Method for improving performance of amine method cold core
By heat treatment of the sand core in the amine cold core process, a more complete cross-linking network structure is formed, which solves the problems of insufficient strength of the sand core and high gas generation, improves the final strength and reduces the gas generation, and achieves more efficient casting production.
Patent Information
- Application Number
- CN202411823732.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-11
- Publication Date
- 2025-03-18
AI Technical Summary
The sand core prepared by the amine cold core process has problems such as insufficient strength, high gas production, and reduced strength after heat treatment, resulting in defects such as pores, leakage and core breakage of the castings.
Heat treatment is carried out within half an hour of the preparation of the sand core, with a temperature of 120-200°C and a treatment time of 20-60 minutes. Heat treatment is carried out through a blow drying box to form a more complete cross-linking network structure, thereby improving the strength of the sand core.
The final strength of the sand core is increased by about 10%, reducing the gas production volume, and avoiding the adverse consequences of increasing the amount of resin added, while extending the service life of the core box.
Smart Images
Figure BDA0005183712510000031 
Figure BDA0005183712510000032 
Figure BDA0005183712510000033
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of casting, in particular to a method for improving the performance of amine process cold cores. Background Art
[0002] The amine cold core process mainly uses phenolic resin (component I) and polyisocyanate (component II) as a two-component adhesive, and the sand core is quickly solidified at room temperature through the catalytic effect of triethylamine.
[0003] However, the sand core obtained by this method has the following problems:
[0004] (1) When the resin model and sand are determined, if the sand core strength does not meet the use requirements, the strength of the sand core must be increased by increasing the amount of resin added, which will increase the sand shooting pressure and aggravate the sand core sticking to the mold and reduce the service life of the core box, the fluidity of the core sand will deteriorate and affect the quality of the sand core, and the gas emission of the sand core will increase, resulting in defects such as pores and leakage in the casting;
[0005] (2) The sand cores produced generally need to be placed for a certain period of time to build up sufficient strength before they can be repaired and poured. Otherwise, some sand cores will be deformed or broken after pouring due to low strength;
[0006] (3) After the sand core is coated with water-based paint and dried, the strength of the sand core is reduced, and the core may break after pouring. Summary of the invention
[0007] Based on the above problems, the object of the present invention is to provide a method for improving the performance of amine cold cores, which can improve the strength of sand core products.
[0008] In order to overcome the deficiencies of the prior art, the technical solution provided by the present invention is:
[0009] A method for improving the performance of an amine cold core, wherein a heat treatment process is added after the preparation process for a sand core prepared by an amine cold core process, and the sand core is heat treated for a period of time within half an hour after the sand core preparation is completed.
[0010] In one embodiment, the temperature of the sand core heat treatment is 120-200° C., and the treatment time is 20-60 min.
[0011] In one embodiment, the temperature of the sand core heat treatment is 150° C. and the treatment time is 40 minutes.
[0012] In one embodiment, the heat treatment is performed using a forced air drying oven.
[0013] In one embodiment, the sand core is supported by a bracket and placed in the blast drying oven for heat treatment.
[0014] In one of the embodiments, during the preparation process of the sand core, the blast drying oven is turned on in advance, the heating temperature is set, and after the temperature stabilizes, the prepared sand core is placed in the blast drying oven for heat treatment.
[0015] Compared with the prior art, the advantages of the present invention are:
[0016] 1. The sand core is prepared by the amine cold core process. The sand core is heat treated within half an hour after the sand core is prepared. This treatment measure intensifies the thermal motion of the resin molecules, more active groups contact and react with each other, the curing reaction is more complete, and a more complete cross-linked network structure is formed, thereby improving the strength of the sand core and increasing the final strength of the sand core by about 10%. At the same time, the gas emission of the sand core is reduced, and the adverse consequences caused by increasing the amount of resin added are avoided;
[0017] 2. For sand cores that do not need to increase the amount of resin added, after heat treatment, the amount of single-component resin added can be reduced by 0.05% to 0.1%, while meeting the use requirements of the sand core;
[0018] 3. After the sand core is heat treated, it is coated and dried in a hot state to improve the final tensile strength of the sample. DETAILED DESCRIPTION
[0019] 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 routine experiments.
