JP4395497B2 - Bath cooling device - Google Patents

Description

  The present invention relates to a bath cooling apparatus for cooling a heated object to be heat-treated.

When heat-treating a heat treatment object such as a mold, heat the heat treatment object for a predetermined time in a vacuum furnace or the like, then introduce a low-temperature inert gas to cool the gas, or put the heat treatment object into a bathtub. It is customary to cool the bath (for example, see the following patent document).
Japanese Patent No. 3516906

  The coolant used for cooling the object to be heat-treated is changing from quenching oil and tempering oil to an aqueous liquid to which water or additives are added. Quenching oil and tempering oil are hazardous materials belonging to the 4th class, 3rd and 4th petroleum, and are subject to regulations on the total amount of storage and require thorough management. Oil with a high flash point has a high viscosity at room temperature, and the work of washing the heat treatment target after cooling the oil bath is troublesome. Also, the cleaning liquid often contains harmful substances, and environmental measures are indispensable. Water bath cooling can avoid these problems. Moreover, water can be obtained at a lower cost than quenching oil and tempering oil.

  On the other hand, due to the difference in density and the boiling point between water and oil, water bath cooling cools the heat treatment object more rapidly than oil bath cooling. Therefore, when water bath cooling is simply performed in the same manner as oil bath cooling, it is inevitable that a crack or a bend will occur in the heat treatment object. Although the surface of the heat treatment object put into the water tub is rapidly cooled, the temperature drop inside does not follow it, and the time difference between the inside and outside quenching (transformation from austenite structure to martensite structure), that is, dimensional change (martensite) There is a high risk of burning cracks due to a large time difference in expansion (according to site transformation).

  Even when the oil bath is cooled, if the heat treatment target is large or thick, the risk of burning cracks and the like due to the time difference between the quenching inside and outside becomes obvious. Similarly, even when there is a difference in thickness in a part, the difference in thickness may cause a difference in cooling rate and cause a crack or the like.

  An object of the present invention made in view of the above is to prevent or reduce burning cracks or the like of an object to be heat-treated in bath cooling.

In order to solve the above-mentioned problems, the present invention is a bath cooling device for bath cooling by immersing a heated heat treatment object in a coolant that is an aqueous liquid to which water or additives are added , and stores the coolant. and tub placing the injection pipe injection port injects coolant from there on the injection port from the water surface of the bath in the tub, and connected to the injection pipe, the gas supplied from the gas cylinder or pressure pump to the injection tube Cooling stored in the bathtub, comprising a gas conduit for injecting gas into the coolant flowing in and flowing through the injection pipe, and a lid that seals the bathtub and allows the interior to be at a pressure higher than atmospheric pressure. A coolant mixed with a gas introduced through the gas conduit is sprayed from the jet pipe to the agent, and the object to be heat-treated is bath-cooled while generating a jet and a bubble in the bathtub, and the lid is , Close the bathtub with this lid State in via the gas conduit to the tub interior by gas is injected into the high pressure from atmospheric pressure to constitute the bath cooling apparatus the temperature of the bath may be raised to more than 100 ° C. in a water bath cooling process.

  In other words, the bath cooling effect given to the heat treatment object is suppressed by mixing a large amount of fine bubbles in the bathtub. If it is such, it can avoid that only the surface of a heat processing target object and a thin part of a thin part cool too quickly. And it becomes possible to make the difference in the degree of baking inside and outside of the heat treatment object and the difference in the degree of baking in the part having a difference in thickness to prevent or reduce the burning crack.

  If the injection port of the injection pipe is positioned in the vicinity of the water surface of the coolant stored in the bathtub, the atmosphere or the air on the water surface can be struck into the bathtub and the amount of bubbles can be increased when the coolant is injected.

  The peripheral part of the heat treatment object is easier to cool than the central part. In particular, the corners quickly drop in temperature. If there are a plurality of injection ports and the coolant is injected from the injection ports toward the center of the bathtub, the central part of the heat treatment object having a relatively large cooling load (heat capacity) is intensively cooled. The peripheral portion of the heat treatment object can be cooled by causing the raised coolant to flow to the peripheral side. Therefore, the temperature drop of the whole heat treatment object becomes uniform, and the occurrence of burning cracks and the like of the heat treatment object can be suppressed.

