Inorganic sand core for preventing mold sticking and molding process thereof
By combining inorganic sand, additives, and modified silicate binders, the problem of sticking to the mold in inorganic cores was solved, ensuring a firm surface after the sand core is formed and achieving reliability for mass production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SUZHOU ALUTECH AUTOMOTIVE PARTS CO LTD
- Filing Date
- 2023-04-26
- Publication Date
- 2026-07-07
AI Technical Summary
In the process of making cores without a mold, the phenomenon of sticking to the mold frequently occurs, resulting in damage or accumulation of sand cores, which affects mass production. Existing technologies are difficult to solve effectively.
By using a specific ratio of inorganic sand, additives and binders, and by using a modified silicate mixture as a binder, the flowability of the mixed sand is controlled, the core adhesion force is reduced, sticking to the mold is prevented, and the surface is ensured to be firm after molding.
It prevents sticking to the mold under high sand injection pressure, ensures the quality of sand core forming, and provides a reliable guarantee for mass production.
Abstract
Description
Technical Field
[0001] This invention relates to the field of core-making technology, and more particularly to an inorganic sand core for preventing sticking to the mold and its molding process. Background Technology
[0002] Core-making technology generally includes hot core box method, cold core box method and warm core box method.
[0003] The hot core box method is a machine-based method for manufacturing cores in casting production. A mixture of casting sand, thermosetting resin, and a hardener is injected into a core box equipped with a heating device and heated to 180–250°C. This heat causes the sand material close to the core box surface to condense and harden under the influence of temperature, forming the core in a very short time.
[0004] The cold box method refers to a technique that uses a gas or aerosol catalyst to catalyze the instantaneous curing of resin sand at room temperature.
[0005] The warm core box method, also known as the inorganic core method, involves mixing sand, resin, and additives in a specific ratio, then injecting the mixture into a core box cavity using compressed air. The core box temperature is typically around 150°C. Hot air is then blown into the core box cavity to solidify the sand core. Compared to the hot and cold core box methods, the warm core box method is more environmentally friendly, which is why inorganic cores have been widely adopted.
[0006] However, mold sticking often occurs during the manufacturing process of machined cores. Sticking typically occurs directly below the nozzle. Due to high injection pressure, the sand core below the nozzle becomes compacted and adheres tightly to the core box surface. During demolding, if the adhesion force exceeds the surface strength of the sand core, the surface will break and the core will remain on the core box, causing mold sticking. Even if sticking doesn't damage the sand core, it can lead to accumulation, requiring machine shutdown for mold cleaning and preventing mass production. Therefore, in this process, high injection pressure causes mold sticking, preventing mass production; low injection pressure prevents the sand core from forming, resulting in defective products, also preventing mass production. Summary of the Invention
[0007] To solve the above-mentioned technical problems, the present invention provides an inorganic sand core for preventing sticking to the mold and its molding process.
[0008] The technical solution of this invention is: an inorganic sand core for preventing mold sticking, comprising the following components in parts by weight:
[0009] 100 parts inorganic sand, 1-1.2 parts additives, and 1.6-1.8 parts binder.
[0010] Furthermore, there are 100 parts of inorganic sand, 1 part of additives, and 1.6 parts of binder.
[0011] Furthermore, the additive components include: 5-10% graphite by weight; the remainder being barium sulfate. Generally, this additive is INOTEC PROMOTOR TC 4000, a commercially available inorganic additive, a composition of natural and synthetic minerals, appearing as a gray powder with a bulk density of approximately 800 kg / m³. 3 .
[0012] Furthermore, the adhesive is a modified silicate mixture, the modified silicate composition comprising the following components by weight percentage: 30-50 wt% sodium silicate, 1-10 wt% potassium silicate, and the remainder being water.
[0013] Furthermore, the modified silicate mixture has a pH of 11.5-12.5. Generally, this binder is INOTEC EP 4703, in liquid form, with a specific gravity of approximately 1.40 g / cm³. 3 The viscosity of Fiberglass is approximately 35 mPa·s.
[0014] The beneficial technical effects of this invention are: by controlling the composition and ratio of inorganic sand cores, the fluidity of the mixed sand is changed, so that when the mixed sand is injected into the mold through the nozzle of the core making machine, it can quickly disperse and not gather, and the adhesion force of the sand core is reduced. Thus, the sand core will not stick to the mold even under a large sand injection pressure, and the surface of the final sand core is firm and free of floating sand.
[0015] A molding process for inorganic sand cores to prevent sticking to the mold, comprising:
[0016] Raw material inspection: Inspect inorganic sand, additives, and binders;
[0017] Mixing: Add inorganic sand to the large sand bin, add additives to the addition hopper, move the binder to the bonding station, and mix the three together in proportion to obtain mixed sand;
[0018] Sand core manufacturing: The mixed sand is conveyed to the sand hopper of the core making machine, where it is formed in a mold and the sand core is ejected through the lower core box;
[0019] Post-processing of sand cores: After the robotic arm removes the sand cores, they are placed on the core-repairing platform for core repair.
