Heating device for roasting

Abstract

Disclosed is one embodiment of a heating device for tempering according to the present invention, said heating device for tempering being suited to tempering of a plurality of kinds of steel materials, while suppressing an increase in investment in equipment. According to the present invention, pre-heating is performed by means of an induction heating device before heating in a heating furnace. Consequently, even if the temperature within the heating furnace and the heating time in the heating furnace are maintained constant regardless of the size, shape or quality of a steel material, the heat quantity applied to the steel material from the induction heating device, namely the induction heating amount, is changed in accordance with the size, shape or quality of the steel material. Since the induction heating amount is able to be immediately changed when the energization time and the applied current value are changed, it is almost not necessary to stop the induction heating device for the purpose of changing the induction heating amount. In other words, even in cases where a plurality of steel materials that are different from each other in size, shape or quality are tempered, there is almost no downtime.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This international application claims priority based on Japanese Patent Application No. 2020-118384, filed with the Japan Patent Office on July 9, 2020, the entire contents of which are incorporated herein by reference. [Technical field]

[0002] The present disclosure relates to a heating device for tempering steel, such as leaf springs. [Background technology]

[0003] Known heating devices for tempering steel include a method of heating in a heating furnace and a method of heating by induction heating (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4261089 Summary of the Invention [Problem to be solved by the invention]

[0005] For example, in a heating device for tempering steel in a heating furnace, the temperature and heating time in the heating furnace are adjusted according to the size, shape, and material of the steel. Therefore, when tempering multiple types of steel in one heating furnace, it is difficult to improve production efficiency for the following reasons.

[0006] That is, it is impossible to change the temperature inside the furnace instantly. And, while the temperature inside the furnace is being changed, the heat treatment is practically stopped. Therefore, when tempering multiple types of steel in one heating furnace, the downtime of the heat treatment increases, making it difficult to improve production efficiency.

[0007] It is possible to reduce downtime by providing a dedicated heating furnace for each type of steel, but this solution increases the capital investment and the installation space for the heating furnace.

[0008] In view of the above, the present disclosure discloses an example of a tempering heating device capable of tempering a plurality of types of steel while suppressing an increase in capital investment. [Means for solving the problem]

[0009] It is desirable for a heating device for tempering steel to have at least one of the following components, for example:

[0010] In other words, the constituent elements desirably include a heating furnace (3) in which the inside is maintained at a predetermined specific temperature regardless of the size, shape, and material of the steel, and which heats the steel for a predetermined time regardless of the size, shape, and material of the steel, and an induction heating device (5) that heats the steel before it is fed into the heating furnace (3) with an induced current, the induction heating device (5) having a setting section (52) that can change the setting of at least one of the current flow time and the current flow value in accordance with at least one of the size, shape, and material of the steel.

[0011] At this time, it is desirable to determine the current flow time and the current flow value so that the amount of heat applied to the steel from the induction heating device (5) is the induction heating amount (Q1).

[0012] The amount of induction heating (Q1) is the amount of heat obtained by subtracting the amount of furnace heating (Q2) from the amount of heat required (ΣQ). The amount of heat required (ΣQ) is the total amount of heat required for tempering, which is determined by the size, shape, and material of the steel. The amount of furnace heating (Q2) is the amount of heat applied to the steel in the heating furnace (3).

[0013] As a result, even if the temperature inside the heating furnace (3) and the heating time in the heating furnace (3) are constant regardless of the size, shape, or material of the steel, the amount of heat applied to the steel from the induction heating device (5), i.e., the amount of induction heating (Q1), is changed depending on the size, shape, or material of the steel.

[0014] In addition, when the current flow time and current flow value are changed, the induction heating amount (Q1) can be changed instantly, so there is almost no need to stop the induction heating device in order to change the induction heating amount (Q1). In other words, even when tempering multiple steels of different sizes, shapes, or materials, there is almost no downtime.

[0015] Therefore, the heating device can handle tempering of a variety of steels while suppressing increases in capital investment and installation space, and can effectively utilize existing manufacturing facilities to temper a wide variety of steels.

[0016] Incidentally, the symbols in the above parentheses are examples showing the corresponding relationship with the specific configurations etc. described in the embodiments described below, and the present disclosure is not limited to the specific configurations etc. shown by the symbols in the above parentheses. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a diagram showing a heating device according to a first embodiment. [Diagram 2] FIG. 2 is a diagram showing an example of a target material to be heat-treated by the heating device according to the first embodiment. [Diagram 3] FIG. 3 is a partial enlarged view of the subject material shown in FIG. 2. [Figure 4] FIG. 3 is a partial enlarged view of the subject material shown in FIG. 2. [Diagram 5] FIG. 13 shows an identification label for the target material. [Explanation of symbols]

[0018] 1… Heating device 3…Heating furnace 5… Induction heating device 51... Control section 52... Setting section 53... Reading section DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The following "embodiments of the invention" are examples of embodiments that fall within the technical scope of the present disclosure. In other words, the invention-specific matters described in the claims are not limited to the specific configurations and structures shown in the following embodiments.

