Kneading Rotor, Kneader, Kneading Method of Rubber Material, and Manufacturing Method of Kneading Rotor

Abstract

The present invention provides a kneading rotor, a kneading machine, a method for kneading a rubber material, and a method for manufacturing a kneading rotor. The kneading rotor is used in a kneading machine, and its base material is formed of carbon steel or alloy steel for mechanical structures. At least a part of the surface of the base material has a stacked layer formed of austenitic stainless steel, and at least a part of the surface of the stacked layer has a hard chromium plating layer. Accordingly, a kneading rotor with excellent corrosion resistance and abrasion resistance, and which is inexpensive and safe can be provided.

Description

Technical Field

[0001] The present invention relates to a kneading rotor for kneading rubber materials, a kneading machine including the kneading rotor, a method for kneading rubber materials using the kneading machine, and a method for manufacturing the kneading rotor. Background Art

[0002] Compared with kneading rotors used in kneading machines for powders and the like, the kneading rotor used in a kneading machine for rubber materials is subjected to a greater load during kneading. In addition, the surface of the kneading rotor is worn by the rubber material during kneading. Therefore, in the kneading rotor used in a kneading machine for rubber materials, for example, a base material having a shaft portion and kneading blades is made of carbon steel having sufficient strength. Moreover, a hard chromium plating layer having abrasion resistance is formed on the surface of the base material. For example, a plating application method for a rotor for a rubber kneading machine is disclosed in Japanese Patent Laid-Open Publication No. 2000-45093 (Patent Document 1).

[0003] In addition, in recent years, there has been a demand for kneading rubber materials containing a large amount of silica. When kneading such a rubber material, an acidic aqueous solution may be generated in the rubber material due to the moisture contained in the silica. Since the hard chromium plating layer is porous, the generated acidic aqueous solution penetrates into the hard chromium plating layer during kneading. Since the carbon steel constituting the base material has poor corrosion resistance, the acidic aqueous solution penetrating into the hard chromium plating layer may corrode the base material.

[0004] Therefore, for the purpose of suppressing corrosion of the base material, in the past, stellite having excellent corrosion resistance was welded to the surface of the base material of the kneading rotor by surfacing, and a hard chromium plating layer was formed on the surface of the stellite.

[0005] However, stellite is an expensive alloy mainly composed of cobalt, and cobalt has a problem of being harmful to human health. Therefore, there is a demand for reducing the amount of stellite used. Summary of the Invention

[0006] The present invention has been made in view of the above problems and demands, and an object thereof is to provide a kneading rotor having excellent corrosion resistance and abrasion resistance, and being inexpensive and safe. In addition, an object of the present invention is to provide a kneading machine including the kneading rotor, a method for kneading rubber materials using the kneading machine, and a method for manufacturing the kneading rotor.

[0007] One aspect of the present invention relates to a kneading rotor for a kneading machine, wherein a base material of the kneading rotor is formed of carbon steel or alloy steel for mechanical structures, at least a part of the surface of the base material has a stacked layer formed of austenitic stainless steel, and at least a part of the surface of the stacked layer has a hard chromium plating layer.

[0008] Another aspect of the present invention relates to a kneading machine for kneading rubber materials, which includes the kneading rotor described above.

[0009] Another aspect of the present invention relates to a method for kneading rubber materials, which is a method for kneading rubber materials using the kneading rotor described above. In this method, the rubber material contains silica and a silane coupling agent, and the kneading is performed while circulating a coolant through the flow path.

[0010] Another aspect of the present invention relates to a method for manufacturing a kneading rotor for a kneading machine. The manufacturing method includes: forming a stacked layer made of austenitic stainless steel on at least a part of the surface of a base material formed of carbon steel or alloy steel for mechanical structures by welding or cladding; and forming a hard chromium plating layer with a thickness of 20 μm or more and a Vickers hardness of 750 or more on at least a part of the surface of the stacked layer by electroplating.

