JP2024061385A - How to determine when to implement burnout - Google Patents

Abstract

[Problem] To provide a method for determining the timing of burnout, capable of determining the timing when burnout is required. [Solution] The method for determining the timing of burnout according to the present disclosure is a method for determining the timing of burnout in a vacuum carburizing furnace 10 that performs vacuum carburizing processing of workpieces, which measures the pressure inside the furnace 20 and at least one of the parts that are conductive to the inside of the furnace 20 during the vacuum carburizing processing, and when a pressure change caused by soot adhering to the inside of the furnace 20 is detected, it is determined that burnout needs to be performed. [Selected Figure] Figure 1

Description

This disclosure relates to a method for determining when to perform burnout.

Vacuum carburizing is a carburizing method in which a hydrocarbon gas such as acetylene gas is decomposed under reduced pressure and high temperature, and the resulting carbon is reacted with the iron surface. When vacuum carburizing is performed in a vacuum carburizing furnace, some of the carbon may turn into soot and adhere to the inside of the vacuum carburizing furnace. If a large amount of soot adheres to the inside of the vacuum carburizing furnace, it may cause the vacuum carburizing furnace to break down. Therefore, it is necessary to perform burnout as appropriate, in which air is introduced into the vacuum carburizing furnace to burn and remove the adhered soot. For example, Patent Document 1 discloses a burnout method for a vacuum carburizing furnace.

JP 2007-131936 A

The technology disclosed in the above-mentioned Patent Document 1 uses a sensor to monitor the end of burnout, making it easy and reliable to determine when burnout is complete. It is preferable to perform burnout when a certain amount of soot has built up inside the vacuum carburizing furnace, as this can prevent breakdowns in the vacuum carburizing furnace. However, the technology disclosed in Patent Document 1 does not allow for the determination of when burnout is necessary.

The present disclosure has been made in consideration of these problems, and aims to provide a method for determining the timing of burnout that can determine the timing when burnout is necessary.

One aspect of the present invention to achieve the above object is to
A method for determining burnout timing of a vacuum carburizing furnace that performs vacuum carburizing treatment on a workpiece, comprising:
The pressure inside the furnace and at least one of the locations connected to the inside of the furnace is measured during vacuum carburization treatment, and if a pressure change caused by soot adhering to the inside of the furnace is detected, it is determined that burnout needs to be performed.

The present disclosure provides a method for determining when to perform burnout, which can determine when burnout is necessary.

1 is a schematic diagram of a vacuum carburizing furnace according to an embodiment; 1 is a flowchart showing the flow of a method for determining the timing of performing burnout according to an embodiment.

Below, the embodiment of the present disclosure will be described in detail with reference to the drawings. In each drawing, the same or corresponding elements are given the same reference numerals, and duplicate explanations will be omitted as necessary for clarity of explanation.

First, referring to FIG. 1, the configuration of a vacuum carburizing furnace (vacuum carburizing furnace according to the present disclosure) for implementing the method for determining the burnout timing according to the present disclosure will be described. FIG. 1 is a schematic diagram of a vacuum carburizing furnace according to an embodiment. As shown in FIG. 1, the vacuum carburizing furnace 10 includes a furnace 20, a heater 30, a vacuum pump 40, and a pressure gauge 50.

Workpieces (not shown) can be stored in the furnace 20. The workpieces are, for example, iron members. The furnace 20 has an opening 20a that communicates with the interior of the furnace. The opening 20a of the furnace 20 can be closed using a door (not shown). The opening 20a is used as an opening for loading and unloading the workpieces and as a maintenance hatch. A heater 30 is disposed in the furnace 20. The interior of the furnace 20 is heated using the heater 30. The heater 30 is, for example, an elongated heater, and multiple heaters are disposed on the upper and lower surfaces of the furnace 20. The heater 30 is usually constructed using an insulating material. The heater 30 is, for example, a ceramic heater.

The furnace 20 is provided with a gas inlet (not shown) that is connected to the inside of the furnace 20. By opening the gas inlet, combustion gas can be introduced into the furnace 20. For example, a gas cylinder filled with combustion gas or a buffer tank may be connected to the gas inlet. The combustion gas is, for example, air. The combustion gas may also be a mixed gas containing oxygen. The furnace 20 is provided with an exhaust port (not shown) that is connected to the inside of the furnace 20. A vacuum pump 40 is connected to the exhaust port. By opening the exhaust port and operating the vacuum pump 40, the atmospheric gas in the furnace 20 can be exhausted to the outside.

The vacuum carburizing furnace 10 further includes a pressure gauge 50. The pressure gauge 50 measures the pressure inside the furnace 20 and at least one of the locations that are connected to the furnace 20. The pressure gauge 50 may be connected to any location that allows measurement of the pressure inside the furnace 20 or the location that is connected to the furnace 20. In the example shown in FIG. 1, the pressure gauge 50 is connected to the furnace 20, but it may also be provided, for example, in the middle of a tube that connects an exhaust port and a vacuum pump. In addition, multiple pressure gauges 50 may be provided.

When performing vacuum carburization, a hydrocarbon gas is introduced into the furnace 20 and heated while reducing the pressure. The hydrocarbon gas is, for example, acetylene gas. The hydrocarbon gas decomposes under reduced pressure and high temperature to produce carbon. The carbon produced penetrates the surface of the workpiece. Some of the carbon produced becomes soot and adheres to the inside of the furnace 20. For example, when soot adheres to the surface of the heater 30 as shown in FIG. 1, a short circuit occurs between the soot adhered to the heater 30 because carbon easily conducts electricity, and a spark discharge may occur. When a spark discharge occurs, the soot explodes and burns, causing a pressure change. In the method for determining the timing of burnout according to the present disclosure, when a pressure change caused by the soot is detected, it is determined that burnout should be performed.

Next, with reference to FIG. 2, a method for determining the timing of burnout implementation according to the present disclosure will be described. FIG. 2 is a flow chart showing the flow of the method for determining the timing of burnout implementation according to the embodiment. The method for determining the timing of burnout implementation according to the present disclosure is performed during vacuum carburization treatment. When the workpiece is placed in the furnace 20 and the vacuum carburization treatment is started (step S1), the pressure gauge 50 is operated to start measuring the pressure inside the furnace 20 (step S2). When the vacuum carburization treatment is completed (step S3), the pressure measurement inside the furnace 20 is completed (step S4).

If there is a change in the measured pressure (step S5 Yes), it is assumed that soot has accumulated in the furnace 20, so burnout is performed (step S6). After burnout is performed, the next workpiece is vacuum carburized (step S1). If there is no change in the measured pressure (step S5 No), burnout is not performed and the next workpiece is vacuum carburized (step S1).

In this way, the method of determining the timing of burnout according to the present disclosure can determine the timing when burnout is required by detecting pressure changes caused by soot accumulated in the furnace 20, without directly visually inspecting the inside of the furnace 20.

Note that this disclosure is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit and scope of the present disclosure.

10 Vacuum carburizing furnace 20 Furnace 20a Opening 30 Heater 40 Vacuum pump 50 Pressure gauge

Claims (1)

A method for determining burnout timing of a vacuum carburizing furnace that performs vacuum carburizing treatment on a workpiece, comprising:
measuring the pressure inside the furnace and at least one of the portions connected to the inside of the furnace during the vacuum carburization treatment, and determining that it is necessary to perform burnout when a pressure change caused by soot adhering to the inside of the furnace is detected;
How to determine when to implement burnout.

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