JPS5924544A - Method and apparatus for heat treatment of forged product - Google Patents

Abstract

PURPOSE:To anneal forged products with saving energy by adjusting cooling capacity of a forged product cooling device to make temperature of forged products nearly equal and charging to a heat treatment furnace when annealing forged products utilizing their retaining heat. CONSTITUTION:Many forged products F coming out from a forging machine 1 retain remaining heat of about 1,200 deg.C. While they are carried by a mesh belt type conveyor 2, they are cooled by air sucked from below by rotation of the vane wheel 5 of a cooling device 3 provided with a hood 4. A specified quantity is put in a basket 11, charged in a heat treatment furnace 13 and annealed. In this case, forged products that entered the basket 11 earlier are naturally cooled in the basket and temperature becomes lower than that of forged products that enter later. By adjusting cooling rate by controlling the rotation speed of a motor for rotating the vane wheel, and charging all the forging products in the basket 11 in the heat treatment furnace 13 at nearly equal temperature, all forged products can be annealed by small heating energy.

Description

[Detailed description of the invention] The present invention relates to a method and apparatus for heat treating a forged product.

Generally, when a forged product is subjected to heat treatment such as annealing, the residual heat of forging is utilized and the metal structure is prevented from coarsening. There is a method in which the product is once cooled to about 500° C. using an air cooling device for standardization, and then annealed using a subsequent heat treatment furnace. In this method, forged products that are continuously forged in large quantities are immediately heat-treated one by one after air cooling D4! Charging the forged products into a furnace for heat treatment requires a long heat treatment furnace, so generally the air-cooled forged products are piled up in baskets, etc., and about a dozen pieces are made into a unit, and the forged products are batch-type. A method of charging into a heat treatment furnace is adopted. However, in the conventional air cooling system mentioned above, cooling was performed with the cooling air volume always kept constant, so forged products placed early in the basket after air cooling would naturally release inside the basket, as shown in Figure 2. As the temperature further decreases due to cooling, sensible heat of the forged product, which is indicated by the shaded area F in the figure, is dissipated, and extra heating is required in the heat treatment furnace to deal with this sensible heat. Not favorable in terms of energy. However, the air cooling system does not perform more cooling than necessary, which means that power is wasted.

This invention solves the above-mentioned conventional drawbacks, and achieves energy savings by adjusting the cooling capacity of the cooling device and charging each forged product into a heat treatment furnace in a state where the temperature of each forged product is approximately equal. The purpose of this paper is to provide a method and apparatus for aging of forged products.

An embodiment of the present invention will be described below with reference to FIGS. 3 to 5.

In the figure, 1 is a forging machine, and 2 is a mesh-held type conveyor that transports the forged product F from this forging machine.

3 is an air-cooled type cooling device equipped with a pipe 4 which opens above the conveyor 2, and is of the type that sucks cooling air from below using an impeller 5 and discharges it to the outside through a duct 6. . 7 is a variable speed motor that drives the impeller 5 with a chain; 8
is a program setting device that outputs an excitation current that increases over time to the excitation winding of the electromagnetic coupling section of this motor. Reference numeral 9 denotes a forged product accumulating device, which consists of a table 10 with a bevel provided below the output 1'' of the conveyor 2, and a basket 11 placed on this -1-. 12 is a bushing, and 13 is a roller hearth type heat treatment furnace.

In order to heat-treat a forged product according to the temperature curve shown in Figure 1 using the apparatus having the configuration described in 2, the forged product F at approximately 1200°C, which is continuously supplied from the forging machine 1, is conveyed by the conveyor 2, and this conveyance Inside, the forged products are cooled by the cooling device 3, and when a predetermined number of forged products (assumed to be N) are accumulated in the basket 11, these are considered as one unit, and the basket 11 is heated to 98 degrees by the busher 12. 13 and annealed. In the above program settings ars
8, when the first forged product F1 is supplied to the conveyor 2-1-, a small excitation current is emitted, so the number of rotations of the i'iJ variable speed motor 7 is low. Therefore, since the cooling air volume is small, the basket 1 of the forged product is
The temperature at the time of charging the forged product into the Vasquera 11 is considerably higher than the typical cooling r#1 degree of 500°C, but when the forged product for one unit is completely charged, it will be approximately 5
It crystallizes at 00'C. As shown in Fig. 5, the cooling air volume of the cooling device 3 increases with the increase in the output of the brochure setter 8, and the temperature at the time of feeding other subsequent forged products into the Basquera) and 11 (after air cooling) increases. temperature) gradually decreases as shown in Figure 4, and the final forged product FN of the unit is approximately 50
0'C and put into the basket 11. At this point, all the other forged products in the basket 11 have cooled down to about 5
Since it is 00'C, I put this in PIV98 immediate furnace 1.
There are 3 inner furnaces 13 inside. Final cooling air of cooling device 3>2
(QN should be the air volume used to air-cool all forged products to 500'C in the conventional equipment. Also, the cooling air volume at the time of starting cooling of the first forged product of one unit and after that is , the temperature drop of each forged product stored in the basket 11 due to natural cooling in the basket 11 is determined by taking into account the amount, - the forged products are accumulated in multiple layers in the basket 11. Since it is also affected by heat dissipation of other forged products, it is better to determine it experimentally 8 Also, the program setting device 8
The output current is the required air volume and cooling device wind! It is preferable that it is determined according to the i characteristics, the rotational characteristics of the motor 7, etc., or it is finally determined by experiment (by adding 1 t). After forging, cooling, and charging for 1 unit, the following The program setter 8 is operated repeatedly by the Sufu-1 signal S associated with the supply of forged products to the conveyor 2, etc., and the cooling air volume is adjusted again to cool the forged products in the same manner as above. As a result of the following operations, compared to the conventional method of forced air cooling of all forged products to 500°C, as shown in Fig. 4, the forged parts corresponding to the shaded areas in the figure are
n Heat radiation 119 or prevention 11. Thus, the amount of heating in the heat treatment furnace 13 can be reduced.

