JP2005213646A5 - - Google Patents

Description

Low strain rapid water quenching method and apparatus

In the heat treatment process of the present invention is a steel 及 beauty alloy part, the use of the fast flowing water as a refrigerant fast cooling after heating quenching, etc., performs a rapid and uniform cooling, the combined cooling strain and transformation strain heat treatment The present invention relates to a technique for reducing distortion and improving cooling capacity.

In the heat treatment process of steel 及 beauty alloy part, the mineral oil is widely used as a refrigerant for rapid cooling after heating quenching or the like. Recently, uniformly cooled in that by the rapidly flowing water cooling increases the cooling ability, also reduce the heat treatment distortion is proposed by the inventors of the present invention (Reference 1). In the range of this method, the strain after heat treatment cannot be said to be less than that of mineral oil.
In addition, it is assumed that the distortion after heat treatment is not a little with a mineral oil refrigerant. Cooling with a neutral gas that does not cause a gas or liquid phase change during cooling (0.5 to 4.0 megapascals). Therefore, it is also practiced to reduce distortion. In general, cooling by this gas has a lower cooling capacity than mineral oil, so it is necessary to improve the cooling capacity compared to conventional alloy steel, and the use of higher-priced steel with higher price is required. .
JP 2002-97520 A

In the quenching to use a mineral oil, which is used in general, "the quality and maintenance of the refrigerant mineral oil" in order to suppress the distortion, "speed management of refrigerant mineral oil" is cumbersome, "of refrigerant expenses", "Post-processing Expenses such as “removal cost of refrigerant” and “disaster prevention cost of buildings etc. because refrigerant is dangerous” are high.

  Even when high pressure gas is used to reduce strain, these "high gas costs" and "high pressure gas safety costs", as well as the low cooling capacity of the gas, "make the material highly alloyed" For example, the material cost is high.

Use water or an aqueous solution (hereinafter referred to as “water”) that does not pollute the environment even if it is discarded as the main component in the literature 1 , and the flow rate is 1.0 m / second or more. This solves the problem of using mineral oil and high-pressure gas. However, the strain after heat treatment obtained there is close to that of mineral oil, which is far from the strain when high-pressure gas is used.

The present invention has been made in view of the above circumstances, and in the case of quenching treatment of steel and alloy parts, in order to cool down more uniformly and reduce distortion and cracking, the processing strain is more aggressive in oil quenching and below. The purpose is to reduce the material cost and the processing cost by reducing to a low alloy steel by improving the quenching performance.

Of the present invention, the invention of claim 1 is a quenching method in which “water” is used as a coolant for rapid cooling after heating in heat treatment of steel and alloy parts, and the treated product is cooled in running water. The speed of running water is 3.0 m / sec or more. Thus, by setting the speed of flowing water to 3.0 m / second or more, the entire surface of the treated product is cooled more uniformly and rapidly. As a result, the temperature drop near the surface and the slow speed of the transformation start time over the entire surface are made negligible in terms of strain generation. Further , a thicker and stronger hardened layer is created in the layer near the surface over the entire surface, and the amount of strain is reduced by suppressing expansion and contraction caused by cooling and transformation occurring later.

The invention of claim 2 among the present invention is characterized in that the treated product is immersed in flowing water at a specified flow velocity at a stroke. By immersing in the specified flowing water (flow velocity of 3.0 m / second or more) at once, all processed products are uniformly cooled even when quenching such as quenching of thin-walled products and complex-shaped products.

Of the present invention, the invention of claim 3 is a quenching apparatus that uses “water” as a coolant for rapid cooling after heating in the heat treatment processing of steel and alloy parts, and cools the treated product in running water. , A quenching water tank for storing the refrigerant, a cooling chamber provided in the quenching water tank, in which the treated product is placed, and a flowing water pump for circulating the refrigerant and maintaining the flow rate of the refrigerant in the cooling chamber at 3.0 m / sec or more It is characterized by having. By comprising in this way, the hardening method of this invention can be implemented.

According to the invention of claim 4 of the present invention, the refrigerant is prevented from flowing into the cooling chamber before the processed product is placed in the cooling chamber, and the refrigerant is added once after the processed product is placed in the cooling chamber. And a cooling auxiliary device for flowing into the cooling chamber. The cooling auxiliary device can be switched between a state in which the inflow of the refrigerant into the cooling chamber is blocked and a state in which the cooling is not blocked by operating, and various shapes can be considered depending on the direction of the flow of the refrigerant with respect to the processed product. By adopting such a configuration, it is possible to prevent partial non-uniform cooling from occurring by touching flowing water at a slow speed before cooling.

The invention according to claim 5 of the present invention has a water channel structure adjusted so that the flow velocity at an arbitrary position in the cross section perpendicular to the direction of the water flow in the cooling chamber is within ± 10% of the prescribed flow velocity. It is characterized by. By equalizing the flow velocity in this way, it is possible to prevent the cooling from being slowed by the installation position of the processed product in the cooling chamber and resulting in uneven cooling. As such a water channel structure, for example, it is conceivable to provide a flow velocity distribution adjustment guide for rectification in the flow channel.

