JP3001164B2 - Heating device with solid heat storage block - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a heating apparatus used for heating a material to be heated in processes such as metal forging, non-ferrous metal processing, metal heat treatment, and ceramics. More specifically, the present invention relates to a heating device using a heat storage solid material.

[Conventional technology]

For example, in a metal die forging line, as shown in FIG. 10, a heating step RS, a forging step ST, and a trimming step TU are sequentially performed.

More specifically, the material to be heated 8 is supplied to the material supply device 100.
Is supplied to the heating furnace 102, and is heated in the heating furnace 102 to, for example, 1250 ° C. which is a forging temperature of a metal material. The heated material to be heated 8 is discharged from the heating furnace 102 and sent to the forging press 104. After the press forming, the material 8 is guided to a trimming device 108 by a conveying means such as a chain conveyor 106 to be finished. Thereafter, the heat treatment process is followed by an inspection process.

Conventionally, a combustion furnace or an induction heating device is used as the heating furnace 102, and the induction heating device occupies a large portion in recent years.

[Problems to be solved by the invention]

As described above, when an induction heating device is used in the heating process, the daytime load factor is mostly or
At 0%, the light load or the load factor is 0% at night, so that the power load is unbalanced between daytime and nighttime, which leads to an increase in the unit price of power consumption in the forging industry and the like. .

By the way, for example, in the case of metal forging etc., significant energy savings can be achieved if a method is used in which the material is preheated and kept warm in the middle temperature range of the forging process temperature by night power with a low kWh unit price and additional heat is applied during the daytime forging process. Can be expected.

In addition, in the case of forging non-ferrous metals such as brass and aluminum, the forging temperature is almost equal to the middle temperature range in the case of steel forging, so forging can be performed without requiring additional heat in the daytime only by preheating and keeping heat by night power, Energy saving efficiency can be further improved.

Accordingly, an object of the present invention is to provide a heating device including a solid heat storage block suitable for effectively using nighttime electric power and reducing the unit cost of power consumption by improving an electric power load factor accompanying the electric power.

[Means for solving the problem]

The present invention has been devised to achieve the above-described object, and is characterized in that a block formed of a heat storage material has a material storage portion for storing a material to be heated, and a heater for heating is embedded. Thus, a solid heat storage block is formed, and an outer surface of the solid heat storage block is covered with a heat insulating material.

Further, according to the present invention, it is possible to provide a configuration in which a material conveying device that supplies the material to be heated to the material storage section and discharges the material to be heated after heating is provided.

[Operation] According to the present invention, the material to be heated is accommodated in the material accommodating portion of the solid heat storage block, and is heated together with the solid heat storage block by the heater for heating. The sensible heat from the heating heater is stored in the solid-state heat storage block, and heat dissipation is suppressed by the heat insulating member.

After the material to be heated is heated, it is discharged from the material storage section and supplied to, for example, a forging process, and is additionally heated by an induction heating device or the like for a portion below the forging temperature.

Further, according to the present invention, the supply and discharge of the material to be heated are uniformly performed by the material transport device.

〔Example〕

 1 to 8 show an embodiment of the present invention.

As shown in FIG. 1, the heating device 2 is provided with a solid heat storage block 4, and the material to be heated 8 is automatically and uniformly supplied to the solid heat storage block 4 by the material conveying device 6. It is designed to be discharged after heating.

The outer surface of the solid heat storage block 4 can be covered with, for example, two layers of heat insulating materials 10 and 12 to suppress heat radiation. In order to obtain a stable installation state, the bottom surface of the solid heat storage block 4 is made of, for example, a firebrick. It can be structured to be supported by a hard heat insulator 14 such as. Further, the outermost surface is made of a reinforcing member 16
It can be a structure covered with.

The solid heat storage block 4 has a main block 18 formed of a heat storage material in a rectangular parallelepiped shape. In the block 18, a plurality of material accommodating portions 20 are formed at equal intervals, and a sensible heat source is provided at appropriate intervals. The heater 22 for heating is embedded. In this example, a magnesia castable containing magnesium oxide (MgO) and silicon dioxide (SiO ₂ ) as main components was used as the heat storage material from the viewpoint of specific heat, density, thermal conductivity, cost, and the like. The specifications of the solid heat storage block 4, the heat insulating materials 10, 12 and the heater 22 in this example are as shown in Table 1.

The inner layer insulation 10 has high thermal insulation under high temperature, safety,
Microtherm (trademark, manufactured by Nippon Aerosil Co., Ltd.) is used in consideration of cost, and fibrous kao wool (trademark, manufactured by Isolite Industry Co., Ltd.)
It was adopted. Of course, the material is not limited to the two-layer structure and the above-mentioned materials, and various materials can be selected as long as high heat insulation can be maintained.

The material accommodating section 20 can be formed, for example, by embedding a pipe member 24 having good heat conductivity in the block 18, and the pipe member 24 is provided with heat insulating materials 10, 1 from both ends of the block 18.
2 and a dimension protruding by the thickness of the reinforcing member 16. As shown in FIG. 3, for example, a solid heat storage block 4 includes a support plate 26 such as a steel plate and a required number of pipe members 24 and a heater for heating.
It can be formed by forming a skeleton through 22, setting it in a mold, and then casting a castable.

