CN111496183A - Pouring system and pouring process for ductile iron thin-wall part - Google Patents

Abstract

The invention discloses a pouring system and a pouring process of a ductile iron thin-wall part, which comprise a sprue, a lower cross runner, an upper cross runner, an inner runner, an outer riser and a casting which are connected in sequence, wherein an oil drain boss is arranged at the edge of the bottom of the casting, a sand core is placed in the casting, a feeding head is arranged in the sand core corresponding to the oil drain boss, and the feeding head comprises a riser sleeve and a riser neck seat fixed at the lower end of the riser sleeve. According to the invention, the independent hot spot is provided with the built-in feeding head, and a sand core pre-embedded process is adopted, so that the later sand core assembly is reduced, and the operation time is saved; the built-in feeding head can be separated by adopting a common separation method, so that the repair work of a cold iron surface of a casting is reduced, the production efficiency is improved, and the product can be prevented from being knocked out and scrapped due to misoperation of operators; the built-in feeding riser of the independent heat joint pre-buried in the sand core is beneficial to discharging scum in molten iron, so that the surface quality of the bottom is improved, and the defects caused by later repair errors are avoided.

Description

A pouring system and pouring process for ductile iron thin-walled parts

technical field

The invention relates to the field of casting of ductile iron thin-walled parts, in particular to a casting system and a casting process of ductile iron thin-walled parts.

Background technique

The gating system of ductile iron castings is generally composed of sprue, lower runner, upper runner, inner runner, riser, and castings. First, the molten iron passes through the sprue cup, sprue, runner, and inner runner. And the riser flows into the product until all filling is completed, and then the molten iron solidifies and cools. Due to the difference in the wall thickness of the same casting, the solidification shrinkage rate is different, and the thick-walled body solidifies and shrinks later than the thin-walled body. Due to the solidification characteristics (mushy solidification), the thick-walled parts of the same casting are prone to defects such as shrinkage porosity and shrinkage cavities. Therefore, under normal circumstances, cold iron technology is used for countermeasures. However, after the cold iron is used, there will be appearance defects such as chill marks and edge marks on the surface of the casting, which must be trimmed and removed later. If the location of the defect is not convenient for manual trimming, special equipment must be used for cutting. , which affects production efficiency and is not conducive to mass production.

At present, the cylindrical thin-walled ductile iron casting ordered by the customer has an independent boss at the bottom edge that is larger than 2.5 times the wall thickness. The boss is the hot node of the casting body, and its heat conduction will be significantly slower than the casting body. Internal defects will also be caused by this. Therefore, how to supplement the shrinkage of molten iron at the boss and eliminate casting defects is the direction of this research.

SUMMARY OF THE INVENTION

In order to solve the above problems, the purpose of the present invention is to provide a pouring system and pouring process for ductile iron thin-walled parts, and an independent built-in feeding riser is arranged at the hot node of the product to solve the feeding of the hot node of the product.

In order to realize the above-mentioned technical purpose and achieve the above-mentioned technical effect, the present invention is realized through the following technical solutions:

A pouring system for ductile iron thin-walled parts, comprising a sprue, a lower runner, an upper runner, an inner runner, an outer riser and a casting which are connected in sequence, and an oil drain is arranged at the bottom edge of the casting A boss, a sand core is placed inside the casting, a feeding riser is arranged in the sand core corresponding to the oil drain boss, and the feeding riser includes a riser sleeve and is fixed on the riser Set the lower end of the riser neck seat.

Further, the connection between the feeding riser and the oil drain boss is a riser neck, and the riser neck seat is connected to the riser neck.

Further, the riser sleeve and the riser neck seat are fixed by casting adhesive.

Further, the thickness of the oil drain boss is greater than 2.5 times the wall thickness of the casting.

Further, the modulus of the feeding riser is greater than the modulus of the casting.

A casting process for ductile iron thin-walled parts, comprising the following steps:

Step 1) Sandbox Preparation:

The upper sand box is ready for use by the automatic molding line, and the cavity is facing down;

The lower flask is ready for use by the automatic molding line, with the cavity facing up;

Place the sand core and filter with the built-in feeding riser in the lower flask, and clean the lower flask;

The upper flask and the lower flask are combined to form the flask, and the casting system of the ductile iron thin-walled part is formed in the flask, and then locked for use by molten iron casting;

Step 2) Hot metal pouring:

The molten iron flows in from the upper part of the sprue and goes down through the lower runner;

Flow from left to right, through the lower runner, and upward through the upper runner;

Flow from left to right, enter the casting after passing through the inner runner and the outer riser;

After filling down the casting, complete filling of the casting.

