Core manufacturing method of sand core

Abstract

The invention discloses a sand core manufacturing method which comprises the following steps: step 1, structural design: dividing a target sand core into a plurality of split sand cores which are easy to manufacture; 2, a split sand core is prepared; 3, a core making platform is prepared, and a sand frame positioning assembly and a sand core guide forming assembly are arranged on the core making platform according to the size of the target sand core; 4, the multiple split sand cores are combined and then positioned on a core manufacturing platform, and a pre-assembled core is formed; 5, a sand frame is placed on the core manufacturing platform and located on the periphery of the pre-assembled core; 6, the multiple split sand cores located in the vertical direction are locked through a first locking assembly, the multiple split sand cores located in the horizontal direction are locked through a second locking assembly, and the pre-assembled core and the sand frame are fixed; 7, a cavity of the split sand core is blocked, and the space between the pre-assembly core and the sand frame is filled with self-hardening sand; and 8, after the self-hardening sand is solidified, drawing is conducted, and the target sand core is obtained. According to the core assembling method of the sand core, the cost is reduced, and the production efficiency is improved.

Description

Technical Field

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

[0002] In the prior art, the demand for super-large castings is about 1,000 pieces per year, and the annual demand is not large. The existing methods for preparing super-large sand cores in the casting process include equipment core making and manual core making. Equipment core making is a super-large core making machine used to prepare sand cores in the casting field. This equipment first injects the mixed resin sand into the super-large sand core mold cavity through air pressure, then blows air to solidify, opens the mold to take out the sand core, and obtains a super-large sand core weighing about 2 tons. Manual core making is to prepare a super-large handmade core box, fill it with sand manually, open the mold and take out the core after solidification to obtain a super-large sand core.

[0003] The disadvantages of the prior art are:

[0004] (1) When the batch size is small, the existing technology requires the preparation of an oversized mold, which results in high production costs;

[0005] (2) When the process or casting structure needs to be adjusted, the mold needs to be modified, which has a long change cycle, high cost and complicated process;

[0006] (3) Since molds need to be made, the development cycle from sand core design to sand core preparation is long. Summary of the invention

[0007] Based on the above problems, the object of the present invention is to provide a method for making a sand core, which can combine multiple split sand cores together and then make a second core to form an ultra-large sand core, thereby reducing costs.

[0008] In order to overcome the deficiencies of the prior art, the technical solution provided by the present invention is:

[0009] A method for making a sand core comprises the following steps:

[0010] Step 1: Structural design, dividing the target sand core into multiple split sand cores that are easy to prepare;

[0011] Step 2: preparing split sand core;

[0012] Step 3: Prepare the core making platform, and set the sand frame positioning assembly and the sand core guide molding assembly on the core making platform according to the size of the target sand core;

[0013] Step 4: Assemble multiple split sand cores and position them on the core making platform to form a pre-assembled core;

[0014] Step 5: Place the sand frame on the core making platform through the sand frame positioning assembly and position it on the periphery of the preassembled core;

[0015] Step 6: Lock multiple split cores in the vertical direction through the first locking assembly, lock multiple split cores in the horizontal direction through the second locking assembly, and fix the pre-assembled cores to the sand frame.

[0016] Step 7: Seal the cavities of the split cores, and fill self-hardening sand between the pre-assembled cores and the sand frame.

[0017] Step 8: Demold after the self-hardening sand is cured to obtain the target core.

[0018] In one embodiment, in Step 2, the split cores are prepared by 3D printing cores, subtractive core making, or equal-material core making.

[0019] In one embodiment, in Step 3, the bottom plate of the core-making platform is a plate-like structure, and the flatness of the bottom plate ≤ 1 mm.

[0020] In one embodiment, in Step 3, the sand frame positioning assembly includes a plurality of positioning members arranged circumferentially on the bottom plate and arranged in the vertical direction.

[0021] The core guiding and forming assembly includes a plurality of first forming members for forming rough positioning holes, a plurality of second forming members for forming fine positioning holes, and a plurality of positioning blocks connecting the split cores and the bottom plate, which are arranged inside the circumference of the sand frame positioning assembly. The first forming members and the second forming members are arranged on the outer circumference of the plurality of split cores to be combined, and the plurality of positioning blocks extend into the split core at the bottom.

