JPS63224837A - Net-like filter structural body - Google Patents

Abstract

PURPOSE:To prevent mispositioning and dropping of casting sand to a molten metal flowing path by fixing circumferential edge part of net-like filter formed by the special glass fiber fitting frame formed by burning body of refractory. CONSTITUTION:In the net-like filter structural body 1, the circumferential edge part of net-like filter 4 is held as burying and fixed to the filter fitting frame 2 forming the molten metal flowing hole 3. And, the filter fitting frame 2 burys the circumferential edge part of the net-like filter 4 into the refractory powder and after pressurizing this to form, it is burnt. Then, the net-like filter 4 coated to the filter fitting frame 2 is the one, which net-like textile woven by the glass fiber having >=75wt.% of SiO2 content is burnt together with the fitting frame 1 at the burning process for the filter fitting frame 1. Therefore, the fitting frame 2 is not collapsed by molten metal heat and at the time of setting the filter to the molten metal flowing path, it can be easily and surely executed and the drop out in the mold is not developed.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is a filter for filtering cast iron and molten cast steel,
This invention relates to what is provided on the mold dividing surface of a sand mold making mold.

(Prior art) When non-metallic inclusions such as slag, which are thermosensitively suspended in ferrous metal such as cast iron or cast steel, flow into the casting cavity together with the molten metal, the slag floats to the surface of the casting and solidifies, causing a black crust on the casting. It aggregates directly below and becomes a casting defect.

Therefore, in order to prevent slag and the like from entering the casting cavity, molten metal filters are installed in molten metal flow paths such as sprues and runners.

Conventionally, as filters applicable to molten metal filtration, strainer cores (porous ceramic filters) made of a solid refractory material, alumina Hanica J type strainers, and foam type strainers made of silicon carbide have been put into practical use. .

However, strainer core and honeycomb types have a small filtration effect, and foam types have a three-dimensional network skeleton structure, so they are prone to clogging, have a large molten metal flow if5 resistance, and delay casting time. It has the disadvantage that casting defects such as poor rotation and mold wrinkles are likely to occur. In addition, honeycomb type and foam type are expensive and less economical.

On the other hand, mesh-type carbon fiber or glass fiber filters have been put into practical use, but these only function as filters for low-melting point metals such as molten aluminum; At present, it cannot be used at all for high-melting-point molten metals.

(Problems to be Solved by the Invention) Therefore, in Japanese Patent Application No. 60-235032, the present inventor developed a mesh filter made of glass fiber that can be used even for high melting point molten metal.

This mesh filter is formed into a mesh shape using glass fibers having an SiO□ content of 75% by weight or more, and is previously shrunk by firing. In addition, phenol resin, silica sol solution, etc. are often applied to impart shape retention.

As shown in FIG. 5, the mesh filter is usually disposed on the mold dividing surface 24 at the bottom of the sprue channel 23 formed by transitioning from the sand molded upper mold 2I to the lower mold 22.
It is used while being held between L22. In the same figure, 2
5 is a mesh filter, 26 is a sprue bottom, 27 is a runner channel,
28 is a feeder casting space, 29 is a product casting space, and 30 is a core for installing a filter.

However, since the net filter 25 is light, usually weighing less than 10 g, it may become misaligned when moving the mold or when cleaning the casting cavity with air blow, and may not function as a filter.

Further, since the filter is fixed by being held between the upper die 21 and the lower die 22, a large pressing area is required, which inevitably reduces the effective usable area.

Furthermore, when the filter is held, the filter is pushed into the sand mold surface, causing the mold to become deformed, and the casting sand to fall into the molten metal channel, resulting in casting defects such as sand pits.

The present invention was developed in view of these problems, and when installing the mesh filter in the molten metal flow path, it is difficult to cause misalignment, requires less pressing allowance, and also prevents casting sand from falling into the molten metal flow path. It is an object of the present invention to provide a filter for filtering high melting point metal molten metal that can prevent the above problems.

(Means for Solving the Problems) The filter of the present invention, which has been made to achieve the above object, has molten metal flow holes 3.3a formed in the filter mounting frames 1 and 1a, and has a SiO□ content. A peripheral portion of a mesh filter 4.4a formed of glass fiber of 75% by weight or more is fixed to the mounting frame 1, 1a, and a central portion thereof is located in the molten metal flow hole 3, 3a portion, and the According to the invention, the filter mounting frames 2 and 2a are formed of a fired body of refractory material.

