JPH07110393B2 - Vacuum cover for vacuum casting - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vacuum casting suction means for sucking gas generated by thermal decomposition from a sand mold when the sand mold is cast.

(Prior Art) When casting is performed using a sand mold, the organic binder in the sand mold is burned by the molten metal, and a large amount of gas is generated. This gas is discharged to the outside through a riser hole and a lift (brush) hole formed in communication with the casting cavity in the sand mold.

However, when the core mold formed of the sand mold is provided in the main mold formed of the sand mold, the gas generated from the core mold is difficult to be discharged to the outside, and therefore it is disclosed in JP-A-57-160565. As shown in the figure, a plurality of gas vent holes communicating with the core die are provided in the main body die, a suction pipe connected to a suction pump is inserted into the gas vent hole, and the gas generated from the core die is inserted by the suction pipe. It is forcibly sucked and discharged to the outside.

(Problems to be Solved by the Invention) However, even with the above means, it is necessary to perform a hole processing such as a riser hole in the main body mold and a step of removing the riser metal after casting. In addition, there is a problem that the work of connecting the suction pipe to each gas vent hole is troublesome and inferior in workability, and further the mold is likely to lose its shape at the time of connection, and casting defects such as sand bite are likely to occur.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a vacuum casting suction means that does not require a riser hole to be formed in a sand mold to process a lifting hole, and that suction work is easy and the shape of the mold does not collapse. To do.

(Means for Solving the Problems) Means of the present invention made to achieve the above object is that a core mold formed of a sand mold is housed in a main mold formed of a sand mold, and the core mold is A suction cover (1) which is placed in close contact with the upper surface of the main body mold of a mold having communicating gas vent holes in the peripheral portion of the upper surface of the main body mold, and the inside of the suction cover (1) is a peripheral area where the lower surface is opened. The space portion 2 and the central space portion 3 are defined and formed, suction holes 5 and 6 communicating with the space portions 2 and 3 are opened, and the peripheral space portion 2 and the gas vent hole are communicated with each other. It is to be configured. In this case, a safety valve communicating with each space of the suction cover may be provided.

(Operation) The air in the casting cavity formed between the main mold and the core mold, and the gas generated by the thermal decomposition of the core mold pass through the gas vent holes formed in the main mold, and then the upper surface of the main mold. Through the lower surface opening of the peripheral space inside the suction cover placed closely to
It is discharged to the outside from a suction hole communicating with the peripheral space portion through an appropriate suction means. On the other hand, the air in the casting cavity and the gas generated by the thermal decomposition of the main mold pass through the gaps of the casting sand particles in the main mold, pass through the lower surface opening of the central space in the suction cover, and communicate with the central space. It is discharged from the suction hole to the outside through an appropriate suction means. Since the casting cavity is in a depressurized state due to suction by the suction cover,
It is possible to easily fill the molten metal without the need for hot water or deep frying.

At this time, since each space of the suction cover is divided and formed, by connecting a separate suction means to each space, the gas generated from the sand and the air in the casting cavity are made into the mold structure. It can be effectively discharged regardless.

Further, since the suction cover only needs to be placed on the upper surface of the main body mold, connection work is easy and mechanization can be easily performed. Further, the gas vent holes may be formed so as to open in the peripheral portion of the upper surface of the main body mold and can be freely arranged, so that one type of suction cover can be used for various types of molds.

The gas generated by burning the binder in the sand mold contains explosive H ₂ and CO gas. During suction, these gases fill each space of the suction cover. Due to the high heat of the molten metal injected into the casting cavity, the gas in the gap of the casting sand in the sand mold is ignited, and this flame may be transmitted to each space and cause an explosion inside the cover. By providing a safety valve on the suction cover, even if an explosion occurs,
The high pressure inside the cover can be easily released to the outside, and damage to the cover and accidents accompanying it can be prevented.

(Example) Hereinafter, the Example of this invention is described based on drawing.

