JPS62167817A - Cooling fan starter for vacuum heat treatment furnace - Google Patents

Abstract

PURPOSE:To simplify mechanism by constituting a cooling fan starter in such a manner that a gas introducing port for introducing a refrigerant gas is provided in the rotating direction of a cooling fan so as to face the cooling fan. CONSTITUTION:A vacuum gas hardening furnace is set with a treating material A in a treatment chamber 2 and the inside of the furnace is evacuated to a vacuum through a discharge pipe 10. After the treating material is heated to the prescribed hardening temp. by a heater 5 for heating, the refrigerant gas is introduced through the furnace into the gas introducing pipe 11 and is circulated by the cooling fan 3 in the furnace by which the treating material A is quickly cooled. The top ends 11a, 11b of the gas introducing pipe 11 for introducing the refrigerant gas into the furnace are provided in the rotating direction of the cooling fan 3 so as to face the cooling fan 3. A motor 7 is turned on to run after the cooling fan 3 is started by the refrigerant gas.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a starting device for a cooling fan provided inside a vacuum heat treatment furnace such as a vacuum quenching furnace or a vacuum sintering furnace.

[Conventional technology] Vacuum extrathermal Pl! Furnace 1 For example, in a vacuum gas quenching furnace,
54 After heating and maintaining the processed material at a predetermined temperature in an empty atmosphere,
Subsequently, refrigerant gas (inert gas) is injected into the processed material in the furnace to rapidly cool it. In this case, an exhaust pipe and a gas inlet pipe are connected to the furnace shell, and the necessary exhaust port and refrigerant gas inlet are provided in the furnace, and a cooling fan is placed on one side of the furnace to provide the necessary exhaust port and refrigerant gas inlet. It is customary to forcefully circulate refrigerant gas inside the furnace by blowing air with a fan to promote forced cooling using a radiator or the like. This cooling fan is normally started to rotate in synchronization with the introduction of refrigerant gas into the furnace by transmitting torque to its rotating shaft from an induction motor installed outside the furnace.

[Problems to be Solved by the Invention] However, when the cooling fan in a vacuum heat treatment furnace is started, the driving electric motor makes a temporary but sharp peak until it reaches steady rotation in the furnace. A phenomenon in which excessive current is required6 is observed6, and this not only increases the power consumption of the furnace, but also causes various problems such as instantaneous abnormalities in the power supply to peripheral equipment. is occurring.

Therefore, in order to improve this phenomenon, a starting method such as a star-delta method or a Condolfer method is adopted for the motor to reduce the peak of the starting current.

The present invention aims to further reduce the peak of the starting current that occurs when starting the cooling fan, and in addition to improving the electrical starting method described above, it also aims to improve the starting of the cooling fan from a mechanical aspect. This is what I did.

[Means for Solving the Problems] That is, the cooling fan starting device for a vacuum heat treatment furnace provided by the present invention has a gas inlet for introducing refrigerant gas into the furnace facing the cooling fan and facing the rotation direction of the cooling fan. It is characterized by being designed for

C action] With this configuration, the refrigerant gas introduced into the furnace from the gas inlet in the process of cooling the material to be treated is injected into the cooling fan and flows through the furnace while urging the cooling fan in its rotational direction. It will flow inside. Therefore, if the cooling fan drive motor is started in synchronization with the introduction of this refrigerant gas,
Since the cooling fan is given rotational driving force by the refrigerant gas, the starting torque that must be borne by the electric motor is reduced, thereby making it possible to suppress the peak of the starting current required for the electric motor.

〔Example] An embodiment of the present invention will be described below with reference to the drawings.

This example illustrates a case in which the present invention is applied to a vacuum gas quenching furnace, in which a product to be processed in the furnace is first heated to a predetermined quenching temperature (for example, 1230°C) and held in a vacuum atmosphere. After that, N1 gas is introduced into the furnace as a refrigerant gas (inert gas), and this is circulated through the furnace by an internal cooling fan, so that the processed material can be rapidly cooled continuously.

Therefore, the configuration of the vacuum quenching furnace will be outlined. This furnace is
A box-shaped processing chamber 2 made of a heat insulating material is disposed in the center of a closed furnace al, and a cooling fan 3 is disposed on one side at the back of the chamber. The processing chamber 2 has a heating heater 5 therein, and roughly injects N1 gas sent from the cooling fan 3 through a blower duct, which will be described later, toward the processing object A set in the processing chamber 2. The injection nozzle group 6 is equipped with a group of injection nozzles 6. This processing chamber 2 has TI%s 2a, 2a on both sides that can be opened and closed, and when cooling the furnace, the doors 2a on both sides are reversed and opened alternately as shown in the figure. . on the other hand,
The cooling fan 3 has its rotating shaft 4 connected to the output shaft of a driving electric motor 7 disposed outside the furnace, and is rotationally driven by the torque transmitted from the electric motor 7. This cooling fan 3 is
It has a suction port 3a at the center of the front facing the processing chamber z side.