  If it has a suction pipe for sucking the coolant in the bathtub and returning it to the injection pipe, it will inject further gas into the coolant containing fine bubbles and inject it from the injection pipe. The amount of bubbles increases further. This is particularly effective in a water bath cooling process using water or an aqueous liquid as a coolant.

  In bath quenching of steel and the like, it is necessary to keep the temperature of the bathtub higher than a certain level. However, the gas used in the bath cooling device according to the present invention is usually supplied at room temperature. If so, the temperature of the coolant is lowered due to the mixing of the gases. In order to sufficiently and sufficiently suppress the bath cooling effect given to the heat treatment object, a considerable amount (or high pressure) of gas must be mixed in the coolant, but if the temperature of the coolant drops significantly, The time difference of quenching inside and outside of the object to be heat treated and the time difference of quenching of the part having a difference in thickness are enlarged, and an adverse effect such as cracking occurs. For the above reasons, it is desirable to provide a coolant heating means for heating the coolant and maintaining the temperature. It is also conceivable to add a gas heating means for heating the injected gas to maintain the temperature of the coolant.

  In addition, it is also preferable to provide a lid that seals the bathtub and enables the interior to be at a high pressure equal to or higher than atmospheric pressure. Then, the water temperature of the bathtub can be raised to 100 ° C. or higher in the water bath cooling treatment, which is more suitable for steel quenching and the like.

  According to the present invention, it is possible to prevent or reduce burning cracks or the like of an object to be heat-treated in bath cooling.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. As shown in FIGS. 1 to 4, the bath cooling device of the present embodiment circulates through a bathtub 1 for storing a coolant, an injection pipe 2 for injecting the coolant into the bathtub 1, and the injection pipe 2. Gas injection means 5 for injecting gas into the coolant. A movable lid (not shown) for opening / closing the bathtub 1 exists at the top of the bathtub 1. It is preferable that this lid can seal the bathtub 1 and can make the inside high pressure above atmospheric pressure.

In this bath cooling device, a heated heat treatment object is put into the bathtub 1 and immersed in the coolant, and a coolant mixed with gas is injected into the coolant filling the bathtub 1, so that It is possible to cool the object to be heat-treated while generating jets and bubbles. Here, it is assumed that the coolant is water and the injection gas is an inert gas such as N ₂ or air. This bath cooling device may be installed in a heat treatment furnace for heating the heat treatment object, or may be installed outside the heat treatment furnace and charged with the heat treatment object carried out of the furnace for cooling.

  More specifically, in the present bath cooling device, upper injection pipes 21, 22, 23, and 24 that inject water as a coolant from above, and lower injection pipes 25, 26, 27, and 28 that inject water from below. It is attached. The upper injection pipes 21, 22, 23, 24 are arranged in four directions along the upper edge of the peripheral wall portion of the bathtub 1, and a plurality of injection openings 21a, 22a are provided from the respective injection pipes 21, 22, 23, 24. , 23a and 24a are projected obliquely downward toward the center of the bathtub 1. The injection ports 21a, 22a, 23a, 24a of the upper injection tubes 21, 22, 23, 24 are at a height position that faces the vicinity of the water surface when the bathtub 1 is filled with water. However, bubbling is possible even if the injection ports 21a, 22a, 23a, and 24a are immersed in water. Caps having a plurality of through holes such as rain dew are attached to the tips of the injection ports 21a, 22a, 23a, 24a. If this cap is replaced with a cap that does not have through holes, the individual injection ports 21a, 22a, 23a, and 24a can be closed. That is, according to the shape, size, etc. of the heat treatment object, which injection port 21a, 22a, 23a, 24a is injected with water and which injection port 21a, 22a, 23a, 24a is not injected, In other words, it is possible to adjust which part of the heat treatment target is to be cooled by focusing water.

