CN103521698B

CN103521698B - Insulating moulding coating and preparation method thereof, metal type dies and metal casting manufacturing apparatus

Info

Publication number: CN103521698B
Application number: CN201310520405.3A
Authority: CN
Inventors: 胡亮
Original assignee: Hebei Xinghua Pipe Co Ltd
Current assignee: Hebei Xinghua Pipe Co Ltd
Priority date: 2013-10-30
Filing date: 2013-10-30
Publication date: 2016-11-16
Anticipated expiration: 2033-10-30
Also published as: CN103521698A

Abstract

Open a kind of insulating moulding coating of the present invention and preparation method thereof, metal type dies and metal casting manufacturing apparatus, wherein, this insulating moulding coating includes: Kaolin, kieselguhr, polyvinyl alcohol, lithium bentonite and water, and its percentage by weight is: Kaolin 11～12%；Kieselguhr 3.6～4.0%；Polyvinyl alcohol 0.09～0.11%；Lithium bentonite 0.50～0.60%；The remaining proportionate share of water；Wherein, described polyvinyl alcohol is as paint adhesive composition, and described lithium bentonite is coating deflocculant, binding agent and dispersion. formulation.The present invention also provides for a kind of metal type dies being coated with above-mentioned insulating moulding coating and is provided with the metal casting manufacturing apparatus of this metal type dies.The present invention can alleviate metal type dies by high temperature liquid iron ablation, improves the service life of metal type dies, increases the die cavity thermal conduction resistance of metal type dies simultaneously, slows down the setting rate after molten iron enters die cavity.

Description

Heat insulation coating and preparation method thereof, metal mold and metal mold casting equipment

Technical Field

The invention relates to the field of metal casting, in particular to a heat-insulating coating and a preparation method thereof, a metal mold and metal mold casting equipment.

Background

The metal mold casting process is a technology which is gradually developed and more widely applied in recent years, has the advantages of high production efficiency, small occupied area of a production field, low technical requirement on operators, easy formation of a mechanical assembly line and suitability for large-scale batch production.

The existing casting machine is relatively complex in structure, and mainly comprises that the whole mechanical action is controlled by hydraulic pressure and electricity, and each machine is provided with a hydraulic work station with a larger volume. The method is mainly used for casting nonferrous metals with lower temperature in the past. The high-temperature casting machine is used for casting high-temperature cast iron castings, the operating temperature and the ambient temperature are high, the hydraulic oil temperature is too high, electrical accessories are easy to damage, the equipment failure rate is high, and the hydraulic pipe is easily burnt by splashed high-temperature molten iron. The hydraulic transmission has slower action speed and low production efficiency.

In addition, the thin-wall gray cast iron pipe fitting is produced by adopting the metal mold with the existing structural form, because molten iron is easy to cool and solidify in the casting process, the conventional casting mode that the casting is horizontally arranged in the cavity is adopted, the casting is easy to solidify when the molten iron is not completely filled in the cavity, and therefore, the phenomena of insufficient casting and difficult forming of the casting due to the fact that the molten iron solidifies quickly are caused, and waste products are caused.

In addition, when the conventional sand mold casting process is used for casting the pipe fitting, because the molding sand can move back and forth, the size change range of the casting is large under the action of gravity and the solidification, expansion and contraction of the molten iron during the casting and filling of the molten iron, and the casting allowance of the size of the casting is increased to ensure the requirement of the minimum wall thickness of the pipe fitting, so that the casting cost is increased.

In addition, the heat-resistant casting blank adopted by the existing metal mold is expensive in metal mold material processing, easy to generate heat cracks, short in service life and high in production cost, so that the bottleneck of popularization and application of the metal mold casting technology is limited.

Disclosure of Invention

In view of the above, the invention provides a heat insulation coating and a preparation method thereof, which can reduce the ablation of a metal mold by high-temperature molten iron, prolong the service life of the metal mold, increase the heat conduction resistance of a cavity of the metal mold, slow down the solidification speed of the molten iron after entering the cavity, and prevent the occurrence of white spots caused by chilling when the high-temperature molten iron contacts the metal mold.

In addition, the invention also provides a metal mold coated with the heat-insulating coating and metal mold casting equipment provided with the metal mold.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

in one aspect, the present invention provides a thermal insulation coating, including: kaolin, diatomite, polyvinyl alcohol, lithium bentonite and water, wherein the weight percentages are as follows:

the coating comprises a coating, a lithium bentonite, a polyvinyl alcohol, a coating suspending agent, a binder and a dispersant.

