JPH0518234B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an induction heating method, and particularly to an induction heating method in which a material to be heated is continuously heated using a plurality of induction furnaces.

B. Summary of the Invention The present invention provides a plurality of induction furnaces each consisting of a furnace body and a heating coil arranged in parallel, each heating coil being electrically connected in series, and the number of induction furnaces being n. If the time required for the heated material to reach a predetermined temperature is T, then the heated material is inserted and removed in the predetermined order of induction furnaces with a shift of T/n time for each induction furnace. Since the material to be heated does not have to be moved over a long distance within the furnace as in the heating method using a continuous heating furnace, damage to the furnace wall during the movement of the material to be heated can be greatly reduced, and Since the heated material can be continuously inserted and taken out in a predetermined order, it is very convenient to incorporate into a production line because it is easy to match the previous and subsequent processes.

C. Prior Art Conventionally, a continuous induction heating furnace typified by a pillar heater for forging, for example, has been used to continuously induction heat a material to be heated such as a steel material. In this induction heating furnace, a furnace body having a heating coil is arranged in a straight line, and a material to be heated therein is heated. To explain with the drawings, 2c in FIG. 5 (cross-sectional view) in FIGS.
are wrapped continuously. Also, the total length of the furnace is, for example, 5
If the length is as long as m, the furnace body 2 is
and dividing the heating coil 1 into multiple blocks,
Induction heating furnaces are often used in which the heating coils 1, 1, . . . are connected in series by lead portions 1a, with both ends thereof serving as input/output connection points. 5 is a power source.

Reference numeral 3 denotes a material to be heated, which is intermittently and sequentially supplied to the furnace inlet 2a from the side of the furnace body 2 having the furnace core tube 2c. The material to be heated 3 is at room temperature when it is supplied to the furnace inlet 2a. Reference numeral 4 denotes a push rod that is movable forward and backward, and when the material to be heated 3 is supplied to the furnace inlet 2a, it temporarily retreats, and when it moves forward next, it inserts the material to be heated 3 into the furnace. By sequentially feeding the heated materials 3 into the furnace from the furnace inlet 2a, the heated materials 3 in the furnace reach a predetermined temperature (e.g.
1200° C.) and are sequentially extruded from the furnace outlet 2b. In addition, in this continuous induction heating furnace, heating power, feeding speed, etc. are appropriately controlled.

D Problems to be Solved by the Invention In the conventional continuous induction heating furnace that continuously extrudes a plurality of materials to be heated 3, for example, there may be an abnormality in the feeding contact surface of the materials to be heated 3, or if the material to be heated 3 is In cases where the cut surface is not appropriate and the extrusion force acts in a direction other than the direction of movement, the mutual extrusion force of the heated materials 3 will not work normally in the direction of movement, and the alignment of the heated materials 3 will be disrupted. As a result, the alignment of the slag → collision with the furnace wall → damage to the furnace wall → abnormal heating of the material to be heated → partial melting → damage to the furnace wall, resulting in the problem that heating operation cannot be continued and repairs must be made. It was hot. (See Figure 6) By the way, the causes of the above problem are the following two points.
The first is that the entire weight of a large number of materials to be heated 3 in the furnace is pushed out at one location at the furnace entrance 2a, and the second is that the temperature of the materials to be heated 3 is increased while moving them. Therefore, the present invention proposes an induction heating method that solves the above problems by reducing the extrusion weight of the material to be heated 3 and increasing the temperature from room temperature to a predetermined temperature at one location.

E Means for Solving the Problems The present invention provides a plurality of induction furnaces each consisting of a furnace body and a heating coil arranged in parallel, and a power supply connected in series between each heating coil with both ends thereof as input/output connection points. If the number of induction furnaces is n and the time required to heat the material to a predetermined temperature is T, then the materials to be heated are inserted in the predetermined induction furnace order with a shift of T/n time for each induction furnace. This is an induction heating method characterized by performing extraction.

F Embodiment FIGS. 1 to 3 are diagrams showing the basic concept of the present invention, and FIG. 4 is a diagram showing the structure of FIG. 1 more specifically. In each figure, a plurality of induction furnaces 6, 6, . The heating coil 1 is connected in series to a power source by a lead portion 1a, with both ends serving as input/output connection points. Therefore, the material to be heated 3 is sequentially inserted into each induction furnace 6, 6... from the inlet side 2a, and the temperature is raised from room temperature to a predetermined temperature (for example,
After raising the temperature to 1200°C), they are sequentially taken out from the outlet side 2b. The material to be heated 3 is inserted into and removed from the induction furnace 6 by means of a push rod 4 which is movably provided for each induction furnace 6 or in common.

