 8 (cast iron) after cooling, the cast product forming material 8 and the core material 3 become the bearing device 1 in which the core material 3 is embedded in the bearing portion 4, and are demolded from the mold 5, The bearing device 1 is completed by removing the cast iron filling the sprue 62 and the runner 63 .

As shown in FIGS. 1 and 2, the bearing device 1 is a bearing device in which a shaft (not shown) for a vehicle or the like is fixed to the side of the vehicle or the like via an annular bearing (not shown). A bearing through which the shaft passes is housed in the bearing housing portion 41 of the bearing portion 4, and the base portion 25 is fixed to the fixed portion of the vehicle or the like with bolts (not shown).

The bearing device 1 includes a cylindrical bearing portion 4 , a pedestal portion 25 , and a bracket 2 that integrally connects the bearing portion 4 and the pedestal portion 25 . , a core material 3 for reinforcing the bearing portion 4 is embedded. As the cast product forming material 8 (cast iron) forming the bearing portion 4, the base portion 25 and the bracket 2, the spheroidal graphite cast iron product FCD400 was used as described above.

The bearing portion 4 has an annular bearing accommodating portion 41 as shown in FIGS. 1 and 2 . As for the metal forming the bearing, the same kind of metal as the metal forming the bearing portion 4 is used. Since the metal forming the bearing and the metal forming the bearing 4 are of the same type, the bearing 4 and the bearing have the same coefficient of thermal expansion, so they are stable against temperature changes and cause vibration. It is possible to suppress the occurrence of a gap between the bearing portion 4 and the bearing, which becomes a problem, and since it is difficult for electric charges to move due to the difference in electrode potential, it is possible to suppress the occurrence of rust. In the embodiment, the metals are of the same type means that the metal elements contained in the largest amount among the elements constituting the metals are of the same type. A bearing made of an iron alloy was used in the embodiment.

The inner diameter of the bearing accommodating portion 41 of the bearing portion 4 is formed to be smaller (narrower) than the outer diameter of the bearing to be accommodated. This is because the inside of the bearing accommodating portion 41 is accurately cut according to the outer diameter of the bearing, and a margin (cutting allowance) is left so that positional accuracy can be ensured.

The bracket 2 is a member that integrally connects the bearing portion 4 and the pedestal portion 25 , and a leg portion 23 connected to the pedestal portion 25 from below the bearing portion 4 is formed.

As shown in FIGS. 1 and 2, the leg 23 is formed with beams 24 perpendicular to the leg 23 (parallel to the shaft axis) at its left and right ends in order to increase strength. there is The pedestal portion 25 is formed in a flat plate shape parallel to the central axis of the shaft penetrating through the bearing portion 4, and the pedestal portion 25 has a bolt hole forming portion 26 that is fixed to a fixed portion on the side of a vehicle or the like with a bolt. It is provided, and is bolted through the bolt hole forming portion 26 to the installation portion of the vehicle or the like.

Inside the outer wall portion 22 of the bearing portion 4 , the core material 3 that reinforces the bearing portion 4 is embedded in the circumferential direction so as not to be exposed on the surface of the bearing portion 4 . The core material 3 is a material that supplements the strength of the bearing portion 4 of the bracket 2, and in the embodiment, as described above, the carbon tool steel SK85 is used for the core material 3. The core material 3 is arranged inside the outer wall portion 22 of the bearing portion 4 and is covered with the casting forming material 8 forming the bearing portion 4 so that the core material 3 is not exposed on the surface of the bearing portion 4 inside the bearing portion 4 . It is embedded in the state and supplements the bearing portion 4 in terms of strength. Since the surface of the bearing device 1 (bearing portion 4) is cast from the cast product forming material 8, which is a single material, and there is no material interface, the mechanical strength is improved.

Further, since the core member 3 is embedded in the outer wall portion 22 of the bearing portion 4 in the circumferential direction, the stress received by the core member 3 is small. Therefore, even when the outer wall portion 22 is damaged by receiving a large load, the outer wall portion 22 itself can be prevented from being broken because the core material 3 remains unbroken.

It should be noted that the bearing device 1 of the embodiment can be put into practice even if its configuration is changed to the following forms.