[0011] According to the present invention, it is possible to provide a kneading rotor that is excellent in corrosion resistance and abrasion resistance, and is inexpensive and safe, a kneading machine equipped with the kneading rotor, a method for kneading rubber materials using the kneading machine, and a method for manufacturing the kneading rotor. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a partial cross-sectional view of the kneading rotor according to the first embodiment of the present invention.

[0013] Figure 2 is a cross-sectional view of the kneading machine according to the first embodiment.

[0014] Figure 3 is a partial cross-sectional view of a modified example of the kneading rotor according to the second embodiment of the present invention.

[0015] Figure 4 is a schematic view of the device used in the corrosion resistance test.

[0016] Figure 5 is a schematic view of the device used in the abrasion resistance test. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described in detail. It should be noted that the scope of the present invention is not limited to the embodiments described herein, and various modifications can be made without departing from the spirit of the present invention.

[0018] <First Embodiment>

[0019] <Kneading Rotor>

[0020] Figure 1 is a partial cross-sectional view of the kneading rotor according to this embodiment. The kneading rotor 1 is a kneading rotor for a kneading machine, asFigure 1 As shown in the cross-sectional part, it has: a base material 2; a stacked layer 3 provided on at least a part of the surface of the base material 2; and a hard chromium plating layer 4 provided on at least a part of the surface of the stacked layer 3.

[0021] The base material 2 is formed of carbon steel or alloy steel for mechanical structures, and has portions forming the shaft portion 1a and the kneading blades 1b. As the carbon steel forming the base material 2, general carbon steel can be used.

[0022] Carbon steel and alloy steel for mechanical structures are inexpensive and have excellent strength and toughness compared to other metal materials such as stainless steel. When kneading rubber materials, a larger force is applied to the kneading rotor 1 compared to kneading powders and the like. However, by using carbon steel as the base material 2, the cost of the kneading rotor 1 can be suppressed, and the deformation or breakage of the kneading rotor 1 during the kneading of rubber materials can be suppressed.

[0023] As general carbon steel, for example, S10C to S58C specified in JIS (Japanese Industrial Standards) G 4051:2016 can be used. Specifically, the following carbon steel can be used: in terms of mass%, the C (carbon) content is 0.08 to 0.61%, the Si (silicon) content is 0.15 to 0.35%, the Mn (manganese) content is 0.30 to 0.60% (when the C content is 0.08 to 0.28%) or 0.60 to 0.90% (when the C content is 0.25 to 0.61%), the P (phosphorus) content is 0.030% or less, the S (sulfur) content is 0.035% or less, the Ni (nickel) content is 0.20% or less, the Cr (chromium) content is 0.20% or less, the Cu (copper) content is 0.30% or less, the total content of Ni and Cr is 0.35% or less, and the balance is Fe (iron) and unavoidable impurities. Among the steel grades specified in JIS G 4051:2016, S45C or S35C is preferred.

[0024] In this embodiment, as the alloy steel for mechanical structures, alloy steel with a composition specified in JIS G 4053:2016 can be used. Specifically, the following alloy steels can be used: in terms of mass%, the C content is 0.13 to 0.48%, the Si content is 0.15 to 0.35%, the Mn content is 0.30 to 1.00%, the P content is 0.030% or less, the S content is 0.030% or less, the Ni content is 0.25% or less, the Cr content is 0.90 to 1.50%, the Mo (molybdenum) content is 0.15 to 0.30%, the Cu content is 0.30% or less, and the balance is Fe and inevitable impurities, such as chromium molybdenum steel, for example, SCM415 to SCM445 can be cited. In addition, the following alloy steels can be used: in terms of mass%, the C content is 0.12 to 0.50%, the Si content is 0.15 to 0.35%, the Mn content is 0.30 to 1.20%, the P content is 0.030% or less, the S content is 0.030% or less, the Ni content is 0.40 to 4.50%, the Cr content is 0.40 to 3.50%, the Mo content is 0.15 to 0.70%, the Cu content is 0.30% or less, and the balance is Fe and inevitable impurities, such as nickel chromium molybdenum steel, for example, SNCM220 to SNCM815 can be cited. Among the steel grades specified in JIS G 4053:2016, SCM435 or SCM440 is preferred.

[0025] The stacked layer 3 is provided on at least a part of the surface of the base material 2. The stacked layer 3 may be provided on the part of the surface of the base material 2 that comes into contact with the rubber material when kneading the rubber material by the kneading rotor 1, and the stacked layer 3 may not be provided on the part that comes into contact with the bearing of the kneading rotor 1. It should be noted that the stacked layer 3 may also be provided on the entire surface of the base material 2.

[0026] The stacked layer 3 can be formed, for example, by welding or cladding. The thickness of the stacked layer 3 is not particularly limited, and can be set to 1 to 10 mm, preferably 3 to 5 mm.

[0027] The stacked layer 3 is formed of austenitic stainless steel. Austenitic stainless steel is more expensive than carbon steel and the like, so austenitic stainless steel has not usually been used for kneading rotors so far. Austenitic stainless steel has excellent corrosion resistance compared to carbon steel. Therefore, by providing the stacked layer 3, corrosion resistance can be imparted to the kneading rotor 1. Accordingly, even when the acidic aqueous solution generated by the rubber material penetrates into the porous hard chromium plating layer 4 when kneading the rubber material, corrosion of the stacked layer 3 can be suppressed.

[0028] Austenitic stainless steel refers to steel with an austenite phase in its metallic structure at room temperature. For example, SUS304, SUS309S, etc., which are classified as austenitic stainless steel in JIS, can be used. In addition, the austenitic stainless steel (hereinafter also referred to as "steel grade a") developed by the inventors of the present invention not only has excellent corrosion resistance but also excellent wear resistance, so it is preferred. When using the austenitic stainless steel of this steel grade a, even if the hard chromium plating layer 4 peels off due to long-term use of the kneading rotor 1, the wear resistance of the kneading rotor 1 can be maintained.

[0029] Table 1

[0030] 。

[0031] The hard chromium plating layer 4 is provided on at least a part of the surface of the stacked layer 3. The hard chromium plating layer 4 is most preferably provided on the entire surface of the stacked layer 3 and can also be provided on the surface of the base material 2. With the hard chromium plating layer 4, the kneading rotor 1 can be given wear resistance.

[0032] There are no particular limitations on the composition, thickness, formation method, etc. of the hard chromium plating layer 4. The hard chromium plating layer 4 can be formed by, for example, electroplating. The thickness of the hard chromium plating layer 4 is preferably 0.1 mm or more. In addition, the thickness of the hard chromium plating layer 4 is preferably 0.3 mm or less. The Vickers hardness (Hv) of the hard chromium plating layer 4 is preferably 600 or more, more preferably 750 or more. In addition, the Vickers hardness of the hard chromium plating layer 4 is preferably 1500 or less, more preferably 1200 or less.

[0033] For example Figure 1 As shown, the kneading rotor 1 can be a rotor having a shaft portion 1a and kneading blades 1b that project radially from the circumferential surface of the shaft portion 1a. In the present embodiment, three kneading blades 1b are provided on the circumferential surface of the shaft portion 1a. In this case, the stacked layer 3 is preferably provided on the surface of the kneading blade 1b including the tip portion 1c and the circumferential surface of the portion of the shaft portion 1b where the kneading blade 1b is provided.

[0034] As Figure 1 shown, the kneading rotor 1 has a flow path 5 through which coolant can flow inside. The flow path 5 is provided so as to penetrate the shaft portion 1a in the axial direction. By providing the flow path 5, the kneading rotor 1 can be cooled during the kneading process, so it is preferably provided with the flow path 5, but the flow path 5 can also not be provided.

