Method for preventing deformation of sand casting embedded large-length-diameter-ratio thin-wall steel pipe

Abstract

The invention provides a method for preventing deformation of a sand mold casting and embedded casting large-length-diameter-ratio thin-wall steel pipe. The method comprises the steps that firstly, one end of an inner cavity of the steel pipe is plugged tightly through a plugging piece; filling a filler into the inner cavity of the steel pipe, and tamping; then the other end of the steel pipe is plugged tightly through a plugging piece so as to prevent the filler from leaking out; penetrating the steel pipe filled with the filler into the mounting hole of the supporting seat; and finally, the bottom of the supporting base is embedded into the sand core, and aluminum alloy liquid needs to be poured. The method is easy and convenient to implement and operate, the casting embedded pipe is good in stability, accurate in positioning and high in casting size precision, the casting embedded pipe cannot float or molten aluminum cannot invade into an embedded pipe inner cavity, the quality of an embedded steel pipe casting product is remarkably improved, and the large-length-diameter-ratio thin-wall steel pipe casting is embedded and cast; supporting force can be provided through the supporting seat outside the pipe body and fine sand grains in the inner cavity of the pipe, deformation of the embedded pipe is prevented, the yield is high, and the problem that the steel pipe deforms due to the thin wall and the long size of the steel pipe is solved.

Description

Technical Field

[0001] The present invention belongs to the field of casting technology, and in particular relates to a method for preventing deformation of large aspect ratio thin-walled steel pipes cast in a sand mold. Background Art

[0002] Although the products of sand mold casting with embedded steel pipe castings are increasing day by day, when casting large aspect ratio thin-walled steel pipe castings, there are problems such as steel pipe deformation and steel pipe floating during the casting process. This is mainly due to the characteristics of the thin wall and long size of the steel pipe itself, resulting in poor stability. Under the impact of high-temperature and high-pressure aluminum liquid during pouring, long thin-walled steel pipes often float or sink, and even the steel pipes are exposed outside the casting and deformed, which affects subsequent production and leads to a very low finished product rate of the casting. In the prior art, for sand core casting with embedded pipe fittings castings, generally, the end of the steel pipe is buried in the sand core, and core supports are placed in the interval area of the steel pipe to support the steel pipe. Under normal circumstances, the core supports are in close contact with the steel pipe, but problems such as local or complete deformation of the sand core and sand core cracks often occur during the processes of baking, transferring, and pouring the sand core. When there is a gap between the deformed sand core and the pipe fitting, applying an adhesive on the core support or grinding the sand core is used to improve the fitting degree, but this cannot completely solve the problem. Since the core supports cannot provide support for the steel pipe from all directions around, there is a risk of steel pipe deformation and aluminum liquid intrusion. Therefore, it is necessary to improve the existing production process of large aspect ratio thin-walled steel pipe castings. Summary of the Invention

[0003] In view of this, the present invention aims to overcome the defects in the prior art and proposes a method for preventing deformation of large aspect ratio thin-walled steel pipes cast in a sand mold.

[0004] To achieve the above object, the technical solution of the present invention is realized as follows:

[0005] A method for preventing deformation of large aspect ratio thin-walled steel pipes cast in a sand mold, comprising the following steps:

[0006] S1. Tightly plug one end of the inner cavity of the steel pipe with a plugging member;

[0007] S2. Fill the inner cavity of the steel pipe with a filling material and tamp it;

[0008] S3. Tightly plug the other end of the steel pipe with a plugging member to prevent the filling material from leaking out;

[0009] S4. Insert the steel pipe filled with the filling material into the installation hole of the support seat;

[0010] S5. Burry the bottom of the support seat in the sand core and wait to pour aluminum alloy liquid.

[0011] Further, the plugging member is made of high-temperature asbestos cloth.

[0012] Further, the filler is made of sand grains.

[0013] Further, the diameter of the sand grains is ≤ 0.3 mm.

[0014] Further, a clearance fit is adopted between the steel pipe and the mounting hole of the support seat.

[0015] Further, the clearance between the steel pipe and the mounting hole of the support seat is 0.5 mm - 1 mm.

[0016] Further, the height of the support seat buried in the sand core is 1 / 5 - 1 / 4 of the total height of the support seat.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] The specific implementation of the method of the present invention is simple and convenient to operate, the cast-in pipe of the casting has good stability and accurate positioning, the dimensional accuracy of the casting is high, there will be no floating of the cast-in pipe of the casting or intrusion of molten aluminum into the inner cavity of the pipe, the quality of the cast-in steel pipe casting product is significantly improved, for the cast-in large long-diameter ratio thin-walled steel pipe casting, the support force can be provided by the external support seat of the pipe body and the sand grains of fine particles in the pipe cavity to prevent the deformation of the cast-in pipe, and the yield is high, solving the problems such as deformation of the steel pipe due to its thin wall and long size. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0020] Figure 1 is a schematic diagram when the present invention is implemented;

[0021] Figure 2 is Figure 1 a sectional view taken along the A-A direction in

[0022] Figure 3 is Figure 1 the left view of

[0023] Description of the reference numerals:

[0024] 1 - large long-diameter ratio thin-walled steel pipe; 2 - support seat; 3 - plugging member; 4 - filler. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0026] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0027] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific circumstances.

[0028] The present invention will be described in detail below with reference to the drawings and in conjunction with embodiments.

