Heating device for tempering

Abstract

Disclosed is a tempering heating device that suppresses an increase in equipment investment and can handle tempering of various steels as an example. Before heating by a heating furnace, preheating is performed by an induction heating device. Thus, regardless of the size, shape, or material of the steel, even if the temperature in the heating furnace and the heating time in the heating furnace are fixed, the amount of heat imparted to the steel by the induction heating device, i.e., the induction heating amount, can be changed according to the size, shape, or material of the steel. Moreover, if the energization time and the energization current value are changed, the induction heating amount can be instantaneously changed, so there is almost no need to stop the induction heating device in order to change the induction heating amount. That is to say, even when tempering a plurality of steels with different sizes, shapes, or materials, almost no stop time is generated.

Description

[0001] Cross - reference to related applications

[0002] This international application claims priority based on Japanese Patent Application No. 2020 - 118384 filed with the Japan Patent Office on July 9, 2020, and incorporates by reference the entire contents of Japanese Patent Application No. 2020 - 118384 into this international application. Technical field

[0003] This disclosure relates to a heating device for tempering steel such as a leaf spring. Background art

[0004] As heating devices for tempering steel, methods of heating in a heating furnace and methods of heating by induction heating (for example, refer to Patent Document 1) are known.

[0005] Prior art documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent No. 4261089 Gazette Summary of the invention

[0008] Problems to be solved by the invention

[0009] For example, in a heating device for tempering steel using a heating furnace, the temperature and heating time inside the heating furnace are adjusted according to the size, shape, and material of the steel. Therefore, when tempering multiple types of steel using one heating furnace, it is difficult to improve production efficiency for the following reasons.

[0010] That is, the temperature inside the furnace cannot be changed instantaneously. Moreover, during the period of changing the temperature inside the furnace, the heat treatment substantially stops. Therefore, when tempering multiple types of steel using one heating furnace, the stop time of the heat treatment increases, so it is difficult to improve production efficiency.

[0011] In addition, if a dedicated heating furnace is provided for each type of steel, the stop time can be shortened. However, this solution increases the equipment investment cost and the installation space of the heating furnace.

[0012] In view of the above problems, this disclosure discloses an example of a heating device for tempering that suppresses an increase in equipment investment cost and can handle the tempering of multiple types of steel.

[0013] Means for solving the problems

[0014] A heating device for tempering steel preferably has at least one of the following constituent elements, for example.

[0015] That is, this constituent element preferably has: a heating furnace (3) that maintains a predetermined temperature inside regardless of the size, shape, and material of the steel, and heats the steel only 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 put into the heating furnace (3) using induced current, and has a setting unit (52) that can set and change at least one of the energization time and the energization current value according to at least one of the size, shape, and material of the steel.

[0016] At this time, it is preferable to determine the energization time and the energization current value such that the heat given to the steel from the induction heating device (5) becomes the induction heating amount (Q1).

[0017] In addition, the induction heating amount (Q1) is the heat obtained by subtracting the in-furnace heating amount (Q2) from the required heat (ΣQ). The required heat (ΣQ) is the total heat required for tempering determined by the size, shape, and material of the steel. The in-furnace heating amount (Q2) is the heat given to the steel by the heating furnace (3).

[0018] Thus, regardless of the size, shape, or material of the steel, even if the temperature inside the heating furnace (3) and the heating time in the heating furnace (3) are fixed, the induction heating amount (Q1), that is, the heat given to the steel from the induction heating device (5), can be changed according to the size, shape, or material of the steel.

[0019] Moreover, if the energization time and the energization current value are changed, the induction heating amount (Q1) can be changed instantaneously, so it is almost unnecessary to stop the induction heating device in order to change the induction heating amount (Q1). That is, even when tempering a plurality of steels with different sizes, shapes, or materials, almost no stop time is generated.

[0020] Therefore, according to this heating device, it is possible to suppress an increase in equipment investment and an increase in installation space, and to cope with the tempering of various steels. Furthermore, it is possible to perform the tempering of various steels while effectively using existing manufacturing equipment.

[0021] In addition, the reference numerals in each of the above parentheses are an example showing the correspondence with the specific structures and the like described in the following embodiments, and the present disclosure is not limited to the specific structures and the like shown by the reference numerals in the above parentheses. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a diagram showing the heating device of the first embodiment.

[0023] Figure 2 is a diagram showing an example of an object material heat-treated by the heating device of the first embodiment.

[0024] Figure 3 is Figure 2 a partially enlarged view of the object material shown.

[0025] Figure 4 is Figure 2 a partially enlarged view of the object material shown.

[0026] Figure 5 is a view showing an identification label of the object material.

[0027] Description of Reference Numerals

[0028] 1: Heating device

[0029] 3: Heating furnace

[0030] 5: Induction heating device

[0031] 51: Control unit

[0032] 52: Setting unit

[0033] 53: Reading unit Detailed Implementation Modes

[0034] The following "Embodiments of the Invention" represent an example of an embodiment belonging to the technical scope of the present disclosure. That is, specific matters of the invention described in the claims are not limited to the specific structures, configurations, etc. shown in the following embodiments.

