CN111644574A - Preparation method of reinforced thin-wall sand core - Google Patents

Abstract

The invention discloses a method for preparing a reinforced thin-walled sand core. During the core-making process, the thin-walled part of the sand core that needs to be reinforced is formed by mixing coated sand and reinforced aggregate. Since the reinforcing aggregate can play the role of aggregate reinforcement at the weak point of the sand core, it can effectively avoid the problems of sand core deformation and core breakage caused by the thin-walled sand core during the core making, handling, baking and pouring process. , thereby reducing casting defects.

Description

A kind of preparation method of strengthening thin-walled sand core

technical field

The invention relates to the technical field of casting, in particular to a method for preparing a reinforced thin-walled sand core.

Background technique

Sand core is a material used to make cores in foundry production, which consists of foundry sand, molding sand binder, etc. Its function is to form the inner cavity, hole and casting shape of the casting. The process of making core sand into a sand core that conforms to the shape of the core box is called core making. Coated sand is a molding sand in which the surface of the sand grains is covered with a solid resin film before the core is formed, and the thermoplastic phenolic resin is added with a latent curing agent (urotropine) and a lubricant (calcium stearate), etc. The material is prepared into coated sand through a certain coating process. The core box is a special mold for making sand cores. According to the core making method, it is divided into ordinary core box, hot core box and cold core box.

In the prior art, casting defects are often caused due to insufficient strength when making complex thin-walled sand cores.

The patent with the authorization announcement number CN104722716B provides a complex thin-walled sand core forming method. The method provides a conformal core according to the shape of the sand core, and sets serrated cast iron reinforcing ribs at the weak position of the sand core to make the core manually. The sand core forming method improves the connection strength of the sand core and realizes the stable production of the sand core with complex water cavity. The patented solution has the following disadvantages: the method of setting metal reinforcing ribs is not suitable for cleaning in complex water cavities, and the cleaning is difficult; the core bone used in this method needs to be extracted during the cleaning process after the pouring is completed, and the shape of the core bone cannot be set. It is too complicated, otherwise it will be difficult to extract the core; the process of this sand core forming method is relatively complicated, and it is not suitable for mechanized core making.

Patent Publication No. CN110076285A provides a high-temperature and deformation-resistant sand core material and a preparation method thereof. The sand core material introduces chromite and steel fiber wires with excellent chilling effect on the basis of ordinary sand core materials, which significantly improves the sand core. The chilling ability of the core makes the surrounding of the sand core solidify and form before other parts, and improves the surface finish and dimensional position accuracy of the inner cavity of the casting. At the same time, high temperature resistant, high strength and low cost whiskers are introduced on the basis of ordinary sand core materials, and the high temperature deformation resistance of the sand core is improved through the high temperature resistance strengthening and deformation resistance of the whiskers. High temperature strengthening and anti-deformation effect, significantly improve the high-temperature deformation resistance of the sand core. The patented solution has the following disadvantages: the way of adding steel fibers and whiskers to the sand will greatly reduce the fluidity of the sand, and the sand core with complex structure and small local size cannot be formed at all; and after the casting is cooled, The cleaning of sand is very difficult, and this method is only suitable for sand cores of large size and simple structure.

Therefore, how to reduce the casting defects caused by the production of complex thin-walled sand cores is a technical problem to be solved by those skilled in the art.

SUMMARY OF THE INVENTION

In view of this, the purpose of the present invention is to provide a method for preparing a reinforced thin-walled sand core, which can strengthen local weak points of the sand core and avoid casting defects caused by insufficient sand core strength.

In order to achieve the above object, the present invention provides the following technical solutions:

A method for preparing a reinforced thin-walled sand core. During the core-making process, the thin-walled part of the sand core that needs to be reinforced is formed by mixing coated sand and reinforced aggregate.

Preferably, in the core making process, prefabricated coated sand is used to shoot sand at the thin wall of the core that needs to be strengthened, wherein the prefabricated coated sand includes: basic aggregate, reinforcing aggregate, binder, curing agent agent, lubricant.

Preferably, in the core making process, prefabricated coated sand is used for sand blasting at the thin wall of the sand core that needs to be strengthened, and reinforcing aggregate is sprayed at the same time.

Optionally, in the core making process, the prefabricated coated sand is used for sand shooting on the whole of the sand core.

Preferably, the prefabricated coated sand comprises: 100 parts by weight of base aggregate, 3-7 parts by weight of reinforcing aggregate, 2-4 parts by weight of binder, 0.35-0.5 parts by weight of curing agent, 0.2-7 parts by weight of curing agent, 0.4 parts by weight of lubricant.

Preferably, the prefabricated coated sand includes: 100 parts by weight of base aggregate, 5 parts by weight of reinforcing aggregate, 3 parts by weight of binder, 0.45 part by weight of curing agent, and 0.3 part by weight of lubricant.