1 to 4 show a suction cover 1 and a mold 31 on which the cover 1 is placed according to an embodiment.

The mold 31 includes an upper mold 34 having an upper body mold 33 formed in an upper frame 32, a lower mold 37 having a lower body mold 36 formed in a lower frame 35, and upper and lower body molds 33, 36. It is composed of a core mold 38 interposed between the upper and lower body molds 33 and 36 and a core mold 3
8 is a sand type such as a raw type and a dry type.

A cavity 39 for casting a product is formed between the upper and lower body dies 33, 36 and the core die 38, and a runner 40 is formed below the cavity 39 so that the runner 40 is an upper body die. A pouring port 41 is opened on the upper surface of the 33.

The core die 38 has a stepped tubular shape, and a hollow portion 42 is formed with a gas vent hole 43 that is open in the peripheral portion of the upper surface of the upper body die 33.

The casting mold 31 is not provided with a riser hole or a lift hole as in the conventional case. The lower mold 37 is a flat plate pallet.
Mounted on 44. The pallet 44 is circulated in a molding place, a pouring place, a sand treatment place, etc. by a conveying means such as a conveyor.

A suction cover 1 made of cast iron is removably and closely mounted on the upper surface of the upper main body 33 at the center or below. A peripheral space 2 is provided inside the suction cover 1 through a partition wall 4.
And the central space portion 3 are partitioned and formed, and each space portion 2, 3
The lower surface of is open and communicates with the upper surface of the upper body mold 33. The opening of the gas vent hole 43 communicating with the core mold 38 is opened at a position communicating with the lower surface opening of the peripheral space 2. The lower surface of the partition wall 4 and the lower surface of the peripheral edge of the suction cover 1 are in close contact with the upper surface of the upper body die 33, and thus the upper surface of the upper body die 33 is divided into a concave peripheral area and a central area. Each area is independently communicated with the opening of each space 2, 3 of the suction cover 1. The upper peripheral area where the pouring port 41 is open is outside the suction cover 1 and is exposed to the atmosphere. 4A is a sealing material, but it is not always necessary.

In the upper part of the suction cover 1, a plurality of pairs (three pairs in the illustrated example) of a pair of suction holes 5 and 6 communicating with the peripheral space 2 and the central space 3 are provided.

An opening / closing valve 7 is attached to each of the suction holes 5 and 6.
In FIG. 1, only one on-off valve 7 is drawn and the others are omitted. The opening / closing valve 7 includes a main body 8 attached to the suction holes 5 and 6, a valve body 9 for opening and closing a flow path of the main body 8,
A spring for biasing and closing the flow path inlet portion 12 of the valve body 9
10 and a valve rod 11 for separating the valve body 9 downward against the elastic force of the spring 10, and the upper portion of the valve rod 11 projects above the main body 8. Therefore, when the downward force is not applied to the valve rod 11, the suction holes 5 and 6 remain closed, and the valve rod 11
By pressing down, suction holes 5, 6 and open / close valve 7
The channel is in communication with. At this time, by connecting suction means to the flow path outlet portion 13 of the opening / closing valve 7, the respective space portions 2 and 3 in the suction cover 1 are in a suction state. A specific example of the suction means will be described later.

Further, at the upper part of the suction cover 1, there are provided openings 14 and 15 for attaching a safety valve, which are communicated with the spaces 2 and 3, respectively.
4, 15 and 16, lids 16 and 17 functioning as safety valves are attached by hinges so that they can be opened and closed. Lid 16,1
7 is in a normally closed state due to its own weight, and is in an open state when the pressure in each space 2, 3 becomes equal to or higher than atmospheric pressure. 18 is a suction cover 1
It is a hanging metal fitting for handling. Reference numeral 19 is a positioning pin that engages with the upper frame 32.