[0035] 〈Kneader〉

[0036] Figure 2This is a cross-sectional view of the kneader according to this embodiment. The kneader 80 is an enclosed kneader for kneading rubber materials and is a two-shaft batch-type. The kneader 80 includes a housing 70, a pair of kneading rotor pairs 10, and a material supply cylinder 77. The pair of kneading rotor pairs 10 includes two of the above-mentioned kneading rotors 1.

[0037] The housing 70 is the main body of the kneader 80 and is formed of a metal material. The housing 70 is supported by a metal support base 70a. Two kneading chambers 70s are provided inside the housing 70. Each kneading chamber 70s is in the shape of a cylinder extending parallel to each other.

[0038] A material supply port 71 for supplying rubber materials to be kneaded is provided at the upper part of the housing 70, which is connected to the material supply cylinder 77. At the lower part of the housing 70, there are provided: a material discharge port 72 for discharging the kneaded materials; and a lid member 73 for opening and closing the material discharge port 72. Inside the housing 70, the material supply port 71, the two kneading chambers 70s, and the material discharge port 72 communicate with each other.

[0039] One kneading rotor 1 is arranged inside each of the two kneading chambers 70s. Power is respectively applied to the kneading rotors 1 from a motor (not shown), and the kneading rotors 1 rotate in opposite directions around the shaft portions 1a ( Figure 2 in the directions of the arrows F, F' in the figure). The rotation direction of the kneading rotor 1 is the direction of discharging the rubber materials supplied from the material supply cylinder 77 to the kneading chamber 70s to the material discharge port 72.

[0040] The material supply cylinder 77 extends vertically at the upper part of the housing 70, and the internal space of the material supply cylinder 77 is continuous with the material supply port 71. The kneader 80 is provided with a hopper 76 for supplying rubber materials from the outside at the upper part of the material supply cylinder 77.

[0041] The kneader 80 according to this embodiment is equipped with kneading rotors 1 having excellent corrosion resistance and abrasion resistance, so that rubber materials can be kneaded stably for a long time.

[0042] The kneader 80 according to this embodiment is equipped with two Figure 1 as shown in the kneading rotors 1. In this embodiment, the kneading rotors 1 are meshing-type rotors arranged adjacent to each other in such a way that the respective kneading blades 1b mesh with each other. However, the kneading rotors 1 can also be tangential-type rotors arranged in such a way that the tips 1c of the kneading blades 1b contact each other. In Figure 1 and Figure 2In the kneading rotor 1 shown, the tip 1c of the kneading blade 1b refers to a constant outer diameter portion having a constant outer diameter (a portion of the outer peripheral surface of the kneading blade 1b that forms an arc of the same radius centered on the rotation axis). Since the kneader 80 according to the present embodiment can use either a meshing rotor or a tangential rotor, various rubber materials can be kneaded.

[0043] In addition, the kneader 80 according to the present embodiment is a batch kneader. However, the kneader 80 according to the present embodiment can also be a continuous kneader.

[0044] 〈Kneading method for rubber material〉

[0045] A kneading method for a rubber material using the kneading rotor according to the present embodiment will be described. The kneading method according to the present embodiment uses a kneading rotor 1 having a flow path 5 through which a coolant can flow inside. The kneading rotor 1 can be a meshing rotor or a tangential rotor.

[0046] In the kneading method for the rubber material according to the present embodiment, a rubber material containing a silane and a silane coupling agent is used, and the rubber material is kneaded while allowing the coolant to flow through the flow path 5.

[0047] More specifically, using a kneader 80 including a kneading rotor 1 having a flow path 5, a rubber material containing a silane and a silane coupling agent is supplied from the hopper 76 of the kneader 80. The supplied rubber material is supplied into the kneading chamber 70s from the material supply port 71 via the material supply cylinder 77, and is kneaded by the kneading rotor 1 rotating in a state where the coolant flows through the flow path 5. The rubber material kneaded by the kneading rotor 1 is discharged downward from the material discharge port 72.