It has a pair of discharge ports 3b, 3b at opposite positions on the outer periphery. One end of the blower ducts 8, 8 provided along the upper and lower inner surfaces of the furnace shell 1 is connected and communicated with each of the discharge ports 3b, and the blower ducts 8, 8 extending to the outer periphery of the processing chamber 2 are connected to Each gas residue inlet of the nozzle group 6 is communicated with each other. Therefore, the N1 gas sent out from the cooling fan 3 in the furnace is guided from the discharge ports 3b, 3b of the cooling fan 3 to the ventilation duct 8.8, and is further injected into the processing chamber 2 from the injection nozzle group 6, where it is processed. Used for forced cooling of object A. Thus, the N1 gas supplied into the processing chamber 2 flows through the space inside the furnace shell l from the openings at both ends with the door 2a open, and is recirculated by the cooling fan 3 from the suction port 3a. A radiator 9 that exchanges heat with the circulating N1 gas in the gas passage near the suction port 3a of the cooling fan 3 for cooling.
has been established. Note that the flow of Ni gas within the furnace is indicated by arrows.

A vacuum furnace with such a furnace internal structure has an exhaust pipe lO for evacuating the inside of the furnace during vacuum heating, and a gas pipe for introducing N1 gas at a constant pressure into the furnace during gas cooling. It is connected to the introduction pipe 11. The exhaust pipe 10 has its open end connected to an appropriate position in the furnace shell l, and is connected to a vacuum pump 1 outside the furnace.
2, the inside of the furnace is evacuated via the exhaust method 13. On the other hand, the gas introduction unit 11 introduces N1 gas supplied from the surge tank 141 outside the furnace through the gas introduction valve F15 into the furnace, and under the operation of the cooling fan 3, the process material A is forcedly cooled with gas. to be carried out.

In this case, the four-person gas pipe 11 is branched into two pipes 11a and llb on the downstream side, and each pipe lla and 1lb (7) penetrates the furnace shell l and is inserted into the furnace. The tips 11A and IIB are piped from the opposite side toward the outer periphery of the cooling fan 3 along the furnace shell l from above and below, and each tip gas inlet 16.16, which forms a nozzle, is placed close to the cooling fan 3. It is placed. These gas inlet ports 16.16 are provided toward the rotational direction H of the cooling fan 3 that injects gas to the blades 3A of the cooling fan 3.

In the vacuum quenching furnace configured in this manner, the cooling fan 3 is activated in the following manner during gas cooling. That is, when starting gas cooling, the gas introduction valve 15 is opened and the N gas supplied from the surge tank 14 etc. is distributed to the two pipes 11a and 11b until the pressure inside the furnace becomes constant. Introduce. Then, each gas inlet 16.16
N? introduced from? The gas is injected into the blades 3A of the cooling fan 3 and then flows into the furnace.In contrast, the cooling fan 3 receives the motion value from the injected N1 gas on the blades 3A, and causes an accidental movement around its rotation axis 4. This generates a force and causes it to idle in a predetermined rotational direction R. Therefore, when the fan rotation is started, the driving electric motor 7 provided outside the furnace is activated.
2. Start the cooling fan 3 electrically.

That is, if this is done, the electric motor 7 will be started while the cooling fan 3 is rotating, and the electric motor 4! ! The starting torque borne by 7 is significantly reduced.

Therefore, compared to the conventional case where the cooling fan 3 is started from a stationary state, the peak appearing in the starting current of the electric motor 7 can be suppressed to a low level. In addition, such a starting method has the advantage that the time from when the cooling fan 3 starts rotating after introducing gas until it reaches its steady rotation state is shortened. In other words, this means that the initial cooling rate of the processed material A in the furnace can be increased, resulting in additional effects such as improved hardening characteristics.

By the way, during gas cooling, N? The time the gas is introduced is such that the inside of the furnace is at a constant pressure of N.
Although it is a very short time until it is filled with one gas,
On the other hand, excessive current flows through the motor 7 of the cooling fan 3 for a moment at the time of startup. Therefore, according to the present invention, as long as the N1 gas is introduced in synchronization with the starting of the electric motor 7, the fluid energy of the introduced gas can be effectively utilized to suppress the occurrence of the peak of the starting current. This makes it possible to realize a system design that is practical.

The present invention has the effects of Structure 1 as described in the above embodiments, but 4. The heat treatment furnace to which the present invention is applied is not limited to a quenching furnace. It is generally applicable to circular forms. Also,
Inert gas other than N1 gas can also be used as the refrigerant gas.

Direct start, star-delta start, Condorpha start, etc. are used to start the electric motor that drives the cooling fan, but if the latter two start methods are adopted, electrical improvements will be achieved. The effect will be doubled.

[Effects of the Invention] With the cooling fan starting device of the present invention, the starting of the cooling fan can be mechanically assisted by the refrigerant gas introduced into the vacuum heat treatment furnace.

The peak of excessive current that appears when starting the drive motor can be suppressed to a low level, and this has the effect of contributing to improving the initial cooling rate inside the furnace.

[Brief explanation of drawings]

Fig. m1 is a schematic sectional view of a vacuum quenching furnace showing one embodiment of the wood grain 1, and Fig. 2 is a view taken along the line x-X of Fig. trJ1. A...Processed material l...Furnace shell, 3...Cooling fan 4...
-Rotating shaft, 7...Electric motor 11...Gas introduction pipe, 11a, llb...Pipe line 11A, IIB
... Tip part 14 ... Surge tank, 15 ... Gas 4-person party 16.
・・Gas inlet

Claims (1)

[Claims] In a vacuum heat treatment furnace in which a refrigerant gas is introduced into the furnace and a cooling fan is rotated to circulate the refrigerant gas within the furnace, the refrigerant gas is introduced into the furnace. A cooling fan starting device for a vacuum heat treatment furnace, characterized in that a gas introduction port is provided facing the cooling fan and facing the rotational direction of the cooling fan.