5 to 6 exemplify a suction means which is attached to the on-off valve 7 and sucks the gas in the suction cover 1. The suction means includes a pair of suction cups 51, 52 and a suction cup 5
Lifting cylinders 53 for fitting 1,52 into the opening / closing valve 7 of the pair of suction holes 5,6 of the suction cover 1, and the suction cups 51,5
A pair of conduits 5 for directing the gas in 2 to separate suction sources
It has 4,55 and. Note that the conduits are shown as overlapping because they are shown as overlapping.

Each of the suction cups 51, 52 has an elastic seal member 56 attached to the lower end thereof, and is slidably attached to an elevating shaft 59 vertically provided on an elevating plate 58 via a spring 57. The elevating plate 58 is supported by a guide rod 66, and ascends and descends by the elevating cylinder 53. A large diameter portion 60 is formed at the lower end of the elevating shaft 59, and the upper portions of the suction cups 51 and 52 are urged toward the large diameter portion 60 side by the spring 57. On the other hand, the suction cups 51, 52 are provided with an elevating cylinder 61 communicating with the space inside the cups 51, 52, and the elevating cylinder 61 is slidably inserted into a suction box 62 via a packing 67. ing. The suction box 62 is connected and fixed to the front ends of the conduits 54, 55. Both the conduits 54, 55 are fixed to a support 63, and at the rear end of each conduit 54, 55, an intake valve 64 whose pressure can be adjusted by adjusting the valve opening is provided.
It is connected to a suction source such as a separate blower, fan or pump via a connecting pipe 65. An intake valve or a dust collector that can be remotely controlled may be provided in the middle of the pipe of the suction source. Further, the lower ends of the suction cups 51, 52 are open, and the air is constantly sucked by operating the suction source. In the figure,
The arrows indicate the suction directions of air and gas.

Next, a method of using the suction cover 1 of the embodiment will be described.

First, the suction cover 1 is placed on the upper surface of the mold 31. At this time, the hanging metal fitting 18 is used and positioned by the positioning pin 19.

Next, the lifting cylinder 53 of the suction means is lowered to bring the lower edges of the pair of suction cups 51, 52 into contact with the upper surface of the mounting flange 20 of the main body 8 of the on-off valve 7 mounted in the pair of suction holes 5, 6. . Further, the lifting shaft 59 is lowered against the spring 57, and the large diameter portion 60 of the lifting shaft 59 is brought into contact with the upper end of the valve rod 11 and pushed down. As a result, the spaces 2, 2 inside the suction cover 1 are brought into communication with the two systems of suction sources, and the air in the mold 31 is exhausted through the gaps between the sand grains of the sand mold. The pair of suction cups 51, 52 may be attached to any one of the three pairs of suction holes 5, 6 to which the opening / closing valve 7 is attached.

In this state, when the molten metal is injected from the pouring port 41, the casting cavity 39 is in a depressurized state, so that the molten metal is quickly filled. Further, the gas generated by the thermal decomposition of the sand in the surface layer of the casting cavity 39 is exhausted to the outside from the suction cover 1 through the space between the sand grains of the upper and lower body molds 34, 37 and the gas vent hole 43. . At this time, the suction source capacity of each system and the intake valve 64
By adjusting the opening degree, the negative pressure in the peripheral space portion 2 of the suction cover 1, and thus in the hollow portion 42 of the core mold 38 and the central space portion 3 is adjusted. The gas flow velocity in the pipe to the suction source is set so that the external air is sucked into the intake valve 64 so that the gas flow velocity is faster than the flame propagation velocity (preferably 30 m / s or more) and the gas concentration is lowered below the explosion limit. It is better to inhale by

After the pouring, the suction is continued until the molten metal in the casting cavity 39 is solidified. After that, the suction cup 51 rises and the suction hole of the suction cover 1 is opened by the spring 10 in the opening / closing valve 7.
5 and 6 are closed. Then, using the hanging metal fitting 18, the suction cover 1 is unloaded, that is, removed from the mold 31. The mold 31 is unmolded as in the conventional case, and the product is taken out.

