JPS62250103A - Method for operating degreasing and sintering furnace - Google Patents

Abstract

PURPOSE:To shorten the operation time of a degreasing and sintering furnace as well as to ensure high quality for a sintered product by measuring the concn. of impurities in exhaust gas, starting the rise of the internal temp. of the furnace according to the measured results and carrying out a sintering stage. CONSTITUTION:A heating chamber 3 is placed in the body 2 of a degreasing and sintering furnace 1. A material 4 to be treated is put in the chamber 3, where it is degreased and sintered by heating with heaters 5. A sensor 10 is fitted to an exhaust pipe 8 and the concn. of gaseous impurities in exhaust gas is measured with the sensor 10. The concn. is high at first but lowers gradu ally in accordance with the progress of exhaust. When the concn. lowers to a prescribed value, an output signal is sent to a controller 11. The controller 11 increases the quantity of heat generated by the heaters 5 and starts the rise of the internal temp. of the furnace 1. The furnace 1 is heated to a pre scribed sintering temp. and kept at the temp.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to an operating method in which a workpiece is continuously degreased and sintered in a degreasing and sintering furnace.

``Prior art'' JF -'l 8,,,h Mame△Kahoshijiku Kujikagnebu Kuruhe l-1↓Is it possible to continuously degrease and sinter the processed material? It is often recommended to use a degreasing sintering furnace.

In this case, the operating procedure is generally to proceed to the sintering process after a degreasing process for a predetermined period of time. That is, first, the inside of the furnace is set to a predetermined degreasing temperature and maintained at that state for a predetermined time, impurities contained in the object to be treated, such as wax used as a binder, are evaporated and exhausted from the furnace (degreasing process). After further heating the inside of the furnace to raise the temperature to the sintering temperature, the inside of the furnace is adjusted to a predetermined pressure as necessary, and sintering is performed while maintaining this state for a predetermined time (sintering process). That's what I do.

By the way, in the above case, it is particularly important to accurately set the time required for the degreasing step. In other words, if the degreasing process time is short, the impurities will not be sufficiently exhausted before proceeding to the sintering process, which will have a negative effect on the quality of the sintered product. Conversely, if the degreasing process time is long, the operating time will be reduced. This will take longer and reduce productivity.

Conventionally, such degreasing time has been set artificially on a case-by-case basis based on experience.

``Problem to be solved by the invention'' However, the time required for darkening not only depends on the amount of wax etc. contained in the object to be processed, but also the size and shape of the object to be processed. However, it is not always easy to set an accurate degreasing time. Therefore, when setting the degreasing time based on conventional experience, it is extremely difficult to make accurate and detailed settings, and often leads to deterioration of the quality of the sintered product, or to avoid degreasing more than necessary. This has caused a problem in that the operating time becomes unnecessarily long.

This invention was made in view of the above circumstances, and aims to provide a method for operating a degreasing sintering furnace that can ensure the quality of sintered products and shorten operating time.

``Means for Solving the Problems'' This invention involves a degreasing process in which the interior of the furnace is maintained at a degreasing temperature to evaporate and remove impurities contained in the workpiece, and then the interior of the furnace is brought to the sintering temperature. In the operating method of a degreasing sintering furnace that moves to a sintering process in which the temperature is raised and the workpiece is sintered, the concentration of impurities in the furnace is measured during the degreasing process, and the concentration of impurities in the furnace is determined based on the measurement results. It is characterized by starting the temperature and then moving to the sintering process.

"Example" Hereinafter, an example of the present invention will be described with reference to FIGS. 1 and 2.

First, with reference to FIG. 2, the configuration of the filter-degreasing sintering furnace 1 used in the method of this embodiment will be described. This degreasing sintering furnace
A heating chamber 3 is disposed inside a furnace body 2, and a workpiece 4 charged into the heating chamber 3 is heated by a heater 5 to perform degreasing and sintering. . The reference numeral 6 in the figure is a gas supply pipe for supplying a carrier gas such as an inert gas into the heating chamber 3, and the reference numeral 7 is a gas supply device. This gas supply device 7 is capable of adjusting the pressure inside the furnace by adjusting the amount of gas supplied. In addition, the reference numeral 8 in the figure indicates the workpiece 4 in the degreasing process.
This is an exhaust pipe for exhausting impurity gas generated from the carrier gas together with the carrier gas, and 9 is an exhaust device. The above configuration is similar to a conventional general degreasing and sintering furnace.

