KR100935113B1 - Rapid air cooling apparatus for heat treatment - Google Patents

Abstract

PURPOSE: A rapid water cooling apparatus for a heat treatment product formed like a hollow pipe is provided to improve the cooling efficiency and to execute the uniform quick cooling by spraying air uniformly. CONSTITUTION: A rapid water cooling apparatus for a heat treatment product formed like a hollow pipe is composed of an air supply unit, an outer spray unit(20), an inner blowing unit(30), a lifting unit(40), and a controller. The air supply unit supplies high pressure air. The outer spray unit is installed outside a heat treatment object(w) to spray the air to the outer surface of the heat treatment object. The inner blowing unit is composed of a blower(32) blowing the air, a duct(34) blowing the air to the inner surface of the heat treatment object, and a blowing angle control unit(36) controlling the blowing angle of the air. The lifting unit lifts the air supply unit at the upside of the heat treatment object. The controller controls the spraying rate and time of the air sprayed from the spray unit.

Description

Rapid air cooling apparatus for heat treatment

The present invention relates to a hollow tube-shaped heat-treatment rapid air cooling apparatus, and more particularly, a hollow tube-shaped heat-treatment rapid air cooling to normalize by injecting air to the inner and outer circumferential surface of the large forged product of the hollow tube shape to rapid cooling Relates to a device.

When the heat treatment method is largely divided, it is possible to remove the segregation and residual stress after casting or forging, and to homogenize or soften the annealing and crystal grains for the purpose of softening to improve mechanical properties and machinability. It can be divided into normalizing, quenching for hardening, and tempering for toughening.

Among these, normalizing is a heat treatment method that refines grains to increase strength, makes uniform austenite state when reheating for quenching or annealing, and removes segregation present in castings or forgings to make a uniform structure. It is usually heated in the austenite range (30 to 50 ° C above the A3 or Acm point) and gradually cooled in the air or by blowing air.

In particular, large ring products in the form of hollow tubes used as flanges for wind towers are produced by forging treatment. In general, slabs or ingots are cut and heated to the size of the product, and then pressed. The first forging is carried out to produce rough shaping. Next, the heat is re-heated to perform secondary forging to determine dimensions and shapes, and to perform heat treatment such as normalizing, quenching, and tempering to homogenize the structure and secure mechanical properties.

At this time, there are some problems because such a large ring forged product is usually air-cooled in the air when heat-treated and cooled by normalizing.

1 is a continuous cooling transformation graph showing a cooling state in the conventional normalizing heat treatment.

As shown, since the temperature decreases slowly in proportion to time, the transformation from austenite to secondary tissues such as ferrite and pearlite occurs at very high temperatures (above 800 ° C). The grains in the tissue become large. As a result, mechanical properties such as tensile strength and low temperature impact characteristics of the finished product are slightly lowered.

In order to solve the above problems, it is possible to induce ferrite and pearlite transformation at a low temperature after rapid cooling to some extent by using a blower, but the above method is suitable for small forgings such as parts, steel sheets, tools, etc. Ring forgings are usually more than 5-6m in diameter and thick, so that the surface area per unit mass is relatively small compared to the plate, making it difficult to rapidly cool the blower. Because the surface is rapidly cooled, but the central part is slow cooled, it is difficult to cool the surface and the interior at the same time at low temperature so that transformation at low temperature occurs.

Because of this problem, there is a device that rapidly cools by spraying water on the surface of the conventional cooling device, but using such a device rather than quenching only the surface to produce martensite (martensite) structure on the surface it is likely to harm the desired mechanical properties It is difficult to control precise water injection amount, injection time and cooling rate.

In addition, in the case of the hollow tube-shaped products there is a disadvantage that the cooling efficiency is low because the water is not sprayed on the inner peripheral surface.

In addition, even after spraying water to the inner circumferential surface there is a disadvantage that residual stress occurs after cooling due to the difference in the cooling temperature or speed of the inside and outside of the heat treatment.

The present invention has been made to solve the above problems is an object of the present invention by uniformly spraying air to the inner and outer circumferential surface of the large forging of the hollow tube shape to enable uniform rapid cooling and excellent cooling efficiency heat treatment of the hollow tube shape To provide a water rapid air cooling system.