[0022] In one embodiment, in Step 4, the misalignment dimension after the split cores are fitted together ≤ 0.5 mm, and the error of the length, width, and height of the pre-assembled cores compared with the theoretical values is within ±0.5 mm.

[0023] In one embodiment, in Step 5, the gap between the sand frame and the pre-assembled cores is 20 - 100 mm.

[0024] In one embodiment, in Step 5, the sand frame includes two side plates arranged opposite to each other, two inner plates connecting the two side plates, and a plurality of cross beams connecting the two side plates and having a spacing from the core-making platform. A pressing plate arranged along the extending direction of the side plates abuts against the upper ends of the cross beams.

[0025] In one embodiment, in Step 6, the first locking assembly includes a plurality of first screws and a plurality of pressing plates. The first screws are arranged in the vertical direction and are locked with the plurality of split cores in the vertical direction through nuts. The pressing plates connect adjacent first screws and abut against the split cores above.

[0026] In one embodiment, in Step 6, the second locking assembly includes a plurality of second screws arranged in the horizontal direction. The second screws are locked with the plurality of split cores in the horizontal direction through nuts.

[0027] In one embodiment, the filling of self-hardening sand in step 7 is completed within 2 hours.

[0028] Compared with the prior art, the advantages of the present invention are:

[0029] 1. Multiple small split sand cores can be combined into a super-large sand core, which is suitable for the preparation of small batches of super-large sand cores. No mold is required, the cost is low, and the sand core preparation cycle is short;

[0030] 2. When the process and casting structure are adjusted, only the 3D data or simple mold needs to be changed. The change process is simple and convenient, the change cycle is short, and the cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0032] Figure 1 A schematic structural diagram of a quarter of a core making device of a sand core according to an embodiment of the present invention;

[0033] Figure 2 It is a structural schematic diagram of a core making platform in an embodiment of the present invention;

[0034] Figure 3 It is a structural schematic diagram of a sand frame in an embodiment of the present invention;

[0035] in:

[0036] 1. Core making platform; 1-1. Bottom plate; 1-2. Positioning piece; 1-3. First molding piece; 1-4. Second molding piece; 1-5. Positioning block; 1-6. Direction mark;

[0037] 2. First locking assembly; 2-1. First screw rod; 2-2. Pressing plate; 2-3. Nut; 2-4. Washer;

[0038] 3. Second screw;

[0039] 4. Sand frame; 4-1. Side plate; 4-1a. Positioning hole; 4-2. Inner plate; 4-3. Crossbeam;

[0040] 5. Split sand core; 5-1. Inverted structure. DETAILED DESCRIPTION

[0041] The above scheme is further described below in conjunction with specific examples. It should be understood that these examples are used to illustrate the present invention and are not limited to the scope of the present invention. The implementation conditions adopted in the examples can be further adjusted according to the conditions of the specific manufacturer, and the unspecified implementation conditions are usually the conditions in conventional experiments.

[0042] A method for making a sand core comprises the following steps:

[0043] Step 1: Structural design, dividing the target sand core into multiple split sand cores that are easy to prepare;

[0044] Step 2: preparing split sand core;

[0045] Step 3: Prepare the core making platform, and set the sand frame positioning assembly and the sand core guide molding assembly on the core making platform according to the size of the target sand core;

[0046] Step 4: Assemble multiple split sand cores and position them on the core making platform to form a pre-assembled core;

[0047] Step 5: Place the sand frame on the core making platform through the sand frame positioning assembly and position it on the periphery of the preassembled core;

[0048] Step 6: Lock the multiple split sand cores in the vertical direction by the first locking assembly, and lock the multiple split sand cores in the horizontal direction by the second locking assembly, so as to fix the preassembled core and the sand frame;

[0049] Step 7: Seal the cavity of the split sand core and fill the space between the pre-assembled core and the sand frame with self-hardening sand;

[0050] Step 8: After the self-hardening sand is solidified, demoulding is performed to obtain the target sand core.