[0020] Transfer and storage: The sand cores after core repair are dehumidified in a dehumidification room, and the dehumidified sand cores are stored in a warehouse.
[0021] Further inspection of inorganic sand includes: weight, particle size, moisture content, mud content, and silica content. The main focus is on selecting the appropriate state of the inorganic sand to ensure it meets requirements: a weight of 1 kg, a particle size of 40-46 mesh, a moisture content of ≤0.2%, and a mud content of ≤0.3%. Controlling the inorganic sand ensures the quality of the subsequent sand core products.
[0022] Furthermore, the type of adhesive and the type and moisture content of the additives are checked. Since the adhesives and additives are commercially available materials, it is only necessary to determine their compliance.
[0023] Furthermore, during mixing, the inorganic sand is conveyed to a fluidized bed and treated at 25±5℃ for at least 30 minutes. Then, 100 parts of the inorganic sand and 1-1.2 parts of additives are mixed in a sand mixing device for at least 2 minutes, followed by the addition of 1.6-1.8 parts of binder and mixing for at least 1 minute. The inorganic sand is dried via the fluidized bed to facilitate subsequent mixing.
[0024] Furthermore, the agitator in the sand mixing equipment operates at 50Hz to ensure uniform mixing of the three materials.
[0025] Furthermore, the specific parameters of the chip-making machine include:
[0026] The sand-shooting pressure is 5 bar, the sand-shooting time is 1 second, the sand volume in the sand-shooting barrel is 25%, and the core box temperature is 170℃.
[0027] The curing pressure is 4 bar, the curing time is 40 seconds, and the hot air temperature is 300°C.
[0028] Furthermore, the chip repair platform performs chip repairs, which is a routine operation.
[0029] Furthermore, the specific parameters for a dehumidification room include: temperature ≥ 40℃, humidity ≤ 30%, and time of 2-72 hours.
[0030] The beneficial technical effects of this invention are: this molding process, combined with the improved sand mixing components, makes the surface of the final sand core compact and prevents sticking between the core and the mold, thus providing a reliable guarantee for the mass production of sand cores. Detailed Implementation
[0031] In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the specific embodiments of the present invention will be described in further detail below with reference to the embodiments. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.
[0032] The composition of the inorganic sand core in Example 1: 150 kg of inorganic sand, 1% of additives, and 1.6% of binder.
[0033] The additive consists of 5-10% graphite by weight, with the remainder being barium sulfate. Generally, this additive is INOTEC PROMOTOR TC 4000, a commercially available inorganic additive, a combination of natural and synthetic minerals, appearing as a gray powder with a bulk density of approximately 800 kg / m³. 3 .
[0034] The adhesive is a modified silicate mixture comprising the following components by weight percentage: 30-50 wt% sodium silicate, 1-10 wt% potassium silicate, and the remainder water. The pH of the modified silicate mixture is 11.5-12.5. Generally, this adhesive is I NOTEC EP 4703, is liquid, and has a specific gravity of approximately 1.40 g / cm³. 3 The viscosity of Fiberglass is approximately 35 mPa·s.
[0035] The composition of the inorganic sand core in Example 2 is: 150 kg of inorganic sand, 1% of additives, and 1.8% of binder.
[0036] The composition of the inorganic sand core in Example 3 is: 150 kg of inorganic sand, 1% of additives, and 2% of binder.
[0037] The composition of the inorganic sand core in Example 4: 150 kg of inorganic sand, 1% of additives, and 1.5% of binder.
[0038] The composition of the inorganic sand core in Example 5: 150 kg of inorganic sand, 1.2% additives, and 1.8% binder.
[0039] The composition of the inorganic sand core in Example 6: 150 kg of inorganic sand, 1.2% of additives, and 2% of binder.
[0040] The composition of the comparative inorganic sand core: 150 kg of inorganic sand, 0.8% of additives, and 2% of binder.
[0041] The comparative examples and six embodiments described above all employed the following molding process, including:
[0042] Raw material inspection: Inspect inorganic sand, additives, and binders;
[0043] Mixing: Add inorganic sand to the large sand bin, add additives to the addition hopper, move the binder to the bonding station, and mix the three together in proportion to obtain mixed sand;
[0044] Sand core manufacturing: The mixed sand is conveyed to the sand hopper of the core making machine, where it is formed in a mold and the sand core is ejected through the lower core box;
[0045] Post-processing of sand cores: After the robotic arm removes the sand cores, they are placed on the core-repairing platform for core repair.
[0046] Transfer and storage: The sand cores after core repair are dehumidified in a dehumidification room, and the dehumidified sand cores are stored in a warehouse.