Preferably, the basic aggregate is silica sand, the binder is phenolic resin or furan resin, the curing agent is an aqueous solution of urotropine, and the lubricant is calcium stearate.

Preferably, in the core making process, firstly, the reinforcing aggregate is placed on the thin wall of the sand core that needs to be strengthened, and then the coated sand is injected into the thin wall of the sand core that needs to be strengthened.

Optionally, the reinforcing aggregate is carbon fiber, or asbestos fiber, or ceramic fiber, or glass fiber.

In the preparation method of the reinforced thin-walled sand core provided by the invention, in the core-making process, the thin-walled part of the sand core that needs to be reinforced is formed by mixing coated sand and reinforced aggregate. Since the reinforcing aggregate can play the role of aggregate reinforcement at the weak point of the sand core, it can effectively avoid the problems of sand core deformation and core breakage caused by the thin-walled sand core during the core making, handling, baking and pouring process. , thereby reducing casting defects.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

Fig. 1 is the flow chart of the preparation method of the reinforced thin-walled sand core in the second embodiment of the present invention;

FIG. 2 is a schematic diagram of sand shooting at the thin wall of the sand core in Embodiment 1 of the present invention.

In Figure 2:

1-Sand nozzle, 2-Inner cavity of core box, 3-Sand core thin wall, 4-Jet nozzle, 5-Prefabricated coated sand.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Please refer to FIG. 1 and FIG. 2. FIG. 1 is a flowchart of a method for preparing a reinforced thin-walled sand core in a specific embodiment of the present invention; Schematic.

Aiming at the problem that the strength of the complex thin-walled sand core is insufficient to easily cause casting defects, the invention proposes a preparation method of a reinforced thin-walled sand core by mixing reinforcing aggregate into the coated sand to make the core. The thin-walled part of the sand core that needs to be strengthened is formed by mixing the coated sand with the reinforcing aggregate. Since the reinforcing aggregate can play the role of aggregate reinforcement at the weak point of the sand core, it can effectively avoid the problems of sand core deformation and core breakage caused by the thin-walled sand core during the core making, handling, baking and pouring process. , thereby reducing casting defects.

It should be noted that, according to the different ways in which the reinforcing aggregate is mixed into the coated sand, the preparation method provided by this solution can have various implementations. For details, please refer to the following embodiments.

Example 1

Example 1 During the core making process, prefabricated coated sand is used to shoot sand at the thin-walled part of the sand core that needs to be strengthened, wherein the prefabricated coated sand includes: basic aggregate, reinforcing aggregate, binder, curing agent, lubricant. In this embodiment, the reinforcing aggregate is mixed with ordinary coated sand to make a special prefabricated coated sand. Therefore, when the prefabricated coated sand is used for sand blasting at the thin wall of the sand core, the reinforcing aggregate can be used in the weak It plays the role of aggregate reinforcement.

Please refer to FIG. 2 , in this embodiment, two sand injection nozzles 1 are used to inject the coated sand into the inner cavity 2 of the core box. In addition, a separate injection system is set up to inject the prefabricated coated sand 5 into the thin wall of the sand core through the injection nozzle 4 3.

Example 1 Two sets of sand shooting systems are designed on the core making equipment. The nozzles 4 are set separately for the thin wall 3 of the sand core. The prefabricated coated sand is injected into the thin wall 3 of the sand core. The core is made of ordinary coated sand and sand.

Embodiment 2

Example 2 During the core making process, prefabricated coated sand was used for sand blasting at the thin-walled part of the sand core that needs to be strengthened, and reinforcing aggregate was sprayed at the same time. This embodiment is further improved on the basis of Embodiment 1, not only using prefabricated coated sand containing reinforcing aggregate to shoot sand at the thin wall of the sand core, but also spraying reinforcing aggregate at the thin wall at the same time, so as to further strengthen the Reinforcing aggregate acts as reinforcement for reinforcing ribs.

Please refer to Fig. 1, the concrete processing flow of Embodiment 2 is as follows:

S1: The core making machine gives a signal for sand, and the sand supply system supplies the prefabricated coated sand to the top of the core making machine and stores them separately;

S2: Inject the prefabricated coated sand into the inner cavity of the core box respectively. The sand injection pressure is generally 0.3~0.5Mpa, the sand injection time is 5~9s, and the exhaust time is 5~9s. A separate injection system for reinforced aggregate is set up, the injection nozzle is set at the thin wall of the sand core, the reinforced aggregate injection system is activated at an appropriate time during the core making process, and the prefabricated coated sand is injected at the same time to complete the sand core. Strengthening at thin walls;

S3: After the sand shooting is completed, the sand core is cured by heating the core box. The heating temperature is generally set to 200~230℃, and the curing time is 70~100s; if it is a cold core box, the corresponding cold core curing method is used to conduct the sand core solidify;

S4: After the sand core is cured, open the core box and take out the qualified sand core.