Preferably, the thermal barrier coating further comprises: dispersants, defoamers and/or rust inhibitors for improving coating performance.

Correspondingly, the invention also provides a preparation method of the heat insulation coating, which comprises the following steps: preparing polyvinyl alcohol paste; preparing lithium bentonite paste; adding powdery diatomite, kaolin and water into a low-speed stirrer, and stirring to completely mix the powdery diatomite, the kaolin and the water with the aqueous solution; after fully stirring without agglomeration, sequentially adding the lithium bentonite paste and the polyvinyl alcohol paste, continuously stirring and fully mixing uniformly, and filtering by a filter screen for later use.

Further, in the above method, the method for preparing a polyvinyl alcohol paste comprises: taking the polyvinyl alcohol and the water according to the proportion of 1: 25; adding polyvinyl alcohol and water into the electric heating kettle in the ratio of 1: 25 to make polyvinyl alcohol and water into transparent paste.

Further, in the above method, the method of preparing a lithium-based bentonite paste comprises: taking lithium bentonite and water according to the proportion of 1: 10; quantitatively adding lithium bentonite and water into a container according to the proportion of 1: 10, standing for more than 24 hours until the bentonite fully absorbs water and swells; adding the fully swelled lithium bentonite into a stirrer for fully stirring before use.

Compared with the prior art, the invention has the following advantages:

therefore, the heat-insulating coating and the preparation method thereof can reduce the ablation of the metal mold by high-temperature molten iron and prolong the service life of the metal mold. Meanwhile, the heat conduction resistance of the cavity of the metal mold is increased, the solidification speed of molten iron after entering the cavity is slowed down, and the phenomenon of white cast caused by chilling when high-temperature molten iron is in contact with the metal mold is prevented.

On the other hand, the invention also provides a metal mold which is arranged on the metal mold casting equipment and comprises a first half mold and a second half mold which are processed by low-carbon structural steel with uniform metal structure; the first half mould and the second half mould are respectively and correspondingly provided with: the casting mold comprises a cavity, a pouring gate, a pouring channel, a fixed support leg and a parting surface, wherein the cavity, the pouring gate and the pouring channel are used for forming the appearance of a casting during casting, the fixed support leg can be fixedly connected to the metal mold casting equipment, and the parting surface can be mutually attached when the first half mold and the second half mold are closed; the cavity is a concave cavity matched with the shape of the outer surface of the casting, and is provided with a sand core for limiting the shape and the wall thickness of the inner surface of the casting; a positioning part for positioning the relative position between the sand core and the cavity is arranged above the cavity; the gates are respectively and correspondingly arranged above the first half mould and the second half mould; the pouring gate is communicated with the pouring gate and extends into the cavity from the upper part of the cavity; wherein the inner surface of the cavity is coated with any one of the heat-insulating coatings.

Furthermore, the positioning part comprises a positioning core slot and a sand core positioning slot, and the positioning core slot is used for positioning the relative position between the positioning core head of the sand core and the cavity; the sand core positioning groove is used for positioning the relative position between the main body of the sand core and the cavity; the sand core is provided with a positioning flange, and the shape of the positioning flange is matched with the shape of the inner wall of the sand core positioning groove; wherein the low-carbon structural steel is Q235 hot-rolled common low-carbon structural steel, and the carbon content of the low-carbon structural steel is within the range of 0.12-0.22%.

Further, the first half mold and the second half mold are further provided with: the positioning pin hole and the positioning pin are used for keeping the relative positions of the two half dies from shifting when the two half dies are closed; the positioning pin hole on the first half die is matched with the positioning pin on the second half die in position and size; and the positioning pin on the first half die is matched with the positioning pin hole on the second half die in position and size.

Further, when the first half mold and the second half mold are closed, the sprue is in a shape of a cavity with a horn-shaped upper part and a cylindrical lower part; and/or the upper part of the pouring channel is communicated with the pouring gate cylinder, and the lower part of the pouring channel is communicated with the cavity; wherein the pouring channel is a concave flat groove processed according to the required size of the casting process.

