High-hardness and high-wear-resistance alloy roller and preparation method thereof

Abstract

The high-hardness and high-wear-resistance alloy roller comprises a roller body and a roller shaft penetrating through the roller body, and the roller body comprises an inner cast iron layer and an outer alloy layer covering the upper portion of the cast iron layer. The alloy layer is prepared from the following raw materials in percentage by weight: 3 to 3.7 percent of carbon, 0.7 to 1 percent of silicon, 0.6 to 0.9 percent of manganese, 0.3 to 0.7 percent of phosphorus, 0.005 to 0.02 percent of sulfur, 2.7 to 3.5 percent of chromium, 3.2 to 3.8 percent of nickel, 0.5 to 0.6 percent of molybdenum and the balance of iron and inevitable impurities; meanwhile, the invention discloses a preparation method of the alloy roller. Through precise design of components of the alloy layer and composite reinforcement of carbon, chromium, nickel and molybdenum, the hardness, toughness and wear resistance of the working layer of the roller are remarkably improved, stripping and fracture are effectively prevented, and the service life is prolonged.

Description

Technical Field

[0001] This invention belongs to the field of rolling mill technology, specifically relating to a high-hardness, high-wear-resistant alloy rolling mill and its preparation method. Background Technology

[0002] As a core component in rolling, crushing, and grinding processes, rolling mill rolls are widely used in steel, non-ferrous metals, metallurgy, grain, food, and feed processing industries. Their performance directly determines the precision, surface quality, and production efficiency of the rolled, crushed, and ground products. During production, rolling mill rolls must withstand enormous rolling forces, shearing forces, frictional forces, and thermal cycling, thus placing extremely high demands on their wear resistance, hardness, toughness, and thermal stability.

[0003] Existing technologies, such as traditional rolling mill rolls, suffer from multiple technical defects: In terms of materials, mainstream cast iron or ordinary alloy rolls lack sufficient wear resistance, leading to rapid degradation of roll surface precision after prolonged use. While high-chromium alloys (such as hypoeutectic white cast iron containing 21-23% Cr) can improve wear resistance, they do not address the issue of an unreasonable hardness gradient, still presenting a contradiction between surface hardness and brittleness and insufficient core toughness. Under long-term alternating loads, fatigue cracks or even roll breakage are prone to occur, and wear causes changes in the roll gap, affecting flour particle size or food forming quality. Therefore, it is necessary to develop a new type of rolling mill roll that meets the current industrial demand for high-hardness, high-wear-resistant rolls. Summary of the Invention

[0004] The purpose of this invention is to provide a high-hardness, high-wear-resistant alloy roll, and a method for preparing the roll.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A high-hardness, high-wear-resistant alloy roll includes a roll body and a roll shaft penetrating the roll body. The roll body comprises an inner cast iron layer and an outer alloy layer covering the cast iron layer. The alloy layer is composed of the following raw materials in weight percentages: carbon 3-3.7%, silicon 0.7-1%, manganese 0.6-0.9%, phosphorus 0.3-0.7%, sulfur 0.005-0.02%, chromium 2.7-3.5%, nickel 3.2-3.8%, molybdenum 0.5-0.6%, with the balance being iron and unavoidable impurities.

[0007] Preferably, the alloy layer is composed of the following raw materials by weight percentage: 3.2-3.5% carbon, 0.7-0.9% silicon, 0.6-0.8% manganese, 0.4-0.6% phosphorus, 0.01-0.02% sulfur, 3-3.2% chromium, 3.5-3.7% nickel, 0.52-0.6% molybdenum, with the balance being iron and unavoidable impurities.

[0008] Preferably, the alloy layer is composed of the following raw materials by weight percentage: 3.2-3.3% carbon, 0.7-0.8% silicon, 0.6-0.7% manganese, 0.4-0.5% phosphorus, 0.01-0.015% sulfur, 3-3.1% chromium, 3.5-3.6% nickel, 0.52-0.58% molybdenum, with the balance being iron and unavoidable impurities.

[0009] Preferably, the inner cast iron layer is gray cast iron HT200; the alloy layer thickness is 18-22mm.

