Sand core for steel casting and core manufacturing method

Abstract

The sand core comprises a chromium ore auxiliary core, a sand filling opening, a chromium ore layer, a core bar and an inner-layer sand core, the sand filling opening is formed in the chromium ore auxiliary core, and the chromium ore layer and the inner-layer sand core are sequentially arranged in the chromium ore auxiliary core from top to bottom; the core bar is further arranged in the chromium ore auxiliary core, and the chromium ore auxiliary core, the chromium ore layer and the inner-layer sand core are stringed into a whole. The invention further discloses a core manufacturing method of the sand core for the steel casting. According to the technical scheme, the problems that a casting is prone to sand burning and sintering, the mold manufacturing period is long, and the cost is high are solved, mold-free rapid production and sand core integrated forming are achieved, the quality of the casting is guaranteed, meanwhile, the sand core weight is reduced, and the production cost is saved.

Description

Technical Field

[0001] The invention relates to the technical field of casting, in particular to a sand core for steel castings and a core making method. Background Art

[0002] During the production process, the temperature of steel castings is high, and the heat is often concentrated in the thickest part. Sintering problems are prone to occur in some narrow and riser parts, which makes it impossible to clean them. In severe cases, the steel castings will be scrapped. At present, large steel castings are usually made by hand mold core making or 3D printing core making. For hand mold core making, there are defects such as difficult to control precision and long production cycle, and the quality and production requirements of steel castings cannot be guaranteed during rapid production; for 3D printing core making, 3D printing in the existing technology usually uses silica sand or chromium ore sand. If all silica sand is used for 3D printing, silica sand cannot meet the production of thick and narrow parts of steel castings, especially for high-alloy steel castings such as elbows; if all chromium ore sand is used for 3D printing, firstly, the production cost is very high, and the price of chromium ore sand is much higher than that of ordinary silica sand. Secondly, the sand core is too heavy, and the density of chromium ore sand is close to 3000kg / M3, which is twice that of ordinary silica sand. It is easy to be damaged or even broken during transportation. Safety risks. Summary of the invention

[0003] Based on this, it is necessary to provide a sand core and a core making method for steel castings to address the problems of easy sintering in thick and narrow parts of steel castings, low product quality, long production cycle and high production cost. The sand core and its core making method adopt a combination of manual and 3D printing methods, and only a small amount of chromium ore sand is needed to solve such problems, thereby realizing rapid production without molds. A new core making method is proposed for the sintering problem of large steel castings.

[0004] A sand core for steel castings comprises a chrome ore sand auxiliary core, a sand filling port, a chrome ore sand layer, a core bone and an inner layer sand core, wherein the sand filling port is arranged on the chrome ore sand auxiliary core, and the chrome ore sand layer and the inner layer sand core are arranged in sequence from top to bottom inside the chrome ore sand auxiliary core; the core bone is also arranged inside the chrome ore sand auxiliary core, and the chrome ore sand auxiliary core, the chrome ore sand layer and the inner layer sand core are strung together.

[0005] In one of the embodiments, the number of the chromium ore sand auxiliary cores is 2-10, and the top of each of the chromium ore sand auxiliary cores is provided with the sand filling port.

[0006] In one embodiment, the chromium ore sand layer has a thickness of 40 mm to 100 mm.

[0007] In one embodiment, the material of the inner sand core is hardenable casting sand, including silica sand, water glass sand and resin sand.

[0008] In one of the embodiments, a chiller is also provided on the chromium ore sand auxiliary core.

[0009] In one of the embodiments, scale lines are provided on the chromium ore sand auxiliary core.

[0010] In one embodiment, the core bar is a double steel bar structure, and the core bar is also provided with core assembly lugs and transfer lugs.

[0011] In one of the embodiments, an air outlet rope is provided on the core bone.