Another purpose is to control the air spraying amount and the spraying time according to the surface temperature of the normalizing heat treatment product so that transformation occurs to ferrite and pearlite at low temperature, so that the hollow tube-shaped heat treatment product rapid air can form fine crystal grains of the secondary structure. It is to provide a cooling device.

The present invention for achieving the above object is a cooling device for cooling the heat treatment of the heat-treated hollow tube shape, the air supply unit for supplying high pressure air; An external injection unit installed outside the heat treatment material and spraying air supplied from the air supply unit to an outer circumferential surface of the heat treatment material; The air blower coupled to the blower and the blower is installed on the lower side of the heat treatment material and guides the air blown from the blower to provide a duct to blow to the inner circumferential surface of the heat treatment material and to adjust the blowing angle of the air is provided at the top of the duct An inner blower configured of a blower angle adjusting means; Elevating means for elevating the outer spray unit from the upper side of the heat treated material so that the heat treated material is accommodated in the outer spray unit; And a control unit for controlling the injection amount and the injection time of the air injected and blown from the external injection unit and the internal blowing unit.

Here, the external injection unit is a horizontal injection pipe in which a plurality of annular pipes in which air flows are arranged up and down, a plurality of vertical injection pipes respectively coupled to the horizontal injection pipe vertically, and the horizontal injection pipe and the vertical injection pipe It is characterized by consisting of a nozzle for injecting air.

In addition, the outer injection portion is provided with a cylindrical frame body of which a plurality of polygonal or annular ring members are arranged up and down and the bar member is vertically coupled to the ring member, and are set up at regular intervals along the outer side of the frame body from the air supply unit. And a plurality of supply pipes through which air is supplied, and an air injection port, one side of which is coupled up and down along the supply pipe and the other side of which is coupled to an outer surface of the frame body, to inject air supplied from the supply pipe to the outer circumferential surface of the heat treatment material. .

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Preferably, the blowing angle adjusting means has a plurality of hinge members coupled to the upper end of the duct at regular intervals along the rim, a plurality of adjusting pieces are pivotally coupled to each of the hinge members, and the adjustment It is characterized by consisting of a drive cylinder coupled to any one of the pieces to drive to rotate.

In addition, the elevating means is a plurality of guides installed upright outside the external injection unit, a lifting support inserted into each of the guides and coupled to the outside of the external injection unit, a motor installed above the external injection unit, and one side A chain coupled to the upper portion of the external injection portion and the other side is wound around the motor, and a weight balancing coupled to the chain end extending from the motor, characterized in that the external injection portion is lifted by the driving of the motor.

Preferably, the motor is controlled to rotate forward or reverse by the control unit, the external injection unit is characterized in that the oscillation (oscillation) along the guide.

The effect of the present invention by the above-described configuration is because the high-pressure air is evenly sprayed on the entire inner and outer circumferential surface of the large forging of the hollow tube shape, it is possible to rapidly cool the entire uniform, so the cooling efficiency is very excellent.

In addition, since the cooling rate can be controlled according to the surface temperature of the heat-treated material, the crystal grains are finely formed since the transformation to ferrite and pearlite at low temperature can improve mechanical properties such as tensile strength and low temperature impact characteristics.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

Figure 2 is a front view showing a rapid heat treatment of the heat treatment material of the hollow tube shape according to an embodiment of the present invention, Figure 3 is a side view of the present invention shown in FIG.

As shown in the present invention, the air supply unit 10, the external injection unit 20, the internal blower unit 30, the lifting unit 40, and the control unit may be formed.

The air supply unit 10 has a compressor 12 for compressing air at high pressure as shown, a hose 14 connecting the compressor 12 and an external injection unit 20 to be described later, and It may be configured as a valve 16 to open and close the air supplied through the hose 14 or to adjust the flow rate. That is, the air compressed by the compressor 12 is supplied to the external injection unit 20 to be described later through the hose 14, and the opening and closing is controlled by the controller 16, which is controlled by the valve 16. Controlled.

Next, the external injection unit 20 will be described with reference to FIGS. 2, 3, and 4. 4 is a perspective view showing an embodiment of an external injection unit of the present invention.