[0010] The preparation method of the above-mentioned high-hardness, high-wear-resistant alloy roll includes the following steps:

[0011] (1) Add various raw materials into the melting furnace according to the proportion of raw materials for the alloy layer, maintain the melting temperature at 1370-1450 degrees, obtain molten iron, use slag remover to purify the molten iron 3-4 times, and then centrifugally cast the alloy layer for 35-70 seconds.

[0012] (2) After casting the alloy layer for 70-100 seconds, maintain the centrifugal speed and use gray cast iron HT200 molten iron to cast the cast iron layer. Then, cool it down to 250-300℃ at a cooling rate of 90-100℃ / h. Finally, use air cooling to bring it down to room temperature to obtain the roller body.

[0013] (3) Roughly machine the roller body surface, and after assembling the roller shaft, perform fine machining to ensure that the thickness difference of the alloy layer of the roller is ≤0.5mm, the surface roughness of the roller body is less than Ra0.2, the total runout is less than 0.005mm, and the dynamic balance imbalance is ≤3g at a speed of 700 rpm. Then, draw wire on the surface of the alloy layer, so that the surface roughness of the teeth is less than Ra3.2, the tooth tip width error is within ±0.02mm, and the tooth edge appears as a line under a 40x magnifying glass without any serrated notches. The alloy roller is thus obtained.

[0014] Preferably, the slag remover is a QC-type molten metal purifier.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] (1) This invention significantly improves the hardness, toughness, and wear resistance of the working layer of the roll by precisely designing the alloy layer composition and using carbon, chromium, nickel, and molybdenum composite reinforcement. The carbon content, combined with manganese and chromium, forms a high-hardness carbide skeleton, nickel enhances the toughness and thermal stability of the matrix, and molybdenum refines the grains and inhibits high-temperature softening, enhancing wear resistance. This allows the alloy layer to maintain excellent performance even under strong friction and thermal cycling, with a surface hardness of HSD78-85, increasing the flexibility and wear resistance of the roll during use. In addition, a double-layer composite structure of high-hardness alloy on the outer layer and tough gray cast iron (HT200) on the inner layer is adopted, taking into account both surface wear resistance and overall impact resistance. The outer layer resists wear, while the inner layer supports and absorbs energy, effectively preventing spalling and breakage and extending service life.

[0017] (2) This invention employs a process of centrifugal casting of the alloy layer and step-by-step casting of the alloy layer and cast iron layer. Combined with precise calculation of centrifugal speed and accurate casting sequence, this achieves a metallurgical bond between the alloy layer and the cast iron layer, avoiding component segregation and porosity defects. This ensures a dense and uniform alloy layer structure, free of porosity and slag inclusions, and forms a strong metallurgical bond with the cast iron layer. Multiple slag removal processes improve the purity of the molten iron. Gradient cooling at 90-100℃ / h and air cooling reduce internal stress and improve the stability of the roll structure. The overall process ensures the uniformity of the alloy composition, preventing element segregation and guaranteeing uniform hardness of the alloy layer. The surface processing and wire drawing control of the rolls in this invention ensure the dimensional accuracy and surface finish of the rolled products.

[0018] (3) The roller of this invention has high hardness and good toughness. During the wire drawing process, it is not easy for the wire to break or break. The processed teeth are sharp, the surface is smooth and the roughness is low. When crushing and grinding materials such as wheat and corn, the heat generated is small, which is 10-15 degrees lower than that of ordinary grinding rollers. This protects the gluten of the flour from being damaged and improves the flour quality. At the same time, it has good wear resistance. When used on the grinding roller of a flour mill, it can be used for 10,000-12,000 hours after one wire drawing, while ordinary grinding rollers can be used for 2,200-3,000 hours after one wire drawing. The service life is 3-4 times that of ordinary grinding rollers, which greatly extends the service life. Detailed Implementation

[0019] The present invention will be further described below with reference to embodiments, but the scope of protection of the present invention is not limited thereto.

[0020] In the following embodiments, the slag remover is a QC type molten metal purifier, purchased from Henan Xinlifan New Material Technology Co., Ltd.