[0012] In one embodiment, the core making method comprises the following steps:

[0013] S01, manufacturing a core box and a chrome ore auxiliary core, designing 3D printing drawings of the core box and the chrome ore auxiliary core according to the structure of the steel casting, and printing the core box and the chrome ore auxiliary core using a 3D printer;

[0014] S02, assembling, placing the chrome ore sand auxiliary core in the core box, and placing the core bone provided with the air outlet rope inside the chrome ore sand auxiliary core through the sand filling port at the top of the chrome ore sand auxiliary core;

[0015] S03, core making, filling the hardenable casting sand through the sand filling opening at the top of the chrome ore sand auxiliary core to a distance of 40 mm to 100 mm from the sand filling opening to form the inner sand core, and then filling with chrome ore sand to form the chrome ore sand layer, which is compacted into a whole;

[0016] S04, static molding.

[0017] In one of the embodiments, during the assembling step, a gap of 1 mm to 5 mm is left between the core box and the chromium ore sand auxiliary core.

[0018] The technical solution adopted by the present invention can achieve the following beneficial effects:

[0019] The present invention provides a sand core for steel castings and a core making method. By combining 3D printing and manual core making, a core bone is built into the chromium ore sand auxiliary core made by 3D printing, and low-cost hardenable casting sand and chromium ore sand are used for filling, so as to form a sand core for steel castings in which the chromium ore sand auxiliary core, the chromium ore sand layer and the inner sand core formed by the low-cost hardenable casting sand are strung together by the core bone. The technical solution of the present invention solves the problems of easy sand adhesion and sintering of castings, long mold making cycle and high cost, realizes rapid production without molds and integrated sand core forming, reduces the weight of sand cores and saves production costs while ensuring the quality of castings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of sand core making;

[0021] Figure 2 It is a schematic diagram of the core bone structure;

[0022] Figure 3 Schematic diagram of the cross section of the sand core.

[0023] Description of reference numerals:

[0024] 100-core box, 101-core box lifting lug, 102-core bone hook, 103-chilled iron mouth;

[0025] 200-chrome ore sand auxiliary core, 201-sand filling port, 202-chrome ore sand layer. 203-inner sand core;

[0026] 300-core bone, 301-core bone frame, 302-transport lifting lug, 303-core assembly lifting lug, 304-air outlet rope. DETAILED DESCRIPTION

[0027] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly understood.

[0028] It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may be a centered element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a centered element at the same time. The terms "vertical", "horizontal", "left", "right", "top", "bottom", "bottom end", "top end" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0030] In the first aspect, an embodiment of the present invention discloses a sand core for steel castings, comprising a chrome ore sand auxiliary core 200, a sand filling port 201, a chrome ore sand layer 202, a core bone 300 and an inner sand core 203. Specifically, the sand filling port 201 is arranged on the chrome ore sand auxiliary core 200, the interior of the chrome ore sand auxiliary core 200 is hollow, and the chrome ore sand layer 202 and the inner sand core 203 are arranged in sequence from top to bottom. The interior of the chrome ore sand auxiliary core 200 is also provided with a core bone 300, and the core bone 300 strings the chrome ore sand auxiliary core 200, the chrome ore sand layer 202 and the inner sand core 203 into a whole.

[0031] like Figure 1 As shown, the number of chrome ore sand auxiliary cores 200 is adjusted according to the shape and size of the steel casting, that is, the number of chrome ore sand auxiliary cores 200 is adjusted according to the shape. Preferably, the number of chrome ore sand auxiliary cores 200 is 2-10 pieces, and a sand filling port 201 is provided at the top of each chrome ore sand auxiliary core 200. For the needs of subsequent filling, the width of the sand filling port 201 is 80mm-160mm. In order to facilitate the placement of chillers during the casting process, a plurality of chiller ports are also provided on the chrome ore sand auxiliary core 200. The chiller ports can be designed in advance according to the needs of the placement position of the chiller of the steel casting. In order to ensure the accurate assembly of the chrome ore sand auxiliary cores 200, scale lines are provided on each chrome ore sand auxiliary core 200 for positioning.

[0032] like Figure 1-3 As shown, the core bone 300 is a device placed inside the chrome ore sand auxiliary core 200 for stringing the sand core into a whole, specifically including a core bone skeleton 301 of a double steel bar structure, on which a transfer lug 302 and a core assembly lug 303 are arranged. When the box is assembled later, the transfer lug 302 and the core assembly lug 303 can be used to install the core bone hook 102. An air outlet rope 304 is also wound around the core bone 300 to ensure ventilation of the sand core.