Embodiment 3

Example 3 In the core making process, the prefabricated coated sand is used to shoot sand on the whole of the core. This example is a further improvement of the second example. Sand is shot at the thin wall of the core, and other parts of the core are also shot, so that the whole of the core is strengthened. This embodiment is suitable for the core making process of the overall complex thin-walled sand core, and the core making equipment only needs to be provided with one set of sand shooting system.

Embodiment 4

Embodiment 4 During the core making process, firstly, the reinforcing aggregate is placed on the thin wall of the sand core that needs to be strengthened, and then the coated sand is injected into the thin wall of the sand core that needs to be strengthened. The effect achieved in this embodiment is similar to the effect of injecting prefabricated coated sand in the above embodiment, and both can strengthen the thin wall of the sand core.

It should be noted that the prefabricated coated sand includes: 100 parts by weight of basic aggregate, 3-7 parts by weight of reinforcing aggregate, 2-4 parts by weight of binder, 0.35-0.5 parts by weight of curing agent, 0.2 to 0.4 parts by weight of lubricant.

Preferably, the above-mentioned prefabricated coated sand includes: 100 parts by weight of base aggregate, 5 parts by weight of reinforcing aggregate (such as carbon fiber), 3 parts by weight of binder, 0.45 part by weight of curing agent, 0.3 part by weight of lubricant agent.

Preferably, the basic aggregate is ordinary silica sand, the angular coefficient is less than 1.3, the content of silica is more than 97.5%, the reinforcing aggregate is preferably carbon fiber, the binder is phenolic resin or furan resin, and the curing agent is The urotropine aqueous solution, the mass ratio of the urotropine aqueous solution is 1:1, and the lubricant is calcium stearate.

It should be noted that the reinforcing aggregate in this solution is carbon fiber, and asbestos fiber, ceramic fiber, or glass fiber can also be selected, and these materials can improve the strength of the sand core.

The present invention has the following beneficial effects:

1) In this scheme, carbon fiber and other reinforcing aggregates are used to act as reinforcing ribs after the sand core is prepared, which can effectively avoid problems such as deformation of the thin-walled sand core and core breakage, thereby reducing casting defects;

2) This scheme can only strengthen the local weak parts of the sand core, which reduces the cost compared with the overall strengthening of the sand core;

3) This scheme is easy to operate, the core making process is simple, suitable for mechanized production, and the core making efficiency is high;

4) This solution will not increase the difficulty of casting cleaning.

The above description of the disclosed embodiments enables any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (9)

1. a preparation method of strengthening thin-walled sand core, is characterized in that, in the core-making process, adopts the mode of mixing coated sand and reinforcing aggregate to the thin-walled place where sand core needs to be strengthened. 2. The method for preparing a reinforced thin-walled sand core according to claim 1, wherein in the core-making process, prefabricated coated sand is used to shoot sand at the thin-walled part of the sand core that needs to be strengthened, wherein the Prefabricated coated sand includes: basic aggregate, reinforcing aggregate, binder, curing agent, lubricant. 3. The method for preparing a reinforced thin-walled sand core according to claim 2, characterized in that, in the core-making process, prefabricated coated sand is used to shoot sand at the thin-walled part of the sand core that needs to be reinforced, while spraying reinforcing bone material. 4 . The method for preparing a reinforced thin-walled sand core according to claim 2 , wherein in the core-making process, the prefabricated coated sand is used to shoot the whole of the sand core. 5 . 5 . The method for preparing a reinforced thin-walled sand core according to claim 2 , wherein the prefabricated coated sand comprises: 100 parts by weight of basic aggregate, 3-7 parts by weight of reinforcing aggregate, 2-7 parts by weight of 4 parts by weight of a binder, 0.35 to 0.5 parts by weight of a curing agent, and 0.2 to 0.4 parts by weight of a lubricant. 6. The method for preparing a reinforced thin-walled sand core according to claim 5, wherein the prefabricated coated sand comprises: 100 parts by weight of basic aggregate, 5 parts by weight of reinforcing aggregate, 3 parts by weight of Binder, 0.45 parts by weight of curing agent, 0.3 part by weight of lubricant. 7. The method for preparing a reinforced thin-walled sand core according to claim 5, wherein the base aggregate is silica sand, the binder is phenolic resin or furan resin, and the curing agent is Uroto The product is an aqueous solution, and the lubricant is calcium stearate. 8 . The method for preparing a reinforced thin-walled sand core according to claim 1 , wherein, in the core making process, firstly, a reinforcing aggregate is placed at the thin-walled place where the sand core needs to be strengthened, and then, the Coated sand is injected into the strengthened thin wall. 9 . The method for preparing a reinforced thin-walled sand core according to claim 1 , wherein the reinforcing aggregate is carbon fiber, or asbestos fiber, or ceramic fiber, or glass fiber. 10 .

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