JPS5825417A - Heat treatment of casting and its device - Google Patents

Abstract

PURPOSE:To save fuel required for quenching, a removing of foundary sand, and tempering, and to elevate the quality of a product, by executing quench-heating of a casting, and removing of the foundry sand by means of indirect heating, and utilizing the combustion exhaust gas of a quenching furnace for tempering. CONSTITUTION:Baskets 1, 1'- containing a casting which is at a high temperature immediately after it has been taken out from a casting machine, and on which foundry sand remains adhered are led into a quenching furnace 3, a hot blast supplied by circulating air blowers 9, 9' is heated up to a necessary temperature by radiant tubes 8, 8', also the casting is heated to a quenching temperature by holding O2 concentration at 17-21%, and the foundry sand is removed. Subsequently, the casting is moved to a quenching barrel 13 by an elevator mechanism 12 through a discharge tablet 4, is quenched, and after that, is led into a tempering furnace 15, and tempering is executed by supplying the combustion exhaust gas of the radiant tubes 8, 8' led in from lead-in holes 21, 21', by circulating air blowers 22, 22'.

Description

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, a cast product taken out from a casting machine is first placed in a quenching furnace and heated to a quenching temperature, then placed in a quenched lump and quenched.
Next, the present invention relates to a method and apparatus for heat treating a cast product, which continuously performs a series of heat treatments in which the product is placed in a tempering furnace and heated to a tempering temperature.

Cast steel products are generally used as products after being removed from a casting machine, heated to a quenching temperature, and then subjected to a heat treatment process in which they are tempered. Aluminum cast products, such as aluminum cylinder heads, are used as products after undergoing a heat treatment process in the same way as cast steel products. Conventionally, before feeding a cast product to a quenching furnace, there was a step of removing molding sand from the cast product immediately after it was taken out of the casting machine, since this molding sand was attached to the product.

Conventionally, there are various methods for removing molding sand, but when casting products are mass produced, removing molding sand using a sand kiln is often adopted. When using a sand kiln to remove molding sand, the binder that solidifies the molding sand is thermally decomposed by the heat and the presence of 02, and is turned into solids, losing its ability to solidify the molding sand, resulting in a loss of its ability to harden the molding sand. A binder with properties that makes it easier for molding sand attached to the product to fall off is used.

To remove sand using a sand kiln, the cast product is placed on a conveyor and transported from the inlet to the outlet of the sand kiln, and several burners are installed on the ceiling of the sand kiln, and the flames emitted from these burners are This method is used to remove sand adhering to the castings being transported, but if the air is supplied excessively to each burner and the 02 concentration in the blown flame is about 15 g. L-conversion of the binder is promoted. However, it is quite difficult to have 15 g of 02 in the flame, and if the 02 concentration is about 10 g, it will take a much longer time to remove the molding sand from the casting than when the concentration is 15%. do. That is, the cast product must remain in the sand kiln for a long time, which requires a large sand kiln and consumes a large amount of fuel. However, the amount of exhaust gas emitted from the sand kiln is still large, and not only is a large amount of thermal energy wasted along with the exhaust gas, but also the combustion exhaust gas contains sand, so it is not necessary to pass it through a sand removal device. The smoke must be evacuated afterwards, thus requiring a large sand removal furnace in addition to a large sand furnace.

The quenching furnace according to the present invention is supplied with a cast product that has been removed from the casting machine and has molding sand still attached to it. The more the cast product is just taken out of the casting machine and has not yet cooled down and is still at a high temperature, the more thermal energy can be saved.

This quenching furnace employs a radiant tube as its heating means. A circulation blower will also be installed. A radiant tube is placed in the hot air circulation path, and the radiant tube applies heat to the circulating hot air, and the cast product is heated by the circulating hot air and is heated relatively uniformly to the quenching temperature. In the case of radiant tube heating, it is easy to maintain the 02 concentration in the quenching furnace at 17% to 21%, so the binder that hardens the molding sand is heated for a short time by the circulating high-temperature hot air and high 02°C. The molding sand can be removed from the cast product, and the molding sand can be supplied to the next quenching process with the molding sand removed, thus shortening the process and simplifying the equipment. This is a quenching furnace that can simultaneously achieve significant savings in fuel consumption and labor.