Further, the manufacturing process of the sand core comprises the following steps:

The riser sleeve is bonded with the riser neck seat and is installed on the positioning pin of the mold movable block, and the lower part of the mold movable block is inserted into the chute of the sand core mold;

The mold block is inserted into the sand core mold together with the riser sleeve and the riser neck seat, so that it is integrated with the sand core mold;

Sand core sand is injected into the cavity of the sand core mold from the upper part, filling the entire cavity, and the outer shell surface of the sand core is heated and solidified to form;

As the sand core is solidified, the combination of the riser sleeve and the riser neck seat is buried in a designated position in the sand core, and the cavity in the riser sleeve naturally forms an independent hot section inside the feeding riser;

After forming, the sand core is pushed out of the sand core mold by the ejector rod, and the production is completed after the mold movable block is removed and separated from the sand core.

The beneficial effects of the present invention are:

The invention is provided with an independent hot section with built-in feeding risers, and adopts the sand core pre-embedded process (integrated with the sand core), which is similar to the traditional pre-embedded cold iron, which reduces the later assembly of the sand core and saves the operation time; The shrink riser can be separated by a general separation method. Since the separation surface is a machined surface, there is no need to perform surface trimming even if there is a residue of the separation material, which reduces the repair work of the cold iron surface of the casting, and eliminates unnecessary labor. The residual gate neck can not be polished (machined surface), which also reduces the cleaning operation time by 50%, improves the production efficiency, and also avoids the operator's operation error causing the product to be knocked out and scrapped. The riser is conducive to the discharge of scum in the molten iron, so that the surface quality of the bottom is improved, and the defects caused by later repair errors are eliminated.

The above description is only an overview of the technical solution of the present invention. In order to understand the technical means of the present invention more clearly, and implement it according to the content of the description, the preferred embodiments of the present invention are described in detail below with the accompanying drawings. Specific embodiments of the present invention are given in detail by the following examples and the accompanying drawings.

Description of drawings

Fig. 1 is the structural representation of the gating system of the present invention;

Fig. 2 is the sand core production state diagram of the present invention;

Fig. 3 is the side view of Fig. 2;

Fig. 4 is the top view of Fig. 2;

Fig. 5 is the structural representation of the riser neck seat of the present invention;

Fig. 6 is the structure schematic diagram of the riser sleeve of the present invention;

FIG. 7 is a schematic diagram of the structure of the mold movable block of the present invention.

Description of the labels in the figure:

1, sprue, 2, lower runner, 3, upper runner, 4, inner runner, 5, outer riser, 6, feeding riser, 7, casting, 8, sand core, 9, Riser neck, 10, oil drain boss, 11, riser neck seat, 12, riser sleeve, 13, die block, 14, sand core mould.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

Referring to Fig. 1, a gating system for ductile iron thin-walled parts includes a sprue 1, a lower runner 2, an upper runner 3, an inner runner 4, an outer riser 5 and a casting 7 connected in sequence , the bottom edge of the casting 7 is provided with an oil drain boss 10, the casting 7 is filled with a sand core 8, and the sand core 8 is provided with a feeding riser 6 at the corresponding oil drain boss 10, see Figure 5, Figure 6 As shown, the feeding riser 6 includes a riser sleeve 12 and a riser neck seat 11 fixed on the lower end of the riser sleeve 12 .

Further, the connection between the feeding riser 6 and the oil drain boss 10 is the riser neck 9 , and the riser neck seat 11 is connected to the riser neck 9 .

Further, the riser sleeve 12 and the riser neck seat 11 are fixed by casting adhesive.

Further, the thickness of the oil drain boss 10 is greater than 2.5 times the wall thickness of the casting 7 .

Further, the modulus of the feed riser 6 is greater than the modulus of the casting 7 .

A casting process for ductile iron thin-walled parts, comprising the following steps:

Step 1) Sandbox Preparation:

The upper sand box is ready for use by the automatic molding line, and the cavity is facing down;

The lower flask is ready for use by the automatic molding line, with the cavity facing up;

Place a sand core 8 and a filter with a built-in feeding riser 6 in the lower flask to clean the lower flask;

The upper sand box and the lower sand box are combined into a sand box, and a pouring system for ductile iron thin-walled parts is formed in the sand box, and then locked for molten iron pouring;

Step 1) Hot metal pouring:

The molten iron flows in from the upper part of the sprue 1 and passes down through the lower runner 2;

Flow from left to right, through the lower runner 2, and upward through the upper runner 3;

Flow from left to right, enter casting 7 through inner runner 4 and outer riser 5;

After the casting 7 is filled downward, the entire filling of the casting 7 is completed.

Further, the manufacturing process of the sand core 8 comprises the following steps:

Referring to Figures 2 to 4 and 7, the riser sleeve 12 and the riser neck seat 11 are bonded together and installed on the positioning pin of the mold movable block 13, and the lower part of the mold movable block 13 is inserted into the slide of the sand core mold 14. in the groove;

The mold block 13 is inserted into the sand core mold 14 together with the riser sleeve 12 and the riser neck seat 11, so that it is integrated with the sand core mold 14;

Sand core sand is injected into the cavity of the sand core mold 14 from the upper part, filling the entire cavity, and the outer shell surface of the sand core 8 is heated and solidified;

As the sand core 8 solidifies, the combination of the riser sleeve 12 and the riser neck seat 11 is buried in the designated position in the sand core 8, and the cavity in the riser sleeve 12 naturally forms an independent thermal section with built-in feed riser 6;

After molding, the sand core 8 is pushed out of the sand core mold 14 by the ejector rod, and the mold block 13 is removed and separated from the sand core 8 to complete the production.