[0048] In the kneading method according to the present embodiment, since a rubber material containing silica is kneaded, an acidic aqueous solution may be generated in the rubber material due to the moisture contained in the silica. However, in this kneading method, since the kneading rotor 1 is used, even if the acidic aqueous solution penetrates into the hard chromium plating layer 4, corrosion of the stacked layer 3 can be suppressed.

[0049] In addition, in the kneading method according to the present embodiment, the kneading rotor 1 can be cooled by the coolant flowing through the flow path 5 while kneading. Therefore, it is possible to suppress the deterioration of the rubber material and the kneading rotor 1 due to overheating during kneading. As a cause of the deterioration of the kneading rotor 1 due to overheating, it can be cited that due to the different thermal expansion coefficients of the base material 2, the stacked layer 3, and the hard chromium plating layer 4 constituting the kneading rotor 1, deformation occurs between these parts in an overheated state.

[0050] Based on the above circumstances, according to the kneading method involved in this embodiment, deterioration of the kneading rotor 1 can be suppressed, and kneading of the rubber material can be stably performed for a long time.

[0051] 〈Manufacturing method of kneading rotor〉

[0052] Refer to Figure 1 , and describe the manufacturing method of the kneading rotor 1 for the kneading machine 80 involved in this embodiment.

[0053] As Figure 1 shown, the manufacturing method of the kneading rotor 1 involved in this embodiment is as follows: on at least a part of the surface of the base material 2 formed of carbon steel or alloy steel for mechanical structures, a stacked layer 3 formed of austenitic stainless steel is formed by welding or cladding. On at least a part of the surface of the stacked layer 3, a hard chromium plating layer 4 with a thickness of 20 μm or more and a Vickers hardness of 750 or more is formed by electroplating. According to this method, a kneading rotor 1 with excellent corrosion resistance and wear resistance can be obtained.

[0054] 〈Second embodiment〉

[0055] 〈Kneading rotor〉

[0056] The following describes the second embodiment of the present invention. Figure 3 is a partial cross-sectional view of the kneading rotor involved in this embodiment. In Figure 3 , the same reference numerals are given to the components substantially the same as those described in Figure 1 , and the description thereof is omitted hereinafter.

[0057] The kneading rotor 1 involved in this embodiment is different from the kneading rotor involved in the first embodiment in the structure of the stacked layer 3, and has the same structure as the kneading rotor 1 involved in the first embodiment except for this. The entire stacked layer 3 of the kneading rotor 1 involved in the first embodiment is formed of austenitic stainless steel. In contrast, the stacked layer 3 of the kneading rotor 1 involved in this embodiment has a first stacked layer 3a formed of Stellite at at least the tip 1c of the kneading blade 1b in the surface of the base material 2, and a second stacked layer 3b formed of austenitic stainless steel in the portion other than the tip 1c.

[0058] The region of the surface of the base material 2 where the stacked layer 3 combining the first stacked layer 3a and the second stacked layer 3b involved in this embodiment is provided is the same as the stacked layer 3 involved in the first embodiment.

[0059] Since Stellite has excellent corrosion resistance, by providing the first stacked layer 3a formed of Stellite, the corrosion resistance of the kneading rotor 1 can be further improved.

[0060] The first stacked layer 3a is preferably provided not only at the tip 1c of the kneading blade 1b but also on the side surface 1d of the kneading blade 1b. When the kneading rotor 1 is an engaging type rotor, it is more preferably provided on the circumferential surface of the shaft portion 1a where the kneading blade 1b is provided.

[0061] Compared with the case where the entire stacked layer 3 is formed of Stellite, the kneading rotor 1 according to the present embodiment can reduce the amount of Stellite used. In addition, austenitic stainless steel is cheaper than Stellite. Therefore, the kneading rotor 1 according to the present embodiment is cheaper and safer than the case where the entire stacked layer 3 is formed of Stellite.