[0020] Example 1
[0021] The laboratory artificially mixes sand, uses recycled Dahu sand with a particle size of 50 / 100, adds 0.45% (phenolic resin content) + 0.45% (polyisocyanate content) of cold core resin, and shoots sand to prepare standard "8-shaped" specimens. The specimens that need heat treatment are placed on the bracket. After the sample is prepared, the bracket is immediately placed in a blast drying oven with different set temperatures. The heat treatment time is 20min, 40min, and 60min respectively.
[0022] During the sand core preparation process, the blast drying oven is opened in advance, the heating temperature is set, and after the temperature stabilizes, the prepared sand core is placed in the blast drying oven for heat treatment.
[0023] After the heat treatment, the samples were placed in the laboratory environment. According to the national standard GB / T 2684-2009 Testing Methods for Foundry Sand and Mixtures, the final tensile strength of each sample was tested using an intelligent strength tester. At least 5 data were tested for each sample, and the average value was calculated after removing the maximum and minimum values. The final tensile strength data and comparison are shown in Table 1:
[0024] Table 1 Comparison of final tensile strength
[0025]
[0026] It can be seen from Table 1 that the final strength is basically the highest when the heat treatment temperature is 150°C and the heat treatment time is 40 minutes. The final strength under this heat treatment condition is 11.1% higher than the strength without heat treatment. The improvement of the final tensile strength after heat treatment for 60 minutes is not obvious. According to the principle of economy, the heat treatment temperature is 150°C and the heat treatment time is 40 minutes.
[0027] The comparison of 24h gas emission is shown in Table 2. It can be seen from Table 2 that the 24h gas emission is reduced by 10.8%.
[0028] Table 2 Comparison of gas emission in 24 hours
[0029]
[0030] Example 2
[0031] Regenerated Dahu sand with a particle size of 50 / 100 was used, and verification was carried out using a disintegrating inner core box (including an "8"-shaped sample). When the sand core was not heat-treated, the resin addition amount was 0.55% (phenolic resin content) + 0.55% (polyisocyanate content); the resin addition amount of the inner core and the "8"-shaped sample after heat treatment at 150°C / 40min was 0.5% (phenolic resin content) + 0.5% (polyisocyanate content). See Table 3 for specific comparison.
[0032] Table 3 Comparison of strength of samples with different resin addition amounts
[0033]
[0034] The single-component resin addition amount of the heat-treated sample was reduced by 0.05%, but the strength was equivalent to the final strength of the non-heat-treated sample of 0.55% (phenolic resin content) + 0.55% (polyisocyanate content), and the quality of the core making and collapsible samples were qualified.
[0035] It can be seen that after the inner core and the 8-shaped sample were heat treated at 150℃ / 40min, the strength of the sand core was improved, so the amount of single-component resin added could be reduced by 0.05%.
[0036] Example 3
[0037] Using regenerated Dahu sand with a particle size of 50 / 100, two samples were prepared: cold core resin addition amount 0.6% (phenolic resin content) + 0.6% (polyisocyanate content), adding 0.3% anti-veining agent; cold core resin addition amount 0.55% (phenolic resin content) + 0.55% (polyisocyanate content), adding 0.3% anti-veining agent, and the final tensile strength test was carried out on the samples coated immediately after core making and the samples coated in hot state after heat treatment. The specific data are shown in Table 4:
[0038] Table 4 Final tensile strength of coating directly after core making and hot coating after heat treatment
[0039]
[0040] It can be seen that the final tensile strength of the product can be improved by coating the sand core specimens in a hot state after heat treatment.
[0041] 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 improving the performance of amine-process cold cores, characterized in that: For the sand cores prepared by the amine cold core process, a heat treatment process is added after the preparation process, and the sand cores are heat treated for a period of time within half an hour after the sand core preparation is completed.
2. The method for improving the performance of amine-process cold core according to claim 1, characterized in that: The temperature of the sand core heat treatment is 120-200°C, and the treatment time is 20-60 minutes.
3. The method for improving the performance of amine-process cold core according to claim 2, characterized in that: The temperature of the sand core heat treatment is 150°C and the treatment time is 40 minutes.
4. The method for improving the performance of amine-process cold core according to claim 1, characterized in that: The heat treatment is carried out in a forced air drying oven.
5. The method for improving the performance of amine-process cold core according to claim 4, characterized in that: The sand core is supported by a bracket and placed in the blast drying box for heat treatment.
6. The method for improving the performance of amine-process cold core according to claim 5, characterized in that: During the preparation process of the sand core, the blast drying oven is opened in advance, the heating temperature is set, and after the temperature is stabilized, the prepared sand core is placed in the blast drying oven for heat treatment.