Compared with the prior art, the invention has the following advantages:

the metal mold consists of a pair of two half molds, a gate is arranged above the molds by adopting vertical parting, and a pouring channel extends from the upper part of the mold cavity to enter the mold cavity. When the two half molds are closed, the parting surfaces are completely attached to form a cavity for molding the casting. The vertical parting and pouring system arrangement mode of the metal mold is beneficial to the rapid filling and forming of molten iron in the narrow gap between the cavity and the sand core under the action of gravity. Compared with the existing upper part rain type pouring gate, the metal mold disclosed by the invention can shorten the casting time, avoid the phenomenon of insufficient casting caused by overlong mold filling time, and improve the yield.

In yet another aspect, the present invention provides a metal mold casting apparatus comprising: the mould comprises a frame, a fixed mould plate, a movable mould plate guide shaft, a mould closing device and any type of mould; the first half mold and the second half mold are respectively and correspondingly arranged on the fixed mold plate and the movable mold plate; the fixed template is arranged on the rack, and the movable template guide shaft is arranged between the rack and the fixed template and penetrates through the movable template; one end of the mold closing device is installed on the rack, and the other end of the mold closing device is installed on the movable mold plate; and under the drive of the mold closing device, the movable mold plate reciprocates on the guide shaft of the movable mold plate to complete the mold opening and closing action.

Compared with the prior art, the invention has the following advantages:

the metal mold casting equipment designed by the invention adopts pneumatic drive control to supply air to the pouring pipeline in a centralized way, only needs an air source and does not need a power supply, has the characteristics of simple structure, small occupied area of the equipment, high action speed of the equipment, high production efficiency, quick mold loading and unloading and the like, and is particularly suitable for the production of a mechanized casting production line.

In addition, the metal mold casting equipment designed by the invention is convenient to maintain and simple and convenient to operate, the failure rate of the metal mold casting equipment is greatly reduced, the production operation cost is reduced, and the mechanical automatic casting production line is very convenient to form.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 is a schematic structural view of a metal mold casting apparatus according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a metal mold in an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a sand core in an embodiment of the invention;

fig. 4 is a schematic structural view of a casting in an embodiment of the invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

Preferred embodiments of the present invention will be further described with reference to the accompanying drawings in which:

examples of Heat-insulating coating

1. A thermal barrier coating comprising: kaolin, diatomite, polyvinyl alcohol, lithium bentonite and water, wherein the weight percentages are as follows:

the coating comprises a coating material, a lithium bentonite, a polyvinyl alcohol, a coating suspending agent, a material adhesive and a dispersing agent, wherein the polyvinyl alcohol is used as a coating adhesive component, and the lithium bentonite is used as a coating suspending agent, a material adhesive and a dispersing agent component. The lithium bentonite is used as a suspending agent, the suspending effect of the coating prepared from the coating pasty solid material is ensured, and when the lithium bentonite is sprayed on the surface of a preheated die cavity of a metal die to form a dry coating, the lithium bentonite has better coating strength, is not easily washed away by molten iron, and forms slag holes in a casting. On the other hand, the coating has better collapsibility, and residual coatings on the surfaces of the die and the casting after casting and forming are easy to remove. Moreover, because the addition amount of the bentonite is less than that of the traditional calcium bentonite, the air permeability of the dry coating is improved, and the defects of air holes, pits and the like on the surface of the casting are reduced.

Preferably, the heat insulation coating can also comprise the following components according to actual requirements: dispersants, defoamers, and rust inhibitors. The types of optional additives in this embodiment are very many, and the addition amount of the additives can be added according to the type of the coating suitable for the selected additives and the recommended proportion. For example: different types of defoaming agents are selected, and the addition amount of the defoaming agents is different. In this embodiment, the addition of the additives has no fundamental influence on the main performance characteristics of the coating, and can improve the performance, so that a person skilled in the art can select whether to add the additives and the addition amount thereof according to actual needs, and optionally, the component content of each additive can be added according to the use instructions of the selected dispersant, defoamer or antirust product.

The metal mold heat-insulating coating is a water-based coating which is sprayed on the surface of a metal mold cavity with a certain temperature before casting each time and can form a dry breathable coating with a certain thickness. In order to ensure the uniformity of the coating and the wall thickness and size precision of the pipe casting, during specific use, spraying is generally adopted before each casting, after the casting is taken out after the casting is finished, residual coating needs to be cleaned, then spraying is carried out again, and then casting is carried out.