The external injection unit 20 is to cool by spraying air to the outer peripheral surface of a large heat-treated forging (hereinafter 'heat treatment') of the hollow tube shape, the structure of the external injection unit 20 of the heat treatment (w) The horizontal injection pipe 22 having a pipe-shaped annular shape to surround the outer circumferential surface and a plurality of stacked and arranged at a predetermined interval up and down, and the horizontal injection pipe 22 to be fixed at regular intervals up and down and the horizontal so as to communicate with each other It consists of a straight pipe-shaped vertical injection pipe 23 vertically coupled to the injection pipe 22, and a plurality of nozzles 24 formed at equal intervals on the horizontal injection pipe 22 and the vertical injection pipe 23. .

 This shape is to obtain a uniform cooling rate by spraying the air evenly on the surface of the heat treatment material (w) of the hollow tube shape, the nozzles 24 are respectively directed toward the outer peripheral surface of the heat treatment material (w) And the inside of the vertical injection pipe (23).

Preferably, the spray angle of the nozzle 24 may be adjusted as well as to allow for easy removal and replacement.

Thus, in order to easily replace the nozzle 24, holes are formed on the horizontal injection pipe 22 and the vertical injection pipe 22b, and each nozzle 24 is fixed to each hole by screwing. Will be common, but is not limited to such.

In addition, any one of the horizontal injection pipe 22 or the vertical injection pipe 23 is connected to the hose 14 is supplied with air from the air supply unit (10).

Since the external injection unit 20 has the structure as described above, the hollow tube-shaped heat-treated material (w) is accommodated inside the external injection unit 20 and uniformly cooled by spraying air evenly on the outer circumferential surface. Can be performed.

Next, the internal blower 30 will be described with reference to FIGS. 2, 3, and 5. 5 is a plan view showing the structure of the blowing angle adjusting means of the present invention.

The inner blower 30 is configured to induce cooling by blowing air to the inner circumferential surface of the heat treatment material (w), it may be composed of a blower 32, duct 34 and the blowing angle adjusting means (36).

The blower 32 is a well-known machine for blowing air, such as a blower (blower), as shown in Figures 2 and 3, the blower 32 is coupled to the circular pipe-shaped duct 34 is the blower 32 The air supplied from the guide to guide the inner peripheral surface from the lower side of the heat treatment (w).

In addition, the upper end of the duct 34 to prevent the diffusion of air discharged from the duct 34 and to accurately guide the air to the inner circumferential surface of the heat treatment material (w) and the blowing angle corresponding to the diameter of the heat treatment material (w) Blowing angle adjusting means 36 that can be blown by is coupled.

The blowing angle adjusting means 36 is coupled to the plurality of hinge members 36a at regular intervals along the upper edge of the duct 34, the plate-shaped adjusting piece (36b) to each of the hinge members (36a) Rotably coupled, the driving cylinder (36c) is connected to any one of the plurality of control pieces (36b) is a structure that can rotate the control piece (36b).

As illustrated in FIG. 6, the adjusting piece 36b is arranged along the edge of the duct 34, such as a camera aperture, and overlaps with a portion overlapping with the adjacent adjusting piece 36b. In other words, a state in which a plurality of the second adjusting piece 36b adjacent to the upper part of the first adjusting piece 36b is superimposed and the third adjusting piece 36b is superposed on the upper part of the second adjusting piece 36b. When the pair of drive cylinders (36c) is installed to face each other to drive each of the adjustment piece (36b) back and forth, each of the adjustment piece (36b) is a rotational force is transmitted to be able to rotate all. In this way it is possible to adjust the blowing angle of the air coming out of the duct as shown in Figs.

Next, the lifting means 40 will be described with reference to FIGS. 2 and 3. As for the lifting means 40, the external injection part 20 is positioned above the heat treatment material w and is transported up and down. As shown, the guide 42 installed upright on both sides of the external injection unit 20, and the lifting support which is fixed to the outside of the external injection unit 20 and inserted up and down in the guide 42 is capable of sliding up and down ( 44, the motor 46 installed on the external injection unit 20, a chain 48 and a weight balancing 49 coupled to the external injection unit 20.

