JPH08257689A - How to add inoculants - Google Patents

Abstract

(57) [Summary] [Structure] In a method of adding an inoculant to a molten metal Y1 just before casting into the mold 2 and injecting the molten metal containing the inoculant into the mold, The level is detected by the level sensor 51, the molten metal surface level detected by this level sensor is compared with a predetermined reference level L1, and the amount of inoculant added from the inoculant adding mechanism 40 is based on this comparison result. A method for adding an inoculant, which comprises adjusting [Effect] Since the amount of the inoculant added can be adjusted to an appropriate amount according to the level of the molten metal in the product part, the amount of the inoculant added can be reduced and the casting cost can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adding an inoculant to a molten metal immediately before it is cast in a mold.

[0002]

2. Description of the Related Art Generally, in order to improve materials and produce high quality castings, an inoculant is often added to a molten metal immediately before being cast into a mold. For example, Japanese Patent Application Laid-Open No. 55-75855 discloses a technique of "inoculation agent addition method", and as shown in FIG. 1 of the above-mentioned publication, the technique adds the inoculation agent 1 stocked in the storage hopper 2. Supplied by the quantity adjusting device 3,
Further, the supplied inoculant 1 is pressure-fed by the air blower 5 and jetted out into the pouring water reservoir 8 of the mold 11 to add the molten metal 9 falling from the pouring ladle 10 to the mold 11. To do. The molten metal 9 flowing from the pouring molten metal reservoir portion 8 passes through the design portion and is filled in the product portion. Here, the "product part" is a so-called cavity. In addition, the “plan section” refers to a section excluding the product section, such as a sprue, a runway, and a cough.

[0003]

[Problems to be Solved by the Invention]
Generally, the addition is finished when the casting into the mold is finished.
The inoculant may be added only to the molten metal filled in the product part, but is also added to the molten metal filled in the design part. Therefore, the amount of the inoculant added is large, which increases the casting cost. An object of the present invention is to reduce the amount of inoculum added.

[0004]

Means and Action for Solving the Problems The present inventors have
Research the characteristics required for the method of adding the inoculant in detail,
We have succeeded in devising a method to control the amount of inoculant added when the level of the surface of the poured molten metal reaches a preset product site. Specifically, in the method of adding the inoculant to the molten metal just before it is cast into the mold and injecting the molten metal containing the inoculant into the mold, the level sensor detects the level of the molten metal surface of the product. , Compares the molten metal surface level detected by this level sensor with a predetermined reference level,
Based on the comparison result, the amount of the inoculant added is adjusted.

Further, the level of the molten metal surface is detected by a non-contact type level sensor through a peephole which extends upward from the product part and through which the product part can be seen directly.

[0006]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a configuration diagram of a mold casting apparatus according to the present invention. The mold casting apparatus 1 includes a mold 2 as a mold, and a gas / air supply unit 20 for supplying gas / air to the mold 2. Pouring mechanism 30 for pouring molten metal into mold 2 and gas / air supply unit 20
And a control mechanism 50 for controlling the pouring mechanism 30. Although not shown, the mold 2 is a separation type including a fixed type and a movable type. The mold 2 is formed with a product part 3, a plan part 4 connected to the product part 3, a feeder part 5 facing the outside of the product part 3 from the top, and a gas vent hole 6. As described above, the "product part 3" is a so-called cavity. Further, the "plan portion 4" means a portion excluding the product portion, and includes a sprue, a runway, a cough, and the like. A porous filter 7 for filtering impurities such as slag contained in the molten metal is interposed in the midway of the bill portion 4, and the porous filter 7 is made of, for example, a ceramic filter.

In the product section 3, a plurality of locations 3a where air is likely to remain, such as a blind alley portion, a complicated shape portion, a thin void portion (a portion forming a thin portion of a cast product) (hereinafter, "Pocket portion 3a ...") is formed. These pockets 3a ... Correspond to the shape of the cast product. For example, when the knuckle arm for an automobile is a cast product, the pocket parts 3a are provided at three to four places on the tie rod arm portion, the axle portion or the like. In this embodiment, upper and lower 4
The individual pocket portions 3a ... Are provided. These pocket portions 3a ... Are communicated with the outside of the mold 2 through mutually independent through holes 8. That is, the plurality of through holes 8 ... Formed in the mold 2 have a size through which gas can flow, the inner opening connected to the product part 3 is narrowed to a small diameter, and the outer opening connected to the outside of the mold 2 is gas. -Connected to the air supply unit 20.