[0021] Example 1

[0022] A high-hardness, high-wear-resistant alloy roll includes a roll body and a roll shaft penetrating the roll body. The roll body comprises an inner cast iron layer and an outer alloy layer covering the cast iron layer. The alloy layer is composed of the following raw materials by weight percentage: carbon 3%, silicon 1%, manganese 0.9%, phosphorus 0.3%, sulfur 0.01%, chromium 2.7%, nickel 3.8%, molybdenum 0.5%, with the balance being iron and unavoidable impurities. The inner cast iron layer is gray cast iron HT200. The alloy layer has a thickness of 22 mm.

[0023] The preparation method of the above-mentioned high-hardness, high-wear-resistant alloy roll includes the following steps:

[0024] (1) Add various raw materials into the melting furnace according to the proportion of raw materials for the alloy layer, maintain the melting temperature at 1370-1450 degrees, obtain molten iron, purify the molten iron three times with a slag remover, and then centrifugally cast the alloy layer for 60-70 seconds.

[0025] (2) After casting the alloy layer for 90-100 seconds, maintain the centrifugal speed and cast the cast iron layer separately using gray cast iron HT200 molten iron. Then, cool it down to 250-260℃ at a cooling rate of 90-100℃ / h. Finally, use air cooling to bring it down to room temperature to obtain the roller body.

[0026] (3) Roughly machine the roller body surface, and after assembling the roller shaft, perform fine machining to ensure that the thickness difference of the alloy layer of the roller is ≤0.5mm, the surface roughness of the roller body is less than Ra0.2, the total runout is less than 0.005mm, and the dynamic balance imbalance is ≤3g at a speed of 700 rpm. Then, draw wire on the surface of the alloy layer, so that the surface roughness of the teeth is less than Ra3.2, the tooth tip width error is within ±0.02mm, and the tooth edge appears as a line under a 40x magnifying glass without any serrated notches. The alloy roller is thus obtained.

[0027] Example 2

[0028] A high-hardness, high-wear-resistant alloy roll includes a roll body and a roll shaft penetrating the roll body. The roll body comprises an inner cast iron layer and an outer alloy layer covering the cast iron layer. The alloy layer is composed of the following raw materials by weight percentage: carbon 3.7%, silicon 0.7%, manganese 0.6%, phosphorus 0.7%, sulfur 0.005%, chromium 3.5%, nickel 3.2%, molybdenum 0.6%, with the balance being iron and unavoidable impurities. The inner cast iron layer is gray cast iron HT200. The alloy layer has a thickness of 18 mm.

[0029] The preparation method of the above-mentioned high-hardness, high-wear-resistant alloy roll includes the following steps:

[0030] (1) Add various raw materials into the melting furnace according to the proportion of raw materials for the alloy layer, maintain the melting temperature at 1370-1450 degrees, obtain molten iron, purify the molten iron 4 times with slag remover, and then centrifugally cast the alloy layer for 35-50 seconds.

[0031] (2) After the alloy layer is cast for 70-80 seconds, the centrifugal speed is maintained, and the cast iron layer is cast using gray cast iron HT200 molten iron. Then, the temperature is reduced to 290-300℃ at a cooling rate of 90-100℃ / h. Finally, the roller body is obtained by air cooling to room temperature.

[0032] (3) Roughly machine the roller body surface, and after assembling the roller shaft, perform fine machining to ensure that the thickness difference of the alloy layer of the roller is ≤0.5mm, the surface roughness of the roller body is less than Ra0.2, the total runout is less than 0.005mm, and the dynamic balance imbalance is ≤3g at a speed of 700 rpm. Then, draw wire on the surface of the alloy layer, so that the surface roughness of the teeth is less than Ra3.2, the tooth tip width error is within ±0.02mm, and the tooth edge appears as a line under a 40x magnifying glass without any serrated notches. The alloy roller is thus obtained.

[0033] Example 3

[0034] A high-hardness, high-wear-resistant alloy roll includes a roll body and a roll shaft penetrating the roll body. The roll body comprises an inner cast iron layer and an outer alloy layer covering the cast iron layer. The alloy layer is composed of the following raw materials by weight percentage: carbon 3.2%, silicon 0.9%, manganese 0.7%, phosphorus 0.4%, sulfur 0.02%, chromium 3%, nickel 3.5%, molybdenum 0.52%, with the balance being iron and unavoidable impurities. The inner cast iron layer is gray cast iron HT200. The alloy layer has a thickness of 20 mm.