[0062] Figure 3 The kneading rotor 1 according to the present embodiment shown also has a flow path 5 through which a coolant can flow inside, but like the kneading rotor according to the first embodiment, the flow path 5 may not be provided. In addition, the kneading rotor 1 according to the present embodiment can also be applied to the kneading machine according to the above-described first embodiment.

[0063] 〈Manufacturing method of kneading rotor〉

[0064] In the manufacturing method of the kneading rotor according to the present embodiment, in the manufacturing method of the kneading rotor according to the first embodiment, as Figure 3 shown, a first stacked layer 3a formed of Stellite is formed on the surface of at least the tip 1c of the kneading blade 1b of the kneading rotor 1 by welding or cladding, a second stacked layer 3b formed of austenitic stainless steel is formed on the portion other than the tip 1c by welding or cladding, and the above-described hard chromium plating layer 4 is formed on at least a part of the second stacked layer 3b or the first stacked layer 3a. According to this method, a kneading rotor 1 with more excellent corrosion resistance can be obtained.

[0065] This specification has disclosed the technology of various aspects as described above, and the main technologies are summarized as follows.

[0066] As described above, one aspect of the present invention relates to a kneading rotor for a kneading machine, the base material of the kneading rotor is formed of carbon steel or alloy steel for mechanical structures, at least a part of the surface of the base material has a stacked layer formed of austenitic stainless steel, and at least a part of the surface of the stacked layer has a hard chromium plating layer.

[0067] According to this configuration, a kneading rotor with excellent corrosion resistance and wear resistance, and being cheap and safe can be obtained.

[0068] In the kneading rotor having the above-described configuration, the kneading rotor may also have a kneading blade, a stacked layer formed of Stellite is provided at least at the tip of the kneading blade, and a stacked layer formed of the austenitic stainless steel is provided at the portion other than the tip.

[0069] According to this configuration, a kneading rotor with more excellent corrosion resistance can be obtained.

[0070] In the kneading rotor with the above configuration, the thickness of the hard chromium plating layer can also be 20 μm or more, and the Vickers hardness can be 750 or more.

[0071] According to this configuration, a kneading rotor with more excellent abrasion resistance can be obtained.

[0072] The kneading rotor with the above configuration may also have a flow path through which a coolant can flow inside.

[0073] According to this configuration, the kneading rotor can be cooled during the kneading process.

[0074] In addition, another aspect of the present invention relates to a kneader for kneading a rubber material, which includes the above kneading rotor.

[0075] According to this configuration, since the kneader includes the above kneading rotor with excellent corrosion resistance and abrasion resistance, the kneading of the rubber material can be stably performed for a long time.

[0076] In the kneader with the above configuration, the kneading rotor can be an engaging type rotor or a tangential type rotor.

[0077] According to this configuration, a kneader capable of kneading various rubber materials can be obtained.

[0078] In addition, another aspect of the present invention relates to a method for kneading a rubber material, which is a method for kneading a rubber material using the above kneading rotor. The rubber material contains silica and a silane coupling agent, and the kneading method kneads the rubber material while allowing a coolant to flow through the flow path.

[0079] According to this method, the deterioration of the kneading rotor due to overheating can be suppressed, and the kneading of the rubber material can be stably performed for a long time.

[0080] In addition, another aspect of the present invention relates to a manufacturing method of a kneading rotor for a kneader. The manufacturing method: forms a stacked layer made of austenitic stainless steel on at least a part of the surface of a base material formed of carbon steel or alloy steel for mechanical structures by welding or cladding; forms a hard chromium plating layer with a thickness of 20 μm or more and a Vickers hardness of 750 or more on at least a part of the surface of the stacked layer by electroplating.

[0081] According to this method, a kneading rotor with excellent corrosion resistance and abrasion resistance can be obtained.

