JP3910396B2 - Induction hardening equipment for steel sheet - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a quenching apparatus by high-frequency heating of a steel plate, and particularly to partial quenching of a steel plate.
[0002]
[Prior art]
When a steel sheet is quenched by high frequency heating, a scale is generated on the heating surface. For this reason, the process of scale removal was required after quenching. Moreover, in order to prevent generation | occurrence | production of a scale, although the method heated while spraying inert gas, such as argon, is also performed, there exists a problem that cost starts. Therefore, there is a demand to omit the post-scale removal process.
[0003]
In addition, there are parts that require strength only in a part formed from a steel plate.
In manufacturing such a part, a part requiring strength is induction-quenched in the state of a steel plate in advance and then molded. In this way, when the steel sheet is partially quenched, simply pressing a part of the steel sheet and partially quenching does not avoid the quenching distortion of the steel sheet, and man-hours are required to correct this. Therefore, in such a case, generally, a method is adopted in which both surfaces of a steel sheet to be quenched are sandwiched between cooling blocks and press-cooled.
[0004]
[Problems to be solved by the invention]
However, the press cooling is difficult to quench by continuous heating and cooling like induction quenching, and since the cooling rate cannot be increased, sufficient quenching and hardening is required when the material and the plate thickness are poor. There is a problem that cannot be obtained.
[0005]
Accordingly, the present invention has been made to solve the above problems, and to provide an induction hardening apparatus for steel sheets that eliminates a post-scale removal process in induction hardening of steel sheets and that does not cause distortion in partial hardening of steel sheets. To do.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, an induction hardening apparatus for steel sheets according to the present invention, in the partial hardening of steel sheets by high frequency heating , injects a cooling liquid onto an induction heating coil that moves relative to the steel sheet to be hardened and a heating surface. A cooling liquid jetting means, and the cooling liquid jetting means is provided on one or both of the heating surface and the back surface thereof, and the cooling liquid jetting pressure of the cooling liquid jetting means rapidly cools the heating surface and at the time of heating. It has the ability to eject and remove the generated scale.
[0007]
2. Description of the Related Art Conventionally, a quenching apparatus including an induction heating coil that moves relative to a steel sheet to be hardened and a cooling means by cooling liquid injection is known. However, the cooling liquid injection of the conventional cooling means is performed so that only quenching cooling is performed. Therefore, the scale generated by quenching heating remains after cooling, and a cleaning operation is necessary in a subsequent process. .
[0008]
In contrast, the present invention is characterized in that the injection pressure of the coolant injection means is increased to the ability to remove the scale, and quenching quenching and removal of the scale by injection are performed at a time. As a result, the quenching surface is sufficiently quenched to obtain sufficient quenching hardness, and the scale on the surface is removed, so that the post-process for removing the scale can be omitted, thereby reducing the cost. it can.
[0009]
The coolant injection means may be provided only on the heating surface of the steel plate, but is preferably provided on both the front and back surfaces. As a result, both the front and back surfaces are quenched at the same time, so that quenching distortion is reduced and the cooling rate is increased to obtain high quenching hardness. In addition, in the case of a steel plate with a thin plate thickness, the back surface is heated and scales are generated on the back surface. However, the scales on both the front and back surfaces can be removed by providing the coolant injection means on both the front and back surfaces. Costs can be reduced by omitting the post-removal process.
[0010]
The apparatus of the present invention can be applied to the entire quenching of steel plates and the partial quenching described later. In order for the induction heating coil and the coolant injection means to move relative to the steel sheet to be hardened, either one of them may be moved.
[0011]
The steel plate induction hardening apparatus of the present invention includes a pressing plate provided with a window portion having a size corresponding to the quenching portion in the partial quenching of the steel plate by induction heating, and the steel plate to be hardened by the pressing plate. A heating and quenching means for induction heating and quenching the quenching portion from the window portion in a state where both surfaces of the window are pressed is provided.
[0012]
As described above, in the partial quenching of the steel sheet, the method of quenching while holding a part of the steel sheet to be hardened could not prevent the occurrence of quenching distortion. Therefore, conventionally, in order to prevent quenching distortion, a method of press-cooling both surfaces of a steel plate with a cooling block has been performed, but continuous heating and quenching with a high frequency has been difficult.