In the plurality of induction furnaces 6, 6..., the materials to be heated 3, 3... are generally incorporated into a production line, so as in the past, the materials to be heated 3, heated to a predetermined temperature, are continuously (sequentially) heated to a predetermined temperature. It must also have the ability to supply to a subsequent process, for example a forging machine (at time intervals). Furthermore, the heating power source is also the same as the conventional one. Therefore, in the present invention, the materials to be heated 3 are inserted and removed in a staggered manner for each induction furnace 6, 6, as follows. That is, the time required for heating the material 3 to be heated to a predetermined temperature in the induction furnace 6 (=furnace residence time) is T, and the number of induction furnaces 6 installed in parallel is n.
Then, the insertion and removal times for each induction furnace 6 are sequentially performed by shifting the time by T/n. That is, the operation is performed at the takt time shown in FIG.

Conventionally, the temperature of the heated material 3 in the induction furnace 6 increases sequentially from a degree Celsius to e degrees Celsius from the inlet side of the induction furnace 6 toward the outlet handle, as shown in FIG. On the other hand, according to the method of the present invention, as shown in FIG. 2, for example, when the temperature of the heated material 3 in the first (left end of FIG. 2) induction furnace 6 is at the heating end temperature e.degree. The temperature of the heated material 3 in the induction furnace 6 is sequentially d, c, b, a degrees Celsius, e>d>c>b>
The relationship is a.

As described above, each induction furnace 6, 6 is heated in the order indicated by the symbols .
When the heated materials 3, 3, etc. are inserted into..., the heated materials heated to a predetermined temperature can be successively taken out in the above order at time intervals of T/n. Therefore, even though the induction furnaces 6, 6... are installed in parallel, the material to be heated 3 is taken out one after another in exactly the same way as in a conventional continuous furnace, so it is not possible to feed the material all at once to the subsequent stage. There is no.

G. Effects of the Invention According to the present invention, when continuously heating a plurality of materials to be heated, the plurality of materials to be heated are inserted into each induction furnace installed in parallel at intervals of T/n time, and heated from room temperature in one place. Since the temperature is raised at a predetermined temperature step by step, damage to the furnace wall can be significantly reduced compared to the conventional method of heating the material while pushing it through a long furnace, thereby helping to prevent accidents. The effect is great. Further, problems such as stopping heating during the period from the occurrence of an accident to recovery, and providing a spare heating coil required for that purpose can be improved. Furthermore, although the present invention has induction furnaces installed in parallel, it is possible to sequentially and continuously heat the materials to be heated and send them out using the same heating power source as the conventional one, so when the present invention is incorporated into a production line. It is convenient because it can be synchronized with the previous and subsequent processes.

[Brief explanation of the drawing]

Figure 1 is a basic conceptual diagram of the induction heating method according to the present invention, Figure 2 is an explanatory diagram showing the relationship between the order of insertion of materials to be heated in each induction furnace and the heating temperature, and Figure 3 is a diagram showing the relationship between the order of insertion of materials to be heated in each induction furnace and the heating temperature. Diagram showing the time lag for inserting materials,
FIG. 4 is a sectional view relating to the method of the present invention, FIG. 7 is a basic conceptual diagram of a conventional continuous induction heating method, and FIGS. 5 and 6 are also sectional explanatory diagrams showing a conventional continuous induction heating method.
FIG. 8 is a diagram showing the relationship of increase in the heating temperature of the material to be heated in the conventional method. DESCRIPTION OF SYMBOLS 1... Heating coil, 2... Furnace body, 2a... Inlet, 2b... Outlet, 3... Material to be heated, 2c... Furnace core tube, 6... Induction furnace.

Claims (1)

[Claims] 1 A plurality of induction furnaces each consisting of a furnace body and a heating coil are arranged in parallel, and both ends of each heating coil are connected to a power source in series as input/output connection points, and the number of induction furnaces is set to n, and the number of heated coils is set to n. An induction heating method characterized in that, where T is the time required to heat the material to a predetermined temperature, the material to be heated is inserted and removed in a predetermined induction furnace order with a shift of T/n time for each induction furnace. .