CN112808945A

CN112808945A - Method for eliminating looseness defect of wear-resistant pump shell casting

Info

Publication number: CN112808945A
Application number: CN202110005583.7A
Authority: CN
Inventors: 韩登峰
Original assignee: Ningbo Rongfa New Material Technology Co ltd
Current assignee: Ningbo Rongfa New Material Technology Co ltd
Priority date: 2021-01-05
Filing date: 2021-01-05
Publication date: 2021-05-18
Anticipated expiration: 2041-01-05
Also published as: CN112808945B

Abstract

The invention provides a method for eliminating the defect of looseness of a wear-resistant pump shell casting, which comprises the following steps: s1, modeling a mould, and arranging an exhaust channel on the sand core and/or the sand mould, wherein the head of the exhaust channel is close to the neck triangular area of the pump shell casting, and the tail of the exhaust channel extends out of the sand core or the sand mould; s2, casting, namely, injecting molten iron into the cavity, and discharging gas generated by a neck triangular area and a core of the pump shell casting from the exhaust passage, so that the loosening defect generated when the molten iron is solidified due to too much gas in the neck triangular area and untimely exhaust. According to the method for eliminating the loosening defect of the wear-resistant pump shell casting, the exhaust passage is arranged in the neck triangular area, so that gas of molten iron on the mold and the core is exhausted from the exhaust passage, and the loosening defect caused by the fact that the gas enters the molten iron and is solidified is avoided; and meanwhile, the sand core mould is baked and heated, so that the gas forming amount of the sand core is reduced, the loosening defect is further eliminated, and the casting quality is improved.

Description

Method for eliminating looseness defect of wear-resistant pump shell casting

Technical Field

The invention relates to a casting method, in particular to a method for eliminating the defect of looseness of a wear-resistant pump shell casting.

Background

The traditional knowledge in the industry is that the triangular area part of the neck of the pump shell belongs to the geometric and physical thermal node of a casting, and the looseness easily appearing in the triangular area part of the casting is considered to be caused by solidification shrinkage and belongs to the defect of shrinkage cavity and shrinkage porosity. Therefore, it is considered that the use of external chill in the triangular space improves the riser feeding efficiency by eliminating the thermal influence, or that a large-capacity feeding head is provided on the top surface thereof, or that the casting temperature is lowered by an excessively high casting temperature. However, as a result of these measures, the loosening defects in the triangular area cannot be completely eradicated, and sometimes even "sink" occurs on the top surface of the triangular area of the casting. The loose defect of pump case neck triangular space exists always, is size of a dimension or the difference of degree weight, and this defect direct influence equipment normal use reduces pump case life. Sometimes, the similar shrinkage crack phenomenon can occur, and internal scrap is directly caused. The traditional method not only reduces the production efficiency due to low yield, but also sometimes has difficult guarantee of delivery date and increases the production cost.

Disclosure of Invention

【1】 Technical problem to be solved

The invention aims to solve the technical problem of providing a method for eliminating the defect of looseness of a casting of a wear-resistant pump shell, which has the advantages of simple process, low cost and good effect.

【2】 Technical scheme for solving problems

The invention provides a method for eliminating the defect of looseness of a wear-resistant pump shell casting, which comprises the following steps:

s1, when the mold is molded, a sand core is arranged in the sand mold, a cavity for casting the pump housing casting is formed between the outer wall of the sand core and the inner wall of the sand mold, an exhaust passage is arranged on the sand core and/or the sand mold, the head of the exhaust passage is close to the neck triangular area of the pump housing casting, and the tail of the exhaust passage extends out of the sand core or the sand mold;

s2, casting, namely, injecting molten iron into the cavity, and discharging gas generated in the neck triangular area of the pump shell casting from the exhaust passage to avoid the loosening defect generated when the molten iron is solidified due to too much gas in the neck triangular area and untimely exhaust.

Further, the distance between the head of the exhaust passage and the neck triangular area of the pump shell casting is more than or equal to 8mm and less than or equal to 30 mm.

Further, the aperture of the exhaust passage is not less than 5mm and not more than 15 mm.

Furthermore, the neck triangular area is a joint of two or more different surfaces.

Furthermore, the included angle between different surfaces is less than or equal to 120 degrees.

Furthermore, when the intersection line of the neck triangular area is arc-shaped, the exhaust channels are arranged around the arc-shaped intersection line at equal angles; when the intersection line of the neck triangular space is a straight line, the exhaust channels are arranged at equal intervals along the length direction of the intersection line of the straight line.

Further, the distance between two adjacent air exhaust channels positioned on the same side is greater than or equal to 2cm and less than or equal to 3 cm.

Further, the casting mould or the whole sand core is baked and heated before casting, so that the gas generation of the sand core during casting is reduced.

Further, the triangular area of the casting mold or the sand core is baked and heated before casting.

Further, the baking temperature is 140-200 ℃, and the baking time is 50-90 min. .

【3】 Advantageous effects

According to the method for eliminating the loosening defect of the wear-resistant pump shell casting, the exhaust passage is arranged in the triangular area at the neck part, so that molten iron gas on the triangular area and the core is exhausted from the exhaust passage, and the loosening defect caused by the fact that the gas enters molten iron and is solidified is avoided; and meanwhile, the sand core mould is baked and heated, so that the gas forming amount of the sand core is reduced, the loosening defect is further eliminated, and the casting quality is improved.

Drawings

FIG. 1 is a casting mold horizontal section of the wear-resistant pump housing casting of the present invention;

Detailed Description

The following describes embodiments of the present invention in detail with reference to the accompanying drawings.