The continuous heat treatment apparatus according to the present invention has the quenching furnace and the tempering furnace arranged such that their inlets and outlets are located on opposite sides, the quenching furnace is provided below, and the tempering furnace is provided above it, Both furnaces are placed one on top of the other, each furnace is provided with an automatic positive drive conveyance means, and an elevator mechanism is provided adjacent to the quenching furnace outlet and the tempering furnace inlet. The lower part of the mechanism is a hardening channel, so the casting automatically passes through the hardening furnace and is hardened in the hardening furnace.
This is an automatic continuous heat treatment device that passes through a tempering furnace. In addition, as mentioned above, a radiant tube is used for heating in the quenching furnace, and quenching heating and mold sand removal are performed at the same time, and the combustion gas generated by the radiant tube is led to the tempering furnace. The radiant tube combustion gas introduced into the furnace is forcibly circulated by a circulation blower to heat the casting to the tempering temperature, thereby achieving effective fuel utilization.

The heat treatment of the present invention has been tested mainly on aluminum cylinder heads, which are aluminum cast products, and in this case, the quenching temperature of the aluminum/cylinder head was set at 480°C.
The temperature is set to 530°C and the 02 concentration in the quenching furnace is 17 cI.
As a result of testing with temperatures ranging from 1 to 21 inches, it was found that not only the sand on the surface of the aluminum cylinder head but also the core sand could be removed, and the unlinder block could be soaked in less than 1 hour. Although it is possible to reach the quenching temperature and remove molding sand at the same time,
#If the degree is less than 15 inches, it will take a long time for the molding sand to fall off.

It was found that the heating time to the quenching temperature could not be matched, resulting in a waste of fuel.

The present invention will be explained in more detail with reference to FIGS. 1, 2, and 3 showing an example in which an aluminum cylinder head was tested.

, In Fig. 1, the aluminum cast cylinder heads are housed in one or several cylinders (1.1', 1), . . . and are first fed onto the supply table 2 in front of the entrance of the quenching furnace. be done.

The cylinder head supplied to the main quenching furnace has not yet cooled down immediately after being taken out from the casting machine and still has residual heat, and the higher the temperature, the more thermal energy will be saved in the quenching furnace. In this case, the molding sand and core sand 75 are supplied to the cylinder head.

The main quenching furnace 3 is surrounded by a mild steel plate on the outside, a stainless steel plate on the inside, and a heat insulating material is filled between the steel plates.

The sketches 1 supplied into the quenching furnace 3 enter the quenching furnace 3 from the supply table 2 position and are taken out to the discharge table 4 position. Known 7-slow rollers 5.5', 5'
, , etc. are provided. The entrance door 6
and the exit door 7 are automatically raised and lowered at regular intervals.

As shown in detail in FIG. 3, one or more radiant tubes 8.8'91 are provided within the main quenching furnace 3. To '1', the main quenching furnace 3 has one or several circulation blowers 9.9', .

is provided. Therefore, the structure is such that hot air is forced to circulate within the main hardening furnace 3 as shown by the arrows in FIG. The circulating hot air receives heat when it comes into contact with the surface of the radiant tube provided in the circulation path, and the heated hot air flows into the basket 1' carried into the circulation path and is generated by the flowing force 1' while contacting the cylinder head. It is possible to heat the cylinder head evenly. In addition, by using the 4-heating method, it is easy to maintain the 5 oz in the furnace at 17% to 21%, and in this way, the circulating hot air, which is at Kusunoki temperature and has a high 02 concentration, is circulated through the cylinder head. If you apply it to the molding sand, the binder that hardens the molding sand will harden in a short time,
Since the adhesive force is lost, molding sand and core sand can be removed from the cylinder head. Below the hearth roller 5 of the main quenching furnace, there are one or several hoppers 10.10', . . . and screw feeders 11.1', 1. A means for carrying out sand is provided.

The basket 1 comes out of the exit door 7 which operates intermittently and is placed on the discharge table 4.

The discharge table 4 is a part of an elevator mechanism 12, and the basket 1 is immersed in a hardening box 13 provided at the bottom of the elevator mechanism for hardening treatment.

The quenching unit is provided with a suction pipe suction port at its bottom and a sand removal pump means, ie, a melary pump 14.

The discharging table 4 carrying the food is located in front of the entrance door 16 of the tempering furnace 15, and the basket 1 is placed in front of the entrance door 16, which is operated intermittently.
6 and is fed into the tempering furnace 15.