In the research process, the heat-insulating coating of the metal mold is determined to have the following characteristics:

1) the alloy has high temperature resistance, can resist high-temperature molten iron, and can ensure the attractive appearance of a casting;

2) the heat insulation and preservation performance is provided so as to slow down the heating speed of the metal mold and the solidification speed of molten iron;

3) the air-permeable layer has good air permeability, so that an air-permeable layer is formed between the casting and the metal mold cavity to absorb gas generated in the casting solidification process;

4) the coating has certain coating strength so as to ensure that the dry coating is not washed and shed when molten iron is cast;

5) the coating has better demolding property and high-temperature collapsibility, and is convenient for demolding of the casting and cleaning of the involved coating in a cavity;

in the embodiment, the defects of the coating used in the traditional process are summarized, the composite water-based coating with high temperature resistance, good heat insulation performance, good air permeability and easy cleaning is developed, and the defect that the coating used in the traditional process only has a single function of high temperature resistance is overcome. The paint formula mainly adopts kaolin, diatomite, bentonite, water-soluble organic adhesive and other components.

The calcined fine powder kaolin is a high-temperature resistant material, and the refractoriness of the calcined fine powder kaolin is about 1700 ℃ generally; the heat insulating coating prepared by the method can form a high-temperature resistant protective coating in a metal mold cavity, so that a mold can resist high-temperature molten iron and cannot be damaged by ablation. Compared with other high-temperature resistant materials, the kaolin has the characteristic of high temperature resistance, the surface roughness of the casting is reduced, and the appearance quality is obviously improved.

The calcined fine powder diatomite is a high-temperature-resistant heat-insulating material, the melting point of the calcined fine powder diatomite is 1650-. High porosity, air permeability and adsorption capacity. The heat-insulating coating prepared by the method can form a heat-insulating protective coating in a metal mold cavity so as to obstruct and slow down the heat conduction speed of high-temperature molten iron to a metal mold, reduce the temperature rise speed of the mold and slow down the solidification speed of the molten iron. The die is protected from high-temperature impact, and meanwhile, white spots of thin-wall pipe castings can be avoided. Due to the porosity and the air permeability of the diatomite, the diatomite can absorb gas generated when high-temperature molten iron is solidified in the cavity, and defects such as pits and air holes on the surface of a casting are avoided.

The calcined fine powdery bentonite is used as a suspending agent, a binder and a dispersing agent of the heat insulation coating for coating preparation, so that powdery high-temperature-resistant heat insulation powder aggregate can be uniformly suspended and dispersed in an aqueous solution, and the high-temperature-resistant heat insulation powder aggregate is mutually bonded to form a coating with certain strength by the bonding property when the coating is dried, so that the defects of slag holes, sand holes and the like caused by the fact that the coating is washed and shed by high-temperature molten iron during casting are prevented. Meanwhile, the bentonite can ensure that the coating has good collapsibility after high-temperature ablation, and is convenient for demoulding of the casting and quick cleaning of residual paint on the inner wall of the cavity.

The water-soluble organic adhesive used in the formula coating is polyvinyl alcohol, and the water glass is often used as the adhesive in the metal type coating in the traditional process, so that although the water glass has higher heat resistance, the water glass is not easy to demould, and the residual coating is firmly adhered after casting and is not easy to clean, so that the problems of map-like stains on the surface of a casting and uneven wall thickness of a pipe casting are often caused. The water-soluble polyvinyl alcohol organic adhesive is adopted, so that the strength of a dry coating can be increased, the dry coating can be easily burnt at high temperature, the strength of the residual coating is reduced, and the residual coating is easy to remove.

The preferred formulation of the thermal barrier coating of this example is: 11.45 percent of calcined kaolin, 3.8 percent of calcined diatomite, 0.095 percent of polyvinyl alcohol, 0.55 percent of calcined lithium bentonite and 84.1 percent of water.

Physical properties of the coating of this example: a. the suspension property of the coating is more than or equal to 96 percent after being placed for 12 hours; b. the refractoriness of the coating is more than or equal to 1700 ℃; c. the coating has good fluidity and does not block a conveying pipeline and a spray head; d. the paint has good spraying performance and uniform coating on the surface of the metal type working surface.

Method for preparing thermal insulating coating

In this embodiment, the preparation method of the heat insulating coating includes: preparing polyvinyl alcohol paste; preparing lithium bentonite paste; adding powdery diatomite, kaolin and water into a low-speed stirrer, and stirring to completely mix the powdery diatomite, the kaolin and the water with the aqueous solution; after fully stirring without agglomeration, sequentially adding the lithium bentonite paste and the polyvinyl alcohol paste, continuously stirring and fully mixing uniformly, and filtering by a filter screen for later use.

Wherein the method for preparing the polyvinyl alcohol paste comprises the following steps: taking the polyvinyl alcohol and the water according to the proportion of 1: 25; adding polyvinyl alcohol and water into the electric heating kettle in the ratio of 1: 25 to make polyvinyl alcohol and water into transparent paste.

In the above embodiment, the method for preparing the lithium-based bentonite paste includes: taking lithium bentonite and water according to the proportion of 1: 10; quantitatively adding lithium bentonite and water into a container according to the proportion of 1: 10, standing for more than 24 hours until the bentonite fully absorbs water and swells; the fully swelled lithium bentonite is added into a stirrer before use and fully stirred, for example, the rotating speed of the stirrer can be about 1400 rpm, and the stirring time can be 5 minutes.

Here, the preparation method of the thermal insulation coating is further described with reference to an example:

formula and preparation method of coating for metal mold

Firstly, a formula unit; KG

Preferably, the weight percentage is as follows: 3.8 percent of diatomite, 11.45 percent of calcined kaolin, 0.095 percent of polyethylene, 0.55 percent of lithium bentonite and 84.1 percent of water. Note: the 5 materials are all weak in alkalinity.

Secondly, preparation method of coating

1. Polyvinyl alcohol paste:

the ratio of polyvinyl alcohol to water is 1: 25;

the manufacturing process of the polyethylene paste comprises the following steps: proportionally and quantitatively adding polyvinyl alcohol and water into an interlayer electric heating kettle (materials in the kettle are indirectly heated by heating the water in the interlayer to keep a certain heating temperature and prevent overheating or scorching), wherein the heating temperature is 80-100 ℃, and the time is about 1 hour according to the condition that the polyvinyl alcohol and the water are transparent paste;

2. the preparation method of the lithium bentonite paste comprises the following steps:

the proportion of the lithium bentonite and the water is as follows: 1: 10;

the manufacturing process of the lithium bentonite paste comprises the following steps: quantitatively adding lithium bentonite and water into a container according to a certain proportion, standing for more than 24 hours until the bentonite fully absorbs water to swell; adding the fully swelled lithium bentonite into a stirrer before use, wherein the rotating speed of the stirrer is about 1400 rpm, and the stirring time is about 5 minutes;

3. the preparation method of the coating comprises the following steps:

firstly, the charging sequence is as follows: diatomaceous earth → calcined kaolin → water → lithium bentonite paste → polyvinyl alcohol paste; the preparation method comprises the following steps of adopting a mixing barrel with a stirring device, completing the mixing process in the mixing barrel with the stirring device, adding the powdery diatomite, the kaolin and the water into a low-speed mixer according to the weight proportion specified by a formula, stirring for 30 minutes at the rotating speed of about 60 revolutions per minute of the low-speed mixer, and mixing the mixture with the aqueous solution completely without agglomeration. Then, sequentially adding lithium bentonite paste and polyvinyl alcohol paste, continuously stirring for 2-3 hours to fully and uniformly mix the 5 materials, filtering by a filter screen such as a 100-mesh sieve, and filling in a paint packaging barrel for later use;

secondly, the development process of the coating mainly comprises the following steps:

1. suspension property of paint-height of sedimentation after the paint is left to stand for a certain time.

2. Heat resistance and heat insulation performance of the coating-the mold sprayed with the coating is tested to cast molten iron at 1400 ℃, and the temperature of the mold is raised before and after casting.

3. Spray uniformity of coating-the uniformity of the coating on the surface of the mold was observed after spraying. And (4) whether the paint adhesion on the surface of the cast piece is uniform after casting.

4. The adhesive strength of the coating, namely whether the coating is uniformly adhered on the surface of the cast product after casting, if the coating is not uniform, the heat-resistant scouring performance of the coating is poor during casting;

5. collapsibility of the coating (which means that the residual coating is easy to pulverize and clean after high-temperature ablation) -whether the residual coating in the cavity of the die and the coating adhered to the surface of the casting are easy to clean after casting.

6. Gas evolution during high-temperature casting of the coating (the gas evolution refers to water vapor and other high-temperature oxidation gas generated by ablation of the coating in high-temperature molten iron), and the number of defects such as pits, pores, wrinkles, cold shut and the like in a unit area of the surface of a casting cast by the coating is checked.

It should be noted that the coating material of the present embodiment has the following advantages:

since polyvinyl alcohol is a preferable embodiment of the present embodiment as a coating material binder component, the production of a polyvinyl alcohol paste is also a dedicated method. The adding method is that water-soluble pasty colloid is firstly prepared, and then the coating is prepared to ensure the even dispersion in the coating.

Since lithium bentonite is a preferable embodiment of the present embodiment as a coating suspension agent, a binder and a dispersant component, the production of a lithium bentonite paste is also a dedicated method.

It should be noted that the main component of the heat insulating material in the above embodiments is a material that determines the functional characteristics of the coating material. For example, the paint carrier water and other auxiliary additives with special characteristics of the formulated paint, such as a dispersant, a defoaming agent, an antirust agent and the like. Because of the wide variety of the auxiliary agents, the auxiliary agents belong to further improved types. No further study and testing was done in this example. The addition of these auxiliaries can also be used in the examples to further improve the properties of the coating, etc. Other auxiliary components in the formula of the heat-insulating coating can further adjust some physical properties of the coating, such as suspension property, dispersibility, low temperature resistance and the like.

Compared with the prior art, the preparation method of the heat insulation coating has the following advantages:

1. the formula of the kaolin and diatomite composite heat-resistant heat-insulating material is adopted to replace the traditional formula of taking single diatomite as the heat-resistant heat-insulating material, so that the defect that the diatomite has good heat-insulating property but poor high-temperature impact resistance is overcome. The high temperature resistance and the heat preservation performance of the coating are improved.

2. The formula of the kaolin and diatomite composite heat-resistant and heat-insulating material is adopted, and the characteristics of fineness and smoothness of kaolin powder are utilized, so that the demolding after casting is facilitated.

3. The formula of the kaolin and diatomite composite heat-resistant and heat-insulating material is adopted, so that the surface of the coating is uniform and delicate, and the appearance quality of a casting is greatly improved;

4. the calcined kaolin and diatomite powder are adopted, so that the problems that the coating prepared by uncalcined kaolin and diatomite powder in the traditional process has overlarge coating gas evolution and more casting defects are solved. The traditional natural kaolin and diatomite contain a large amount of crystal water, and a large amount of water vapor is released during high-temperature casting to cause casting defects. The calcined kaolin and diatomite powder remove the crystallization water, and greatly reduce the gas evolution of the coating. (since the water for preparing the dope is free water, it is evaporated when it is sprayed on a mold having a certain temperature, and crystal water is released only when it is cast with molten iron having a high temperature)

5. The polyvinyl alcohol high molecular organic material adhesive is adopted to replace the non-polar material adhesive-water glass in the traditional coating formula process. Because the water glass has higher heat resistance, the water glass still remains and adheres to the die cavity and the surface of the casting after being ablated by high-temperature molten iron, is not easy to clean, and is not easy to demould after casting because of stronger adhesive force. On the other hand, water glass forms a glassy gel in a high temperature state, and the air permeability of the coating material is reduced, resulting in an increase in casting defects. The polyvinyl alcohol high molecular organic material adhesive is adopted, when the adhesive is sprayed on the surface of a metal mold with a certain temperature, the adhesive has good bonding strength, and the coating is not easy to wash away. The organic material can be ablated and carbonized through ablation of high-temperature molten iron, so that residual coating becomes loose, the air permeability is good, the cleaning is easy, and the casting is easy to demould. Due to the high viscosity and low addition amount, the gas forming amount is greatly reduced.

6. The lithium bentonite is used as a coating suspending agent, a material adhesive and a dispersant to replace the traditional calcium bentonite formula. Because the traditional calcium-based bentonite has poor suspension effect, the addition amount is usually larger (more than 2 times of the amount of lithium-based bentonite) in order to ensure the suspension property of the coating, the air permeability of the coating is reduced, the rejection rate of castings is increased, and the appearance quality is reduced. The lithium bentonite is used as a suspending agent, so that the suspending effect of the coating prepared from the powdery solid material of the coating is ensured, and when a dry coating is formed on the surface of a die cavity, the coating has better coating strength and is not easy to be washed away by molten iron to form slag holes in a casting. On the other hand, the coating has better collapsibility, and residual coatings on the surfaces of the die and the casting after casting and forming are easy to remove. Moreover, because the addition amount of the bentonite is less than that of the traditional calcium bentonite, the air permeability of the dry coating is improved, and the defects of air holes, pits and the like on the surface of the casting are reduced.