Curve A in Figure 4 is a temperature drop curve when a 1200'C forged product is allowed to cool naturally in Vaskera) 11.
After adding the unit, the temperature will reach 500°C if it is only left to cool naturally.
If the above is not possible, forced air cooling is performed from the beginning, but if the accumulation time in the Vasquera 11 is long or the surface area of the forged product is large, it will naturally cool as shown in Figure 6. If the temperature drop curve A due to cooling intersects the 500°C line by the time the charging of one unit is completed, that is, if the forged product at the initial stage of charging becomes 500°C or less only by natural cooling in the basket 11, As shown in Figures 6 and 7, the forged product was placed into the basket 11 at 1200'C without forced air cooling at the beginning of 1 unit passage 11, and the point at which the temperature drop curve A reached approximately 500°C. Thereafter, it is best to start the air cooling control 41, increase the air volume up to the maximum air volume QN, and control the rotational speed of the motor 7 so that the air volume as shown in FIG. 7 is obtained. In this case, as shown in Figure 6, the initial forged product is
If the temperature is below oC, the radiation of sensible heat corresponding to the shaded area in the figure will be prevented on the 1st floor. This means that the amount of heating in the heat treatment furnace can be reduced.

In the above embodiment, the number of revolutions of the electric motor for blowing air is controlled to adjust the amount of cooling air, so it is possible to reduce the electricity cost for blowing air. A damper may be provided to adjust the cooling air volume by opening and closing the damper. Furthermore, in the cooling device 3, the cooling capacity may be adjusted by adjusting the cooling air temperature instead of adjusting the air volume. Furthermore, the cooling device 3 may be a cooling device using a gas other than air, a liquid, a gas-liquid mixture, or the like.

Although this invention has been described above for the case of annealing a forged product, this invention can also be applied to cases where other heat treatments such as quenching and tempering are performed, and the cooling temperature before heat treatment is also limited to 500°C. It is not something that will be done.

As explained above, according to this method, the cooling capacity of the cooling device is adjusted by taking into account the amount of heat dissipated from the forgings during the accumulation time of the forgings by the basket, etc., so that the temperature of each forging in the unit is approximately equal. Since it is charged into the heat treatment furnace in this state, it is possible to reduce the fuel cost for heating in the heat treatment furnace, and it is possible to achieve energy saving.

[Brief explanation of the drawing]

Fig. 1 is a temperature curve diagram showing an example of a heat treatment method for forged products to which the present invention is applied, Fig. 2 is a temperature curve diagram of a forged product by a conventional heat treatment method, and Fig. 3 is a diagram showing an example of the present invention. 4 is a temperature diagram of a forged product, FIG. 5 is a cooling air volume curve, and FIG. 6 is a diagram equivalent to FIG. 4 showing another embodiment of the present invention. , FIG. 7 is a diagram corresponding to FIG. 5. 1... Forging machine, 2... Conveyor, 3... Cooling device,
7... Number of variable speed motors, 8... Program setting device,
9...Forged product accumulating device, 11...Basket, 13...
...Heat treatment furnace. Applicant Daido Steel Co., Ltd. Agent Akira Inui

Claims (1)

[Claims] ■ A method for heat treating a forged product, in which a forged product supplied from a forging machine is cooled by a cooling device, and a plurality of forged products are charged into a heat treatment furnace as a unit to be heat treated, the unit comprising: When the forged product passes through the cooling device, the cooling capacity of the cooling device is adjusted to be low at the beginning and high at the end, so that the temperature of each forged product in the unit is approximately equal. A method for heat treating a forged product, characterized by charging the above unit into a heat treatment instant furnace. 2. A forging machine, a conveyor for conveying the forged products from the forging machine, an air cooling device for cooling the forged products on the conveyor, and In a heat treatment apparatus comprising an accumulation device for collecting units into units 1-, and a heat treatment chamber into which the units mentioned above are charged, when the forgings constituting the units pass through the air cooling device section The unit is charged into the heat treatment furnace in a state where the temperature of each forged product in the unit is approximately equal, by providing an air volume adjustment device that adjusts the cooling airflow so that it is small in the initial stage and increases in the final stage. Heat treatment equipment for forged products featuring: