A rapid forming method of water glass sand mold

Abstract

The invention discloses a rapid molding method of a sodium silicate sand mould and belongs to the field of rapid casting. The rapid molding method comprises the following steps: (1), establishing a three-dimensional entity model of a sodium silicate sand mould to be molded, taking the Z axis as the molding direction, and setting molding layer thickness; (2), first, paving one layer of molding sand material, and then spraying an adhesive so as to form the current layer of outline pattern, wherein the adhesive is a mixed solution of sodium silicate and polyvinyl alcohol; (3), carrying out microwave heating on the current layer of outline pattern, and forming the current layer of sand mould outline; (4), stopping microwave heating, and lowering the work table for a height of one layer thickness along the Z axis; and (5), repeating steps (2-4) until the sodium silicate sand mould is molded. The method meets the high requirement of sodium silicate sand hardened through microwave heating on the mould, solves the problems that the surface of the sodium silicate sand mould becomes powdery due to overheating and easily absorbs moisture, and further overcomes the poor feasibility, difficult molding sand storage and difficult molding sand recycling defects of the existing micro-injection bonding sodium silicate sand rapid molding technology.

Description

technical field [0001] The invention belongs to the field of rapid casting, and more specifically relates to a micro-spray bonding additive manufacturing technology of a water glass sand mold (core). Background technique [0002] Green and clean production is the technological development trend of the machine manufacturing industry, especially the foundry industry, in the 21st century. Among the three widely used sand castings such as clay sand, water glass sand and resin sand, water glass sand casting is environmentally friendly and is the most likely type of sand to achieve green casting. [0003] The commonly used hardening method of water glass sand is CO 2 There are three types: blowing hardening, liquid organic ester hardening, and heat hardening. In the application of more CO 2 In the two processes of hardened water glass sand and ester hardened water glass sand, CO 2 There are the following problems in the hardened water glass sand process: high water glass addit...

AI Technical Summary

Problems solved by technology

In the application of more CO 2 In the two processes of hardened water glass sand and ester hardened water glass sand, CO 2 The hardened water glass sand process has the following problems: high water glass addition (6% to 8% of the quality of the molding sand), poor collapsibility of old sand, and difficulty in recycling

However, there are also many disadvantages in the ester-hardened water glass sand process: due to the residual ester and residual Na 2 O accumulates in the process of recycling, and the collapsibility and recyclability of old sand after recycling tend to deteriorate

[0005] The main problem in the application of microwave hardened water glass sand is: the hardened water glass sand mold (core) has strong hygroscopicity, and the hardening strength of the microwave hardened water glass sand mold parked in the air environment for 1 to 2 hours drops rapidly

In addition, it is difficult for existing mold materials to meet the requirements of microwave hardened water glass sand molds, because metal mold materials cannot be used, and wood molds and plastic molds are easily deformed by heat.

[0006] The patent application number is 200810197391.5 Chinese patent application discloses a microwave hardening method of water glass sand mold or sand core, which first puts the sand mold together with the mold into a microwave oven and heats it for a short time (heating time 5 seconds to 20 seconds) to make it resistant to compression After the strength is greater than 15KPa (mold strength), the mold is demoulded; then the sand mold without the mold is heated twice by microwave (heating time is greater than 40 seconds), so that it can be completely hardened, so as to solve the high requirements of microwave hardened sodium silicate sand on the mold material. However, the problem of this method is that the manufacturing cycle of sand mold and core box is long and the cost is high, and the difficulty of sand mold demoulding after the first microwave heating is strictly limited by the complexity of the structure of sand mold and core box.

The publication number is CN 104493101A Chinese patent application discloses a rapid prototyping system and method for a high-precision ester-cured water glass sand mold / core, which uses water glass and molding sand mixture as a forming powder material, and sprays organic ester to harden the water glass. The main problem that the method exists is: after the water glass is mixed with the molding sand, the fluidity of the molding sand drops sharply, and a complete sand layer cannot be formed on the surface of the workbench, and the process is difficult to proceed smoothly; Provide a certain strength to the sand layer, and the powder layer on it will be compressed under the pressure generated by its own weight. This phenomenon will seriously affect the accuracy of the subsequent forming layer thickness after being enlarged layer by layer.

Moreover, after the water glass sand mold is formed, it needs to wait for 1h-8h before it can be solidified, and its preparation efficiency is low.

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