Lifting of the external injection unit 20 is made along the guide 42, the guide 42 induces the lifting by the rail method, using the motor 46 for lifting, the motor 46 ) Is a state in which forward and reverse rotation are possible by the control unit described later, and the chain 48 is wound. One end of the chain 48 is coupled and fixed to the upper portion of the external injection unit 20, and the other end is coupled to the weight balancing 49 corresponding to the weight via the motor 46.

Therefore, the entire external injection unit 20 can be moved up and down by the driving of the motor 46. At this time, when the weight balancing 49 acts as a weight, the external injection unit 20 rises. If it is going up, the external injection unit 20 will be lowered.

On the other hand, the motor 46 is controlled by the control unit to oscillate the external injection unit 20 (oscillation). In other words, the external injection unit 20 may be repeatedly moved up and down at a predetermined interval. This is because the air injected from the nozzle 24 is radially spread, so the amount injected on the surface of the heat treatment material (w) is different for each point. Therefore, as described above, when oscillation is applied, air may be evenly sprayed on the surface of the heat treatment material w.

Next, the control unit will be described.

The controller controls the amount of air supplied through the hose 14 from the air supply unit 10 to control the amount of air injection and the injection time that are injected through the nozzle 24 to the optical temperature sensor (not shown). And a computer (not shown) in which the program is embedded.

The optical temperature sensor is a sensor for measuring the temperature of the surface of the object, the sensor is installed and measured without contacting the object and is a known configuration. It is installed at a certain distance from the heat treatment (w) to measure the temperature.

The computer is programmed therein to control the injection amount and the injection time of the air according to the temperature measurement value of the heat treatment product w measured by the optical temperature sensor.

Supplementally, when the quenching is required to control the cooling rate according to the time, control is performed to increase the air injection amount and injection time and to appropriately reduce the injection amount and injection time when slow cooling is required. It is also programmed to determine the injection amount and the injection time according to the shape, size and type of the heat treatment product w.

Such control is possible by opening or closing the valve 16 of the air supply unit 10 or adjusting the supply amount, and thus a detailed description thereof will be omitted.

For reference, the air is injected into the heat treatment material (w) from the external injection unit (20) and the internal blower (30) above the external injection unit (20) to cool and inhale and discharge a large amount of hot air generated. Exhaust port 70 and exhaust blower 80 is preferably further provided to be recycled to other heat exchangers.

With reference to Figures 6 and 7 in the present invention looks at another embodiment of the external injection unit 20. 6 is a plan view showing another preferred embodiment of the present invention, Figure 7 is a plan view showing an external injection unit of the present invention shown in FIG.

Since the other components except for the external injection unit 20 are similar to those described above, detailed descriptions will be omitted and other embodiments of the external injection unit 20 will be described in detail.

Another embodiment of the external injection unit 20 may be composed of a frame body 26, a supply pipe 27, the air injection port 28, the frame body 26 is arranged horizontally in a polygon or annular shape A plurality of ring members (26a) are arranged at a predetermined interval up and down, and a bar-shaped bar member is vertically coupled to each of the ring members (26a) to fix each ring member (26a) up and down ( 26b). Accordingly, the frame 26 as a whole is cylindrical in shape having a lattice.

As shown in FIG. 7, a plurality of supply pipes 27 are erected at regular intervals along the outer circumference of the frame 26. The supply pipe 27 is in the form of a passage through which air passes and the air supply unit 10 for supplying air to the lower side is coupled to each.

In addition, as shown in FIG. 6, a plurality of air injection holes 28 are coupled to the inside of the supply pipe 27 up and down, and the air injection holes 28 heat-process the air supplied through the supply pipe 27. The outlet is open to spray on the outer circumferential surface of w). The outlet of the air injection port 28 is coupled to and fixed to the outer surface of the frame 26 and has a shape in which a cross-sectional area is enlarged so as to uniformly reach the surface of the heat treatment product w by expanding the sprayed air.

Accordingly, the air supplied from the air supply unit 10 is dividedly supplied to the air injection holes 28 through the supply pipes 27, and subsequently is injected from the air injection holes 28 so that the outer circumferential surface of the heat treatment product w is provided. Cool down.