[0020] In addition, arrows and diagonal lines indicating directions are provided in each drawing to facilitate understanding of the relationship between the drawings and the shapes of each member or part. Therefore, the invention disclosed in this disclosure is not limited to the directions in each drawing.

[0021] At least one of the members or parts described with a reference symbol is provided, unless otherwise specified by "one". In other words, unless otherwise specified by "one", two or more of the members may be provided. The heating device shown in the present disclosure includes at least the components such as the members or parts described with a reference symbol, as well as the structural parts shown in the drawings.

[0022] (First embodiment) <1. Heating device configuration> In this embodiment, an example of the heating device 1 according to the present disclosure is applied to a heating device for tempering a leaf spring (hereinafter referred to as steel) that constitutes an automotive leaf spring. As shown in Fig. 1, the heating device 1 includes at least a heating furnace 3 and an induction heating device 5.

[0023] The heating furnace 3 heats the steel via the atmospheric gas in the furnace. The atmospheric gas in the heating furnace 3 is maintained at a specific temperature regardless of the size, shape, or material of the steel. Furthermore, the heating time of the steel, i.e., the transport speed of the steel in the heating furnace 3, is maintained at a specific time regardless of the size, shape, or material of the steel.

[0024] The method of heating the atmospheric gas is not limited. In other words, any heating furnace may be used, such as a combustion furnace that burns heavy oil gas, or an electric furnace that utilizes Joule loss of electricity. The heating furnace 3 according to this embodiment is an electric furnace.

[0025] The induction heating device 5 generates an induction current in the steel to heat the steel. Specifically, the induction heating device 5 has an induction coil (not shown) arranged around the steel to be heated, and heats the steel by passing current through the induction coil.

[0026] The induction heating device 5 has at least a control unit 51, a setting unit 52, and a reading unit 53. The control unit 51 controls the induction coil with the current flow time and current flow value set or changed by the setting unit 52. The control unit 51 has a CPU 51a and a memory 51b that stores an operation program for the CPU 51a.

[0027] The setting unit 52 sets or changes the energization time and energization current value using the information read by the reading unit 53. The reading unit 53 reads an identification label (for example, a one-dimensional code or a two-dimensional code) on which information regarding the size, shape, and material of the steel is written.

[0028] The heating device 1 heats the steel that has completed heat treatment by the induction heating device 5 in the heating furnace 3. That is, the steel is heated while being transferred in the order of induction heating device 5 → heating furnace 3. The heating temperature in the heating furnace 3, i.e., the atmospheric gas temperature and heating time, are fixed to a predetermined temperature and time, regardless of the size, shape, and material of the steel.

[0029] The heating device 1, i.e., the control unit 51, changes at least one of the current application time and the current value according to the steel to be heated, depending on at least one of the size, shape, and material of the steel. Note that the control unit 51 according to this embodiment changes the current application time according to the steel to be heated.

[0030] <2. How to determine the current application time and current application value> The control unit 51, that is, the setting unit 52, determines the current flow time and current flow value in the induction heating device 5 so that the amount of heat applied to the steel from the induction heating device 5 becomes the induction heating amount (Q1).

[0031] The amount of induction heating (Q1) is the amount of heat obtained by subtracting the amount of heating in the furnace Q2 from the amount of heat required (ΣQ). The amount of heat required (ΣQ) is the total amount of heat required for tempering, which is determined by the size, shape, and material of the steel. The amount of heating in the furnace (Q2) is the amount of heat applied to the steel in the heating furnace 3.

[0032] Therefore, the setting unit 52 determines the required heat amount (ΣQ) using information about the steel to be heated, and then determines the induction heating amount (Q1) by subtracting the furnace heating amount (Q2) from the required heat amount (ΣQ).

[0033] In this embodiment, the amount of heat in the furnace (Q2) is a predetermined amount of heat that is stored in advance in the control unit 51. The required amount of heat (ΣQ) is a heat amount that is predetermined by experiments or the like, and the required amount of heat (ΣQ) according to the type of steel, that is, the size, shape and material of the steel, is stored in advance in the control unit 51.

[0034] That is, the setting unit 52 determines the required heat amount (ΣQ) according to the type of steel from the information read by the reading unit 53, and then determines the induction heating amount (Q1) by subtracting the furnace heating amount (Q2) from the required heat amount (ΣQ).

[0035] <3. Features of the heating device according to this embodiment> Leaf springs for automobiles are usually used by stacking a number of leaf springs together and fastening the center portion with a bolt and nut, but during manufacturing, each leaf spring is produced one by one.

[0036] Each leaf spring is not necessarily flat, but comes in a variety of shapes, such as one with a cylindrical eye that is connected to the body (frame) of the automobile, or one that is rolled into a tapered shape and has a chamfered cut at the tip.

[0037] For this reason, if the steel (leaf spring) were heated only by the induction heating device 5, there would be a high possibility that the temperature distribution in the steel would be non-uniform. Therefore, in this embodiment, the steel heated by the induction heating device 5 is heated in the heating furnace 3, thereby achieving a uniform temperature distribution.