The main tempering furnace 15 is surrounded by steel plates on its outside and inside, and a heat insulating material is filled between the steel plates.

The common wall 17 between the two furnaces, which is the ceiling wall of the quenching furnace 3 and the floor wall of the tempering furnace 15, can be made thinner than a normal wall thickness, and the heat insulating material can be thinned or eliminated.

A conveyance means such as a hearth roller 19 is provided to convey the basket 18 fed into the main tempering furnace 15 from its entrance to its exit at a predetermined speed.

The entrance door 16 and the exit door 20 are each opened and closed intermittently.

As shown in detail in FIG. 3, on the side wall of the main tempering furnace 15,
Each radiant tube of the quenching furnace 8.8'03. An introduction hole 21.21''09. into which combustion exhaust gas is introduced is provided.A circulation blower 22.27' is also provided fixed to the ceiling wall of the tempering furnace 15. Return east 1
Furnace gas exhaust pipe 23.23' with damper on the side wall of 5
is provided.

The tempering furnace according to the present invention has the above-described structure, and the combustion exhaust gas of the radiant tube adopted in the quenching furnace is introduced into the tempering furnace as a heating gas, and this combustion exhaust gas is circulated in the furnace by a circulation blower. , the supplied cylinder head is therefore heated relatively uniformly to the tempering temperature.

The cylinder head has an exit door 20 that opens and closes at regular intervals.
The product is sent out to the product take-out table 24 through the.

In the heat treatment according to the present invention, heating in the quenching furnace is an indirect heating method using radiant tubes, and the circulating hot air in the quenching furnace comes into contact with the radiant tubes and heat is transferred to reach a high temperature. Content 17 to 21%
At the same time, the cylinder head can be heated to the quenching temperature and any molding sand that has adhered to it can be removed. The radiant tube heating device used in the quenching furnace is expensive, and its fuel LP gas is also more expensive than conventional liquid fuel, but the combustion gas can be used as a heating means for the tempering furnace to effectively utilize thermal energy. By using a radiant tube in the above-mentioned quenching furnace, the inside of the furnace can be made to have a high 02 concentration and the molding sand can be effectively deodorized.

In addition, it is possible to supply such a quenching furnace with a cast product that has been removed from the casting machine and still has residual heat, with mold sand attached to it. This eliminates a step, which ultimately results in a huge saving in thermal energy.

The heat treatment of the present invention begins immediately after the casting is taken out of the casting machine and placed on the supply table of the quenching furnace, and the casting is automatically fed into the quenching furnace where it is heated to the quenching temperature. After quenching, it is automatically supplied to the quenching furnace and is hardened. After quenching, it is automatically supplied to the tempering furnace where it is heated to the tempering temperature and taken out, which not only saves fuel but also improves quality. It has a variety of great effects, such as improving productivity, saving labor, shortening the process, reducing work space, and making the production process smoother.

In the above description, the embodiments have been described with respect to an aluminum cast cylinder head, but of course the present invention is applicable not only to cylinder heads but also to other aluminum cast products, and the present invention is applicable not only to aluminum cast products. It can also be applied to cast steel products.

Further, FIG. 4 is an explanatory diagram showing duct piping for each combustion exhaust gas discharged from several radiant tubes 8, 8', . . . adopted in the quenching furnace 3. Each combustion exhaust gas discharged from several radiant tubes 8, 8', . A recovery fan 32 is provided at the other end, and the delivery pipe 33 of the recovery fan 32 is provided with several branch pipes 34, 34', . 21', . By operating the hot air temperature control damper 31, the temperature of the combustion exhaust gas supplied to the tempering furnace can be controlled to an appropriate temperature. Further, a purge damper 35 is provided at one end of the delivery pipe 33. By operating the purge damper 35, the amount of combustion exhaust gas supplied to the tempering furnace can be controlled to an appropriate amount. In addition, the tempering furnace is provided with two damper-equipped smoke exhaust pipes 23.2ff. One damper-equipped smoke exhaust pipe 23 has its tip opened above the supply table 2 of the quenching furnace, and is then connected to the quenching furnace. If the cylinder head entering the cylinder is at a low temperature, it is used to preheat it to a certain temperature. Another smoke exhaust pipe 23' with a damper has its tip opened above the supply table of the tempering furnace, and is used to dry the cylinder head that is about to enter the tempering furnace or to preheat it to a certain temperature. .

