A thin-wall water jacket sand core for engine casting cylinder

Abstract

The present invention discloses a thin-walled water jacket sand core for a cast cylinder block of an engine. The water jacket sand core for the cylinder block includes a main body, and a first core head and a second core head are adjacent to each other on the main body. An annular core head is arranged at the center hole position of the water jacket sand core for the cylinder block, and the annular core head is arranged at the bottom position of the center hole of the sand core. An L-shaped core head is arranged outside the first core head and the second core head on the main body, and the L-shaped core head connects the first core head and the second core head together. The method for preparing the thin-walled water jacket sand core for the cast cylinder block of an engine adopts a cold core method of 100% of the pearl sand according to the mass fraction. The water jacket sand core of the present invention has an annular core head, which can effectively fill the hollow area at the bottom of the water jacket core; the L-shaped core head not only increases the local sand core structural strength, but also protects the main body of the sand core. According to recent production statistics, the qualified rate has been increased from the original 95% to 100%, and the implementation effect is remarkable.

Description

Technical Field

[0001] The invention belongs to the technical field of casting, and in particular relates to a thin-wall water jacket sand core of a cast cylinder block of an engine. Background Art

[0002] With the increasingly stringent national fuel consumption regulations, in order to meet the national fourth-stage fuel consumption target value (5L / 100km in 2020), JAC Motors launched the "Green Journey Plan" from the perspective of strategic needs, which includes the topic of "Traditional fuel-saving technology based on engines". In accordance with the requirements of national regulations and the needs of the company's strategy, JAC Motors launched the product development project of the 1.2LTGDI three-cylinder engine, which is intended to match JAC small / medium-sized passenger cars.

[0003] like Figure 1 The figure shows the sand core structure of the water jacket of the 1.2LTGDI gasoline engine casting cylinder block. Its features are:

[0004] (1) Sand core wall thickness: 5-7mm;

[0005] (2) Overall dimensions: length 290 mm × width 145 mm × height 60 mm;

[0006] (3) The whole structure is circular and open;

[0007] (4) There are 7 sand holes distributed;

[0008] (5) The contour structure is highly undulating and the parting surface is complex.

[0009] The water jacket sand core of this cylinder body is a typical thin-walled complex structure, which has quality risks such as difficulty in molding, low strength, and easy deformation / fracture during the preparation process.

[0010] The existing technology adopts the "coated sand hot core preparation process", which has high overall strength of the sand core and good anti-veining effect, but also has the following defects: 1. High production cost; 2. Long heating and curing time of the sand core and low production efficiency; 3. The sand core has a large amount of gas emission, which can easily lead to pore defects, and has high requirements for the design of the exhaust system of the mold / core.

[0011] The prior art adopts the process of "adding core supports", which increases the strength and prevents the deformation of the annular sand core, but also has the following defects: 1. The production cost of the core supports is high and the versatility is poor; 2. After the core supports are dipped with the water jacket core, the residual coating on the surface is easy to form defects such as cylinder hole sand holes and subcutaneous pores, and special personnel need to be arranged to check and clean the residual coating, which is cumbersome; 3. During the pouring process, there is a hidden danger of poor fusion of the metal core support and the casting, and the melting point of the core support and the pouring problem are stringent. Summary of the invention

[0012] The present invention aims at the deficiencies in the prior art and proposes a thin-wall water jacket sand core for a casting cylinder block of an engine.

[0013] To solve the above problems, the technical solutions adopted by the present invention are as follows:

[0014] A thin-wall water jacket sand core for a cast cylinder block of an engine, the cylinder block water jacket sand core comprising a main body, a first core head and a second core head adjacent to each other on the main body, an annular core head arranged at the center hole position of the cylinder block water jacket sand core, the annular core head arranged at the bottom position of the center hole of the sand core, an L-shaped core head arranged outside the first core head and the second core head on the main body, and the L-shaped core head connects the first core head and the second core head together.

[0015] As an improvement of the above technical solution, the annular core head includes a first step and a second step, the first step is in direct contact with the water jacket sand core, and the first step is higher than the second step.

[0016] A method for preparing a thin-wall water jacket sand core of an engine casting cylinder block is provided, wherein the sand core is prepared by a cold core method using 100% of gemstone sand in parts by mass.

[0017] As an improvement of the above technical solution, the size of the pearl sand is 40-70 meshes.