[0047] Further inspection of inorganic sand includes: weight, particle size, moisture content, mud content, and silica content. The main focus is on selecting the appropriate state of the inorganic sand to ensure it meets requirements: a weight of 1 kg, a particle size of 40-46 mesh, a moisture content of ≤0.2%, and a mud content of ≤0.3%. Controlling the inorganic sand ensures the quality of the subsequent sand core products.
[0048] Furthermore, the type of adhesive and the type and moisture content of the additives are checked. Since the adhesives and additives are commercially available materials, it is only necessary to determine their compliance.
[0049] Furthermore, during mixing, the inorganic sand is conveyed to a fluidized bed and treated at 25±5℃ for 30 minutes. Then, the inorganic sand and additives are mixed in a sand mixing device for 2 minutes, followed by the addition of a binder and mixing for 1 minute. The inorganic sand is dried via the fluidized bed, facilitating subsequent mixing.
[0050] Furthermore, the agitator in the sand mixing equipment operates at 50Hz to ensure uniform mixing of the three materials.
[0051] Furthermore, the specific parameters of the chip-making machine include:
[0052] The sand-shooting pressure is 5 bar, the sand-shooting time is 1 second, the sand volume in the sand-shooting barrel is 25%, and the core box temperature is 170℃.
[0053] The curing pressure is 4 bar, the curing time is 40 seconds, and the hot air temperature is 300°C.
[0054] Furthermore, the chip repair platform performs chip repairs, which is a routine operation.
[0055] Furthermore, the specific parameters for a dehumidification room include: temperature ≥ 40℃, humidity ≤ 30%, and time of 2-72 hours.
[0056] Data analysis was performed on the seven sets of sand cores obtained:
[0057] Group Does it stick to the mold? Are the sand cores qualified? Example 1 no yes Example 2 no yes Example 3 yes no Example 4 no no Example 5 no yes Example 6 yes no Comparative Example yes no
[0058] Based on the above experimental data analysis, what is needed is a non-stick and qualified sand core. According to the experimental data, it can be seen that Example 1, Example 2, and Example 5 are qualified sand cores, while the others are unqualified.
[0059] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A molding process for inorganic sand cores to prevent sticking to the mold. Its features are, This includes: Raw material inspection: inspecting each component of the inorganic sand core; Mixing: Add inorganic sand to the large sand bin, add additives to the addition hopper, move the binder to the bonding station, and mix the three together in proportion to obtain mixed sand; Sand core manufacturing: The mixed sand is conveyed to the sand hopper of the core making machine. The core making machine injects the mixed sand into the heated mold for sand injection molding and heating and solidification, and then ejects the sand core through the lower core box; Core post-processing: After the robotic arm removes the core, it is placed on the core repair platform for core repair. Transfer and storage: The sand cores after core repair are dehumidified in a dehumidification room, and the dehumidified sand cores are stored in the warehouse; The inorganic sand core comprises the following components in parts by weight: 100 parts of inorganic sand, 1-1.2 parts of additives, and 1.6-1.8 parts of binder, wherein the additives consist of 5-10% graphite by weight, and the remainder is barium sulfate; the binder is a modified silicate mixture, which comprises the following components by weight percentage: 30-50 wt% sodium silicate, 1-10 wt% potassium silicate, and the remainder is water.
2. The molding process for the inorganic sand core to prevent sticking to the mold according to claim 1, characterized in that, The items to be checked for inorganic sand include: weight, particle size, moisture content, mud content, and silica content; the type of binder to be checked; and the type and moisture content of additives to be checked.
3. The molding process for the inorganic sand core to prevent sticking to the mold according to claim 1, characterized in that, During mixing, inorganic sand is conveyed to a fluidized bed and treated at 25±5℃ for at least 30 minutes. Then, 100 parts of inorganic sand and 1-1.2 parts of additives are mixed in a sand mixing device for at least 2 minutes. Then, 1.6-1.8 parts of binder are added and mixed for at least 1 minute.
4. The molding process for the inorganic sand core to prevent sticking to the mold according to claim 1, characterized in that, The specific parameters of the chip-making machine include: The sand injection pressure is 5 bar, the sand injection time is 1 second, the sand volume in the sand injection barrel is 25%, the core box temperature is 170℃, the curing pressure is 4 bar, the curing time is 40 seconds, and the hot air temperature is 300℃.
5. The molding process for the inorganic sand core to prevent sticking to the mold according to claim 1, characterized in that, The specific parameters for a dehumidification room include: temperature ≥ 40℃, humidity ≤ 30%, and time 2-72 hours.
6. The molding process for the inorganic sand core to prevent sticking to the mold according to claim 1, characterized in that, The inorganic sand core comprises the following components in parts by weight: 100 parts inorganic sand, 1 part additive, and 1.6 parts binder.
7. The molding process for the inorganic sand core to prevent sticking to the mold according to claim 1, characterized in that, The modified silicate mixture has a pH value of 11.5-12.5.