JP2011127214A - Heat treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat treatment apparatus capable of favorably gas-cooling an object for heat treatment by rotating a stirring fan at high speed without using any prime mover of a large output. <P>SOLUTION: The heat treatment apparatus includes a cooling chamber in which an object for heat treatment is carried, a fan 5 for executing the stirring by sucking and discharging filled cooling gas, and a plurality of prime movers 91, 92, 93 for feeding the rotational driving force to a fan shaft. The fan is not rotation-driven by one prime mover of large output but the driving forces to be output by the plurality of prime movers 91, 92, 93, respectively, are transmitted to rotate the fan 5. Then, the fan 5 is rotated at high speed by combining the prime movers 91, 92, 93 of the realistic output to be available in a relatively easy manner, and the flow rate of the cooling gas flowing in the cooling chamber can be increased. When the flow rate of the gas flowing in the chamber is sufficiently high, the cooling gas flow is also applied easily to the recessed portion of the object for heat treatment, and the temperature of the entire object for heat treatment is uniformly dropped thereby. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a heat treatment apparatus for quenching a heat treatment object.

  A vacuum heat treatment furnace is known as an apparatus for heat treating steel products such as molds, parts, and materials. In this type of heat treatment furnace, it is customary to heat the object to be heat-treated for a predetermined time in a state where the inside of the furnace is evacuated, and then perform a rapid cooling treatment while charging with a low-temperature inert cooling gas and stirring with a fan. .

  In the quenching process, if the entire object to be heat-treated cannot be cooled uniformly, there will be a difference in the quenching result of each part. That is, a time difference of expansion occurs due to a time difference of transformation from the austenite structure to the martensite structure in each part, and quenching deformation such as elongation, warpage, and bending is caused. In extreme cases, it develops into burn cracks. In the cooling treatment of heat treatment objects with uneven shapes with large mass differences, shapes with sharp edges, and shapes with a large number of holes with different diameters, the cooling gas flows in many directions and places with less resistance. This causes a time delay in expansion and causes quenching deformation.

  Recently, when gas-cooling an object having a complicated shape, the pressure of the cooling gas injected into the furnace is increased to an ultra-high pressure of 1 MPa to 3 MPa in an attempt to make the temperature drop of the entire heat treatment object uniform. ing. However, an enormous amount of gas is consumed, and improvement of the pressure resistance of the furnace body is essential. These increases in running costs and equipment costs are directly linked to a rise in heat treatment costs. In addition, there is a problem that a prime mover that exhibits a huge output capable of rotating the fan in an ultra-high pressure atmosphere must be used.

  The applicant adopts a high-power diesel engine as a fan drive source and performs gas cooling processing (see the following patent document). This product is always effective for special purposes such as processing large heat treatment objects. However, the size and number of objects to be heat-treated are different each time. For example, the required cooling gas pressure and the fan output differ between a case where eight objects of 50 kg are processed and a case where one object of 400 kg is processed. A current furnace that drives a fan using a high-power engine is inefficient for processing a relatively small amount of small objects, and there is a problem in terms of versatility and versatility corresponding to various objects.

  On the other hand, a large mold, which is one of heat treatment objects, will continue to be an important tool for manufacturing industrial products, and its heat treatment technology and equipment cannot be neglected. Nevertheless, the procurement of high-powered motors essential for large heat treatment facilities is becoming more difficult, and there are many operational restrictions.

Utility Model Registration No. 3125138

  The present invention made in view of the above is intended to provide a heat treatment apparatus capable of suitably cooling the object to be heat-treated by driving a stirring fan at a high speed without using a prime mover with a large output.

  The present invention is an epoch-making cooling system that realizes highly reliable heat treatment for large precision molds, etc., which is expected to become increasingly important as a global trend in the future, while avoiding an increase in cost and risk. Equipment and cooling processes are provided.

  A heat treatment apparatus according to the present invention cools (mainly quenches) a gas for cooling after heating the object to be heat treated. As a basic configuration, a cooling chamber into which the object to be heat treated is loaded, and filling And a plurality of prime movers for supplying a rotational driving force to the fan shaft.