[0013]
In the present invention, since the quenching part is heated and cooled from the window provided in the presser plate in a state where the steel plate is pressed by the presser plate, continuous heating and cooling by high frequency can be performed. Thereby, since a higher cooling rate than press cooling by the cooling block can be obtained, sufficient quenching hardness can be obtained even in the case of a material having poor hardenability. At the same time, the non-quenched part of the steel sheet to be hardened is restrained by the presser plate, so that quenching distortion can be prevented.
[0014]
The window portion of the press plate is preferably provided on the press plates on both the front and back surfaces of the steel plate to be hardened. In the case of the above thick plate, a window may be provided only on the heating surface, but in the case of a thin plate, a holding plate provided with windows on both the front and back sides is used, and the above-mentioned coolant injection means is provided on both the front and back sides. Moreover, the scale removal of the front and back of a steel plate can be performed, and the partial quenching of a steel plate can be performed more efficiently.
[0015]
Here, the partial quenching of the steel plate includes not only one quenching portion of the steel plate in the window portion of the presser plate but also partial quenching of two or more locations.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be specifically described with reference to an illustrated embodiment.
[First Embodiment]
FIG. 1 is a diagram showing the configuration of an induction hardening apparatus for steel sheets according to a first embodiment of the present invention. In FIG. 1, a high-frequency heating coil 1 and a coolant injection means 2 are provided on the surface (upper surface in the figure) of a heated steel plate (hereinafter referred to as a workpiece) W, and the rear surface (lower surface in the figure) of the target position of the coolant injection means 2. ) Is provided with coolant injection means 3. In this embodiment, the high frequency heating coil 1 and the coolant injection means 2 are fixed, and the workpiece W moves in the direction of the arrow so that the workpiece W, the high frequency heating coil 1 and the coolant injection means 2 move relative to each other. Yes.
[0017]
The high frequency heating coil 1 is placed with its coil surface parallel to the workpiece plane, and heats the workpiece plane. The coolant injection means 2 has a hollow box shape, and the coolant introduced into the hollow portion from the introduction pipe 2b is injected from the nozzle 2a onto the surface of the workpiece W. The coolant injection means 3 has a target shape with the coolant injection means 2 and is disposed at a symmetrical position on the back surface of the workpiece W.
[0018]
When the workpiece W is moved in the direction of the arrow while being heated by the high frequency heating coil 1, the heating surface is quenched and quenched by the coolant sprayed by the coolant spraying means 2. The front and back surfaces of the workpiece W are simultaneously and uniformly cooled, and the scale is removed by jetting the coolant. The cooling liquid introduced into the introduction pipe 2b is injected at a pressure of 0.3 MPa or more, and is 0.5 MPa in this embodiment. It was found that the higher the spray pressure, the greater the effect of removing the scale, but it should be practically 0.3 MPa or more.
[0019]
The surface of the steel plate quenched using the quenching apparatus of the present invention having the above configuration was compared with the surface of the steel plate quenched by a conventional cooling means. FIG. 4 (a) shows the steel plate surface of the present invention, and FIG. 4 (b) shows the steel plate surface by a conventional apparatus. As can be seen from the figure, in the case of the conventional apparatus shown in FIG. 4B, a large amount of scale remains on the surface. However, in the apparatus of the present invention shown in FIG. Is allowed only to the extent that does not interfere with
[0020]
As described above, according to the steel sheet quenching apparatus of the present invention, scales generated during heating can be removed simultaneously with quenching cooling, so that no post-treatment step for scale removal is required.
[0021]
Second Embodiment
Next, a second embodiment of the present invention will be described. FIG. 2 is a view showing the structure of an induction hardening apparatus for steel sheets according to a second embodiment of the present invention, and FIG. 3 is a view showing a hardened portion of the steel sheets. 2nd Embodiment of this invention is related with the apparatus which induction-hardens only the 2 quenching parts W1 and W1 of the workpiece | work W shown in FIG. The same applies to partial quenching.