According to the method of the present invention, in the quenching treatment of steel and alloy parts, if the flow rate of the water quenching refrigerant is set to 3.0 m / second or more, the total amount of strain after quenching is generally determined using mineral oil. It was possible to make it smaller than the above method. In particular, it was found that the strain can be further reduced by setting the flow rate to 5.0 m / sec or more. This is intended to increase reduces the processing steps after accompanying the largest problem of the thermal treatment of steel parts "distortion".

According to the method of the present invention, quenching and cooling ability is improved as compared with the conventional method , and steel parts with high hardness and high strength can be obtained with inexpensive simple carbon steel. Compared to material costs. Since no mineral oil is used as the refrigerant, the cost of the quenching oil itself, the cost required for degreasing after the treatment, and the disaster prevention equipment and building costs required by using the mineral oil can be reduced. By using a low alloy material, forging pressure and cutting become easy, and the processing costs before and after can be reduced. Further, low strain can be realized without cooling with an expensive and dangerous high-pressure gas that is expected to further reduce strain.

According to the method of the present invention uses no oil of mineral oil as a refrigerant, oil itself, and a solvent for degreasing becomes unnecessary, reduction of carbon dioxide, which contributes greatly to reduction of the ozone layer depleting substances. In addition, the use of dangerous materials (oils and fats) and high-pressure gas can improve work safety and the environment.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an example of a rapid water quenching apparatus. This apparatus has a quenching water tank 1 for storing refrigerant, a flowing water duct 2 for defining the flow direction of the refrigerant, and a cooling chamber 4 for placing a processed product, and a heating furnace zone above the cooling chamber 4. 9 is directly connected. In order to prevent outside air from entering the cooling chamber 4, a tank atmosphere blocking wall 8 is provided. In this apparatus, a treated product that has been heated in the heating furnace zone 9 is installed in the cooling chamber 4 so as not to come into contact with a loose water flow or the like that causes non-uniform cooling (treatment product carry-in path 11) , and a prescribed flow rate Cool at once with running water.

The speed of water flowing into the cooling chamber 4 is 3.0 m / sec or more, and the speed is obtained by the pump 7 and the pump power 6 in the same water channel. The water discharged from the pump 7 is circulated after discharging the air bubbles brought in, enters the cooling chamber 4 again, and is used for cooling (cooling flowing water flow direction 13) . The pump 7 is for ensuring the flow rate of water, and may be a propeller type or any other type .

Here, the example of the method of installing a processed product in the cooling chamber 4 without touching a loose water flow etc. is shown in FIGS.
FIG. 2 shows a case where the refrigerant flows downward with respect to the processed product. Before starting cooling, the processed product guide 3 is substantially cylindrical and is substantially cylindrical and is in close contact with the outer periphery of the processed product guide 3. However, the flow of the refrigerant into the cooling chamber 4 is blocked by the variable stretchable product guide (cooling auxiliary device) 10 whose upper end protrudes from the liquid level of the refrigerant. At the time of cooling, the expansion / contraction variable processing product guide 10 moves downward, so that the refrigerant flows into the cooling chamber 4 from above at once. The bottom surface on which the processed product is placed has a saw-like shape and does not hinder the flow of the refrigerant. However, before the start of cooling, the refrigerant is sucked from below, so that the refrigerant does not flow into the cooling chamber 4.
FIG. 3 shows the case where the refrigerant flows upward with respect to the processed product, and before starting cooling, the running water blocking damper (cooling auxiliary device) 12 installed below the processed product is closed. Inflow of the refrigerant into the cooling chamber 4 is blocked. During cooling, the running water blocking damper 12 is opened, and the refrigerant flows into the cooling chamber 4 from below at once.
FIG. 4 shows a case where the refrigerant flows laterally with respect to the processed product. Before the cooling is started, the running water cutoff dampers 12 installed on the upstream side and the downstream side of the processed product are closed. Inflow into the cooling chamber 4 is blocked. At the time of cooling, the two running water cutoff dampers 12 are simultaneously opened, and the refrigerant flows into the cooling chamber 4 from the upstream side at once.

Moreover, it is an essential condition for uniform cooling of the processed product that the velocity of the water flowing in the cooling chamber 4 is uniform in a cross section perpendicular to the flowing direction. In the present invention, the flow velocity distribution adjusting guide 5 is attached so that the water flow velocity of each part in the cooling chamber 4 is within ± 10% of the prescribed flow velocity. If it exceeds ± 20%, the strain may be remarkably increased.

