JPH0657845B2 - Operating method of degreasing sintering furnace - Google Patents

Description

TECHNICAL FIELD The present invention relates to an operating method in which degreasing and sintering are continuously performed on an object to be treated by a degreasing and sintering furnace.

"Prior Art" When sintering ceramics, metal powder, or the like, a degreasing and sintering furnace that can continuously degrease and sinter an object to be treated is often used.

In that case, the operating procedure is generally such that a degreasing process for a predetermined time is followed by a sintering process. That is, first, the furnace is kept at a predetermined degreasing temperature for a predetermined time, and impurities contained in the object to be treated, such as wax used as a binder, are evaporated and exhausted from the furnace (degreasing step), After that, the inside of the furnace is further heated to raise the sintering temperature, and if necessary, the inside of the furnace is adjusted to a predetermined pressure, and the state is maintained for a predetermined time for sintering (sintering step). ing.

In the above case, it is important to accurately set the time required for the degreasing process. That is, if the time of the degreasing process is short, the impurities move to the sintering process without being sufficiently exhausted, which adversely affects the quality of the sintered product, and conversely, if the time of the degreasing process is long, the operating time is long. It will become long and productivity will decrease.

Conventionally, it is the actual situation that such degreasing time is artificially set each time based on experience.

"Problems to be Solved by the Invention" However, the time required for degreasing obviously depends on the amount of wax contained in the object to be treated, but also depends on the size and shape of the object to be treated. However, accurately, it is not always easy to set the degreasing time. Therefore, it is extremely difficult to set the degreasing time based on the conventional experience accurately and precisely.
In many cases, the quality of the sintered product is deteriorated, or in order to avoid it, the degreasing time is unnecessarily lengthened, which causes a problem that the operation time becomes unnecessarily long.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for operating a degreasing and sintering furnace that can ensure the quality of a sintered product and shorten the operating time.

"Means for Solving Problems" The present invention has a degreasing process in which a furnace is kept at a degreasing temperature to evaporate and remove impurities contained in an object to be treated, and then the furnace is heated to a sintering temperature. In the operating method of the degreasing and sintering furnace in which the temperature is raised to the sintering step of sintering the object to be processed, the impurity concentration in the furnace is measured during the degreasing step, and the temperature inside the furnace is raised based on the measurement result. It is characterized by starting the temperature and shifting to the sintering process.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

First, the configuration of the degreasing and sintering furnace 1 used in the method of this embodiment will be described with reference to FIG. This degreasing and sintering furnace 1
Is provided with a heating chamber 3 inside the furnace body 2.
The object 4 to be treated placed inside the furnace is heated by a heater 5 to degrease and sinter. Reference numeral 6 in the drawing is a gas supply pipe for supplying a carrier gas such as an inert gas in the heating chamber 3, and reference numeral 7 is a gas supply device. The gas supply device 7 can adjust the pressure in the furnace by adjusting the gas supply amount.
Reference numeral 8 in the drawing is an exhaust pipe for exhausting the gas of impurities generated from the object to be treated 4 in the degreasing step together with the carrier gas, and 9 is an exhaust device. The above configuration is the same as that of a conventional general degreasing sintering furnace.

In addition to the above configuration, in this degreasing and sintering furnace 1, a sensor 10 that can measure the gas concentration of impurities is attached in the middle of the exhaust pipe 8, and the output signal of this sensor 10 is the control device 1.
It will be sent to 1. This control device 11
The furnace temperature can be controlled by changing the heat generation amount of the heater 5 based on the signal from the sensor 10, and the furnace pressure can also be controlled by controlling the gas supply device 7.

Next, an operating procedure in the case where the degreasing and sintering furnace 1 is used to continuously degrease and sinter the object 4 will be described with reference to FIG. FIG. 1 shows changes over time in the gas concentration C of impurities in the furnace, the temperature T in the furnace, and the pressure P in the furnace in this operating procedure, which are superimposed on the common vertical axis. The horizontal axis represents the elapsed time t after the start of operation.