[0035] In addition, arrows indicating directions, slashes, etc. marked in each figure are described to facilitate understanding of the mutual relationship between each figure and the shape of each component or part. Therefore, the invention shown in the present disclosure is not limited to the directions marked in each figure.

[0036] For at least the components or parts marked with reference numerals and described, unless it is limited to "one", etc., at least one is provided. That is, in the case where it is not limited to "one", etc., two or more of these components may be provided. The heating device shown in the present disclosure has structural elements such as at least the components or parts marked with reference numerals and described, and the illustrated structural parts.

[0037] (First Embodiment)

[0038] <1. Structure of Heating Device>

[0039] This embodiment is an example of applying the heating device 1 of the present disclosure to a heating device for tempering a leaf spring (hereinafter referred to as steel) constituting an automotive leaf spring. As Figure 1 shown, the heating device 1 has at least a heating furnace 3 and an induction heating device 5, etc.

[0040] The heating furnace 3 heats the steel by means of the ambient gas inside the furnace. Regardless of the size, shape or material of the steel, the ambient gas inside the heating furnace 3 is maintained at a specified temperature. Furthermore, regardless of the size, shape or material of the steel, the heating time of the steel, that is, the transfer speed of the steel inside the heating furnace 3 is maintained at a specified time.

[0041] There is no limitation on the heating method of the ambient gas. That is, it can be any heating furnace such as a combustion furnace that burns gas using heavy oil and an electric furnace that utilizes the Joule loss of electricity. In addition, the heating furnace 3 of the present embodiment is an electric furnace.

[0042] 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) disposed around the steel to be heated, and the steel is heated by energizing the induction coil.

[0043] The induction heating device 5 includes at least a control unit 51, a setting unit 52, and a reading unit 53, etc. The control unit 51 controls the induction coil according to the energization time and the energization current value set or changed by the setting unit 52. The control unit 51 has a CPU 51a and a memory 51b that stores the operation program of the CPU 51a.

[0044] The setting unit 52 sets or changes the energization time and the energization current value by using the information read by the reading unit 53. The reading unit 53 reads an identification label (for example, a one-dimensional code, a two-dimensional code) that records information related to the size, shape, and material of the steel.

[0045] The heating device 1 uses the heating furnace 3 to heat the steel that has been heat-treated by the induction heating device 5. That is to say, the steel is heated while being transferred in the order of the induction heating device 5 → the heating furnace 3. Regardless of the size, shape, and material of the steel, the heating temperature in the heating furnace 3, that is, the ambient gas temperature and the heating time are fixed at predetermined temperatures and times.

[0046] Moreover, the heating device 1, that is, the control unit 51 changes at least one of the energization time and the energization current value according to at least one of the size, shape, and material of the steel according to the steel to be heated. In addition, the control unit 51 of the present embodiment changes the energization time according to the steel to be heated.

[0047] <2. Determination method of energization time and energization current value>

[0048] The control unit 51, that is, the setting unit 52 determines the energization time and the energization current value in the induction heating device 5 in such a way that the heat imparted to the steel from the induction heating device 5 becomes the induction heating amount (Q1).

[0049] The induction heating amount (Q1) refers to the heat obtained by subtracting the in-furnace heating amount Q2 from the required heat (ΣQ). The required heat (ΣQ) refers to the total heat required for tempering determined according to the size, shape, and material of the steel. The in-furnace heating amount (Q2) refers to the heat imparted to the steel by the heating furnace 3.

[0050] Therefore, after determining the required heat (ΣQ) using the information about the steel to be heated, the setting unit 52 determines the induction heating amount (Q1) by subtracting the in-furnace heating amount (Q2) from the required heat (ΣQ).

[0051] In addition, in the present embodiment, the in-furnace heating amount (Q2) is pre-stored in the control unit 51 as a pre-determined heat amount. The required heat (ΣQ) is a heat amount pre-determined through experiments or the like, and the required heat (ΣQ) corresponding to the type of steel, that is, the size, shape, and material of the steel, is pre-stored in the control unit 51.

[0052] That is, after determining the required heat (ΣQ) corresponding to the type of steel according to the information read by the reading unit 53, the setting unit 52 determines the induction heating amount (Q1) by subtracting the in-furnace heating amount (Q2) from the required heat (ΣQ).

[0053] <3. Features of the heating device of the present embodiment>

[0054] Automotive leaf springs are usually used with the central part fixed by bolts and nuts in a state where multiple leaf springs overlap. However, during manufacturing, each leaf spring is manufactured one by one.

[0055] Each leaf spring is not necessarily flat, and there are various shapes, such as a shape with a cylindrical ear (eye) formed for connecting to the vehicle body (frame) of the car, or a shape rolled into a cone with a chamfered cutting part provided at its front end, etc.

[0056] Therefore, if the structure is such that only the steel (leaf spring) is heated by the induction heating device 5, there is a high possibility of uneven temperature distribution in the steel. Therefore, in the present embodiment, the temperature distribution is made uniform by heating the steel heated by the induction heating device 5 with the heating furnace 3.