[0082] In the above method for manufacturing a kneading rotor, the kneading rotor may also have kneading blades. By welding or cladding, a stacked layer formed of Stellite is formed on the surface of at least the tip of the kneading blades, and a stacked layer formed of the austenitic stainless steel is formed on the portion other than the tip by welding or cladding. The hard chromium plating layer is formed on at least a part of the stacked layer formed of the austenitic stainless steel or the stacked layer formed of Stellite.

[0083] According to this method, a kneading rotor with more excellent corrosion resistance can be obtained.

[0084] Hereinafter, examples will be listed to illustrate the present invention more specifically. However, the present invention is not limited to the following examples and can be implemented with modifications within the scope that conforms to the above and the following gist. All such modifications are included in the technical scope of the present invention.

[0085]

Examples

[0086] In the examples, corrosion resistance tests and wear resistance tests were conducted using steel materials and metal materials with the chemical compositions shown in Table 2 (No. 1 to 4). The steel materials of No. 1 and No. 2 are austenitic stainless steels and are examples of the present invention that conform to the steel type a shown in Table 1 above. The steel material of No. 3 is a martensitic stainless steel and is a comparative example of the present invention. The metal material of No. 4 is an alloy (Stellite) mainly composed of cobalt and is an example of the present invention. "0.00" shown in Table 2 indicates a case where it is lower than the measurement limit. In Table 1, the hardness, tensile strength, and elongation values of each steel material are also recorded. It should be noted that the value marked with * in the column of HRC hardness in the hardness of the steel material of No. 1 is HRB hardness.

[0087] Table 2

[0088] 。

[0089] 〈Corrosion resistance test〉

[0090] Figure 4 is a schematic diagram of the device used in the corrosion resistance test. As Figure 4 shown, the corrosion resistance test device 50 includes: a constant temperature water bath 52 that houses hot water 51 in a state of maintaining a specified temperature; and a container 54 that houses a corrosion liquid 53. The container 54 is immersed in the hot water 51, and the corrosion liquid 53 is maintained at a constant temperature. In the corrosion resistance test, the specimen 56 wrapped in a net 55 is suspended by a sling 57 and immersed in the corrosion liquid for a specified time in a state of not contacting the container 54. The test conditions are as described below.

[0091] Corrosion liquid: A mixed liquid of HCl and H2SO4 (hydrogen ion ratio is 1:1)

[0092] Hydrogen ion index of the etching solution: pH 2.0

[0093] Temperature of the etching solution: 80 °C

[0094] Immersion time: 24 hours

[0095] The results of the corrosion resistance test are shown in Table 3.

[0096] Table 3

[0097] 。

[0098] As shown in Table 3, the steel materials of No. 1 and 2 and the metal material of No. 4 in the examples of the present invention all have good corrosion resistance with a corrosion rate of less than 0.015 mm / year. The corrosion rate of the steel material of No. 3 in the comparative example is greater than 1 mm / year, and the corrosion resistance is poor.

[0099] 〈Abrasion resistance test〉

[0100] Figure 5 is a schematic diagram of the device used in the abrasion resistance test. As Figure 5 shown, the abrasion resistance test device 60 includes: a rubber wheel 61 with a diameter of 220 mm; and a hopper 62 for supplying test sand 63 between the rubber wheel 61 and the test piece 65. The test piece 65 is pressed against a substantially vertical portion of the circumferential surface of the rotating rubber wheel 61, and the test sand 63 is supplied from above the contact portion between the rubber wheel 61 and the test piece 65.

[0101] The abrasion resistance test (sand abrasion test) was carried out in accordance with ASTM (American Society for Testing and Materials) G65-00e1. The test conditions are as follows.