[0035] The preparation method of the above-mentioned high-hardness, high-wear-resistant alloy roll includes the following steps:

[0036] (1) Add various raw materials into the melting furnace according to the proportion of raw materials for the alloy layer, maintain the melting temperature at 1370-1450 degrees, obtain molten iron, purify the molten iron three times with a slag remover, and then centrifugally cast the alloy layer for 40-50 seconds.

[0037] (2) After casting the alloy layer for 80-90 seconds, maintain the centrifugal speed and use gray cast iron HT200 molten iron to cast the cast iron layer. Then, cool it down to 260-270℃ at a cooling rate of 90-100℃ / h. Finally, use air cooling to bring it down to room temperature to obtain the roller body.

[0038] (3) Roughly machine the roller surface, then finish machine it after assembling the roller shaft, ensuring the thickness difference of the alloy layer is ≤0.5mm, the surface roughness is less than Ra0.2, the total runout is less than 0.005mm, and the dynamic imbalance is ≤3g at 700 rpm. Afterward, draw the alloy layer surface, ensuring the tooth surface roughness is less than Ra3.2, the tooth tip width error is within ±0.02mm, and the tooth edge appears as a straight line under a 40x magnifying glass, without any serrated notches. This yields the alloy roller.

[0039] Example 4

[0040] A high-hardness, high-wear-resistant alloy roll includes a roll body and a roll shaft penetrating the roll body. The roll body comprises an inner cast iron layer and an outer alloy layer covering the cast iron layer. The alloy layer is composed of the following raw materials by weight percentage: carbon 3.5%, silicon 0.8%, manganese 0.8%, phosphorus 0.6%, sulfur 0.015%, chromium 3.2%, nickel 3.7%, molybdenum 0.58%, with the balance being iron and unavoidable impurities. The inner cast iron layer is gray cast iron HT200. The alloy layer has a thickness of 21 mm.

[0041] The preparation method of the above-mentioned high-hardness, high-wear-resistant alloy roll includes the following steps:

[0042] (1) Add various raw materials into the melting furnace according to the proportion of raw materials for the alloy layer, maintain the melting temperature at 1370-1450 degrees, obtain molten iron, purify the molten iron 4 times with slag remover, and then centrifugally cast the alloy layer for 60-70 seconds.

[0043] (2) After casting the alloy layer for 90-100 seconds, maintain the centrifugal speed and use gray cast iron HT200 molten iron to cast the cast iron layer. Then, cool it down to 250-260℃ at a cooling rate of 90-100℃ / h. Finally, use air cooling to bring it down to room temperature to obtain the roller body.

[0044] (3) Roughly machine the roller body surface, and after assembling the roller shaft, perform fine machining to ensure that the thickness difference of the alloy layer of the roller is ≤0.5mm, the surface roughness of the roller body is less than Ra0.2, the total runout is less than 0.005mm, and the dynamic balance imbalance is ≤3g at a speed of 700 rpm. Then, draw wire on the surface of the alloy layer, so that the surface roughness of the teeth is less than Ra3.2, the tooth tip width error is within ±0.02mm, and the tooth edge appears as a line under a 40x magnifying glass without any serrated notches. The alloy roller is thus obtained.

[0045] Example 5

[0046] A high-hardness, high-wear-resistant alloy roll includes a roll body and a roll shaft penetrating the roll body. The roll body comprises an inner cast iron layer and an outer alloy layer covering the cast iron layer. The alloy layer is composed of the following raw materials by weight percentage: carbon 3.3%, silicon 0.75%, manganese 0.65%, phosphorus 0.5%, sulfur 0.01%, chromium 3.1%, nickel 3.6%, molybdenum 0.55%, with the balance being iron and unavoidable impurities. The inner cast iron layer is gray cast iron HT200. The alloy layer has a thickness of 20 mm.

