CN113894263A

CN113894263A - Method for manufacturing roller for grinding powder and product thereof

Info

Publication number: CN113894263A
Application number: CN202111103320.6A
Authority: CN
Inventors: 费尔南德斯·卢华·菲利克斯·马丁; 普拉·贝伦古埃尔·帕特里西亚·克里斯蒂娜; 森佩雷·森佩雷·埃利塞奥
Original assignee: Baililai Roll Changzhou Co ltd
Current assignee: Baililai Roll Changzhou Co ltd
Priority date: 2021-02-23
Filing date: 2021-09-22
Publication date: 2022-01-07
Anticipated expiration: 2041-09-22
Also published as: CN113894263B; ES2921973B2; ES2921973A1; TR2021012306A2

Abstract

The invention relates to a compression roller for integral grinding, which has uniform components and hardness, high wear resistance, low hardness and high elasticity and is cast by adopting a tough matrix with high carbon and high silicon contents. The alloying elements chromium or nickel give them a low hardness, between 250 and 320 HB, which gives them a high wear resistance, and, in use, the milling productivity is improved by the fact that it is possible to apply a greater pressure to them, the milling temperature being reduced by 1 ℃ compared with conventional rollers. The roughness can be continuously regenerated, so that the service life of the coating is prolonged, the energy consumption is reduced, and the maintenance cost is reduced.

Description

Method for manufacturing roller for grinding powder and product thereof

Technical Field

The present invention relates to a roller for milling produced by a centrifugal casting process, which is formed of a single material, has very low hardness and high wear resistance, thereby improving the yield and efficiency of grain pressing during milling.

The aim of the invention is to provide the market with a roller for milling made of a single material with which, thanks to its characteristics of toughness and high elasticity, higher yields and lower energy consumption can be obtained. These characteristics make it possible to adapt to the operation and reduce the generation of heat. Lower operating temperatures will degrade the food less and enable milling at lower temperatures, thus enabling a higher quality milled product.

The tests carried out so far in different plants clearly illustrate the advantages of the above-mentioned products. In this way, a new roller made of a single material by centrifugal casting saves on average 5% of energy per mill motor.

In addition, the single material rollers also reduce their temperature and the temperature of the flour, the product produced by milling. In the case of rolls, the temperature differences of rolls currently available on the market average 6 ℃. With respect to the temperature of the flour, the difference is on average 3 ℃.

As we see, the temperature difference in the bowl is greater than the temperature difference in the flour. This is because flour is not a good conductor of heat.

The capacity of the roller for extracting flour is obviously higher than that of the prior roller cast by two materials. Therefore, the extraction rate of the flour is 8 percent higher on average by using the invention.

The advantage of this invention is that the roll is ductile, less hard than commercially available rolls, and wear resistant, which allows for longer maintenance down time and longer service life. Because the mill bowl does not have to be disassembled, the waste of time and effort is greatly reduced.

Background

The roller has a wide application range and is an important part in processes such as grinding and the like. The crushing and yield of the grain depends on the pressure applied between the rollers. The higher the degree of compaction, the more flour is obtained, but the higher the risk of the drum warming up. Elevated temperatures can affect production as proteins are degraded and of reduced quality.

The performance characteristics that the roll must have will vary widely depending on the department and process used. The hardness, wear resistance, elasticity of the rollers can vary greatly due to their chemical composition, casting process and machining finish quality, etc.

Therefore, it is necessary to confirm the characteristics required for the type of work and to design rolls satisfying these characteristics to meet the expectations of the end users, thereby achieving more efficient, higher-yield milling.

There is a need for a more resilient and abrasion resistant roller. When one roll is more resilient and flexible, in other words less brittle and harder, it fits better with the other roll. Therefore, hardness is important, the lower the better. The soft rollers may reduce the fit and friction between each other. Because of the low friction, the heat generated is low; in other words, the roll temperature will be lower if we compare them to the temperature of a normal roll. Thus, the flour will be milled at a lower temperature and its proteins will be less degraded. This will produce a better flour since the gluten contained therein will not be compromised.