[0038] In the heating device 1 according to this embodiment, the energization time and energization current value are determined so that the amount of heat applied to the steel from the induction heating device 5 becomes the induction heating amount (Q1).

[0039] As a result, even if the temperature inside the heating furnace 3 and the heating time in the heating furnace 3 are constant regardless of the size, shape or material of the steel, the amount of heat applied to the steel from the induction heating device 5, i.e., the amount of induction heating (Q1), is changed depending on the size, shape or material of the steel.

[0040] In addition, when the current flow time and current flow value are changed, the induction heating amount (Q1) can be changed instantly, so there is almost no need to stop the induction heating device in order to change the induction heating amount (Q1). In other words, even when tempering multiple steels of different sizes, shapes, or materials, there is almost no downtime.

[0041] Therefore, the heating device 1 can handle tempering of a plurality of types of steel while suppressing increases in capital investment and installation space. In turn, it becomes possible to temper a wide variety of steels while effectively utilizing existing manufacturing facilities.

[0042] In other words, with the heating device 1 according to this embodiment, there is no need to adjust the temperature of the heating furnace 3 when tempering multiple types of steel. In other words, with the heating device 1, it is possible to handle tempering of multiple types of steel without stopping the heating device to adjust the temperature of the heating furnace 3. In turn, it becomes possible to temper a wide variety of steels while effectively utilizing existing manufacturing facilities. Example 1 Figure 2 is a diagram showing an example of a leaf spring that is to be tempered by the heating device 1. Figures 3 and 4 are enlarged views of a portion of the leaf spring. The leaf spring of this example is manufactured from materials such as SUP9 and SUP10, and has the shape shown in Table 1 below.

[0043] [Table 1] The heating furnace 3 used in the present invention is the same as a normal heating furnace, but the dimensions in the work flow direction are 50% or less of the normal dimensions. If the dimensions of the heating furnace are 28 m in the work flow direction, 3 m in width, and 2.6 m in height, when the present invention is applied, the dimensions of the heating furnace 3 in the flow direction are 14 m or less. The energy consumption of this heating furnace is approximately 280,000 kcal when the present invention is not applied, but is approximately 140,000 kcal or less when the present invention is applied.

[0044] In the present invention, the target material is heated by an induction heating device 5 before being loaded into the heating furnace 3. The induction heating furnace 5 preferably has an output capacity of 100 kW to 200 kW and an oscillation frequency of 400 Hz to 10 kHz.

[0045] (Other embodiments) The setting unit 52 according to the embodiment described above determines the energization time and energization current value by using the information read by the reading unit 53. However, the present disclosure is not limited to this. That is, the disclosure may be, for example, a method of determining the energization time and energization current value by combining an imaging device such as a camera with artificial intelligence, or a method in which an operator inputs necessary information to the setting unit 52.

[0046] In the above-described embodiment, the energizing current value is fixed and only the energizing time is changed depending on the steel to be heated. However, the present disclosure is not limited to this. That is, the present disclosure may be configured, for example, to fix the energizing time and change only the energizing current value depending on the steel to be heated, or to change the energizing current value and the energizing time depending on the steel to be heated.

[0047] In the above embodiment, the heating device is for tempering leaf springs for automobiles. However, the present disclosure is not limited thereto. That is, the present disclosure can be applied to other steels such as coil springs.

[0048] Furthermore, the present disclosure is not limited to the above-mentioned embodiments as long as it is consistent with the gist of the disclosure described in the above-mentioned embodiments. Therefore, the present disclosure may be a configuration in which at least two of the above-mentioned embodiments are combined, or a configuration in which any of the components illustrated or the components described with reference numerals in the above-mentioned embodiments are eliminated.

Claims

1. In a heating device for tempering steel, A heating furnace in which the inside is maintained at a predetermined specific temperature regardless of the size, shape, or material of the steel, and the steel is heated for a predetermined time regardless of the size, shape, or material of the steel; an induction heating device that heats steel before it is fed into the heating furnace with an induction current, the induction heating device having a setting unit that can change the setting of at least one of a current flow time and a current flow value according to at least one of the size, shape, and material of the steel; A tempering heating device comprising:

2. 2. The tempering heating device according to claim 1, wherein the setting unit includes a reading unit that reads an identification label on which at least one piece of information regarding the size, shape, and material of the steel is written.

3. A method for determining a current flow time and a current flow value in the induction heating device according to claim 1 or 2, comprising the steps of: When the total amount of heat required for tempering, which is determined by the size, shape, and material of the steel, is defined as the required heat amount, the amount of heat applied to the steel in the heating furnace is defined as the furnace heating amount, and the amount of heat obtained by subtracting the furnace heating amount from the required heat amount is defined as the induction heating amount, A method for determining electric power, the energization time and the energization current value being determined so that the amount of heat imparted to steel from the induction heating device becomes the induction heating amount.

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