(Function) The periphery of the mesh filter is fixed to the filter mounting frame, and the center part is attached to the molten metal flow hole formed in the mounting frame, so it is easy to install the mesh filter in the molten metal flow path. In this case, it is sufficient to install the above-mentioned mounting frame together, which makes the installation easy and prevents the filter from shifting.

In addition, when installing the mounting frame, there is no need to hold the mounting frame between the molds, and it is only necessary to store the mounting frame in the four parts appropriately provided in the molten metal flow path. It is possible to prevent sand from falling.

In addition, since the filter mounting frame is made of a fired refractory material, it is thermally stable and will not collapse even when exposed to the heat of molten metal.Therefore, the mesh filter can be securely attached to the filter mounting frame with less sticking. can be fixed to.

Further, since the mesh filter has a 5iO7 content of 75% by weight or more, it has excellent heat resistance and can filter iron-based high melting point molten metal.

(Example) Next, an example of the present invention will be described with reference to the drawings.

The mesh filter structure 1 according to the embodiment shown in FIG.
A peripheral portion of a mesh filter 4 is embedded and fixed in a filter mounting frame 2 in which a molten metal flow hole 3 is formed.

The filter mounting frame 2 is obtained by embedding the peripheral edge of the reticular filter 4 in refractory material powder, press-molding it, and then firing it.

As the refractory material powder, a usual refractory brick raw material powder can be used, and examples thereof include waxite powder, chamotte powder, silica powder, and the like.

In the filter mounting frame 2, a mesh filter 4 is provided.
A solid portion 7 made only of fireproof material is formed between the peripheral edge of the mounting frame 2 and the outer peripheral side surface of the mounting frame 2.

By forming such a solid portion 7, the filter mounting frame 1 becomes difficult to be separated even by the presence of the mesh filter 4. Particularly effective during molding. In addition, enhancement part 7
The width, that is, the distance between the peripheral edge of the mesh filter 4 and the outer peripheral side surface of the mounting frame 2, is preferably set to 211 mm or more.

The center portion of the mesh filter 4 attached to the molten metal flow hole 3 is preferably left slack as shown in FIG. This is because the mounting frame 2 expands during molten metal filtration, and the central portion of the mesh filter 4 tends to contract. The amount of slack is
The tension should be such that no tensile stress is applied to the center of the filter.

A mesh filter 4 attached to a filter mounting frame 2
A net-like woven fabric made of glass fiber having a Si0g content of 75% or more was fired together with the filter mounting frame 1 during the firing process of the filter mounting frame 1.

The reason why the SiO□ composition of the glass fiber is set to 75% by weight or more is that, as the inventor of the present invention clarified in Japanese Patent Application No. 60-235032, it is compatible with all kinds of molten cast iron at temperatures below 1450°C. . If 5i02 is of high purity, it can be applied to molten cast steel at 1500°C or higher. Here, compatibility means that the glass fibers do not turn into slag even when immersed in molten metal for 20 seconds. Said 2
The reason for 0 seconds is that most of the normal pouring time is within this time.

As a method for increasing the SiO□ composition in the glass fibers to 75% by weight or more, after weaving a reticulated woven fabric using glass fiber with a low 5i02 content that is rich in economy and processability, the reticulated woven fabric The SiO□ content may be highly purified by subjecting it to acid treatment as described below.

The acid treatment is performed by immersing a reticulated fabric woven from glass fibers with a low 5i02 content in an acidic solution such as hydrochloric acid, nitric acid, or sulfuric acid to which a catalyst for accelerating the reaction is added. , Cab, which is an impurity in the glass fiber, while controlling the concentration of the acidic solution.

MgO, FezO3, Crz(L++ Na2oz+
This process lowers the content of K2O1Ti0z+BzOz, etc., and increases the content of 5iO7 as a result.

The area porosity of the mesh filter 4 is 12.5 to 32.5.
% is preferable. This is because within this range, delays in casting time are less likely to occur, and the casting can be easily divided at the filter installation part. Incidentally, the area porosity ratio (%) is expressed as the mesh pore area on the filter surface x100/total surface area of the filter. In addition, casting time delay refers to the difference between the casting time until the molten metal fills the casting cavity when a filter is used and the casting time when a filter is not used. If this value is large, the casting time will be poor. Casting defects such as hot water and hot water wrinkles are more likely to occur.

After the reticular filter structure 1 described above is compression-molded using the mold illustrated in FIG.
0 (preferably 1200 to 1350)" c. In the figure, a mesh filter material 40 is vertically slidable in a tapered molding chamber 42 formed inside a cylindrical outer mold 41. It is sandwiched between an upper mandrel 43 and a lower mandrel 44. 45 is a refractory material powder;
6.47 are upper and lower pressure plungers.