The gas / air supply unit 20 is switched between a gas supply source 21 such as a gas cylinder for supplying an inert gas to the mold 2 and an air source 22 such as an air compressor for supplying high-pressure air to the mold 2. It consists of a four-way valve 23 as a valve. In the four-way valve 23, the first port a is connected to the gas supply source 21, the second port b ... Is connected to the air source 22, the third port c is connected to the outer opening of each through hole 8 ,. Port d is open to the atmosphere. For this reason, when the first port a and the third port c communicate with each other by the operation of the valve body incorporated in the four-way valve 23, the “gas supply path” is opened and the second port b is opened.
When the third port c and the third port c communicate with each other, the "air supply path" is opened, and when the third port c and the fourth port d communicate with each other, the "atmosphere opening path" is opened. As the inert gas, argon gas having a specific gravity larger than that of air is preferably used.

The pouring mechanism 30 is a pouring furnace 3 for putting the molten metal Y1.
1 and the valve body 3 for opening and closing the pouring port 31a of the pouring furnace 31
2, a drive source 33 such as an air cylinder for driving the valve element 32, and an inoculant adding mechanism 40 for adding an inoculant to the molten metal Y1. The inoculant adding mechanism 40 includes a hopper 41 that stores an inoculant to be added to the molten metal, and a feeder 42 that supplies a predetermined amount of the inoculant from the lower part of the hopper 41.
And a feed pipe 43 for feeding the inoculant from the feeder 42 to the pouring port 31a by natural fall. The inoculant is used to obtain a stable graphite structure. For example, Fe-Si
It consists of alloys.

The control mechanism 50 includes a level sensor 51 for detecting the molten metal level of the product section 3 and a display unit 52 for displaying or recording the molten metal level by the detection signal of the level sensor 51.
And a control unit 53 that controls the gas / air supply unit 20 and the pouring mechanism 30 based on the detection signal of the level sensor 51. The level sensor 51 extends upward from the product part 3 and allows the product part 3 to be directly seen (the feeder part 5 serves as a peephole) to measure the level of the molten metal surface. It is composed of a sensor, preferably an optical level sensor. The optical level sensor is, for example, an infrared type or laser type level sensor that measures a molten metal level by projecting a modulated light type infrared ray or a laser beam and measuring a reflection distance thereof. The control unit 53 may directly input the detection signal of the level sensor 51 regardless of the presence or absence of the display unit 52.

Specifically, the control unit 53 compares the molten metal surface level detected by the level sensor 51 with a predetermined reference level, and based on the comparison result, the drive source 33 and the inoculant adding mechanism 40. It controls the feeder 42. That is, the control unit 53 controls the plurality of parts L1 and L2 (hereinafter referred to as “first.
The second reference level ". ) Is reached by the level sensor 51, and the drive source 33 and the inoculant adding mechanism 40 are controlled. Further, the control unit 53 controls the four-way valve 2
3 switching control is performed.

The reference levels L1 and L2 are set as follows. That is, the first reference level L1 is a state where the molten metal Y2 added with the inoculant (hereinafter referred to as “inoculant-containing molten metal Y2”) is injected, and the molten metal Y1 not added with the inoculant (hereinafter, It is set to a level for switching to a state of injecting "molten metal Y1 without inoculant". The second reference level L2 is set to the uppermost level of the product unit 3.

Next, a typical use example of a method of adding an inoculant using the mold casting apparatus 1 having the above-mentioned structure will be described with reference to FIGS. 2 (a) to 2 (c) are explanatory views showing the first stage of the usage example of the method for adding an inoculant according to the present invention, FIG. 3 (a),
(B) is explanatory drawing which shows the latter part of the usage example of the addition method of the inoculant which concerns on this invention. First, as shown in FIG.
The fixed mold and the movable mold of the mold 2 are closed, and the control unit 53 (see FIG. 1) is operated. Along with this, the level sensor 51 starts detecting the molten metal level in the product unit 3. And FIG.
As shown in, the control unit 53 sends a switching signal to the four-way valve 23 to open the "gas supply path". Therefore, the inert gas flows and is filled into the product portion 3 (including the pocket portions 3a ...) And the design portion 4 through the path of the gas supply source 21-> the four-way valve 23-> the through hole 8.

Next, as shown in FIG. 2B, the product section 3
Then, the injection of the inoculant-containing molten metal Y2 is started via the plan unit 4. That is, the control unit 53 shown in FIG.
And an operation signal to the feeder 42. Therefore, the valve body 3
2 is pulled up by the drive source 33 to open the pouring port 31a, and the feeder 42 starts the supply of the inoculant in the hopper 41.
Therefore, the inoculant supplied from the feeder 42 is added to the molten metal Y1 during the injection. Then, the molten metal Y1 becomes the inoculant-containing molten metal Y2 to which the inoculant is added. The inoculant-containing molten metal Y2 is poured into the design unit 4. In addition, inoculant-containing melt Y
Immediately before the start of injection of No. 2, the control unit 53 sends a switching signal to the four-way valve 23 to open the "atmosphere opening path". Therefore, the inert gas filled in the pockets 3a is pushed by the inoculant-containing molten metal Y2 and discharged into the atmosphere.