[0033] Sand core for steel castings Figure 3 As shown, the outermost layer is a chrome ore sand shell composed of multiple chrome ore sand auxiliary cores 200, which is closely attached to the chrome ore sand layer 202. In order to solve the sintering problem on the basis of cost saving, the thickness of the chrome ore sand layer is set to 40mm-100mm. The chrome ore sand layer 202 is closely attached to the inner sand core 203. The inner sand core 203 can use hardenable and strong casting sand. In this embodiment, silica sand, water glass sand and resin sand are mainly used. These are cheap and have good hardening effect. The casting sand is suitable for large-scale casting process and has good economic effect. The core bone 300 is used to string the chrome ore sand auxiliary core 200, the chrome ore sand layer 202 and the inner sand core 203 into a whole. The sand filling port 201 is used to fill the chrome ore sand layer 202 and the inner sand core 203 on the one hand, and the core bone 300 is also inserted from the sand filling port 201 on the other hand.

[0034] In a second aspect, an embodiment of the present invention further discloses a core making method for a sand core for a steel casting as described in the above embodiment, which specifically comprises the following steps:

[0035] S01, making core box 100 and chrome ore auxiliary core 200:

[0036] The core box 100 and the chrome ore sand auxiliary core 200 need to be designed in advance according to the structure of the steel casting. In order to facilitate lifting, a core box lifting lug 101 is designed on the outside of the core box 100. The core box 100 and the chrome ore sand auxiliary core 200 are printed by a 3D printer. The number of the core box lifting lug 101 is set according to the size and shape of the steel casting. In the embodiment of the present invention, 2-6 core box lifting lugs 101 are set.

[0037] S02, assembly:

[0038] The core box 100 printed in step S01 is placed on a workbench, and a plurality of chrome ore sand auxiliary cores 200 printed in step S01 are placed in the core box 100. After the air outlet rope 304 is wound around the core bone 300, the core bone 300 is placed inside the chrome ore sand auxiliary core 200 through the sand filling port 201 on the top of the chrome ore sand auxiliary core 200.

[0039] S03, core making:

[0040] Fill the hardenable casting sand into the chrome ore sand auxiliary core 200 through the sand filling port 201 at the top of the chrome ore sand auxiliary core 200, fill it to a distance of 40mm-100mm from the sand filling port 201, and form an inner sand core 203, and then fill it with chrome ore sand to form a 40mm-100mm chrome ore sand layer 202, which becomes a whole after being compacted;

[0041] S04, static forming;

[0042] The finished sand core is placed in a static state for forming. The static time is related to the adhesive used. Preferably, the static time is 3-10 hours to ensure that the sand core is completely formed.

[0043] In order to facilitate the complete removal of the sand core, a gap is left between the core box 100 and the chrome ore sand auxiliary core 200 during the assembly step. Preferably, the gap distance is 1 mm-5 mm.

[0044] This embodiment takes the production of the inner sand core of the pipeline as an example, and uses silica sand to fill the inner sand core 203, so as to further understand the concept of the core making method of the sand core for the steel casting:

[0045] According to the structure of the inner cavity of the pipeline, a 3D printing drawing is designed in advance to make a core box 100 and a chrome ore sand auxiliary core 200. In the embodiment of the present invention, the number of the chrome ore sand auxiliary cores 200 is 4, and the core box 100 is provided with 4 hanging ears 101. The 4 chrome ore sand auxiliary cores 200 are placed in the core box 100, and after the air outlet rope 304 is wound around the core bone 300, the core bone 300 is placed inside the chrome ore sand auxiliary core 200 through the sand filling port 201 at the top of the chrome ore sand auxiliary core 200, and silica sand is placed through the sand filling port 201 at the top of the chrome ore sand auxiliary core 200. The chrome ore sand auxiliary core 200 is filled to a distance of 40 mm from the sand filling port 201 to form an inner sand core 203, and then chrome ore sand is used for filling to form a chrome ore sand layer 202 with a thickness of 40 mm. After compaction, it becomes an integral sand core. The time for static molding is adaptively adjusted according to the different adhesives used. In this embodiment, furan resin is used as the adhesive, and it takes 4-5 hours to statically mold. Epoxy asphalt rubber (EAR) is used as the adhesive, and it takes 6-10 hours to ensure that the sand core is completely molded.