  The lower injection pipes 25, 26, 27, and 28 extend in a substantially vertical direction along the wall surface of the bathtub 1, and project the injection ports 25a, 26a, 27a, and 28a obliquely upward toward the center of the bathtub 1 at the lower ends. ing. The injection ports 25a, 26a, 27a, and 28a of the lower injection tubes 25, 26, 27, and 28 are submerged below the water surface when the bathtub 1 is filled with water. Caps having a plurality of through holes are also attached to the tips of the injection ports 25a, 26a, 27a, and 28a. Valves 25b, 26b, 27b, 28b are provided in the middle of the lower injection pipes 25, 26, 27, 28. If these valves 25b, 26b, 27b, 28b are closed, the individual injection ports 25a, 26a, It is possible to prevent water from being ejected from 27a and 28a.

  The lower injection pipes 25 and 26 are connected to the upper injection pipe 23, and the upper injection pipe 23 is connected to the upper injection pipe 22 and is connected to the discharge side of the hydraulic pump 72. The lower injection pipes 27 and 28 are connected to the upper injection pipe 24, and the upper injection pipe 24 is connected to the upper injection pipe 21 and is connected to the discharge side of the hydraulic pump 71.

  A suction pipe 3 for sucking water in the bathtub 1 is connected to the suction side of the hydraulic pumps 71 and 72. The suction ports 33 a and 33 b of the suction pipe 3 open at the bottom of the bathtub 1. More specifically, a hollow box-shaped bottom structure 33 is fixed on the bottom surface of the bathtub 1, the bottom structure 33 and the suction pipe main bodies 31 and 32 are communicated, and a suction port is formed on the top surface of the bottom structure 33. 33a and 33b are formed. The suction pipe main body 31 recirculates the water in the bathtub 1 to the injection pipes 21, 24, 27, and 28 via the hydraulic pump 71. In addition, the suction pipe main body 32 causes the water in the bathtub 1 to flow back to the injection pipes 22, 23, 25, and 26 via the hydraulic pump 72.

  Thus, gas conduits 51 and 52 for introducing gas into the injection pipe 2 are inserted at the branch points between the upper injection pipes 21 and 22 and the upper injection pipes 24 and 23. The gas conduits 51 and 52 are connected to a gas cylinder (not shown) or a pressure pump (not shown) that sucks the atmosphere or the atmosphere, and sends pressurized gas supplied from either into the injection pipe 2. The gas conduits 51 and 52, the gas cylinder, the atmospheric pressure pump, and the like are elements of the gas injection means 5.

  In addition, a plurality of heaters 61 and 62 are laid in the bathtub 1 as the coolant heating means 6 for heating the water and maintaining the temperature.

  When the object to be heat-treated is bath-cooled, water is poured into the bathtub 1 and the heaters 61 and 62 are energized to heat the water to a temperature just before boiling (about 98 ° C. or higher). Thereafter, the heated heat treatment object is put into the bathtub 1 and immersed therein. Next, the hydraulic pumps 71 and 72 are activated to pump water into the injection pipe 2, and pressurized gas is injected into the water from the gas conduits 51 and 52, and the injection ports 21a, 22a, 23a, 24a and 25a are injected. , 26a, 27a, and 28a. In particular, the water jetted from the jet ports 21 a, 22 a, 23 a, and 24 a on the water surface of the bathtub 1 violently collides with the water surface and enters the water, and the atmosphere or air on the water surface is involved in the bathtub 1. As a result, a large amount of fine bubbles are generated in combination with the previously injected pressurized gas. This bubble is such that it stays in the bathtub 1 for several minutes or more even when the water injection is stopped.