Hereinafter, referring to FIG. 8, the method for cooling the heat treated material and the mechanical property test result of the heat treated product according to the present invention will be mentioned.

7 is a continuous cooling transformation graph showing a cooling state during the heat treatment according to the present invention. Here, the continuous cooling transformation diagram is a graph showing the cooling state of the heat treated material with temperature as a time graph showing the time of transformation according to the cooling path.

First, the heat treatment material (w) is heated to 900 ° C or more to austenite the tissue, and then installed below the external injection portion (20). Then, the lifting means 40 is operated so that the external injection unit 20 is lowered so that the heat treatment material w is accommodated in the external injection unit 20.

At this time, the optical temperature sensor senses the temperature of the heat treatment material (w) and determines the air injection amount and the injection time as programmed in the computer and outputs the electrical signal by the operation of the valve 16, the air is the hose ( 14 is supplied to the external injection unit 20 at high pressure.

The air introduced into the external injection unit 20 is supplied to the horizontal injection pipe 22 and the vertical injection pipe 23 and injected through the nozzle 24 or through the supply pipe to the air injection hole 28. It is supplied and sprayed toward the heat treatment product w.

At the same time, the blower 32 is operated to blow air through the duct 34, and the adjusting piece 36b is rotated by the driving cylinder 36c so as to match the diameter of the heat treatment product w. Adjust.

For example, when the diameter is large, the inclination of the control piece 36b is decreased to increase the diffusion degree of air blown through the duct 34, and when the diameter is small, the inclination of the control piece 36b is increased. Air can be accurately blown to the inner peripheral surface of the heat treatment (w).

As shown in FIG. 7, during the initial time (about 10 s), the heat-treated material (w) should be sprayed lightly so as to be cooled slowly. Should be.

And a large amount of air is sprayed strongly from about 10s until the temperature of the heat treatment (w) is 550 ℃ ~ 600 ℃ to quench. Due to this rapid cooling, the cooling curve is transformed into ferrite (723 ° C. and below) and pearlite (600 ° C. and below) at low temperatures. By causing transformation at low temperature, the growth of crystal grains in secondary tissues is delayed and the transformation nucleation site is increased to form fine grains. Therefore, the microstructure increases the mechanical strength and toughness significantly.

After rapid cooling in a short time, the air is continuously sprayed lightly to about 1000 s to maintain a constant temperature. Because large forgings have a thick thickness, unlike the surface, the inside is not cooled quickly and is warmer than the surface. Therefore, if the air is not injected, the temperature of the surface may rise again, so that the computer is maintained at a temperature between 550 ℃ and 600 ℃. Inject air as appropriate. As a result, transformation occurs not only on the surface but also inside.

After the above constant temperature section, the air is sprayed again to finish cooling.

Through the cooling path, transformation occurs at low temperature to obtain fine grain of steel, which is superior in tensile strength or toughness than steel obtained by transformation at high temperature while being slowly cooled in the air.

These results can be compared through tensile strength test and low temperature impact test. The results are as follows.

 Conventional cooling method  Cooling method according to the present invention  Seal characteristics  Yield strength  295-325 MPa  335 to 360 MPa  Ultimate strength  450 to 515 MPa  490 to 550 MPa  Low temperature shock  Average  97 J  140 J  range  25 to 135 J  135-175 J

Here, the low temperature impact test represents a test in which the 'V' notch test piece is cooled to -40 ° C. and subjected to an impact.

As described above, in the present invention, when heat treating (normalizing) a large forging product having a hollow tube shape, the hollow tube-shaped heat-treatment material can improve mechanical properties by spraying air on the inner and outer circumferential surfaces and controlling the cooling rate by a computer. It is to provide a rapid air cooling device and what is described with reference to the drawings is only one embodiment, the true technical protection scope of the present invention will be determined by the claims.

1 is a continuous cooling transformation graph showing a cooling state in the conventional normalizing heat treatment.

Figure 2 is a front view showing a rapid heat treatment of the heat treatment material of the hollow tube shape according to an embodiment of the present invention.

3 is a side view of the present invention shown in FIG.

Figure 4 is a perspective view showing an embodiment of the external injection unit of the present invention.

5 is a plan view showing the structure of the blowing angle adjusting means of the present invention.