[0057] Moreover, in the heating device 1 of the present embodiment, the energization time and the energization current value are determined such that the heat imparted to the steel from the induction heating device 5 becomes the induction heating amount (Q1).

[0058] Thereby, regardless of the size, shape, or material of the steel, even if the temperature in the heating furnace 3 and the heating time in the heating furnace 3 are fixed, the heat imparted to the steel from the induction heating device 5, that is, the induction heating amount (Q1), changes according to the size, shape, or material of the steel.

[0059] Moreover, if the energization time and the energization current value are changed, the induction heating amount (Q1) can be instantaneously changed, so it is almost unnecessary to stop the induction heating device in order to change the induction heating amount (Q1). That is to say, even when tempering a plurality of steels with different sizes, shapes or materials, almost no stop time is generated.

[0060] Therefore, according to the heating device 1, an increase in equipment investment and an increase in installation space can be suppressed, and tempering of various steels can be achieved. Furthermore, while effectively utilizing existing manufacturing equipment, tempering of various steels can be carried out.

[0061] In other words, if it is the heating device 1 of the present embodiment, temperature adjustment of the heating furnace 3 is not required when tempering a plurality of steels. That is to say, in the heating device 1, it is not necessary to stop the heating device in order to adjust the temperature of the heating furnace 3, and tempering of various steels can be achieved. Furthermore, while effectively utilizing existing manufacturing equipment, tempering of various steels can be carried out.

[0062] Example 1

[0063] Figure 2 It is a diagram showing a leaf spring as an example of an object to be tempered by the heating device 1. Figure 3 And Figure 4 It is a diagram showing a part of the leaf spring in an enlarged manner. The leaf spring of this example is made of materials such as SUP9 and SUP10 and has the shape shown in Table 1 below.

[0064] [Table 1]

[0065] Width of plate [mm] Span L after rolling [mm] Outer diameter of coiler ear [mm] Thickness of plate [mm] Height of arc (camber) [mm] 60～90 360～1800 40～95 6～32 0～200

[0066] *There are also those without eyelets.

[0067] The heating furnace 3 used in the present invention is the same as a normal heating furnace, but the size in the flow direction of the workpiece is 50% or less of its size. For the size of the heating furnace, if the size in the flow direction of the workpiece is 28 m, the width is 3 m, and the height is 2.6 m, then in the case of applying the present invention, the size in the flow direction of the heating furnace 3 is 14 m or less. The energy consumption of this heating furnace is about 280,000 kcal without applying the present invention, but about 140,000 kcal or less in the case of applying the present invention.

[0068] In the present invention, before loading the object material into the heating furnace 3, the object material is heated by the induction heating device 5. As the induction heating furnace 5, the output capacity is preferably 100 kW to 200 kW, and the transmission frequency is preferably 400 Hz to 10 kHz.

[0069] (Other embodiments)

[0070] The setting unit 52 of the above-described embodiment determines the energization time and the energization current value using the information read by the reading unit 53. However, the present disclosure is not limited thereto. That is, the disclosure may be, for example, a method of determining the energization time and the energization current value in combination with a photographing device such as a camera and artificial intelligence, or a method in which an operator inputs necessary information to the setting unit 52, and the like.

[0071] In the above-described embodiment, the energization current value is fixed and only the energization time is changed according to the steel to be heated. However, the present disclosure is not limited thereto. That is, the disclosure may be configured to, for example, fix the energization time and only change the energization current value according to the steel to be heated, or change the energization current value and the energization time according to the steel to be heated.

[0072] The above-described embodiment is a heating device for tempering an automotive leaf spring. However, the present disclosure is not limited thereto. That is, the disclosure can be applied to other steels such as coil springs, for example.

[0073] In addition, the present disclosure only needs to conform to the gist of the disclosure described in the above-described embodiment and is not limited to the above-described embodiment. Therefore, it may also be a structure in which at least two of the above-described embodiments are combined, or a structure in which any one of the constituent elements shown in the drawings or the constituent elements described with reference numerals removed from the above-described embodiment is removed.

Claims

1. A heating device for tempering, which is used for tempering steel, wherein, The heating device for tempering has: a heating furnace that maintains a predetermined temperature inside regardless of the size, shape, or material of the steel, and heats the steel for only a predetermined time regardless of the size, shape, or material of the steel; and an induction heating device that heats the steel before it is placed in the heating furnace by an induced current and has a setting unit that can set and change at least one of the energization time and the energization current value according to at least one of the size, shape, and material of the steel.

2. The heating device for tempering according to claim 1, wherein the setting unit is configured to have a reading unit that reads an identification tag recording information on at least one of the size, shape, and material of the steel.

3. A method for determining energization power, which is a method for determining the energization time and the energization current value in the induction heating device according to claim 1 or 2, wherein when the total heat required for tempering determined by the size, shape, and material of the steel is set as the required heat, the heat imparted to the steel by the heating furnace is set as the in-furnace heating amount, and the heat obtained by subtracting the in-furnace heating amount from the required heat is set as the induction heating amount, the energization time and the energization current value are determined such that the heat imparted to the steel from the induction heating device becomes the induction heating amount.

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