[0022]
In FIG. 2, the front and back surfaces of the workpiece W are pressed and held by the front pressing plate 4 and the rear pressing plate 5 by pressing means (not shown). The pressing plates 4 and 5 on the front and back sides have the same thick plate shape, and are provided with penetrating windows 4a and 5a (5a not shown). The high frequency heating coil 1 and the coolant injection means 2 similar to those shown in the first embodiment are disposed inside the window portion 4a of the surface pressing plate 4. Further, the back surface coolant injection means 3 is disposed inside the window portion 5a of the back surface pressing plate 5 (not shown). In the present embodiment, the high frequency heating coil 1 and the coolant injection means 2 are fixed, and the workpiece W is held by the press plates 4 and 5 and moves in the direction of the arrow.
[0023]
The size of the window portions 4a and 5a of the presser plates 4 and 5 is such that the high-frequency heating coil 1 and the coolant injection means 2 move relative to the workpiece W so that the two quenching portions in FIG. Has been.
[0024]
While moving the work 1, high-frequency heating and cooling are performed to partially quench the two hardened portions in FIG. At this time, since the workpiece W is quenched while being pressed by the edges 4b and 5b of the presser plates 4 and 5, quenching distortion is prevented. When quenching is finished, the work W is taken out by pulling the holding plates on the front and back sides.
[0025]
The steel plate was quenched under the following conditions using the quenching apparatus having the above configuration. That is, E = 300 mm width, L = 800 mm length T = 1.4 mm thickness steel plate having the shape shown in FIG. 3 and two long portions of A25 mm × D300 mm are spaced apart by B = 60 mm. Quenching was performed. As a result, in the conventional method, a curved bend of 40 mm was generated for a total length of 800 mm, but in the method of the present invention, a flatness of a bend of 10 mm was obtained for the same total length of 800 mm. Moreover, the prospect that the flatness could be further improved by selecting quenching and cooling conditions was also obtained.
[0026]
As described above, according to the quenching apparatus of the second embodiment of the present invention, sufficient flatness can be obtained in the partial quenching of the steel sheet, so that the distortion removing step is not required and the cost can be reduced.
[0027]
【The invention's effect】
As described above, according to the induction hardening apparatus for steel sheets of the present invention, scale removal is performed simultaneously with quenching, so post-treatment for scale removal is not required, and costs can be reduced. Further, since the quenching distortion can be significantly reduced in the partial quenching of the steel sheet, the quality of the quenched product is improved, the distortion removing process can be omitted, and the cost of the steel sheet part is reduced.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an induction hardening apparatus for steel sheets according to a first embodiment of the present invention.
FIG. 2 is a diagram showing a configuration of an induction hardening apparatus for steel sheets according to a second embodiment of the present invention.
FIG. 3 is a diagram showing a state of partial quenching of a steel plate according to a second embodiment of the present invention.
FIG. 4 is a diagram comparing a surface (a) of a steel plate quenched by an induction hardening apparatus for a steel plate according to the first embodiment of the present invention and a surface (b) of a steel plate quenched by a conventional induction hardening apparatus.
[Explanation of symbols]
1 High-frequency heating coil, 2 upper coolant injection means, 3 lower coolant injection means, 4 upper presser plate, 5 lower presser plate, W workpiece (hardened steel plate)

Claims (2)

  In partial quenching of a steel plate by induction heating, a press plate having a window portion having a size corresponding to the quenching portion is provided, and both sides of the steel plate to be hardened are pressed from the window portion with the press plate pressed. An induction hardening apparatus for steel sheets, comprising a heating and quenching means for induction heating and quenching a quenched portion. In the partial quenching of the steel sheet by high frequency heating, the steel sheet includes an induction heating coil that moves relative to the steel sheet to be hardened and a coolant spraying means that sprays a coolant onto the heating surface. The cooling liquid spraying pressure of the coolant spraying means is provided on any one or both surfaces of the back surface, and has a capability of rapidly cooling the heating surface and spraying and removing the scale generated during heating. Induction hardening apparatus for steel sheet.

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