The material transfer device 6 includes a fixed leg 28, a movable base 30 supported by the fixed leg 28 and movable in the height direction and the width direction of the solid heat storage block 4, a pneumatic cylinder mounted on the movable base 30, and the like. And a pusher 32.

A shutter mechanism 34 is provided on the side of the solid thermal storage block 4 corresponding to the material transfer device 6 to guide the supply of the material to be heated 8 and to suppress heat radiation during supply and discharge. The shutter mechanism 34 includes, for example, the reinforcing member 16
A motor 36 installed on the upper surface of the drum, a drum 38 driven by the motor 36, a closing plate 40 wound around the drum 38 to close the opening of the material storage portion 20, and a material guide 42 attached to the closing plate 40. Can be composed of When the material to be heated 8 is set on the material guide 42 by a supply robot (not shown), the material to be heated 8 is pushed into the material storage section 20 by the telescopic rod 44 of the pusher 32 and supplied.

For example, when the supply to the material storage unit 20 in the top row is completed,
The operation of the shutter mechanism 34 causes the material guides 42 to correspond to the next row, and the extended opening end 45 of the material storage section 20 in the uppermost row is closed by the closing plate 40 to suppress heat radiation. Shutter mechanism 34
May be configured to drive the material guides 42 over the entire width direction by a single driving source, or may be configured to correspond the motor 36, the drum 38, and the like for each row.

After the material to be heated 8 is heated to a predetermined temperature, the material storage unit is sequentially operated from the lower row by the reverse operation of the shutter mechanism 34.
20 extension open ends are opened, pusher 32 telescopic rod
With the entry of 44, the material to be heated 8 is pushed down from the extended opening end 47 on the back side and discharged. In order to suppress heat radiation from the extended opening end 47 on the back side when the heated material 8 is discharged, for example, as shown in FIG.
Can be provided. Each insulation door 46 is, for example, a reinforcing member
The elastic support piece 48 can be fixed to the door 16 and a door body 50 attached to a free end of the elastic support piece 48. The door body 50 is always urged so as to be in close contact with the side surface of the reinforcing member 16 except at the time of discharging, and at the time of discharging, rotates by the pressing force of the telescopic rod 44 and automatically returns after the heated material 8 is discharged. ing.

Next, a description will be given of a cycle of a heating step in which a forging steel material having a diameter of 28 mm and a length of 200 mm is used as the material to be heated 8. However, the supply function of the material transfer device 6 is set to 4 sec / unit, and the discharge function is set to 15 sec / unit.

As shown in FIG. 6, in the initial heating step FG, heating is performed from room temperature to 750 ° C., which is a middle temperature range of the forging temperature. Next, the material to be heated 8 is discharged in a material discharging step BC, and the heating material 8 is supplied in a material supplying step CD. Next, a second heating step DE is started, and is sequentially repeated. The time spent in each step is as follows: the initial heating step FG is 10 hours, the material discharging step BC is 2.5 hours, the material supplying step CD is 0.5 hours, and the second heating step DE is performed.
Was 5 hours.

As a result of the experiment, the heat balance in the first heating step FG is a value as shown in Table 2, and the thermal efficiency is 24%. However, the heat balance in the second and subsequent heating steps DE is as shown in Table 3. Yes, the thermal efficiency is based on the amount of residual heat stored in the previous process.
It is improved to 56.3%.

Incidentally, Table 2, heat calculation method of the Table 3, Q _1; amount input power (measured _{value) × 860 Q 2, Q 3} , Q 4; specific heat × weight × heating temperature (measured value) Q _5; Q ₁ − (Q ₂ + Q ₃ + Q ₄ ).

The temperature distribution of the solid heat storage block 4 and the material to be heated 8 in the initial heating step FG is as shown in Table 4,
Of the measurement locations TC ₁ to Tc ₈ by the temperature sensor, for example, the bulk temperature control method that collectively controls the entire Buroku at block temperature TC ₄ (Figure 7), a solid heat storage block 4 in the material to be heated 8, the maximum temperature difference respectively, 125 ° C., but it is 130 ° C., as shown in FIG. 8, the first zone and the second divided temperature control for controlling each zone in each value of TC _1, TC ₄ is divided into a second zone In the method, it was confirmed by experiments that the maximum temperature differences between the solid thermal storage block 4 and the material to be heated 8 were 20 ° C. and 10 ° C., respectively. For this reason, in this example, a two-part temperature control method was adopted.

Assuming that the specific heat of 1250 ° C steel is 0.162 (kcal / kg ° C), the required heat quantity for heating from room temperature to 1250 ° C is Q ₍₁₂₅₀₎ = 0.1
62 (kcal / kg ° C) x 1250 ° C x 10 ³ (kg) = 202500 (kcal / t
on). From kWh = 860 (kcal), the theoretical electric energy of steel is Wh
₍₁₂₅₀₎ = 202500 (kcal / ton) x (1/860) = 235 (kWh / to
n). Therefore, the actual power consumption Wh ₁ in daytime use of the induction heating device is W, given that the thermal efficiency of the induction heating device is 45%.
h ₁ = 235 (kWh / ton) × (1 / 0.45) = 525 (kWh / ton).