In addition to the above configuration, this degreasing sintering furnace! In this case, a sensor IO capable of measuring impurity gas concentration is installed in the middle of the exhaust pipe 8, and the output signal of this sensor 10 is sent to the control device 1.
1. This control device 11 is
The temperature inside the furnace can be controlled by changing the calorific value of the heater 5 based on the signal from the sensor IO, and the pressure inside the furnace can also be controlled by controlling the gas supply device 7.

Next, the operating procedure for continuously degreasing and sintering the workpiece 4 using the above degreasing and sintering furnace (2) will be explained with reference to FIG. FIG. 1 shows changes over time in the gas concentration of impurities in the furnace C1, the furnace temperature T1, and the furnace pressure P in this operating procedure, as well as the elapsed time since the start of the operation.

As shown in FIG. 1, when the workpiece 4 is loaded into the heating chamber 3, heating by the heater 5 is started, and the temperature inside the furnace is T.
Let be a predetermined degreasing temperature T. At the same time, the exhaust device 9 evacuates the inside of the furnace to a predetermined degreasing pressure P, (vacuum).
At the same time, the impurity gas concentration C in the exhaust gas is measured by the sensor IO. This gas concentration C initially increases, but gradually decreases as the gas is exhausted.

Then, when the sensor 10 detects that the gas concentration C has reached a predetermined value CI, at a time point t1, the control device 2 increases the calorific value Uo of the heater 5 and starts raising the temperature in the furnace. And the furnace temperature′! When ゛ reaches a predetermined sintering temperature T, that state is maintained.

Note that for this sintering temperature T, the furnace pressure P is the sintering pressure P,
It is made to reach the time point ta (described later) or at the same time as the time point ta (described later). Further, the value of the above gas concentration C may be set in consideration of the ability to exhaust impurities, etc.

At time t when 1 is detected, the control device 11 controls the gas supply device 7 to increase the furnace pressure P, and the furnace pressure P reaches a predetermined sintering pressure P.

If so, maintain that state.

By doing this, the time t3 when the pressure inside the furnace reaches P2
(At this time, the furnace temperature T has already reached the sintering temperature T2), and the process automatically shifts to the sintering process. After sintering in this state for a predetermined period of time, 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 rise starts from the degreasing temperature T1 to the sintering temperature T, and the pressure starts increasing from the degreasing pressure P to the sintering pressure P, that is, from the degreasing process to the sintering process. The transition is performed automatically and at an optimal time based on the measurement result of the gas concentration C by the sensor IO. Therefore, if you rely on experience and set the degreasing time in advance, you may end up with sintering even though sufficient degreasing has not been done, or conversely, you may make the degreasing time longer than necessary. This ensures that the quality of the sintered products is ensured, and that the operating time does not become too long.

In addition, when processing limbs whose shape and size are similar to stomach, there is no need to change the degreasing time setting each time, and the sintering process automatically takes place after the necessary and sufficient degreasing has been performed. Therefore, it is possible to sufficiently simplify and optimize operations.

In addition, in the above embodiment, sintering was performed in a pressurized state in the furnace, and the timing to start increasing the pressure was controlled by a sensor, but it can also be applied to cases where sintering is performed at normal pressure or in a vacuum state. Moreover, pressure control is not necessarily based on sensors.

Furthermore, in carrying out the present invention, it is possible to use not only the degreasing and sintering furnace shown in FIG. 2 but also any appropriately configured degreasing and sintering furnace. For example, in the above description, the temperature setting and pressure setting are automatically performed by the control device, but they may also be performed manually by monitoring the measurement results by the sensor. Alternatively, the sensor may be installed inside the furnace body.

"Effects of the Invention" As explained in detail above, according to the present invention, the impurity concentration is measured, and based on the measurement result, the temperature is started and the sintering process is started, so the transition is optimized. This can be carried out at the same time, thus ensuring the quality of the sintered product and reducing the operating time.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 show an embodiment of this invention.
Fig. 1 is a diagram showing changes over time in impurity concentration, furnace temperature, and furnace pressure in the procedure of this example, and Fig. 2 is a sectional view showing the schematic configuration of the degreasing and sintering furnace used in this example. . 1... Degreasing sintering furnace, 10... Sensor,
'r1... Degreasing temperature, 'I゛2... Sintering temperature.

Claims (1)

[Claims] A sintering process in which the temperature inside the furnace is raised to a sintering temperature to sinter the object after a degreasing step in which the interior of the furnace is maintained at a degreasing temperature to evaporate and remove impurities contained in the object. A method of operating a degreasing and sintering furnace that is transitioning to How to operate a degreasing and sintering furnace.