The components of the casting 7 are all located in the sand box, and the external environment is clay sand, that is, the sand mold in sand casting. All the cavity surfaces formed by the sand mold reflect the external shape of the casting 7.

The solidification sequence of molten iron: casting 7 thin wall → inner runner 4 → oil drain boss 10 → lower runner 2 → upper runner 3 → sprue 1 → outer riser 5

The outer riser 5 only acts on the thin-walled part of the casting 7, and an independent thermal joint is provided with a built-in feeding riser 6, which acts on the oil drain boss 10. The molten iron is injected into the feeding riser 6 through the riser neck 9, and it solidifies. The speed is later than that of the oil discharge port boss 10, and the thermal node transfer is successfully completed to achieve local filling.

Description of molten iron solidification process:

Solidification starts from the thin wall of the casting with lower temperature and faster cooling, and gradually solidifies;

When the casting is solidified, the solidification of the runner begins, and the runner solidifies before the riser (casting first and then the riser);

When the thin wall of the casting solidifies to the thick wall, an independent hot joint will be formed (thin wall first and then thick wall);

When the hot joint is solidified, since the surrounding thin wall has been completely solidified, the hot joint is prone to form internal defects;

The hot-node molten iron is compensated by the built-in feeding riser to avoid the formation of shrinkage porosity, so as to produce defect-free castings.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (7)

1. A casting system for ductile iron thin-walled parts, comprising a sprue (1), a lower runner (2), an upper runner (3), an inner runner (4), and an outer riser connected in sequence (5) and the casting (7), characterized in that: an oil drain boss (10) is provided at the bottom edge of the casting (7), a sand core (8) is placed inside the casting (7), and the A feeding riser (6) is provided in the sand core (8) corresponding to the oil drain boss (10), and the feeding riser (6) includes a riser sleeve (12) and a feeder sleeve (12) fixed on the riser. The riser neck seat (11) at the lower end of the muzzle (12). 2 . The pouring system for ductile iron thin-walled parts according to claim 1 , wherein the connection between the feeding riser ( 6 ) and the oil drain boss ( 10 ) is a riser neck ( 9 ). 3 . ), the riser neck seat (11) is connected to the riser neck (9). 3 . The pouring system for ductile iron thin-walled parts according to claim 2 , wherein the riser sleeve ( 12 ) and the riser neck seat ( 11 ) are fixed by casting adhesive. 4 . 4 . The pouring system for ductile iron thin-walled parts according to claim 3 , wherein the thickness of the oil drain boss ( 10 ) is greater than 2.5 times the wall thickness of the casting ( 7 ). 5 . 5 . The pouring system for ductile iron thin-walled parts according to claim 4 , wherein the modulus of the feeding riser ( 6 ) is greater than the modulus of the casting ( 7 ). 6 . 6. the casting technique of ductile iron thin-walled part as claimed in claim 1 to 5, is characterized in that, comprises the following steps: Step 1) Sandbox Preparation: The upper sand box is ready for use by the automatic molding line, and the cavity is facing down; The lower flask is ready for use by the automatic molding line, with the cavity facing up; Place the sand core (8) and the filter with the built-in feeding riser (6) in the lower flask, and clean the lower flask; The upper flask and the lower flask are combined to form the flask, and the casting system of the ductile iron thin-walled part is formed in the flask, and then locked for use by molten iron casting; Step 2) Hot metal pouring: The molten iron flows in from the upper part of the sprue (1) and passes downward through the lower runner (2); Flow from left to right, through the lower runner (2), and upward through the upper runner (3); Flow from left to right, enter the casting (7) after passing through the inner runner (4) and the outer riser (5); After the casting (7) is filled downward, the whole filling of the casting (7) is completed. 7 . The casting process of ductile iron thin-walled parts according to claim 6 , wherein the manufacturing process of the sand core ( 8 ) comprises the following steps: 8 . The riser sleeve (12) is bonded to the riser neck seat (11) and installed on the positioning pin of the mold movable block (13), and the lower part of the mold movable block (13) is inserted into the sand core mold ( 14) in the chute; The mold block (13) is inserted into the sand core mold (14) together with the riser sleeve (12) and the riser neck seat (11), so that it is connected with the sand core mold (14) become one; Sand core sand is injected into the cavity of the sand core mold (14) from the top, filling the entire cavity, and the outer shell surface of the sand core (8) is heated and solidified to form; As the sand core (8) is solidified, the riser sleeve (12) and the riser neck seat (11) are combined into a designated position in the sand core (8). The cavity in (12) naturally forms an independent thermal section and the feeding riser (6) is built in; After forming, the sand core (8) is pushed out of the sand core mold (14) by the ejector rod, and the mold block (13) is removed and separated from the sand core (8) to complete the production.

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