Metal mold embodiment

Referring to fig. 1 and 2, there are shown the structure of the metal mold of the present embodiment and the structure of the metal mold casting apparatus provided with the metal mold, respectively.

In the present embodiment, the metal mold is provided on a metal mold casting apparatus, and the metal mold includes a first half mold 21 and a second half mold 22 machined from low-carbon structural steel having a uniform metal structure. The first half mold 21 and the second half mold 22 are respectively provided with: a cavity 10 for forming the outer shape of a casting at the time of casting, a gate 11, a runner 12, a fixing leg 16 fixedly attachable to a metal mold casting apparatus, and a parting surface 18 engageable with each other when the first and second mold halves 21 and 22 are closed.

Wherein, the die cavity 10 is a concave cavity matched with the shape of the outer surface of the casting and is provided with a sand core 3 for limiting the shape and the wall thickness of the inner surface of the casting; a positioning part for positioning the relative position between the sand core 3 and the cavity 10 is arranged above the cavity 10. The gates 11 are respectively arranged above the first half mold 21 and the second half mold 22; the runner 12 communicates with the gate 11 and extends from an upper portion of the cavity 10 into the interior of the cavity 10.

In the above examples, the low-carbon structural steel was Q235 hot-rolled ordinary low-carbon structural steel, and the carbon content thereof was in the range of 0.12% to 0.22%. Because of the damage of the ferroalloy metal at high temperatures, in addition to being melted at high temperatures, structural cracking is caused mainly by thermal stress expansion of the metal at high temperatures. The stress failure is determined by the high-temperature heat deformation resistance of the structure components of the metal material, namely, the expansion deformation is small at high temperature, and the material has certain plasticity, is not easy to harden and crack. The other aspect is determined by the metal material tissue structure, namely whether the metal tissue structure is uniform or not, because fine cracks, shrinkage cavities, holes, sand holes and the like can form stress concentration points under the thermal stress state, so that the mold is cracked.

Therefore, the trade-off between the two factors determines the technical effect and the cost. Most of the existing metal mold designs pay attention to a casting blank processing mold made of expensive heat-resistant metal so as to improve the heat stress cracking resistance of the mold. In the practical application of the embodiment, it is found that the actual cause of the cracking damage of the die is mainly the reason that the metal structure of the casting blank is uneven and has fine defects, which is just the problem that the casting blank cannot overcome and is not the material composition itself.

Therefore, the main reason for causing the thermal stress cracking of the die is the structural uniformity of the die material, and the selected material has certain plasticity. Based on this knowledge, Q235, which is the most common hot-rolled ordinary low-carbon structural steel, was selected for this example.

On one hand, the common material is a formed hot-rolled thick plate, and the material is uniform after rolling, has few internal tissue defects and is low in price. On the other hand, the low carbon content of the low carbon structural steel Q235 ensures that the steel has better plasticity and is not easy to harden under the alternate cold and hot impact. Tests prove that the service life of the die made of the material can reach more than 8000 times, which is 4 times of that of a heat-resistant alloy casting blank die.

In addition, cracks generated in the heat-resistant alloy casting blank die cannot be repaired by welding, but the metal die made of the hot-rolled common low-carbon structural steel Q235 has excellent welding performance, and the service life of the die can be prolonged by more than 2000 times by repairing the damaged part by welding.

The service life of the hot-rolled common low-carbon structural steel Q235 metal mold is 5 times longer than that of the existing mold, the material price is only 40% of that of the existing heat-resistant alloy casting blank, and the use cost of the mold is greatly reduced. The cost of the metal mold is very important to the economic applicability of the whole metal mold casting technology and is also a key factor that the metal mold casting technology cannot be widely applied at present.

Therefore, the present embodiment focuses more on the influence of the uniformity of the material structure on the mold life from the material selection method.