After that, as shown in FIG. 2C, at the time when the molten metal surface level L0 of the inoculant-containing molten metal Y2 detected by the level sensor 51 reaches the first reference level L1, the control unit 53 causes the feeder. Send a stop signal to 42. Therefore, the feeder 42 is stopped. Therefore, since the supply of the inoculant is stopped, the inoculant-free melt Y1 is injected into the plan portion 4.

As the injection time elapses, as shown in FIG. 3A, the inoculant-free melt Y1 is filled in the upper part of the design part 4. As a result, the product portion 3 is gradually filled with the inoculant-containing molten metal Y2. After that, the control unit 53 controls the molten metal level L.
When 0 reaches the second set level L2, the injection of the molten metal into the product part 3 is stopped as shown in FIG. That is, the control unit 53 sends a stop signal to the drive source 33. Therefore, the valve body 32 is pulled down by the drive source 33 and the pouring port 31
A is closed and the injection of the melt Y1 without inoculant is completed.

By the way, the capacity of the plan portion 4 is set to be 1.1 to 1.2 times larger than the capacity of the product portion 3 between the first reference level L1 and the second reference level L2. Therefore, when the state of FIG. 2C is changed to the state of FIG. 3B, the lower end of the inoculant-containing molten metal Y2 is inside the plan portion 4. Therefore, there is no concern that the product portion 3 is filled with the inoculant-free melt Y1.

Next, when the cast product in the product section 3 is in a semi-solidified state (a shell-like solidified layer is formed on the surface layer and the inside is not solidified), the mold 2 is opened and the cast product is taken out (commonly known as , Called "quick casting."). Finally, the control unit 5
3 operates the four-way valve 23 shown in FIG. 1 to open the "air supply path". Therefore, the air is jetted to each of the through holes 8 ... In the path of the air supply source 22 → the four-way valve 23. Therefore, each through hole 8
The air is blown to remove foreign matter such as solidified matter that has accumulated inside. This completes the work.

According to this example of use, the inoculant is added at the time when the molten metal of an amount necessary to fully fill the product portion 3 is injected (when the molten metal surface L0 reaches the first reference level L1). Since it is stopped (the amount of inoculum added is adjusted to zero), the amount of inoculum added may be small. According to the experiment, in the case of the present embodiment in which the inoculant-containing molten metal is filled only in the product portion, about 20% inoculation is made as compared with the conventional case where the inoculant-containing molten metal is filled in the plan portion and the product portion. It was possible to reduce the number of agents.

Next, a modification of the method of adding the inoculant will be described with reference to FIG. 4 (a) to 4 (c) are explanatory views showing a modified example of the method of adding the inoculant according to the present invention, and show an example in which the amount of the inoculant added is changed depending on the site of the product part 3. Y
Reference numeral 11 is a molten metal to which no inoculant is added, Y12 is a molten metal with a large amount of the inoculant added, and Y13 is a molten metal with a small amount of the inoculant added. In the modified example shown in (a) and the modified example shown in (b), a large-diameter portion (a thick-walled portion) of the product portion 3 is filled with the molten metal Y13 containing a small amount of the inoculant, and a small-diameter portion ( Molten metal Y12 with a large amount of inoculant added to the thin part)
Molten metal Y that has been filled with the inoculant added to the design part 4
Fill 11. The modified example shown in (c) is such that when a casting of a long material such as a camshaft for automobiles is manufactured using a mold having a rapid temperature drop, an inoculant is added to the upper part of the product part 3. The molten metal Y13 with a small amount is filled, the molten metal Y12 with a large amount of the inoculant added is filled in the lower portion, and the molten metal Y11 with no inoculant added is filled in the plan portion 4.

In these modifications, the reference levels L11 ...
L13 is set as follows. That is, the first reference level L11 is set to a level for switching between the injection of the molten metal Y12 containing a large amount of the inoculant added and the injection of the molten metal Y13 containing a small amount of the inoculant added. Second reference level L12
From the injection of molten metal Y12 and Y13 to which the inoculant was added,
The level is set to switch to the injection of the molten metal Y11 to which no inoculant is added. Third reference level L13 is molten metal Y
It is set to the level for stopping the injection of 11 (the uppermost level of the product part 3).

When the molten metal surface level detected by the level sensor 51 reaches the first reference level L11, the control unit 53 sends an addition amount change signal to the feeder 42. Therefore, the feeder 42 increases or decreases the added amount of the inoculant. At the time when the molten metal level reaches the second reference level L12, the control unit 5
3 sends a stop signal to the feeder 42 to stop it. Therefore, the molten metal Y11 containing no inoculant is injected into the plan portion 4. When the molten metal level reaches the third set level L13, the controller 53 sends a stop signal to the drive source 33. Therefore, the valve body 32 is pulled down by the drive source 33 and the pouring port 3
1a is closed and the injection of the molten metal Y11 is completed. According to this modification, the amount of the inoculant added can be changed depending on the part of the product part 3, so that the material of the cast product can be changed for each part.
It can be more appropriate.