The rollers used for milling are generally composed of two materials: the outer material is wear resistant but brittle white cast iron and the inner material is very resilient and ductile grey cast iron. White cast iron is hard, typically having a hardness ranging from 400 HB to 490 HB. In contrast, gray cast iron has a hardness of about 180 to 230 HB. The innovation is that we have previously achieved the coexistence of ductility and wear resistance by the combination of two materials, which are now achieved in a unique material. At the level of physical properties, a roller made of a single material has a greater advantage, since it eliminates the interface zones, stress concentration zones and weak zones of the two cast iron materials, giving the roller consistency and integrity and therefore more sturdiness.

The cartridge of the present invention is made of a centrifugally cast cartridge, made of a single material, for milling of flour, having very soft hardness and wear resistance.

The reason why compression rollers of this type have not been developed before is evident, since on the one hand, it is not possible on the technical level to obtain such a low hardness in white cast iron. In addition, during pouring into a pipe die for centrifugal casting, the liquid iron is quenched upon contact with the cold die, and a typical quenching hardness is obtained on the roll surface.

In addition, although attempts have been made to change the composition of the roll in the past, the roll of the present invention is a result of the study of a new structure and design concept. It is composed of a single material and specific wear and toughness components. This is based on a commitment to the end consumer, i.e. the person, business and technology of the milling enterprise. In other words, this is a real, current market demand result.

Disclosure of Invention

The roll of the invention solves the above-mentioned problems in a completely satisfactory manner.

In order to solve the above problems, the roll of the present invention is composed of a one-piece member having a uniform composition and hardness, high wear resistance, low hardness and high elasticity, obtained by casting a tough substrate having a high carbon and silicon content, and containing an alloying element such as chromium or nickel.

More specifically, when the roller is produced, the roller is cast once by a horizontal centrifugal casting forming technology, and molten iron comprises 3.23-3.85 mass percent of high-content carbon, 0.5-2 mass percent of silicon, 0.2-0.6 mass percent of manganese, 0.10 mass percent of sulfur, 0.4-0.8 mass percent of phosphorus, 0.3-0.8 mass percent of chromium and 0.5-1.2 mass percent of nickel. The refractory material is coated on the pipe die to prevent quenching and hardness increase, and the casting temperature is between 1290-1310 ℃.

In the centrifugal casting process, a slow, gradual and force-free intervention cooling process will occur.

After demolding, the rolls are cooled in a closed housing to prevent sudden temperature changes and thermal shock.

By this process, a roller having a hardness of between 250 and 320 HB was obtained.

Since the roll wears away and creates new rough areas during the milling and compression process, the surface roughness of the roll will be maintained throughout its service life.

Drawings

In addition to the description provided herein, and in order to make the features of the invention more comprehensible, the description is accompanied by a set of drawings. The drawings constitute a part of this description, by way of illustration, and not limitation. The following set of diagrams will provide:

figure 1 is a cross-section of a roller for milling powder made according to the object of the invention.

Fig. 2 shows a plan view of the device in the above figure.

Detailed Description

From the above figures it can be seen that the arrangement of the roll of the invention is not different from the traditional roll, but it has a cylindrical grinding roll surface 1 and a transverse axis 2, through which the roll is connected to the corresponding transmission.

The invention therefore concerns the composition of the roll and the process for obtaining the roll.

In this sense, the invention adopts new chemical components, designs special castings with high-carbon and high-silicon-content toughness matrixes, and controls the addition of alloy chemical elements such as chromium or nickel, thereby obtaining the roller with high wear resistance, low hardness and high elasticity.

The roller is made of a single material, the components and hardness of the whole roller body are uniform from the surface to the inner hole, and the roller is cast at one time by adopting a horizontal centrifugal casting molding technology. The use of refractory material in the pipe die prevents quenching from occurring and producing high hardness, while not increasing quenching in view of the designed chemical composition. Also, for greater safety, when smelting rolls, it is contemplated to leave a roll outer diameter large enough to eliminate such unacceptable skin material.

The hardness of the roller is 250 HB and 320 HB.

The rolls are not made from static cast steel. The cast iron is obtained by a centrifugal casting process, and the centrifugal casting process has some particularity, so that the hardness value of the finished roller is 250-320 Brinell hardness. The cast iron is composed of an iron alloy, wherein the iron alloy comprises 3.23-3.85 mass% of high-carbon content, 0.5-2 mass% of silicon, 0.2-0.6 mass% of manganese, less than 0.10 mass% of sulfur, 0.4-0.8 mass% of phosphorus, 0.3-0.8 mass% of chromium, 0.5-1.2 mass% of nickel and the balance of iron. The roller has the advantages of wear resistance, heat conductivity convenient for heat dissipation and self-matching performance by combining other related production parameters.

The centrifugal casting process is suitable for manufacturing such rolls. The specification parameters of the processes of temperature, brushing, centrifugal casting, refrigeration, cooling and the like are adopted in the processing method, so that the product has specificity.

The raw materials necessary to obtain the above combination were charged into an electric furnace at a casting temperature of 1290-1310 ℃. The rotating tube die or chill mold die is lined with a refractory coating having a thickness in the range of 2-4mm sufficient to allow subsequent demolding of the roll and proper thermal insulation from the tube die. The coating provides uniformity to the roll. And the thickness and the application temperature are more than 100 ℃, so that a film can be formed on the pipe die, and the roller can obtain the hardness and self-matching property.

In the centrifugal casting process, the rotating speed range of 600 and 800 rpm is 7000 Kg/m³The refrigeration of the material density is slow, gradual and has no external force intervention. After demolding, the rolls are cooled in a closed housing to prevent sudden temperature changes and thermal shock.

The chemical composition of the roll is closely related to its properties of wear resistance, thermal conductivity and high efficiency of the milling process, which are formed on the basis of the addition of alloying elements to high carbon cast iron. The addition of a proper amount of chromium improves the mechanical property of the alloy. The other function of chromium is to increase the hardness and wear resistance of the alloy, and it also increases the temperature stability, which is reflected in the performance of the rolls in the grinding. The nickel serves to homogenize the metallographic structure and properties of the roll, since it promotes uniform solidification and prevents uneven distribution of hardness on the roll. It gives malleability and makes the rollers self-matching, the roughness of which remains unchanged throughout the service life.

Since the roll wears away and creates new rough areas during the milling and compression process, the surface roughness of the roll will be maintained throughout its service life. This is an advantage because when the roll becomes smooth, it needs to be replaced; in this case, the roller will always maintain roughness, thereby improving the efficiency of material suction.

Claims

1. A method for manufacturing a roller for grinding powder is characterized in that molten iron comprises 3.23-3.85 mass percent of high-content carbon, 0.5-2 mass percent of silicon, 0.2-0.6 mass percent of manganese, less than 0.10 mass percent of sulfur, 0.4-0.8 mass percent of phosphorus, 0.3-0.8 mass percent of chromium and 0.5-1.2 mass percent of nickel in the casting process;

coating a refractory material on a pipe die by adopting a horizontal centrifugal casting molding technology, and casting at the casting temperature of 1290-; in the centrifugal casting process, the refrigeration is slow, gradual and no external force is intervened; it is expected that after demolding, no temperature jump or thermal shock will occur during the roll cooling process.

2. A method of manufacturing a roller for milling according to claim 1, characterized in that the rotating tube die or the chill die is lined with a refractory coating having a thickness in the range of 2-4 mm.

3. Method for manufacturing a roller for milling according to claim 1, characterized in that the centrifugal casting process is carried out in the rotation speed range of 600-800 rpm.

4. A roller for grinding powders, of the conventional construction of grinding rollers, having a cylindrical roller surface (1) and a transverse shaft (2) by means of which the roller is connected to a corresponding drive, characterized in that the roller is cast from a single piece, of uniform composition and hardness, high wear resistance, low hardness and high elasticity, from a tough matrix, containing 3.23-3.85% by mass of high-content carbon, 0.5-2% by mass of silicon, 0.2-0.6% by mass of manganese, less than 0.10% by mass of sulphur, 0.4-0.8% by mass of phosphorus, 0.3-0.8% by mass of chromium and 0.5-1.2% by mass of nickel.

5. Roller for milling according to claim 4, characterized in that its hardness is between 250 and 320 HB.