The refractory material powder 45 is filled around the periphery of the mesh filter material 40 in the form of powder or slurry.

As the reticulated filter material 40, a reticulated woven fabric coated with a shape preservation agent is suitable because of its good workability. Note that the shape retaining agent burns and disappears during the firing process.

By the way, it is also possible to mold the filter mounting frame by Pepse Soto molding, cold box molding, shell molding, etc., but in this case, there is a risk that the sand frame will collapse due to the heat of the molten metal, so the filter mounting frame of the present invention is not suitable. Difficult to apply.

FIG. 3 shows a mesh filter structure 1a according to another embodiment.
shows. In this embodiment, the peripheral edge of the mesh filter 4a is fixed to the lower surface of the filter mounting frame 2a with an inorganic adhesive such as silica/alumina adhesive.

The center portion of the mesh filter 48 is attached to the molten metal flow hole 3a of the filter mounting frame 2a, and leaving the center portion slack is effective in preventing damage, as in the previous embodiment.

As the reticular filter 48 used in this embodiment, any one can be used, regardless of whether or not a shape preservation agent is applied. In addition, if the mesh filter 48 is attached with a slack central portion, there is no need to shrink the glass fibers in advance to prevent shrinkage.

FIG. 1 shows the procedure for installing a mold for the reticulated filter structure of the present invention as described above. In the figure, a sprue passage 13 is formed by transitioning from the second mold 11 to the lower mold 12, and is opened at the mold dividing surface of the lower mold 12 and installed along the inner circumferential surface of the sprue passage 13. A recess 14 is provided, and the reticular filter structure 10 according to the present invention is accommodated in the recess I4.

Reference numeral 15 denotes a runner flow path, and a product casting space etc. is formed in front of this, as is conventional.

By using the mesh filter structure according to the present invention, it is possible to omit the filter installation core 30 as in the conventional case, and the molten metal can flow extremely easily and reliably without having to sandwich the filter between the upper mold and the lower mold. Can be installed on the road.

(Effects of the Invention) As explained above, the reticular filter structure of the present invention has the following features:
Since the peripheral edge of the mesh filter is fixed to the filter mounting frame formed of a fired body of refractory material, the mounting frame will not collapse due to the heat of the molten metal, and therefore the peripheral edge of the mesh filter will be less likely to stick. Can be securely fixed to the filter mounting frame. In addition, when installing the filter in the molten metal flow path, there is no need to hold it between the upper mold and the lower mold, and it can be installed easily and reliably.
Moreover, the mold does not lose its shape. Furthermore, since there is no need to provide a core for installing a filter as in the prior art, the mold structure can be simplified.

Further, the mesh filter is made of glass fiber with a Si0g content of 75% or more, has excellent heat resistance, and can filter high-temperature molten metal such as cast iron.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a mesh filter structure according to an example;
FIG. 2 is an explanatory cross-sectional view of a main part of a mold for the same structure, FIG. 3 is a cross-sectional view of a mesh filter structure according to another embodiment, and FIG.
The figure is an explanatory cross-sectional view of a main part of a mold showing how to install a mesh filter structure, and FIG. 5 is a cross-sectional view of the mold in which a mesh filter is installed. 2+28---Filter mounting frame, 3,3a-molten metal flow hole, 4.4a--reticular filter. Figure 5

Claims (4)

[Claims] (1) Molten metal flow holes 3, 3a in filter mounting frames 1, 1a
Reticulated filters 4, 4 formed of glass fibers with a SiO_2 content of 75% by weight or more
The peripheral part of the filter a is fixed to the mounting frame 1, 1a, and the center part thereof is located in the molten metal flow hole 3, 3a, and the filter mounting frame 2, 2a is formed of a fired body of refractory material. A mesh filter structure characterized by: (2) The peripheral edge of the mesh filter 4 is attached to the filter mounting frame 2
A reticular filter structure according to claim 1, wherein the reticulated filter structure is embedded in and fixed to. (3) A solid portion 7 made of only a fireproof material is formed on the outer periphery of the mounting frame 2 between the periphery of the mesh filter 4 and the outer peripheral side of the filter mounting frame 2. Reticulated filter structure. (4) The mesh filter structure according to any one of claims 1 to 3, wherein the mesh filters 4, 4a are attached in a slack state in the molten metal flow holes 3, 3a.