  That is, the fan is not rotationally driven by one high-power prime mover, but the driving force output from each of the plurality of prime movers is transmitted to the same fan shaft to rotationally drive the fan. According to the present invention, it is possible to achieve a large output as a whole by combining a plurality of prime movers with realistic outputs that are relatively easily available, and the flow velocity of the cooling gas (wind speed) flowing in the cooling chamber by rotating the stirring fan at high speed. ) Can be effectively increased. Even if the flow rate of the gas flowing in the room can be increased sufficiently without increasing the pressure of the gas introduced into the room, the cooling gas wind will easily hit the concave part of the object to be heat treated. The temperature drop of the entire object can be made uniform.

  In the quenching process of steel molds, etc., the steel molds are heated to 940 ° C to 1050 ° C, rapidly cooled to around the Ms point (martensite formation temperature), and then slowly cooled. During the rapid cooling period, it is necessary to increase the rotational speed of the fan and thus the flow rate of the cooling gas as much as possible, and it is desirable that the rotational driving force supplied to the fan shaft is also large. On the other hand, in the slow cooling period, the flow rate of the cooling gas is not required as in the previous rapid cooling period, and the rotational driving force supplied to the fan shaft may be small. If the heat treatment apparatus can selectively take a state in which only a part of the plurality of prime movers is operated as a driving force supply source and a state in which the heat treatment apparatus is operated as an entire driving force supply source It is possible to suppress the energy consumption of the prime mover while obtaining a desired metallurgical effect by operating all the prime movers during the rapid cooling period and operating some prime movers during the slow cooling period. Further, even in the case of processing a small heat treatment object, it is efficient because only a part of the prime movers can be operated to ensure a necessary fan output.

  Each of the plurality of prime movers is preferably an electric motor. A battery motor may be employed as the prime mover. The time for driving the motor and driving the fan is one hour or two hours at most in one day, which is considerably shorter than the time for heating the object to be heat-treated by several% to several tens%. In the case of using a battery motor, the battery can be charged at night when the power demand is relatively small, which contributes to power load leveling.

  ADVANTAGE OF THE INVENTION According to this invention, the heat processing apparatus which can carry out the gas cooling of the heat processing target object suitably is achieved by driving a stirring fan powerfully and at high-speed rotation, without using a prime mover of huge output.

The sectional side view which shows the heat processing apparatus in one Embodiment of this invention. The front sectional view showing the heat treatment apparatus of the embodiment. The fragmentary top view which shows the motor | power_engine used as the stirring fan and drive source of a fan in the embodiment. FIG. 4 is a skeleton diagram corresponding to FIG. 3.

  An embodiment of the present invention will be described with reference to the drawings. The heat treatment apparatus of the present embodiment is a vacuum heat treatment furnace that heats an object to be heat treated in a vacuum state, and then fills a cooling gas, stirs, and quenches.

  First, the basic configuration of the heat treatment apparatus excluding the drive source of the fan 5 will be described. As shown in FIGS. 1 and 2, the heat treatment apparatus is a one-chamber type in which a heating chamber 2 for heating a heat treatment target object also serves as a cooling chamber for cooling the heat treatment target object. Specifically, a processing chamber casing 2 having a substantially box shape or a substantially cylindrical shape is arranged in a furnace barrel 1 serving as an outer shell of the heat treatment apparatus, and a part of the inside of the furnace barrel 1 is formed by the processing chamber casing 2. The space is partitioned as a heating chamber and a cooling chamber.

The furnace body 1 is provided with a vacuum exhaust system 3, a gas introduction system 4, a fan 5 and a heat exchanger 6. The evacuation system 3 evacuates the furnace body 1 and is formed by connecting, for example, a diffusion pump, a mechanical booster pump, an oil rotary vacuum pump, or the like in series. The gas introduction system 4 feeds a cooling gas for gas-cooling the object to be heat-treated, for example, an inert gas such as N ₂ from the gas cylinder into the furnace body 1. Each of the evacuation system 3 and the gas introduction system 4 is connected to the furnace body 1 through a valve so as to be connected and disconnected.

  The fan 5 that stirs the cooling gas is a turbofan that sucks the cooling gas filled in the furnace body 1 in the thrust direction and blows it in the radial direction. The fan 5 exists on the rear end side of the furnace body 1, and the fan shaft penetrates the furnace body 1 and protrudes outward. A portion where the fan shaft passes through the furnace body 1 is vacuum-sealed. The heat exchanger 6 is in the immediate vicinity of the fan 5 and cools the cooling gas sucked into the fan 5.

  The front end side of the furnace body 1 serves as a carry-in / out port for the object to be heat-treated, and an opening / closing door 11 is provided at the carry-in / out port.