  Moreover, the water sprayed from the jet nozzles 21a, 22a, 23a, 24a, 25a, 26a, 27a, 28a first heads toward the center of the bathtub 1 and hits the central part of the heat treatment object, then flows from there to the peripheral side, and is subjected to the heat treatment object. It becomes the jet containing the bubble which flows into the suction inlet of the bathtub 1 bottom part, contacting with the peripheral part of a thing. And it recirculates to the injection pipe 2 via the suction pipe 3 and the pumps 71 and 72, receives injection of further pressurized gas, and again from the injection ports 21a, 22a, 23a, 24a, 25a, 26a, 27a, and 28a. Be injected. In this way, the action of stirring the water is performed, the bubbles are spread over substantially the entire area of the bathtub 1, and the cooling rate of the entire heat treatment object is equalized while suppressing the bath cooling effect given to the heat treatment object. During the bath cooling process of the heat treatment object, the heaters 61 and 62 are controlled to maintain the water temperature at about 98 ° C. or higher.

  According to the present embodiment, the bathtub 1 for storing water as a coolant, the injection pipe 2 for injecting water into the bathtub 1, and the gas injection for injecting gas into the water flowing through the injection pipe 2 And a means for spraying water mixed with gas to the water stored in the bathtub 1 and bubbling the bathtub 1 while bath-cooling the object to be heat-treated. The effect of cooling the bath can be suppressed. At the same time, it is possible to suppress the cooling effect of the spray water sprayed from the spray pipe 2 and directly hitting the heat treatment object. Therefore, the difference in the degree of baking inside and outside the object to be heat-treated and the difference in the degree of baking in the part having a difference in thickness are reduced, and it is possible to prevent or reduce the occurrence of burning cracks.

  Since the injection ports 21a, 22a, 23a, and 24a of the injection pipe 2 are positioned in the vicinity of the water surface of the water stored in the bathtub 1, the atmosphere or air on the water surface is struck into the bathtub 1 when water is injected. The amount of can be increased.

  A plurality of injection ports 21a, 22a, 23a, 24a, 25a, 26a, 27a, 28a are used, and water is injected from the injection ports 21a, 22a, 23a, 24a, 25a, 26a, 27a, 28a toward the center of the bathtub 1 Therefore, the peripheral portion of the heat treatment object can be cooled by causing the water heated to flow to the peripheral side while cooling the central portion of the heat treatment object with a relatively large cooling load. Therefore, the temperature drop of the whole heat treatment object becomes uniform, and the occurrence of burning cracks and the like of the heat treatment object can be suppressed.

  Since the suction pipe 3 for sucking the water in the bathtub 1 and returning to the jet pipe 2 is provided, the gas is further injected into the water containing fine bubbles and jetted from the jet pipe 2. The amount of bubbles in 1 is further increased. This is particularly effective in a water bath cooling process using water.

  In bath quenching of steel and the like, it is necessary to keep the temperature of the bathtub 1 higher than a certain level, but the gas supplied from a gas cylinder or a pressure pump is usually at room temperature. In the present embodiment, a coolant heating means 6 is provided for warming water and maintaining the temperature, and is suitable for bath quenching and bath tempering by compensating for a drop in water temperature due to gas mixing. Can be kept at temperature.

  In addition, by injecting gas through the gas injection means 5 in a state where the bathtub 1 is sealed with a lid, the inside of the bathtub 1 can be set to a high pressure equal to or higher than atmospheric pressure. Then, since the water temperature of the bathtub 1 can be raised to 100 ° C. or higher in the water bath cooling process, it is further suitable for quenching steel.

  The present invention is not limited to the embodiment described in detail above. In the above embodiment, the upper injection pipes 21, 22, 23, and 24 and the lower injection pipes 25, 26, 27, and 28 are provided side by side, but only the upper injection pipes 21, 22, 23, and 24, or the lower side. It is not prevented that only the injection pipes 25, 26, 27, and 28 are used. Moreover, you may arrange | position the injection pipe which injects water toward the inner side in the surrounding wall part of the bathtub 1. FIG.

  The injection ports 21 a, 22 a, 23 a, 24 a, 25 a, 26 a, 27 a, and 28 a of the injection pipe 2 are not necessarily directed to the center of the bathtub 1. The direction of the injection ports 21a, 22a, 23a, 24a, 25a, 26a, 27a, and 28a may be variable. If the heat treatment object has a large thickness difference depending on the part, adjust the injection direction so that water is focused on the thicker part, and increase or decrease the water injection amount effectively. Try to suppress burning cracks.