[0051] In step 2, a split sand core is prepared by 3D printing sand core, subtractive core making or equal material core making. When the casting process or casting structure is adjusted, for 3D printing sand core and subtractive core making, the 3D data can be directly changed. For equal material core making (simple mold), a small mold needs to be adjusted. Compared with an oversized mold, the adjustment amount is small, the cycle is short, and the cost is low. Therefore, this method is simple and convenient to adjust the sand core structure, and there is no need to adjust the mold structure a lot.

[0052] like Figure 2 As shown, in step 3, the bottom plate 1 - 1 of the core making platform 1 is a plate-like structure, and the flatness of the bottom plate 1 - 1 is ≤ 1 mm.

[0053] In step 3, the sand frame positioning assembly includes a plurality of positioning members 1-2 arranged on the circumference of the base plate 1-1 and arranged in the vertical direction. The sand core guide molding assembly includes a plurality of first molding members 1-3 located on the inner periphery of the sand frame positioning assembly for forming rough positioning holes, a plurality of second molding members 1-4 for forming fine positioning holes, and a plurality of positioning blocks 1-5 connecting the split sand core and the base plate 1-1. The first molding members 1-3 and the second molding members 1-4 are arranged on the outer periphery of the plurality of split sand cores 5 to be combined, and the plurality of positioning blocks 1-5 extend into the split sand core 5 located at the bottom. After the self-hardening sand and the split sand core are combined and molded, rough positioning holes and fine positioning holes are formed on the target sand core. When the target sand mold is subsequently assembled, positioning pins are set in the rough positioning holes and fine positioning holes for positioning.

[0054] In step 4, the split sand cores 5 are placed on the core making platform 1 in the order of pre-core assembly. During each placement of a split sand core 5, the gap between the split sand core 5 and the positioning block 1-5 is observed to be in place. It is required that the misalignment size between the split sand cores 5 after matching is ≤0.5mm, and the length, width and height of the pre-core assembly have an error within ±0.5mm compared with the theoretical value.

[0055] In step 5, the first locking assembly includes a plurality of first screws 2-1 and a plurality of pressure plates 2-2. The first screws 2-1 are arranged in the vertical direction and locked with the plurality of split sand cores 5 located in the vertical direction via nuts. The pressure plate 2-2 connects the plurality of adjacent first screws 2-1 and abuts against the split sand core 5 located above. Specifically, a nut is prefabricated in the split sand core 5 located at the bottom, and the first screw 2-1 passes through the plurality of split sand cores 5 located in the vertical direction and is threadedly connected with the nut at the bottom. The pressure plate 2-2 is locked with the first screw 2-1 via the nut at the top. The second locking assembly includes a plurality of second screws 3 arranged in the horizontal direction. The second screws 3 are locked with the plurality of split sand cores 5 located in the horizontal direction via nuts at both ends.

[0056] In step 6, the gap between the sand frame 4 and the pre-assembled core is 20 to 100 mm, which is convenient for filling with self-hardening sand.

[0057] like Figure 3 As shown, in step 6, the sand frame 4 includes two side panels 4-1 arranged opposite to each other, two inner panels 4-2 connecting the two side panels 4-1, and a plurality of cross beams 4-3 connecting the two side panels 4-1 and having a spacing between them and the core making platform 1. The pressing plate 2-2 arranged along the extending direction of the side panel 4-1 abuts against the upper end of the cross beam 4-3. There is a gap between the cross beam 4-3 and the pre-assembled core to prevent the sand frame 4 from interfering with the pre-assembled core when the sand frame 4 is placed. A wedge block is filled in the gap between the cross beam 4-3 and the pre-assembled core, the pressing plate 2-2 is passed through the cross beam 4-3, and the first screw 2-1 and the pressing plate 2-2 are locked with the nut 2-3 to achieve the fixation of the pre-assembled core and the sand frame 4 (as shown in FIG. Figure 1 shown).

[0058] In step 7, refractory material is used to fill the cavity of the split sand core 5 to prevent self-hardening sand from falling into the cavity when it is filled.