As shown in FIG. 1, when the object to be treated 4 is loaded into the heating chamber 3, first heating by the heater 5 is started to set the temperature T in the furnace.
To a predetermined degreasing temperature T ₁ . At the same time, the exhaust device 9 exhausts gas to maintain the inside of the furnace at a predetermined degreasing pressure P ₁ (vacuum), and the sensor 10 measures the gas concentration C of the impurities in the exhaust gas. The gas concentration C initially increases, but gradually decreases with exhaust.

When the sensor 10 detects that the gas concentration C has reached the predetermined value C ₁ , the controller 11 increases the heat generation amount of the heater 5 at the time t ₁ to start the temperature rise in the furnace.
Then, when the temperature T in the furnace reaches a predetermined sintering temperature T ₂ , that state is maintained. The sintering temperature T ₂ should be reached before the time t ₃ (described later) when the furnace pressure P becomes the sintering pressure P ₂ or at the same time. Also, the above gas concentration
The value of C ₁ may be set in consideration of the exhaust capacity of impurities.

Then, at time t ₂ when the sensor 10 detects that the gas concentration C has become almost zero, the control device 11 controls the gas supply device 7 to increase the reactor internal pressure P, and the reactor internal pressure P increases. When the predetermined sintering pressure P ₂ is reached, the state is maintained.

By doing so, the time t ₃ at which the furnace pressure reaches P ₂ (at this time, the furnace temperature T has already reached the sintering temperature T ₂ )
Will automatically shift to the sintering process. Then, after performing sintering for a predetermined time in that state, heating by the heater 5 is stopped and the inside of the furnace is cooled to complete the operation.

According to the above procedure, the temperature starts to be increased from the degreasing temperature T ₁ to the sintering temperature T ₂ and the pressure increase from the degreasing pressure P ₁ to the sintering pressure P ₂ , that is, the transition from the degreasing process to the sintering process is performed. , Automatically based on the measurement result of the gas concentration C by the sensor 10,
And at the optimal time. Therefore, as in the case where the degreasing time is set in advance based on experience, it is possible to shift to sintering despite insufficient degreasing, or conversely, to extend the degreasing time longer than necessary. In addition, the quality of the sintered product is ensured, and the operating time does not become unnecessarily long.

Further, even when continuously processing objects having different shapes and sizes, it is not necessary to change the setting of the degreasing time each time, and after the necessary and sufficient degreasing, the process automatically shifts to sintering. Therefore, it is possible to sufficiently simplify the operation and optimize the operation.

It should be noted that, in the above-mentioned embodiment, the sintering is performed in a state where the pressure in the furnace is increased, and the pressurization start timing is also controlled by the sensor, but it can be applied to the case of sintering under normal pressure or vacuum, Further, pressure control does not always depend on a sensor.

Further, in carrying out the present invention, not only the degreasing and sintering furnace shown in FIG. 2 but also a degreasing and sintering furnace having an appropriate structure can be used. For example, in the above, the temperature setting and the pressure setting are automatically performed by the control device, but they may be manually performed by monitoring the measurement result by the sensor. The sensor may be mounted inside the furnace.

[Effect of the Invention] As described in detail above, according to the present invention, the impurity concentration is measured, and the temperature rise is started based on the measurement result to shift to the sintering step. Therefore, the quality of the sintered product can be ensured and the operation time can be shortened.

[Brief description of drawings]

1 and 2 show an embodiment of the present invention,
FIG. 1 is a diagram showing changes with time in the impurity concentration, furnace temperature, and furnace pressure in the procedure of this embodiment, and FIG. 2 is a sectional view showing a schematic configuration of a degreasing and sintering furnace used in this embodiment. . 1 ... Degreasing sintering furnace, 10 ... Sensor, T ₁ ... Degreasing temperature,
T ₂ …… Sintering temperature.

Claims (1)

[Claims] 1. A furnace is heated to a sintering temperature to burn the object to be treated through a degreasing step of removing impurities contained in the object to be treated by evaporating and removing impurities contained in the object to be treated at the degreasing temperature. In the operating method of the degreasing sintering furnace that shifts to the sintering process that binds, the impurity concentration in the furnace is measured in the process of the degreasing process, and the temperature rise in the furnace is started based on the measurement result to start the sintering process. A method for operating a degreasing and sintering furnace, which is characterized by a transition.