  The processing chamber 2 is surrounded by a heat-resistant graphite material and a heat insulating material. The processing chamber 2 has a lid 21 that can be opened and closed following the open / close door 11 on the front end side, and a partition wall 22 that cannot be opened and closed on the rear end side. A heater 7 is installed in the chamber 2. The heater 7 is, for example, a graphite heater or the like that can heat the object to be heat-treated to a required temperature, and is disposed at a position surrounding the object to be heat-treated carried into the processing chamber 2.

  A large number of nozzles 23 are provided on the upper and lower walls of the processing chamber 2 as outlets for spraying the cooling gas to the heat treatment target in the processing chamber 2. In addition, the partition wall 22 and the lid 21 before and after the processing chamber 2 are provided with a reflux port 24 for sucking out the cooling gas that has been heated from the heat treatment object. The reflux port 24 is a slot hole that is long in the width direction.

  Around the processing chamber 2 (in the illustrated example, the furnace body 1 including the open / close door 11), a coolant jacket 12 for circulating the coolant is attached. The cooling water jacket 12 absorbs radiant heat and the like emitted from the processing chamber 2 during heating, and suppresses a temperature rise caused by friction of the cooling gas during gas cooling.

  A gap is interposed between the outer periphery of the processing chamber 2 and the inner periphery of the furnace shell 1, and a cooling gas flow path is set in the gap. That is, the cooling gas discharged from the rotating fan 5 passes between the upper and lower walls of the processing chamber 2 and the furnace body 1 and blows out into the processing chamber 2 through the upper and lower nozzles 23. The cooling gas blown out into the processing chamber 2 is sucked out of the processing chamber 2 through the reflux ports 24 in a plurality of directions (front and rear in the illustrated example). The cooling gas passing through the reflux port 24 (on the rear end side) provided in the partition wall 22 passes through the heat exchanger 6 as it is and is sucked into the fan 5. The cooling gas passing through the reflux port 24 (on the front end side) provided in the lid 21 passes between the left and right side walls of the processing chamber 2 and the furnace body 1, reaches the vicinity of the heat exchanger 6, and is sucked into the fan 5. .

  Therefore, an adjustment mechanism 8 for adjusting the opening degree is attached to the cooling gas recirculation port 24. The adjustment mechanism 8 includes a shutter 81 that opens and closes the reflux port 24 through an elevating operation and an actuator 82 that drives the shutter 81. The adjusting mechanism 8 can reduce the opening area (total) of the reflux port 24 to be equal to or smaller than the opening area (total) of the blower outlet 23. That is, a state where the opening area of the reflux port 24 is larger than the opening area of the outlet 23 and a state where the opening area of the outlet 23 is smaller can be selectively taken. When the shutter 81 is raised and the reflux port 24 is fully opened, the total opening area of the plurality of reflux ports 24 is 300% (or 200%) of the total opening area of the plurality of nozzles 23. If the shutter 81 is lowered, the opening degree of the reflux port 24 can be reduced. When narrowed to the limit, the sum of the opening areas of the plurality of reflux ports 24 becomes 10% (or 20% to 30%) of the sum of the opening areas of the plurality of nozzles 23.

  By the function of the opening degree adjusting mechanism 8, the behavior of the cooling gas corresponding to the shape of the heat treatment object, the single mass, the state of the mass difference depending on the part, etc., that is, the amount of gas blown to the heat treatment object, the gas flow rate, the gas pressure The gas flow direction can be controlled within a certain limit.

  Subsequently, the drive source of the fan 5 will be described. As shown in FIGS. 3 and 4, in this heat treatment apparatus, a plurality of prime movers 91, 92, 93 installed outside the furnace are mechanically connected to the fan shaft, and rotations output from the prime movers 91, 92, 93 are output. A driving force is supplied to the fan shaft to rotationally drive the fan 5. The prime movers 91, 92 and 93 are placed on and supported by a stand constructed separately from the furnace body 1. Each prime mover 91, 92, 93 is an electric motor. As the electric motors 91, 92, 93, for example, battery motors for automobiles can be employed. The power sources of the prime movers 91, 92, and 93 and the power source of the heater are different systems. The sum total of the outputs of the prime movers 91, 92, and 93 can reach several times the power output that supplies power to the heater 7.