[0047] The preparation method of the above-mentioned high-hardness, high-wear-resistant alloy roll includes the following steps:

[0048] (1) Add various raw materials into the melting furnace according to the proportion of raw materials for the alloy layer, maintain the melting temperature at 1370-1450 degrees, obtain molten iron, purify the molten iron 4 times with slag remover, and then centrifugally cast the alloy layer for 50-60 seconds.

[0049] (2) After the alloy layer is cast for 70-80 seconds, the centrifugal speed is maintained, and the cast iron layer is cast separately using gray cast iron HT200 molten iron. Then, the temperature is reduced to 270-280℃ at a cooling rate of 90-100℃ / h. Finally, the roller body is obtained by air cooling to room temperature.

[0050] (3) Roughly machine the roller body surface, and after assembling the roller shaft, perform fine machining to ensure that the thickness difference of the alloy layer of the roller is ≤0.5mm, the surface roughness of the roller body is less than Ra0.2, the total runout is less than 0.005mm, and the dynamic balance imbalance is ≤3g at a speed of 700 rpm. Then, draw wire on the surface of the alloy layer, so that the surface roughness of the teeth is less than Ra3.2, the tooth tip width error is within ±0.02mm, and the tooth edge appears as a line under a 40x magnifying glass without any serrated notches. The alloy roller is thus obtained.

[0051] Example 6

[0052] A high-hardness, high-wear-resistant alloy roll includes a roll body and a roll shaft penetrating the roll body. The roll body comprises an inner cast iron layer and an outer alloy layer covering the cast iron layer. The alloy layer is composed of the following raw materials by weight percentage: carbon 3.6%, silicon 0.85%, manganese 0.75%, phosphorus 0.6%, sulfur 0.013%, chromium 3%, nickel 3.5%, molybdenum 0.53%, with the balance being iron and unavoidable impurities. The inner cast iron layer is gray cast iron HT200. The alloy layer has a thickness of 19 mm.

[0053] The preparation method of the above-mentioned high-hardness, high-wear-resistant alloy roll includes the following steps:

[0054] (1) Add various raw materials into the melting furnace according to the proportion of raw materials for the alloy layer, maintain the melting temperature at 1370-1450 degrees, obtain molten iron, purify the molten iron 4 times with slag remover, and then centrifugally cast the alloy layer for 60-70 seconds.

[0055] (2) After casting the alloy layer for 90-100 seconds, maintain the centrifugal speed and cast the cast iron layer separately using gray cast iron HT200 molten iron. Then, cool it down to 290-300℃ at a cooling rate of 90-100℃ / h. Finally, use air cooling to bring it down to room temperature to obtain the roller body.

[0056] (3) Roughly machine the roller body surface, and after assembling the roller shaft, perform fine machining to ensure that the thickness difference of the alloy layer of the roller is ≤0.5mm, the surface roughness of the roller body is less than Ra0.2, the total runout is less than 0.005mm, and the dynamic balance imbalance is ≤3g at a speed of 700 rpm. Then, draw wire on the surface of the alloy layer, so that the surface roughness of the teeth is less than Ra3.2, the tooth tip width error is within ±0.02mm, and the tooth edge appears as a line under a 40x magnifying glass without any serrated notches. The alloy roller is thus obtained.

[0057] In the above embodiments, the determination of the centrifugal speed for centrifugal casting is a known technique; the diameter of the roll is 300mm.

[0058] The hardness of the alloy rolls in Examples 1-6 was tested according to GB / T 13313-1991 "Shore Hardness Test Method for Rolls". The test results are shown in Table 1.

[0059] Table 1 Hardness of alloy rolls in Examples 1-6

[0060] product HSD Example 1 Alloy Roll 79 Example 2 Alloy Rolls 85 Example 3 Alloy Rolls 80 Example 4 Alloy Rolls 78 Example 5 Alloy Rolls 82 Example 6 Alloy Rolls 83

[0061] The results in Table 1 show that the hardness of the rolls of the present invention is between 78 and 85, which is high.