As the carbon steel plate used for forming the core material 3, carbon tool steel SK85 was used in the embodiment, but carbon tool steel (SK140, SK120, SK105, SK95, SK90, SK95, SK90, SK80, SK75) can also be used. As the carbon steel plate, high-carbon steel piano wire and spring steel materials (SUP6, SUP7, SUP9, SUP9A, SUP10, SUP11A, SUP12, SUP13) specified in JIS G 4801:2011 can also be used. These are superior in mechanical strength such as tensile strength compared to the cast iron of the casting forming material 8 .

As the core material 3, in the embodiment, one processed into a cylindrical shape is used. A wire whose both ends are not overlapped or a wire-shaped piano wire spirally wound can also be used.

As the cast iron of the casting forming material 8 used for molding the bearing device 1, in the embodiment, the spheroidal graphite cast iron FCD400 was used, but the spheroidal graphite cast iron products (FCD350, FCD500, FCD450 , FCD600, FCD700, FCD800) can also be used.

In the embodiment, the organic support material 7 for fixing the core material 3 to the mold for forming the bracket 2 uses a two-liquid mixed reactive epoxy resin, which is a reaction-curable synthetic resin. Urethane resin, 2-liquid mixing reaction type urethane resin, UV-curing urethane resin, moisture-curing acrylate resin, 2-liquid mixing reaction-type acrylate resin, UV-curing acrylate resin, moisture-curing silicone resin, 2-liquid mixing reaction type silicone resin etc. can also be used. In addition, even a curable synthetic resin whose solvent evaporates and dries and solidifies can be used as the organic support material 7. As the curable synthetic resin, general-purpose resins such as polypropylene resin, vinyl chloride resin, acrylate resin, and styrene resin can be used. curable synthetic resins can also be used. Also, as the organic support material 7, a paper material such as wood or corrugated paper can be used, and the core material 3 can be arranged and fixed so as not to come into contact with the mold 5. FIG.

Further, in the method for manufacturing the bearing device 1 of the embodiment, the core material 3 provided with the epoxy resin adhesive of the organic support material 7 is arranged and fixed in the outer wall mold portion 65 of the mold 5 . The epoxy resin adhesive of the organic support material 7 is arranged at 3 to 6 places equally divided in the circumferential direction of each of the upper side and the lower side of the outer wall mold part 65, or over the entire circumference. A core material 3 not provided with a resin adhesive can also be placed and fixed.

DESCRIPTION OF SYMBOLS 1... Bearing device, 2... Bracket, 3... Core material, 4... Bearing part, 5... Mold, 6... Mold part, 7... Organic support material, 8... Cast product forming material, 22... Outer wall part, 23... Leg part , 24... beam, 25... pedestal part, 26... bolt hole forming part, 41... core body, 51... upper mold, 52... lower mold, 62... sprue, 63... runner, 65... outer wall mold part.

Claims (6)

A step of placing the core material in the mold using an organic support material that supports the core material so as not to contact the mold ; and forming the casting in the mold in which the core material is placed. A method of manufacturing a bearing device, comprising a step of melting and pouring a material,
The step of placing the core material in the mold includes the step of adhering the organic support material to the front and rear ends of the cylindrical core material, and the step of forming a cylindrical hollowed out bearing portion of the mold. A method of manufacturing a bearing device, comprising: disposing and fixing the core material to which the organic support material is adhered in an outer wall mold. 2. The method of manufacturing a bearing device according to claim 1, wherein said organic support material is a curable synthetic resin. 3. The method of manufacturing a bearing device according to claim 2, wherein the curable synthetic resin is a reactive curable synthetic resin. 4. The method of manufacturing a bearing device according to claim 3, wherein the reaction-curable synthetic resin is a two-liquid mixing reaction-type epoxy resin adhesive. 2. The method of manufacturing a bearing device according to claim 1, wherein the core material is a carbon steel plate, and the casting forming material is cast iron. 6. The method of manufacturing a bearing device according to claim 5, wherein the carbon steel plate is a carbon tool steel (JIS G 4401:2009), and the cast iron is a spheroidal graphite cast iron product (JIS G 5502:2001). .

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