Through the duct piping shown in Figure 4, the combustion exhaust gas from several radiant tubes used in the quenching furnace is controlled to an appropriate temperature and amount and is supplied to the tempering furnace for effective heating. and, if necessary, preheat the castings to be supplied to the quenching furnace and preheat the castings to be supplied to the tempering furnace.Then, the combustion gas for such preheating can be extracted. Even in such cases, the amount of combustion exhaust gas supplied to the tempering furnace can always be kept at an appropriate amount.

[Brief explanation of the drawing]

1, 2, and 3 are a side sectional view, a JiI-11 sectional view, and a plan view, respectively, of a heat treatment apparatus according to the present invention. FIG. 4 is an explanatory diagram showing a duct piping for combustion exhaust gas of a radiant tube including a tempering furnace. - 1 is a basket 2 is a supply tape 3 is a quenching furnace 4 is a discharge table 5 is a no-thrower 6 is an inlet door 7 is an outlet door 8 is a radiant tube 9 is a circulation blower 1
0 is a hopper 11 is a screw kider 12 is an elevator mechanism 13 is a quenching tank 14 is a slurry pump 15 is a tempering furnace 16 is an inlet door 17 is a common wall 18 is a basket 19 is a hearth roller 20 is an exit door 21 is a combustion gas introduction hole 22 is a circulation blower 23 is a smoke exhaust pipe with a damper 24 is a product removal table 30 is a recovery duct 31 is a hot air temperature control damper 32 is a recovery fan 33
is delivery pipe 34 is branch pipe 35 is barge dumper

Claims (3)

[Claims] (1) A cast product with molding sand attached is installed with a radiant tube and a circulation blower so that the 02 concentration in the furnace is 17% to 211, and hot air is forcibly circulated. The cast product is supplied to a quenching furnace, and the casting is heated to the quenching temperature by circulating hot air, and at the same time is heated to the quenching temperature by circulating hot air and high-temperature
The binder that solidifies the molding sand is converted into 4 by the concentration and loses its adhesive strength, and the molding sand is dropped from the cast product.The cast product taken out from the quenching furnace is supplied to the quenching tank, and then A method for heat treatment of a cast product, wherein the extracted cast product is supplied to a tempering furnace, and the heating of the cast product to the tempering temperature in the tempering furnace is performed by combustion exhaust gas from a radiant tube used in the quenching furnace. . (2) A radiant tube and circulation blower are installed to remove the cast product with molding sand attached, and the 02 concentration in the furnace is 17.
% to 21%, and is supplied to a quenching furnace in which hot air is forcedly circulated, and the casting is heated to the quenching temperature by the circulating hot air, and at the same time is heated to the quenching temperature by the circulating hot air. 02 concentration, the binder that solidifies the molding sand is precipitated and loses its adhesive strength, and the molding sand is dropped from the casting. The removed casting is supplied to a tempering furnace, where the casting is heated to the tempering temperature by the combustion exhaust gas of the radiant tube used in the quenching furnace, and is then discharged from the tempering furnace. A method for heat treatment of castings, in which the combustion exhaust gas from the furnace is used to preheat the castings on the supply table of the quenching furnace, and the castings on the supply table of the tempering furnace are preheated. (3) The quenching furnace 3 and the sintering furnace 15 are installed so that their populations and exits are located in opposite directions, respectively, and below the quenching furnace 3 pipes, and the sintering furnace 15 is installed above them. are placed in a stacked state, and the supply table 2 is placed in the quenching furnace 3.
A conveying means 5 is provided for conveying the casting from the quenching furnace 3 to its discharge table 4, and the quenching furnace 3 is equipped with one or several radiant tubes 8.811. and these radiant tubes are placed in the hot air circulation path, one or several circulation blowers 9.9', , , are provided, sand conveyance means 10.11 are provided at the bottom of the quenching furnace, An elevator mechanism 12 is provided in contact with the furnace outlet and the tempering furnace inlet, and a quenching barrel 13 is provided at the bottom of the elevator mechanism. The tempering furnace 15 is provided with a conveying means 19 for conveying the combustion exhaust gas, and the tempering furnace 15 has one or several combustion exhaust gas inlet holes connected to the combustion exhaust gas outlet pipes of one or several radiant tubes used in the quenching furnace. 21.21' , , , and these introduction holes are placed in the circulation path, and one or several circulation blowers 22 are installed.
．． 22'