The example implemented with the cooling method and apparatus of this invention is demonstrated. In order to investigate the relationship between the cooling water speed and the cooling capacity, for each of the steel types S25C, S35C, and S45C, which are high hardenability high carbon chromium bearing steel SUJ2 and simple carbon steel, φ20 mm, φ40 mm, and φ60 mm. After austenitizing heating, cooling with conventional oil cooling, still water, running water of 1.0 m / second, running water of 3.0 m / second was performed, and the surface hardness and the hardness of the central part were compared. Table 1 shows the respective cooling conditions and the hardness after quenching.

The cooling capacity in the cooling method of the present invention increases as the flow rate of water increases. In cooling with flowing water at a flow rate of 3.0 m / sec, the hardness of the surface of a simple carbon steel with a material having a size of φ20 mm is close to the maximum hardness of the carbon steel. The greater the flow rate, it is possible to increase the cooling capacity, without distortion or defect.

The specimen shown in FIG. 5 was used to investigate quenching strain reduction, which is the main effect of the present invention. After this specimen was austenitized and heated at 850 ° C., conventional oil cooling, static water, 1.3 m / sec running water, 2.0 m / sec running water, 2.9 m / sec running water, 4.8 m / sec running water And quenching distortion was measured. The position and method of measurement are shown in FIG. Table 2 shows the variation and average value of the amount of strain after cooling.

The amount of distortion of the treated specimen decreased as the flow rate of the refrigerant increased . The specimen was subjected to tests, the water flow rate exceeds 3.0 m / sec, the strain amount is smaller than the cooling by mineral oil commonly practiced. After heat treatment distortion of increasing Suhodo steel part if the flow rate of the water for cooling Maze is said to decrease. In small steel parts, rapid water quenching at a refrigerant flow rate of 3.0 m / sec or more can increase quenching hardness and reduce post-quenching distortion as compared with oil cooling. If the flow rate is 5.0 m / sec or more, the strain can be further reduced.

If the flow rate of the refrigerant on the surface of the processed product increases, the entire surface will be cooled more uniformly, and the internal surface will be delayed in order to harden (cool, transform) deeply under the surface in a short time. This is thought to be due to the fact that the volume change and stress to be contained are contained to prevent external strain generation. If merely intended only reduction of quenching distortion, not only "water" without environmental impact as the refrigerant, the more aqueous solution of high inorganic salt heat transfer rate, etc., also be used after having taken environmental measures Conceivable.

The whole schematic diagram during processing goods cooling in the low distortion rapid water quenching apparatus of the present invention . Example of processed product guide when flowing water flows from top to bottom After the processed product is installed at a fixed position, the guide is contracted and flowing water at a specified flow rate is introduced from the top. Example of treated product guide when running water flows upward from below After the treated product is installed at a fixed position, open the lower damper and enter the running water at the specified flow rate from below. Example of treated product guide when flowing water flows from the lateral direction After the treated product is installed at a fixed position, open the upstream and downstream dampers at the same time, and supply the flowing water at the specified flow rate from the upstream. It is the shape size and material of the specimen used for the quenching strain measurement. This is the position and method for measuring the distortion of the quenched specimen. All the distortions were arc-shaped bends with the groove portions convex.

Explanation of symbols

1 quenching water tank 2 water flow ducts 3 treated product guide 4 cooling chamber 5 the flow velocity distribution adjusting guide 6. pump power 7 pumps <br/> 8 bath atmosphere blocking wall 9 furnace zones 10 stretch variable treated product guide (auxiliary cooling device)
11 Processed goods delivery route 12 Flowing water cutoff damper (cooling auxiliary device)
13 Flow direction of cooling water

Claims (5)

In the heat treatment process of steel and alloy components, using pressurized as coolant rapid cooling after thermal, aqueous never be discarded as a main component, water or water to pollute the environment (hereinafter referred to as "water") and, a quenching method of cooling the treated product in running water, low distortion rapid water quenching how, characterized in that the water flow rate and the 3.0 m / second or more. Low distortion rapid water quenching method according to claim 1, characterized in that processing article is immersed in flowing water in the flow rate of the prescribed in elevation. In the heat treatment of steel and alloy parts, a quenching device that uses “water” as a coolant for rapid cooling after heating and cools the treated product in running water, a quenching water tank for storing the coolant, and the quenching A low distortion characterized by having a cooling chamber provided in a water tank for placing a processed product, and a flowing water pump for circulating the refrigerant and maintaining a flow rate of the refrigerant in the cooling chamber at 3.0 m / sec or more. Rapid water quenching equipment. There is a cooling auxiliary device that prevents the refrigerant from flowing into the cooling chamber before the processed product is placed in the cooling chamber, and allows the refrigerant to flow into the cooling chamber at once after the processed product is placed in the cooling chamber. The low-distortion rapid water quenching apparatus according to claim 3. In the cooling chamber, flowing water velocity of any position of the cross section perpendicular to the direction of water flow, according to claim 3 or 4, characterized in that it has the adjusted water channel to be within ± 10% of the prescribed flow rate Low distortion rapid water quenching equipment.