Referring to fig. 1, the invention provides a method for eliminating the loose defect of the wear-resistant pump housing casting, which comprises the steps of manufacturing a die and casting;

s1, manufacturing a mold, namely, filling the sand core 3 into the sand mold 2, wherein the sand core and the sand mold are manufactured by resin sand, which is the prior art, and therefore, detailed description thereof is omitted in this embodiment, a cavity for casting the pump housing casting 1 is formed between the outer wall of the sand core 3 and the inner wall of the sand mold 2, the sand mold 2 is provided with a first exhaust passage 201, or the sand core 3 is provided with a second exhaust passage 202, or the sand mold 2 is provided with the first exhaust passage 201 and the sand core 3 is provided with the second exhaust passage 202, the head of the exhaust passage is close to the triangular region of the neck of the pump housing casting, and the tail of the exhaust passage extends out of the sand core or the sand mold; the neck triangular area is the joint of two or more different surfaces (side walls) of the pump shell to form a structure of a type step and a step, the included angle between the different surfaces is less than or equal to 120 degrees, the smaller the included angle is, the more easily the gas generated during casting can not be discharged in time and enter molten iron to cause the loosening defect during solidification, in the embodiment, the preferable triangular area with the included angle between the different surfaces being less than or equal to 90 degrees is provided with an exhaust channel; the distance between the head of the exhaust passage and a neck triangular area (the intersection line of different surfaces) of the pump shell casting is more than or equal to 8mm and less than or equal to 30 mm; in order to improve the exhaust efficiency, the aperture of the exhaust passage in the present embodiment is not less than 5mm and not more than 15 mm; because the curvatures of different surfaces (side walls) are different, the formed intersection line comprises an arc and a straight line; when the intersecting line is an arc, the exhaust channels are arranged at equal angles around the arc intersecting line, namely when the intersecting line is an arc, the exhaust channels are uniformly distributed in the circumferential direction, so that the exhaust efficiency and the exhaust uniformity are improved, when the intersecting line of the neck triangular region (different surfaces) is a straight line, the exhaust channels are arranged at equal intervals along the length direction of the straight line intersecting line, so that the exhaust efficiency and the exhaust uniformity are improved, when the intersecting line is of a complex structure, for example, when the intersecting line comprises a plurality of sections of arcs and a plurality of sections of straight lines, the arrangement principle is the same, namely, when the intersecting line is an arc, equal-angle arrangement is adopted, and when the intersecting line; in order to discharge the gas in the triangular area smoothly and quickly, the distance between every two adjacent rows of gas channels (heads) positioned on the same side (positioned on the sand core or positioned on the sand mold simultaneously) is more than or equal to 2cm and less than or equal to 3 cm; the equidistant or equiangular arrangement refers to the head part of the exhaust channel, namely one end of the intersecting line close to the triangular area;

s2, casting, namely injecting molten iron into the cavity, and discharging gas generated in the neck triangular area of the pump shell casting from the

exhaust passages

201 and 202, so that the loosening defect generated during solidification due to too much gas in the neck triangular area and untimely exhaust is avoided; in order to further improve the casting quality, the die is integrally baked and heated before casting, the casting mould (comprising sand core and sand mould) can be integrally baked and heated, or only the sand mould or a triangular area on the sand core is heated, the baking temperature is 140-200 ℃, the baking time is 50-90 min, and the gas generation of the sand core during casting can be reduced, so that the defect of looseness is eliminated.

According to the method for eliminating the loosening defect of the wear-resistant pump shell casting, the exhaust channel is arranged in the neck triangular area, so that gas generated by high temperature of the core on the triangular area is exhausted from the exhaust channel, and the loosening defect caused by solidification of the gas entering molten iron is avoided; and meanwhile, the sand core mould is baked and heated, so that the gas forming amount of the sand core is reduced, and the loosening defect is further eliminated.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the technical principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. A method for eliminating the loosening defect of a wear-resistant pump shell casting is characterized by comprising the following processes:

2. The method of eliminating loose casting defects in an antiwear pump housing according to claim 1, wherein: the distance between the head of the exhaust passage and the neck triangular area of the pump shell casting is more than or equal to 8mm and less than or equal to 30 mm.

3. The method of eliminating loose casting defects in an antiwear pump housing according to claim 1, wherein: the aperture of the exhaust passage is not less than 5mm and not more than 15 mm.

4. The method of eliminating loose casting defects in an antiwear pump housing according to claim 1, wherein: the neck triangular area is the junction of two or more different faces.

5. The method of eliminating loose casting defects in an antiwear pump housing according to claim 4, wherein: the included angle between different surfaces is less than or equal to 120 degrees.

6. The method of eliminating loose casting defects in an antiwear pump housing according to claim 1, wherein: when the intersection line of the neck triangular area is arc-shaped, the exhaust channels are arranged around the arc-shaped intersection line at equal angles; when the intersection line of the neck triangular space is a straight line, the exhaust channels are arranged at equal intervals along the length direction of the intersection line of the straight line.

7. The method of eliminating the loosening defects of castings of abrasion resistant pump housings of claim 6, further comprising: the distance between two adjacent air exhaust channels positioned on the same side is more than or equal to 2cm and less than or equal to 3 cm.

8. The method of eliminating loose casting defects in an antiwear pump housing according to claim 1, wherein: before casting, the casting mould or the sand mould or the whole sand core is baked and heated so as to reduce the gas generation of the sand core during casting.

9. The method of eliminating loose casting defects in an antiwear pump housing according to claim 1, wherein: and baking and heating the triangular area of the casting mold or the sand core before casting.

10. A method of eliminating the loosening defects of wear resistant pump housing castings according to claim 8 or 9, wherein: the baking temperature is 140-200 ℃, and the baking time is 50-90 min.