  It is also possible to arrange a heater as the coolant heating means 6 outside the bathtub 1. That is, it is possible to adopt a mode in which a heater is laid at a position where the water flowing through the suction pipe 3 or the injection pipe 2 can be heated, thereby maintaining the temperature.

  In addition, it is also conceivable to provide a gas heating means for heating the gas injected into the water to suppress the water temperature drop caused by the gas injection. For example, a pressurized gas supplied from a gas cylinder or a pneumatic pump is once guided into the bathtub 1, warmed with water that fills the bathtub 1 (heated), and then fed into the injection pipe 2. In this case, as shown in FIG. 5, the gas conduit 4 is disposed along the peripheral wall portion of the bathtub 1 so as to surround the inside of the bathtub 1, both ends thereof are exposed to the outside of the bathtub 1, and one end is a gas cylinder or atmospheric pressure. Connect to the pump and connect the other end to the injection tube 2. The part in the bathtub 1 of the gas conduit 4 is produced using a material having high thermal conductivity such as copper. In this example, the heaters 61 and 62 for heating water also serve as the gas heating means 6 for heating the gas.

  Of course, as the gas heating means, a heater or a heat exchanger for heating the gas supplied from the gas cylinder or the atmospheric pressure pump may be additionally provided. Furthermore, the gas may be adiabatically compressed when the gas is fed into the injection pipe 2 to heat the gas.

  In addition, the coolant used is not limited to water. It may be an aqueous liquid, an oil or an oily liquid to which an additive is added.

  Other specific configurations of the respective parts are not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

The front view which shows the bath cooling device of one Embodiment of this invention. FIG. The YY line front sectional drawing. The line X-X cross-sectional side view. The XX line sectional side view which shows one of the modifications of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Bathtub 2 ... Injection pipe 21a, 22a, 23a, 24a, 25a, 26a, 27a, 28a ... Injection port 3 ... Suction pipe 5 ... Gas injection means 6 ... Coolant heating means, gas heating means

Claims (6)

A bath cooling device for bath cooling by immersing a heated heat treatment object in a coolant which is an aqueous liquid to which water or additives are added ,
A tub for storing coolant,
And injection pipe injection port injects coolant into the bath from the present on the injection port from the water surface of the bath,
A gas conduit connected to the injection pipe, for injecting a gas supplied from a gas cylinder or a pressure pump into the injection pipe, and injecting the gas into a coolant flowing through the injection pipe;
A lid that seals the bathtub and enables the interior to be at a pressure higher than atmospheric pressure;
A coolant mixed with a gas introduced through the gas conduit is injected from the injection pipe to the coolant stored in the bathtub, and the heat treatment target is bath-cooled while generating a jet and bubbles in the bathtub. With
It said lid, through the gas conduit while sealed tub with a lid and a tub inside Rukoto are injected gas pressure higher than atmospheric pressure, the water temperature of the bathtub can be raised to more than 100 ° C. in a water bath cooling process A bath cooling device characterized by being a thing. The bath cooling device according to claim 1, wherein there are a plurality of injection ports of the injection pipe, and the coolant in which the gas has already been mixed is injected from each of the injection ports. An injection pipe for injecting a coolant from the injection port into the bathtub, and the injection port exists below the surface of the bathtub;
The bath cooling according to claim 1 or 2, further comprising a gas conduit connected to the injection pipe, for sending a gas supplied from a gas cylinder or a pressure pump into the injection pipe, and injecting the gas into a coolant flowing through the injection pipe. apparatus. 4. The bath cooling device according to claim 1, 2 or 3, further comprising a suction pipe for sucking a coolant containing fine bubbles in the bath and returning to the injection pipe. The bath cooling device according to claim 1, 2, 3 or 4, further comprising a coolant heating means for heating the coolant and maintaining the temperature. The bath cooling device according to claim 1, 2, 3, 4, or 5, further comprising a gas heating means for heating the injected gas to maintain the temperature of the coolant.

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