In the above embodiment, the suction cover 1 has a pair of suction holes 5 and 6.
Although three sets are shown, at least one set is enough. However, if there are three sets, it is convenient to suction while moving the mold 31. That is, the mold 31 is normally and intermittently transferred to the suction cover loading station S1, the pouring station S2, the coagulation and suction cover unloading station S3 in the direction of the arrow in FIG. ing. In S1 and S3, the fixed suction means sucks air through suction holes 5 and 6 having two sets of rear and front on-off valves in the direction of the arrow. From S1 to S3, by suction means that can move between this,
Intake is performed through suction holes 5 and 6 equipped with a pair of open / close valves in the center.
At this time, the suction means on the moving side can be attached while the suction means on the fixed side is attached, and vice versa, so that the suction state can be always secured.

In addition, the gas vent holes 43 communicating with the core mold 38 may be provided in an appropriate number. At that time, even if the product shape is changed, the opening of the gas vent holes corresponds to the peripheral space of the suction cover 1, Since it may be opened in the peripheral area on the upper surface of the upper main body mold 33, one type of suction cover 1 can be used for various types of molds.

(Effects of the Invention) As described above, according to the suction cover of the present invention, vacuum suction can be performed simply by placing the suction cover on the upper surface of the main body mold formed of the sand mold, and the suction work is extremely simple. Therefore, it is not necessary to provide a riser hole or the like in the main body mold, and the mold shape is unlikely to occur, resulting in excellent productivity. In addition, the suction cover has a peripheral space portion and a central space portion that are independently partitioned and formed, and a separate suction hole is provided in each of them, so that gas and core generated from the main body mold during casting are formed. The gas generated from the mold can be effectively sucked and removed according to the generated amount.

Also, by providing a safety valve in the suction cover, even if the decomposition gas containing CO and H ₂ is explosively combusted in the cover, the pressure inside the suction cover does not become high. It is possible to prevent damage to the car and accidents caused by this, and it is excellent in safety.

[Brief description of drawings]

FIG. 1 is a plan view of a suction cover and a mold according to an embodiment,
2 is a sectional view taken along line AA of FIG. 1, and FIG. 3 is B of FIG.
-B line sectional view, FIG. 4 is a sectional view of a main part of the suction cover, FIG.
FIG. 6 is a sectional side view of the main part of the suction means, and FIG. 6 is a front view of the suction means. 1 ... Suction cover, 2 ... Peripheral space, 3 ... Central space, 5,6 ... Suction hole, 16, 17 ... Lid

Front page continued (72) Inventor Kenji Kibumi 7-22, Minamienkajima, Taisho-ku, Osaka-shi, Osaka Prefecture Kubota Iron Works Co., Ltd., Onkajima Plant (72) Inventor Naoki Ueda, Minamienkajima, Taisho-ku, Osaka-shi, Osaka 7-1-222 Kubota Iron Works Co., Ltd., Onkajima Plant (56) Reference JP-A-1-289538 (JP, A) JP-A-51-104430 (JP, A) JP-A-3-216258 (JP, A) A) Actual public Sho 35-10711 (JP, Y1)

Claims (2)

[Claims] 1. A main body of a mold in which a core mold made of a sand mold is housed in a main mold made of a sand mold, and a gas vent hole communicating with the core mold is opened in a peripheral portion of an upper surface of the main mold. A suction cover (1) placed in close contact with an upper surface of a mold, wherein a peripheral space portion (2) having a lower surface opened and a central space portion (3) are partitioned inside the suction cover (1). It is characterized in that suction holes (5) and (6) that are formed and communicate with the respective space portions (2) and (3) are opened, and that the peripheral space portion (2) and the degassing hole communicate with each other. Suction cover for vacuum casting. 2. A space (2) for each space in the suction cover (1).
The suction cover for vacuum casting according to claim (1), wherein safety valves (16) (17) communicating with (3) are provided.