[0018] Compared with the prior art, the implementation effects of the present invention are as follows:

[0019] The water jacket sand core of the present invention has an annular core head that can effectively fill the hollow area at the bottom of the water jacket core, which plays a role in stabilizing the state and strengthening the structure; the L-shaped core head not only increases the local sand core structural strength, but also protects the body of the sand core. In addition, the overall core head design has a large plane space, which is convenient for adding a large-sized exhaust needle on the outer mold to improve the exhaust effect. The water jacket sand core is prepared by the 40-70 mesh 100% gem sand cold core process. According to recent production statistics, the qualified rate has increased from the original 95% to 100%, and the implementation effect is remarkable. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the sand core structure of the cylinder water jacket in the background technology;

[0021] Figure 2 It is a schematic diagram of the structure of the cylinder water jacket sand core with an annular core head according to the present invention (partial);

[0022] Figure 3 It is a schematic diagram of the structure of the cylinder water jacket sand core with an L-shaped core head according to the present invention;

[0023] Figure 4 The actual quality trend table of the cylinder body cast by adopting the water jacket sand core preparation process of the present invention (production number 450 pieces). DETAILED DESCRIPTION

[0024] The content of the present invention will be described below with reference to specific embodiments.

[0025] like Figure 1 The figure is a schematic diagram of the cylinder water jacket sand core structure in the background art. The cylinder water jacket sand core comprises a body 10, on which a first core head 11 and a second core head 12 are arranged at adjacent positions.

[0026] like Figure 2 The cylinder water jacket sand core with an annular core head is provided with an annular core head 20 at the center hole of the sand core, and the annular core head 20 is provided at the bottom of the center hole of the sand core, so as to accelerate the cooling of the bottom.

[0027] The annular core head 20 includes a first step 21 and a second step 22. The first step 21 is in direct contact with the water jacket sand core, and the first step 21 is higher than the second step 22. Since the first step 21 is in direct contact with the water jacket sand core, its temperature is higher, so a larger area is required for heat dissipation. Therefore, the use of a stepped annular core head 20 not only reduces the manufacturing cost, but also more effectively utilizes its structure for heat dissipation. The annular core head of the present invention can effectively fill the hollow area at the bottom of the water jacket core, which plays a role in stabilizing the state and strengthening the structure.

[0028] like Figure 3 The figure shows a schematic diagram of the cylinder water jacket sand core structure with an L-shaped core head according to the present invention. The cylinder water jacket sand core according to the present invention has a first core head 11 and a second core head 12 at adjacent positions on the main body 10, and an L-shaped core head 30 is arranged outside the first core head 11 and the second core head 12, and the L-shaped core head 30 connects the first core head 11 and the second core head 12 together. The L-shaped core head 30 not only increases the local sand core structural strength, but also protects the main body 10 of the sand core. In addition, the overall core head design has a larger plane space, which is convenient for adding a large-sized exhaust needle on the outer mold to improve the exhaust effect.

[0029] The cylinder water jacket sand core of the present invention has the following preparation process:

[0030] The cylinder water jacket sand core of the present invention is designed to be shaped with gemstone sand or silica sand.

[0031]

[0032] From the performance parameter comparison table above, it can be seen that the pearl sand has a high refractoriness and a very small thermal expansion rate, which can effectively reduce the high-temperature deformation of the thin-walled water jacket sand core, inhibit the formation of veins, and provide reliable guarantees for improving the dimensional accuracy and cleanliness of the inner cavity of the casting. In addition, compared with the pointed silica sand, the spherical pearl sand has a smaller surface area under the same volume, so the consumption of cold core process resin is relatively lower.

[0033] In production practice, in order to reduce the production cost as much as possible, we have successively adopted the cold core preparation process of 100% silica sand, 50% jelly sand + 50% silica sand, 80% jelly sand + 20% silica sand, and 100% jelly sand according to the mass ratio. The relevant performance comparison is as follows:

[0034]

[0035] Through the above practical comparison, taking into account the production cost and rework cost, we adopted the 40-70 mesh 100% bead sand cold core process to prepare the 1.2LTGDI casting cylinder water jacket sand core.

[0036]

[0037] The above content is a detailed description of the present invention in combination with specific embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be regarded as falling within the scope of protection of the present invention.

Claims

1. A thin-walled water jacket sand core for a cast cylinder block of an engine, the water jacket sand core comprising a body (10), a first core head (11) and a second core head (12) adjacent to each other on the body (10), wherein: An annular core head (20) is arranged at the center hole of the water jacket sand core, and the annular core head (20) is arranged at the bottom of the center hole of the sand core; an L-shaped core head (30) is arranged outside the first core head (11) and the second core head (12) on the body (10), and the L-shaped core head (30) connects the first core head (11) and the second core head (12) together; The annular core head (20) comprises a first step (21) and a second step (22), the first step (21) being in direct contact with the water jacket sand core, and the first step (21) being higher than the second step (22); The water jacket sand core is prepared by a cold core method using 100% of the gem sand in terms of mass.

2. The engine casting cylinder block thin-wall water jacket sand core as claimed in claim 1, characterized in that: The size of the pearl sand is 40-70 meshes.

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