6 is a plan view showing another preferred embodiment of the present invention.

7 is a plan view showing an external injection unit of the present invention shown in FIG.

8 is a continuous cooling transformation graph showing a cooling state during the heat treatment according to the present invention.

<< Explanation of symbols for main part of drawing >>

10: air supply unit 12: compressor

14 hose 16 valve

20: external injection unit 22: horizontal injection pipe

23: vertical injection pipe 24: nozzle

26 frame 26a ring member

26b: bar member 27: supply pipe

28: air jet

30: blower 32: blower

34: duct 36: blowing angle adjusting means

36a: hinge member 36b: adjustment piece

36c: driving cylinder

40: lifting means 42: guide

44: lifting support 46: motor

48: chain 49: weight balancing

70: exhaust port 80: exhaust blower

w: heat treatment A: austenite

F: Ferrite P: Pearlite

M: Martensite Ms: Martensite start temperature

Claims (7)

In the cooling device for cooling the heat-treated material (w) of the heat-treated hollow tube shape, Air supply unit for supplying high pressure air (10) An external injection unit 20 installed outside the heat treatment material w to inject air supplied from the air supply unit 10 to an outer circumferential surface of the heat treatment product w; Blower 32 for blowing air, and coupled to the blower 32 and installed below the heat treatment material (w), and guides the air blown from the blower 32 to blow to the inner peripheral surface of the heat treatment product (w) An inner blower unit 30 formed of a duct 34 and a blower angle adjusting unit 36 for adjusting a blower angle of air blown through the upper portion of the duct 34; Elevating means (40) for elevating the external spraying unit (20) above the heat treating material (w) so that the heat treating material (w) is accommodated in the external spraying unit (20); And And a control unit for controlling the injection amount and the injection time of the air injected and blown from the external injection unit 20 and the internal blower unit 30, and the heat treatment product of the hollow tube shape rapid air cooling device. The method of claim 1, The external injection unit 20, A horizontal injection pipe 22 in which a plurality of annular pipes through which air flows are arranged up and down, a plurality of vertical injection pipes 23 vertically coupled to the horizontal injection pipes 22, and the horizontal injection pipes 22 And a nozzle (24) provided in the vertical injection pipe (23) for injecting air, characterized in that the heat treatment material rapid air cooling device of the hollow tube shape. The method of claim 1, The external injection unit 20, A cylindrical frame 26 having a plurality of polygonal or annular ring members 26a arranged up and down and having a bar member 26b vertically coupled to the ring member 26a, and an outer side of the frame body 26 A plurality of supply pipes 27, which are installed at regular intervals and are supplied with air from the air supply unit 10, and one side thereof are coupled up and down along the supply pipe 27, and the other side is connected to the outer surface of the frame 26. Heat treatment material rapid air cooling device of the hollow tube shape, characterized in that consisting of the air injection port 28 coupled to inject the air supplied from the supply pipe 27 to the outer peripheral surface of the heat treatment. delete The method of claim 1, The blowing angle adjusting means 36, A plurality of hinge members 36a coupled to the upper end of the duct 34 at predetermined intervals along a rim, a plurality of adjustment pieces 36b rotatably coupled to the hinge members 36a in a flat plate shape, Heat treatment material rapid air cooling device of the hollow tube shape, characterized in that consisting of a drive cylinder (36c) coupled to any one of the control piece (36b) to rotate. The method of claim 1, The lifting means 40, A plurality of guides 42 installed upright to the outside of the external injection part 20, a lifting support 44 inserted into each of the guides 42 and coupled to the outside of the external injection part 20, and the external powder Motor 46 is installed on the upper part of the sand 20, a chain 48, one side is coupled to the upper portion of the external injection unit 20, the other side is wound around the motor 46, and in the motor 46 Consisting of weight balancing 49 coupled to an end of the chain 48 that extends, Heat treatment material rapid air cooling device of a hollow tube shape, characterized in that the external injection unit 20 is elevated by the drive of the motor (46). The method of claim 6, The motor 46 is controlled to be rotated forward or reverse by the control unit, so that the external injection unit 20 can be oscillated (oscillation) along the guide 42 Heat treatment rapid air cooling system.

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