  3 and 4 show three prime movers 91, 92, and 93. FIG. This does not mean that the number of prime movers as drive sources is limited to three, and it is natural that two prime movers are used or the fan 5 is driven using four or more prime movers. Is possible. The output shafts of the prime movers 91, 92, and 93 are positioned substantially symmetrically about the fan shaft. When three or more prime movers are used, the output shaft of each prime mover can be arranged around the fan shaft at substantially equal angular intervals around the axis.

  The output shaft of the prime mover 91 is connected to a gear 912 via a clutch (hydraulic clutch, electromagnetic clutch, etc.) 911 that can be switched between connection and disconnection. The gear 912 meshes with the gear 51 attached to the fan shaft, either directly or indirectly through other mechanical elements. The output shaft of the prime mover 92 is connected to a gear 922 via a clutch 921 that can be connected and disconnected. The gear 922 meshes with the gear 51 attached to the fan shaft, either directly or indirectly through other mechanical elements. The output shaft of the prime mover 93 is also connected to the gear 932 via a clutch 931 that can be connected and disconnected. The gear 932 meshes with the gear 51 attached to the fan shaft directly or indirectly through other mechanical elements.

  An example of the process of the gas cooling (quenching) process by this heat processing apparatus is shown. The object to be heat-treated is carried into the processing chamber 2, the lid 21 and the opening / closing door 11 are closed and evacuated, and the heater 7 is energized to heat the object to be heat-treated. After the heating is completed, the energization to the heater 7 is interrupted, and the clutch 911 is connected to transmit the rotational driving force output from the prime mover 91 to the fan shaft to rotate the fan 5. Since the fan is activated in vacuum, the load is small, and the rotational speed of the fan 5 immediately reaches the required rotational speed. Therefore, it is not necessary to drive all the prime movers 91, 92, 93 when the fan is activated. The clutches 921 and 931 between the prime movers 92 and 93 that are not operated and the fan shaft are disconnected.

  Next, a cooling gas is introduced and filled into the furnace shell 1 from the gas introduction system 4, and the object to be heat-treated is rapidly cooled while being stirred and circulated by the fan 5. Gas cooling can be performed in a plurality of stages. For example, in the first stage of cooling to a predetermined temperature under a condition where the cooling gas pressure is relatively low, all the prime movers 91, 92, 93 are not operated and the clutches 911, 921 of some prime movers 91, 92 are connected. Then, the rotational driving force from the prime movers 91 and 92 is transmitted to the fan 5. After that, in the second stage in which cooling gas is additionally injected to rapidly cool the gas pressure, the clutches 911, 921, and 931 of all the prime movers 91, 92, and 93 are connected to start from all the prime movers 91, 92, and 93. Is transmitted to the fan 5.

  Alternatively, the opening degree of the reflux port 24 of the processing chamber 2 may be adjusted by an appropriate amount according to the shape, size, mass, number, total weight, etc. of the heat treatment object. For example, in the cooling process of a heat treatment target object having a large difference in mass of each part or having a concave hole or hole in which the cooling gas is difficult to hit, a part where the temperature drop is fast, that is, a part where the flow of the cooling gas is easy to hit or a part where the mass is small Until the part approaches the Ms point (by means of a radiation temperature measurement method through the observation window provided in the furnace shell 1, a fire-colored eye measurement determination, or a direct temperature measurement method using a specimen, etc.) The opening of the reflux port 24 is opened relatively large, and the fans 5 are driven to rotate at high speed using all the prime movers 91, 92, 93 to keep the flow velocity of the cooling gas flowing in the processing chamber 2 high. When the temperature of the part decreases to near the Ms point, the clutch 931 (and / or 921) between some of the prime movers 93 (and / or 92) and the fan shaft is disconnected, and the prime mover 93 ( And / or 92) is stopped. At the same time, the opening degree of the reflux port 24 is narrowed down. Then, the flow rate of the cooling gas decreases and the gas pressure is increased only in the processing chamber 2, so that the cooling of the part where the temperature drop is early is delayed, and the cooling of the part where the temperature drop is slow catches up with this. As a result, the temperature drop of the entire object becomes substantially uniform. In this way, the martensitic transformation is performed on both the relatively small mass and large mass sites.

  When the cooling is completed, the operation of all the prime movers 91, 92, 93 is stopped. Then, the inside of the furnace body 1 is lowered to atmospheric pressure, and the heat treatment object is carried out.