[0059] In step 7, self-hardening sand is filled layer by layer from bottom to top. The filling of self-hardening sand is completed within 2 hours to prevent the self-hardening sand from hardening during the filling process, which affects the strength of the sand core. Finally, the sand filling surface is scraped flat with a scraper. After the self-hardening sand is hardened, the mold is removed to obtain an extra-large sand core.

[0060] In step 7, in order to improve the bonding force between the self-hardening sand and the split sand core 5, an undercut structure 5-1 is provided on the end surface of the split sand core 5 in contact with the self-hardening sand, and the undercut structure 5-1 is gradually reduced from away from the split sand core 5 to close to the split sand core 5.

[0061] In summary, this method can combine multiple small sand cores into a super-large sand core without the need for mold opening, thereby reducing production costs and improving production efficiency.

[0062] The above examples are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for making a sand core, characterized in that: The following steps are involved: Step 1: Structural design, dividing the target sand core into multiple split sand cores that are easy to prepare; Step 2: preparing split sand core; Step 3: Prepare the core making platform, and set the sand frame positioning assembly and the sand core guide molding assembly on the core making platform according to the size of the target sand core; Step 4: Assemble multiple split sand cores and position them on the core making platform to form a pre-assembled core; Step 5: Place the sand frame on the core making platform through the sand frame positioning assembly and position it on the periphery of the preassembled core; Step 6: Lock the multiple split sand cores in the vertical direction by the first locking assembly, and lock the multiple split sand cores in the horizontal direction by the second locking assembly, so as to fix the preassembled core and the sand frame; Step 7: Seal the cavity of the split sand core and fill the space between the pre-assembled core and the sand frame with self-hardening sand; Step 8: After the self-hardening sand is solidified, demould to obtain the target sand core.

2. The method for making a sand core according to claim 1, characterized in that: In step 2, the split sand core is prepared by 3D printing sand core, subtractive core making or equal material core making.

3. The method for making a sand core according to claim 1, characterized in that: In step 3, the bottom plate of the core making platform is a plate-like structure, and the flatness of the bottom plate is ≤1 mm.

4. The method for making a sand core according to claim 3, characterized in that: In step 3, the sand frame positioning assembly includes a plurality of positioning members arranged in the circumferential direction of the bottom plate and in the vertical direction; The sand core guide molding assembly includes a plurality of first molding parts located on the inner periphery of the sand frame positioning assembly for forming rough positioning holes, a plurality of second molding parts used to form fine positioning holes, and a plurality of positioning blocks connecting the split sand core and the base plate. The first molding parts and the second molding parts are arranged on the outer periphery of the plurality of split sand cores to be combined, and the plurality of positioning blocks extend into the split sand core located at the bottom.

5. The method for making a sand core according to claim 1, characterized in that: In step 4, the misalignment size between the split sand cores after matching is ≤0.5mm, and the length, width and height of the pre-assembled core are within ±0.5mm compared with the theoretical value.

6. The method for making a sand core according to claim 1, characterized in that: In step 5, the gap between the sand frame and the pre-assembled core is 20 to 100 mm.

7. The method for making a sand core according to claim 1, characterized in that: In step 5, the sand frame includes two side plates arranged opposite to each other, two inner plates connecting the two side plates, and a plurality of cross beams connecting the two side plates and having a distance between the two side plates and the core assembly platform, and a pressure plate arranged along the extension direction of the side plates abuts against the upper ends of the cross beams.

8. The method for making a sand core according to claim 1, characterized in that: In step 6, the first locking assembly includes multiple first screws and multiple pressure plates. The first screws are arranged in the vertical direction and locked with multiple split sand cores located in the vertical direction via nuts. The pressure plates connect the adjacent multiple first screws and abut against the split sand cores located above.

9. The method for making a sand core according to claim 1, characterized in that: In step 6, the second locking assembly includes a plurality of second screws arranged in the horizontal direction, and the second screws are locked with a plurality of split sand cores located in the horizontal direction via nuts.

10. The method for making a sand core according to claim 1, characterized in that: The filling of self-hardening sand in step 7 is completed within 2 hours.

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