[0029] A method for preventing the deformation of a large aspect ratio thin-walled steel pipe in sand casting includes the following steps as shown: Figures 1 to 3 as follows:

[0030] S1. Use a plugging member 3 to tightly plug one end of the inner cavity of the large aspect ratio thin-walled steel pipe 1;

[0031] S2. Fill the inner cavity of the large aspect ratio thin-walled steel pipe with a filler 4 and tamp it. Usually, the plugging member is made of high-temperature asbestos cloth. The filler is sand grains. For example, the diameter of the sand grains is ≤0.3 mm.

[0032] S3. Use a plugging member to tightly plug the other end of the large aspect ratio thin-walled steel pipe to prevent the filler from leaking out. The filler can provide a supporting force for the pipe fitting to prevent the pipe fitting from deforming;

[0033] S4. Insert the above-mentioned large aspect ratio thin-walled steel pipe filled with the filler into the installation hole of the support seat 2. Usually, a clearance fit is adopted between the large aspect ratio thin-walled steel pipe and the installation hole of the support seat. For example, the clearance between the large aspect ratio thin-walled steel pipe and the installation hole of the support seat is 0.5 mm - 1 mm.

[0034] The bottom of the support base is buried in the sand core, and then the aluminum alloy liquid is to be poured. Preferably, the height of the support base buried in the sand core is 1 / 5 - 1 / 4 of the total height of the support base.

[0035] The high-temperature asbestos cloth can prevent the sand grains from leaking out of the inner cavity of the steel pipe, and at the same time can also prevent the external aluminum liquid from invading the pipe. After the thin-walled steel pipe with a large length-diameter ratio is filled with fillers, it is then inserted into the installation hole of the support base. The support base can not only support and fix the steel pipe, but also form a limit on the steel pipe in the circumferential direction, preventing the steel pipe from floating and deforming due to the impact of high-temperature and high-pressure aluminum liquid around, thermal expansion and contraction, etc.

[0036] In practical applications, for an intake pipe casting embedded with a high-temperature and high-pressure steam steel pipe, the main wall thickness of the intake pipe casting is 6 mm, the pipe length is about 1300 mm, the whole casting is in a long strip shape, and the total weight is about 40 kg. It is required that the inner cavity of the steam pipe be subjected to a high-temperature and high-pressure hydrostatic test after processing, and no leakage is allowed. There are also no defects such as air holes, shrinkage cavities, slag inclusions, cracks, etc. in the casting. When the embedded pipe of the thin-walled steel pipe type is relatively long, due to the high-temperature and high-pressure environment during the casting process, the steel pipe will inevitably float and deform, resulting in inaccurate subsequent processing positioning and the air flow not meeting the design requirements. Using the method of the present invention, fine sand grains with a diameter ≤ 0.3 mm are stuffed into the embedded pipe and tamped. Then, high-temperature asbestos cloth is stuffed at both ends of the steel pipe. Then, 2 positioning support bases are assembled at intervals in the interval area of the embedded pipe, and about 1 / 4 of the tail of the support base is buried in the sand core. This method effectively solves the floating problems such as the deformation of the embedded cast steel pipe, the floating up or sinking of the steel pipe, avoids the invasion of aluminum liquid into the inner cavity of the embedded pipe, significantly improves the quality of the intake pipe embedded pipe casting, and the effect has been verified.

[0037] The specific implementation of the method of the present invention is simple and convenient to operate, the stability of the embedded pipe of the casting is good and the positioning is accurate, the dimensional accuracy of the casting is high, there will be no floating of the embedded pipe of the casting or invasion of aluminum liquid into the inner cavity of the embedded pipe, significantly improving the quality of the embedded cast steel pipe casting. For the embedded cast thin-walled steel pipe with a large length-diameter ratio, the support force can be provided by the support base outside the pipe body and the fine-grained sand in the inner cavity of the pipe to prevent the embedded pipe from deforming, and the finished product rate is high, solving the problems such as the deformation of the steel pipe due to its thin wall and long size.

[0038] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preventing deformation of thin-walled steel pipes with large aspect ratio during sand casting, characterized in that: The steps include: S1. Use a plugging piece to plug one end of the inner cavity of the steel pipe; S2, filling the inner cavity of the steel pipe with filler and tamping it; S3. Use a plugging piece to plug the other end of the steel pipe to prevent the filler from leaking out; S4, inserting the steel pipe filled with filler into the mounting hole of the support seat; S5. The bottom of the support seat is buried in the sand core, waiting for the pouring of aluminum alloy liquid.

2. A method for preventing deformation of thin-walled steel pipes with large aspect ratio during sand casting according to claim 1, characterized in that: The sealing piece is made of high-temperature asbestos cloth.

3. The method for preventing deformation of thin-walled steel pipes with large aspect ratio during sand casting according to claim 1, characterized in that: The filler is sand particles.

4. A method for preventing deformation of thin-walled steel pipes with large aspect ratio during sand casting according to claim 3, characterized in that: The diameter of the sand particles is ≤0.3 mm.

5. The method for preventing deformation of thin-walled steel pipes with large aspect ratio during sand casting according to claim 1, characterized in that: The steel pipe and the mounting hole of the support seat are clearance-matched.

6. A method for preventing deformation of thin-walled steel pipes with large aspect ratio during sand casting according to claim 5, characterized in that: The gap between the steel pipe and the mounting hole of the support seat is 0.5mm-1mm.

7. The method for preventing deformation of thin-walled steel pipes with large aspect ratio during sand casting according to claim 1, characterized in that: The height of the support seat embedded in the sand core is 1 / 5-1 / 4 of the total height of the support seat.

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