  According to this embodiment, the processing chamber (cooling chamber) 2 into which the heat treatment object is carried in, the fan 5 that stirs by sucking and discharging the filled cooling gas, and the rotational driving force is supplied to the fan shaft. Since the heat treatment apparatus including the plurality of prime movers 91, 92, 93 is configured, the stirring fan 5 is rotated at a high speed by combining a plurality of prime outputs 91, 92, 93 having realistic outputs that can be obtained relatively easily. It is possible to effectively increase the flow rate of the cooling gas flowing in the cooling chamber. Since the flow velocity of the gas flowing in the processing chamber 2 can be sufficiently increased without increasing the pressure of the gas introduced into the processing chamber 2 to an extremely high pressure (increasing the amount), the cooling gas flow is also applied to the concave portion of the heat treatment object. It becomes easy to hit, and the temperature drop of the whole heat treatment target object can be made uniform.

  The heat treatment apparatus selectively takes a state in which only a part of the plurality of prime movers 91, 92, 93 is operated as a driving force supply source and a state in which all are operated as a driving force supply source. Therefore, all the prime movers 91, 92, 93 are operated during the rapid cooling period, and a part of the prime movers 91 (and / or 92) are operated during the slow cooling period. The energy consumption of the prime movers 91, 92, 93 can be suppressed while acquiring Even in the case of processing a small heat treatment object, only a part of the prime movers 91 (and / or 92) can be operated to secure a necessary fan output, which is efficient.

  Since the plurality of prime movers 91, 92, and 93 are electric motors, speed control and other handling are facilitated as compared with the case where an engine is employed. Furthermore, if the prime movers 91, 92, and 93 are battery motors, the batteries can be charged and operated at night when power demand is relatively low, which contributes to power load leveling. In the case of a normal motor, a large-scale power transmission / reception facility is not necessary, and it is streamlined.

  The present invention is not limited to the embodiment described in detail above. To enumerate, the driving force transmission mechanism interposed between the prime mover and the fan shaft is not limited to that shown in FIG. A differential gear or a planetary gear may be used to connect the output shaft of each prime mover to the fan shaft, or a winding transmission mechanism may be used to connect the output shaft of each prime mover to the fan shaft. .

  The output shafts of the prime movers may be rotationally synchronized via a winding transmission mechanism (timing belt or chain) or the like.

  Not all prime movers are electric motors. One part may be an electric motor and the rest may be a heat engine such as a practical small diesel engine or turbine engine. Alternatively, all the prime movers may be heat engines.

  In the above embodiment, one shutter is provided for one return port, but a plurality of shutters may be provided for one return port. For example, if shutters that can be moved up and down independently of each other are arranged opposite to each other, not only the opening degree of the reflux port but also the height position of the opening portion of the reflux port can be adjusted.

  In the above embodiment, the opening degree of the reflux port provided in the processing chamber casing is adjusted by the adjustment mechanism. However, the processing chamber casing is always provided with a gas outlet that is fully open, and the outlet A mode in which a reflux port with an opening degree adjusting mechanism is separately provided between the fan and the fan may be employed.

The gas used for cooling the heat treatment object is not limited to an inert gas such as N ₂ . Air or the like may be used.

  When the processing chamber casing is not a heat insulating material, a heater can be installed outside the chamber and around the casing. When installing a heater outside the housing, heat insulation is mounted on the furnace shell.

  In the above embodiment, the one-chamber heat treatment apparatus in which the heating chamber also serves as the cooling chamber is used. However, a two-chamber heat treatment apparatus in which the heating chamber and the cooling chamber are separately provided may be used.

  Furthermore, it does not matter as an apparatus for exclusive use of the cooling process which carries in and cools the heat processing target object without installing a heater.

  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 present invention can be used as an apparatus for heat-treating steel products such as molds, parts, and materials.

2 ... Cooling chamber 23 ... Air outlet 24 ... Recirculation port 5 ... Fan 8 ... Adjustment mechanism 91, 92, 93 ... Motors 921, 922, 932 ... Clutch

Claims (3)

A heat treatment apparatus for cooling an object to be heat treated by filling a cooling gas,
A cooling chamber into which the heat treatment object is carried, and
A fan that stirs by sucking and discharging the filled cooling gas;
A heat treatment apparatus comprising a plurality of prime movers for supplying rotational driving force to a fan shaft. The heat treatment apparatus according to claim 1, wherein a state in which only a part of the plurality of prime movers is operated as a driving force supply source and a state in which all of the prime movers are operated as a driving force supply source can be taken selectively. The heat treatment apparatus according to claim 1, wherein each of the plurality of prime movers is an electric motor.

Images