[0102] Test force (the force pressing the test piece against the rubber wheel): 130 N (13.3 kgf)

[0103] Rotational speed of the rubber wheel: 145 rpm (revolutions per minute)

[0104] Test sand flow rate: 350 g / minute

[0105] Test sand: silica sand No. 6

[0106] Under the above test conditions, while supplying the test sand, the test piece was pressed against the rotating rubber wheel, and the mass of the specimens at 2000, 4000, and 6000 rotations of the rubber wheel was measured. The wear reduction amount was calculated by subtracting the mass of the specimens at each measured rotation number from the mass of the specimen in the initial state. The abrasion resistance test was carried out on the steel materials of No. 1 and 3 and the metal material of No. 4.

[0107] The results of the abrasion resistance test are shown in Table 4.

[0108] Table 4

[0109] 。

[0110] As shown in Table 4, the wear reduction amounts of the steel No.1 and the steel No.3 are both below 5 g after 6000 rotations, showing good wear resistance. The wear reduction amount of the metal material No.4 is greater than 5 g after 6000 rotations, and its wear resistance is poor compared with that of the steel No.1.

[0111] 〈Summary〉

[0112] From the above test results, it can be seen that the austenitic stainless steels No.1 and No.2 and the Stellite No.4 of the present invention example all have the same corrosion resistance, and their corrosion resistance is excellent compared with that of the martensitic stainless steel No.3. Therefore, it can be known that by using these austenitic stainless steels and Stellite as the stacked layers of the kneading rotor and providing a hard chromium plating layer on the surface of the stacked layer, a kneading rotor with excellent corrosion resistance and wear resistance can be obtained.

[0113] Moreover, it can be seen that the wear resistance of the austenitic stainless steel No.1 is excellent compared with that of the Stellite No.4. Therefore, it can be known that by using the austenitic stainless steel of steel type a as the stacked layer of the kneading rotor, a kneading rotor with excellent corrosion resistance and wear resistance that can be maintained even when the hard chromium plating layer is peeled off can be obtained.

Claims

1. A kneading rotor for a kneader, characterized in that the base material of the kneading rotor is formed of carbon steel or alloy steel for mechanical structures, at least a part of the surface of the base material has a stacked layer formed of austenitic stainless steel, at least a part of the surface of the stacked layer has a hard chromium plating layer.

2. The kneading rotor according to claim 1, characterized in that the kneading rotor has kneading blades, at least the tips of the kneading blades have a stacked layer formed of Stellite, and the parts other than the tips have a stacked layer formed of the austenitic stainless steel.

3. The kneading rotor according to claim 1, characterized in that the thickness of the hard chromium plating layer is 20 μm or more and the Vickers hardness is 750 or more.

4. The kneading rotor according to claim 1, characterized in that the kneading rotor has a flow path through which a coolant can flow inside.

5. A kneading machine for kneading rubber materials, characterized in that Including: the kneading rotor according to claim 1.

6. The kneading machine according to claim 5, characterized in that the kneading rotor is an engaging type rotor.

7. The kneading machine according to claim 5, characterized in that the kneading rotor is a tangential type rotor.

8. A kneading method for a rubber material, characterized in that A method for kneading a rubber material using the kneading rotor according to claim 4, wherein the rubber material contains silica and a silane coupling agent, and in the kneading method, the rubber material is kneaded while allowing a coolant to flow through the flow path.

9. A manufacturing method of a kneading rotor for a kneader, characterized in that: at least a part of the surface of a base material formed of carbon steel or alloy steel for mechanical structures is formed with a stacked layer formed of austenitic stainless steel by welding or cladding; a hard chromium plating layer with a thickness of 20 μm or more and a Vickers hardness of 750 or more is formed on at least a part of the surface of the stacked layer by electroplating.

10. The manufacturing method of the kneading rotor according to claim 9, characterized in that the kneading rotor has kneading blades, a stacked layer formed of Stellite is formed on at least the surface of the tips of the kneading blades by welding or cladding, a stacked layer formed of the austenitic stainless steel is formed on the parts other than the tips by welding or cladding, and the hard chromium plating layer is formed on at least a part of the stacked layer formed of the austenitic stainless steel or the stacked layer formed of Stellite.

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