On the other hand, the theoretical electric energy required for heating from room temperature to 750 ° C. becomes Wh ₍₇₅₀₎ = 130 (kWh / ton) by the same calculation method, and the heating device 2 including the solid heat storage block 4 is used at night. Assuming that the thermal efficiency of the solid thermal storage block 4 is approximately 60%, the actual power consumption is Wh ₂ = 130 (kWh / ton) × (1 / 0.6
0) = 217 (kWh / ton).

The theoretical electric energy for heating from 750 ° C to 1250 ° C is Wh ₍ 750-1250 ₎ = Wh ₍₁₂₅₀₎ -Wh ₍₇₅₀₎ = 105 (kWh / to
n), and the actual power consumption by the induction heating device is Wh ₃ =
105 (kWh / ton) x (1 / 0.45) = 233 (kWh / ton).

Therefore, when taking a method of preheating and keeping the material to be heated 8 in the middle temperature range of the forging temperature by the heating device 2 according to the present embodiment at night and performing additional heat at the time of forging in the daytime, the energy saving effect ε is as follows. Also in this case, the nighttime power load factor mu ₁ is Therefore, the daytime and nighttime power load factors can be made almost equal,
Therefore, the power consumption unit price can be reduced.

In addition, in the case of forging non-ferrous metals such as brass and aluminum, the forging temperature is almost equal to the medium temperature range in the case of steel forging. Energy saving can be achieved.

Further, the present invention can be applied not only to the forging process but also to metal heat treatment, ceramic industry, and the like, and similarly, it is possible to reduce the unit cost of power consumption and, consequently, the production cost.

In addition, in the heating device 2 according to this example, the reduction rate due to the oxide scale in the heating step is as shown in Table 5, and it was confirmed that the value was extremely low compared to 2.5% in the conventional combustion furnace. Was. Although the cost is high, the loss rate can be further suppressed in an atmosphere of an inert gas such as argon (Ar) as compared with that in the air.

When a soft material such as brass is to be used, for example, as shown in FIG.
By providing the 52, 52 to prevent rolling of the material to be heated 8 and reduce the contact area, it is possible to avoid damage such as scratches in the supply / discharge process, and to prevent deterioration in product quality. it can.

〔The invention's effect〕

According to this invention, a material to be heated in a metal forging process or a heat treatment process is heated using nighttime electric power, and a portion less than the forging temperature or the like is additionally heated in the daytime and supplied to the processing process. Therefore, it is possible to improve the imbalance of the power load ratio between the daytime and the nighttime, and to reduce the unit cost of power consumption and the production cost.

According to the present invention, the material to be heated can be quickly supplied to the material storage section of the solid heat storage block by the material transfer device, and the heated material to be heated can be quickly discharged, so that the working efficiency can be improved. In addition, it is possible to control a decrease in thermal efficiency due to heat radiation during supply and discharge.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a heating device provided with a solid heat storage block according to the present invention, wherein (A) is a partial cross-sectional plan view, (B) is a partial cross-sectional side view, and FIG. Fig. 3 is a perspective view showing a main part of the solid heat storage block, Fig. 3 is a schematic perspective view showing a frame of the solid heat storage block, Fig. 4 is a view showing the solid heat storage block, (A) is a front view thereof, and (B) is a front view. FIG. 5A is a cross-sectional view taken along line IV-IV, FIG. 5 is a partial perspective view on the back side of the heating device, FIG. 6 is a graph showing the relationship between temperature and time in a heating cycle, FIG. 7 and FIG. FIG. 9 is a view showing a temperature control system of the solid heat storage block, FIG. 9 is a partially cutaway perspective view showing another example of the material storage section, and FIG. 10 is a view showing a conventional forging line. 2 ... Heating device with solid heat storage block 4 ... Solid heat storage block 6 ... Material transfer device 8 ... Material to be heated 10,12 ... Insulation material 18 ... Block 20 ... Material storage part 22 ... Heating Heater

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Masao Nishioka 1-3-1 Uchisaiwai-cho, Chiyoda-ku, Tokyo Inside Tokyo Electric Power Company (72) Inventor Seiji Yonezawa 1-8-19 Shiba, Minato-ku, Tokyo Stock (72) Inventor Hisashi Yoshida 1-8-19 Shiba, Minato-ku, Tokyo Inside Hakusan Manufacturing Co., Ltd. (58) Field surveyed (Int. Cl. ⁷ , DB name) F27D 11/02 C21D 1 / 40 B21J 17/02 H05B 3/00

Claims (2)

(57) [Claims] 1. A solid heat storage block is formed by forming a material storage portion for storing a material to be heated in a block formed of a heat storage material, and a heating heater is embedded therein. Is a heating device with a solid heat storage block covered with heat insulating material. 2. A heating apparatus having a solid heat storage block according to claim 1, further comprising a material transfer device for supplying the material to be heated to said material storage section and discharging the heated material after heating.