[0046] This embodiment takes the production of the inner sand core of the pipeline as an example, and uses water glass sand to fill the inner sand core 203, so as to further understand the concept of the core making method of the sand core for steel castings:

[0047] According to the structure of the inner cavity of the pipeline, a 3D printing drawing is designed in advance to make a core box 100 and a chrome ore sand auxiliary core 200. In the embodiment of the present invention, the number of the chrome ore sand auxiliary cores 200 is 4, and the core box 100 is provided with 4 hanging ears 101. The 4 chrome ore sand auxiliary cores 200 are placed in the core box 100, and after the air outlet rope 304 is wound around the core bone 300, the core bone 300 is placed inside the chrome ore sand auxiliary core 200 through the sand filling port 201 at the top of the chrome ore sand auxiliary core 200, and the water glass sand is placed in the core bone 300. The chrome ore sand auxiliary core 200 is filled into the interior of the chrome ore sand auxiliary core 200 through the sand filling port 201 at the top thereof, and is filled to a distance of 60 mm from the sand filling port 201 to form an inner sand core 203, and then chrome ore sand is used for filling to form a chrome ore sand layer 202 with a thickness of 60 mm, which is compacted to form an integral sand core. Since water glass sand is a non-self-hardening sand, carbon dioxide (CO2) needs to be blown into the interior through the air outlet rope 304 to harden the water glass sand to ensure a certain hardness.

[0048] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0049] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A sand core for steel castings, characterized in that: The sand core comprises a chrome ore sand auxiliary core, a sand filling port, a chrome ore sand layer, a core bone and an inner layer sand core, wherein the sand filling port is arranged on the chrome ore sand auxiliary core, and the chrome ore sand layer and the inner layer sand core are arranged in sequence from top to bottom inside the chrome ore sand auxiliary core; The core bone is also arranged inside the chrome ore sand auxiliary core, stringing the chrome ore sand auxiliary core, the chrome ore sand layer and the inner sand core together.

2. The sand core according to claim 1, characterized in that: The number of the chromium ore sand auxiliary cores is 2-10, and the top of each of the chromium ore sand auxiliary cores is provided with the sand filling port.

3. The sand core according to claim 1, characterized in that: The thickness of the chromium ore sand layer is 40mm-100mm.

4. The sand core according to claim 1, characterized in that: The material of the inner sand core is hardenable casting sand, including silica sand, water glass sand and resin sand.

5. The sand core according to claim 1, characterized in that: The chromium ore sand auxiliary core is also provided with a cold iron port.

6. The sand core according to claim 1, characterized in that: The chromium ore sand auxiliary core is provided with scale lines.

7. The sand core according to claim 1, characterized in that: The core bar is a double steel bar structure, and a core assembly lifting lug and a transport lifting lug are also provided on the core bar.

8. The sand core according to claim 1, characterized in that: An air outlet rope is arranged on the core bone.

9. A method for making a sand core for a steel casting according to any one of claims 1 to 8, characterized in that: The core making method comprises the following steps: S01, manufacturing a core box and a chrome ore auxiliary core, designing 3D printing drawings of the core box and the chrome ore auxiliary core according to the structure of the steel casting, and printing the core box and the chrome ore auxiliary core using a 3D printer; S02, assembling, placing the chrome ore sand auxiliary core in the core box, and placing the core bone provided with the air outlet rope inside the chrome ore sand auxiliary core through the sand filling port at the top of the chrome ore sand auxiliary core; S03, core making, filling the hardenable casting sand through the sand filling opening at the top of the chrome ore sand auxiliary core to a distance of 40 mm to 100 mm from the sand filling opening to form the inner sand core, and then filling with chrome ore sand to form the chrome ore sand layer, which is compacted into a whole; S04, static molding.

10. The core making method according to claim 9, characterized in that: In the assembling step, a gap of 1 mm to 5 mm is left between the core box and the chromium ore sand auxiliary core.

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