In the method of adding the inoculant in the above embodiment, the level of the molten metal in the product is detected by a level sensor, and the level of the molten metal detected by this level sensor is compared with a predetermined reference level. The amount of the inoculant to be added is adjusted based on this comparison result, and it is free to use other than the above-mentioned examples and modifications thereof, taking into consideration the shapes and dimensions of the product part and the plan part. The amount of the inoculant added can be arbitrarily set from zero to a predetermined amount.

Further, the peep hole of the die 2 extends upward from the product portion 3 so that the product portion 3 can be directly seen, and the level sensor 51 can measure the molten metal level L0. The configuration shown in FIG. 5 may be used. 5 (a) and 5 (b) are modification examples of the mold (main part) according to the present invention. (A) is a peephole 1 which communicates with the product part 3 and extends upward along the product part 3.
1 is formed, and the level L0 of the molten metal in the product portion 3 is measured through the inspection hole 11. According to the configuration of (a), the product section 3
Even if the feeder part 5 cannot play the role of a peephole due to its complicated shape, the molten metal level L0 can be measured freely. (B) is a modified example of (a) above, in which the lower portion 11a of the peephole 11 communicates with the plan portion 4. Lower part 11
The a is formed at a position where the level sensor 51 can measure the reference levels L1, L2, L11 to L13 shown in FIGS. According to the configuration of (b), since the length of the viewing hole 11 is shorter than that of the configuration of (a), the amount of extra molten metal accumulated in the viewing hole 11 can be reduced.

The "reference level" described in claim 1 is a reference level for adjusting the amount of the inoculant added. The "reference level" corresponds to, for example, the first reference level L1 of the embodiment shown in FIG. 1 and the first reference level L11 and the second reference level L12 of the modification shown in FIG. Here, the "first reference level L" of the embodiment shown in FIG.
1 ”indicates that the molten metal Y2 containing the inoculant is being injected.
This is a level for switching to a state where the molten metal Y1 without inoculant is injected. Further, the "first reference level L11" of the modification shown in FIG. 4 is a level for switching between the injection of the molten metal Y12 containing a large amount of the inoculant and the injection of the molten metal Y13 containing a small amount of the inoculant. . The “second reference level L12” of the modified example shown in FIG. 4 is the molten metal Y12 containing the inoculant,
This is a level for switching from the injection of Y13 to the injection of the melt Y11 to which no inoculant is added.

[0026]

The manufacturing method of the present invention has the following effects. In the method of adding an inoculant according to claim 1, the level sensor detects the level of the molten metal in the product, and the molten metal level detected by the level sensor is compared with a predetermined reference level. By adjusting the amount of inoculant added based on the above, the amount of inoculant added can be adjusted to an appropriate amount according to the level of the molten metal surface of the product, so the amount of inoculant added can be reduced and casting costs reduced. it can.

In the method of adding the inoculant according to the second aspect, the level of the molten metal surface is detected by a non-contact type level sensor through a peephole extending upward from the product portion so that the product portion can be directly seen. This makes it possible to measure the level of the molten metal with high accuracy, which is optimal when adjusting the amount of the inoculant added according to the level of the molten metal.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a mold casting apparatus according to the present invention.

FIG. 2 is an explanatory diagram showing the first stage of a usage example of the method for adding an inoculant according to the present invention.

FIG. 3 is an explanatory diagram showing the latter stage of a usage example of the method for adding an inoculant according to the present invention.

FIG. 4 is an explanatory view showing a modified example of the method of adding an inoculant according to the present invention.

FIG. 5 is a diagram showing a modification of the mold (main part) according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Mold casting apparatus, 2 ... Mold, 3 ... Product part, 4 ... Design part, 5 ... Peephole (rise), 30 ... Pouring mechanism, 40 ... Inoculant adding mechanism, 41 ... Hopper, 42 ... feeder, 50 ... control mechanism, 51 ... level sensor, 53 ... control unit, L0 ... molten metal level, L1, L2, L11 to L13 ... reference level,
Y1, Y2, Y11 to Y13 ... Molten metal.

Claims (2)

[Claims] 1. In a method of adding an inoculant to a molten metal immediately before casting into a mold and pouring the molten metal containing the inoculant into the mold, the level sensor detects the level of the molten metal surface of the product. A method for adding an inoculant, which comprises comparing a molten metal surface level detected by the level sensor with a predetermined reference level, and adjusting the amount of the inoculant added based on the comparison result. 2. The level of the molten metal surface is detected by a non-contact type level sensor through a peephole which extends upward from the product portion so that the product portion can be seen directly. Method of adding inoculants.