[0062] Using the alloy rolls from Example 2 and conventional rolls (both with gray cast iron HT200 for the cast iron layer, the alloy layer being composed of the following weight percentages: carbon 2.7%, silicon 0.6%, manganese 0.3%, phosphorus 0.2%, sulfur 0.08%, chromium 1.5%, nickel 0.6%, molybdenum 0.15%, with the balance being iron and unavoidable impurities; dimensions identical to those in Example 2; runout 0.01–0.02 mm; roll surface roughness Ra 1.6; and dynamic balance imbalance of 20 g ± 5 g at each end of the roll body when the roller speed is 700 rpm), wheat was processed. The crushing and grinding process is as follows: 1000 tons of wheat are processed daily, with the humidity error between the two groups of wheat being less than 3%. Then, the wheat is ground. It can be measured that the heat generated by the rollers in Example 2 during grinding is small, 10-15 degrees lower than that of ordinary grinding rollers, which protects the gluten of the flour from being damaged and improves the flour quality. At the same time, it has good wear resistance. When used on the grinding rollers of the flour mill, after actual verification, one filament drawing lasts for 10,000-12,000 hours, while ordinary grinding rollers last for 2,200-3,000 hours. The service life is 3-4 times that of ordinary grinding rollers, which greatly extends the service life.

Claims

1. A high-hardness, high-wear-resistant alloy roll, comprising a roll body and a roll shaft penetrating the roll body, characterized in that, The roller body comprises an inner cast iron layer and an outer alloy layer covering the cast iron layer. The alloy layer is composed of the following raw materials by weight percentage: carbon 3-3.7%, silicon 0.7-1%, manganese 0.6-0.9%, phosphorus 0.3-0.7%, sulfur 0.005-0.02%, chromium 2.7-3.5%, nickel 3.2-3.8%, molybdenum 0.5-0.6%, with the balance being iron and unavoidable impurities.

2. The high-hardness, high-wear-resistant alloy roll according to claim 1, characterized in that, The alloy layer is composed of the following raw materials by weight percentage: 3.2-3.5% carbon, 0.7-0.9% silicon, 0.6-0.8% manganese, 0.4-0.6% phosphorus, 0.01-0.02% sulfur, 3-3.2% chromium, 3.5-3.7% nickel, 0.52-0.6% molybdenum, with the balance being iron and unavoidable impurities.

3. The high-hardness, high-wear-resistant alloy roll according to claim 2, characterized in that, The alloy layer is composed of the following raw materials by weight percentage: 3.2-3.3% carbon, 0.7-0.8% silicon, 0.6-0.7% manganese, 0.4-0.5% phosphorus, 0.01-0.015% sulfur, 3-3.1% chromium, 3.5-3.6% nickel, 0.52-0.58% molybdenum, with the balance being iron and unavoidable impurities.

4. The high-hardness, high-wear-resistant alloy roll according to claim 3, characterized in that, The inner cast iron layer is gray cast iron HT200; the alloy layer has a thickness of 18-22mm.

5. A method for preparing a high-hardness, high-wear-resistant alloy roll according to any one of claims 1-4, characterized in that, Includes the following steps: (1) Add various raw materials into the melting furnace according to the proportion of raw materials for the alloy layer, maintain the melting temperature at 1370-1450 degrees, obtain molten iron, use slag remover to purify the molten iron 3-4 times, and then centrifugally cast the alloy layer for 35-70 seconds. (2) After the alloy layer is cast for 70-100 seconds, the centrifugal speed is maintained, and the cast iron layer is cast separately using gray cast iron HT200 molten iron. Then, the temperature is reduced to 250-300℃ at a cooling rate of 90-100℃ / h. Finally, the roller body is cooled to room temperature by air cooling. (3) Roughly machine the surface of the roll body, and after assembling the roll shaft, perform fine machining to make the thickness difference of the alloy layer of the roll ≤0.5mm, the surface roughness of the roll body less than Ra0.2, the total runout less than 0.005mm, and the dynamic balance imbalance ≤3g at a speed of 700 rpm. Then, draw the wire on the surface of the alloy layer, the surface roughness of the teeth less than Ra3.2, and make the tooth tip width error within ±0.02mm. When observed under a 40x magnifying glass, the tooth edge appears as a line without serrated notches, thus obtaining the alloy roll.

6. The method for preparing a high-hardness, high-wear-resistant alloy roll according to claim 5, characterized in that, The slag remover is a QC-type molten metal purifier.