Preferably, the inner surface of the mould cavity 10 is coated with a thermally insulating layer. The metal mold heat-insulating coating is a water-based coating which is sprayed on the surface of a metal mold cavity with a certain temperature before casting each time and can form a dry breathable coating with a certain thickness. In order to ensure the uniformity of the coating and the wall thickness and size precision of the pipe casting, during specific use, spraying is generally adopted before each casting, after the casting is taken out after the casting is finished, residual coating needs to be cleaned, then spraying is carried out again, and then casting is carried out.

5) has better demolding performance and high-temperature collapsibility, and is convenient for the demolding of the casting and the cleaning of the involved coating in the cavity.

In an alternative embodiment, the positioning part comprises a positioning core groove 13 and a sand core positioning groove 17, and the positioning core groove 13 is used for positioning the relative position between the positioning core head 30 of the sand core 3 and the cavity 10; the sand core positioning groove 17 is used for positioning the relative position between the main body of the sand core 3 and the cavity 10. The sand core 3 is provided with a positioning flange 31, and the shape of the positioning flange 31 is matched with the shape of the inner wall of the sand core positioning groove 17.

The inventor repeatedly tests the material of the metal mold 2 to determine that the thick plate profile of the hot-rolled common low-carbon structural steel Q235 is selected for processing. The selected Q235 hot-rolled common low-carbon structural steel has the carbon content generally selected within the range of 0.12-0.22%, has the characteristic of low hardenability, is not easy to form a hardening layer which is easy to generate cracks on the surface of a metal mold cavity under the impact of high-temperature molten iron, and has good hot cracking resistance. The selected Q235 hot-rolled common low-carbon structural steel adopts a general thick plate profile, has good material uniformity, avoids the internal defects and casting stress which are easily caused by selecting a heat-resistant alloy casting blank for a traditional metal mold, has better welding performance, and is convenient for welding repair when the local burning loss of the mold occurs.

Particularly, the Q235 hot-rolled common low-carbon structural steel thick plate section is selected to process a metal mold, and the blanking size during mold processing is as follows:

A. the total weight of the finished metal mold is not less than 75 times of the weight of the casting. The sufficient weight can make the metal mold have strong capability of absorbing heat, and the metal mold ablation caused by the excessive temperature rise can not be generated.

B. When the die blank is blanked, the rolling direction texture of the hot-rolled section is in the horizontal direction after the die is processed, namely the metal structure fiber direction of the die is in the horizontal state and is vertical to the casting direction, so that the die is ensured to have enough bending strength, and the crack resistance is improved.

In conclusion, the Q235 hot-rolled common low-carbon structural steel is used for processing the metal mold, the material price is low, the material price is only 40% of that of a heat-resistant alloy casting blank, and the metal mold is easy to purchase. The material uniformity is good, the heat crack resistance is good, the service life of the die is long, the die can be repeatedly maintained, the repairability is good, the number of times of die use for the first time can reach more than 5000 times, and the service life of the repaired die can be prolonged to 8000-10000 times. The heat-resistant alloy casting blank adopted by the traditional process has the service life of the die of only 1500-2000 times under the same process condition and cannot be repaired. Compared with the prior art, the service life of the metal mold is prolonged by 4-5 times, the proportion of the mold cost in the product cost is reduced to below 2.5% from the prior 10-15%, and the production cost is greatly reduced, so that the technology makes a breakthrough in the aspect of economic applicability of casting application of the thin-wall gray cast iron pipe fitting.

In addition, it should be noted that the above embodiment preferably employs a dual-positioning sand core structure. This is because, due to the processing deviation, the assembly and matching portion of the shell core sand core and the metal mold must be designed to have a certain clearance margin to ensure that the metal mold is not broken and cracked when the sand core is closed after being installed. The existence of the gap often causes the sand core to be installed in a metal mold to have micro displacement, so that the wall thickness of the cast part after casting is uneven. To solve this technical problem, the present embodiment proposes a new sand core structure, and referring to fig. 1 to 4, the sand core structure described in the present embodiment is shown. The sand core structure of the embodiment is additionally provided with an auxiliary positioning structure, namely a positioning flange, so that the degree of freedom of the sand core main body in the vertical direction is limited. Compared with the traditional process which only adopts a single positioning mode, the displacement of the sand core in the metal mold is reduced, and the uniformity of the wall thickness of the casting is ensured.

As shown in fig. 1, a sand core 3 is provided on a metal mold 2 for casting a casting, the sand core comprising: the sand core comprises a sand core main body 19, a positioning core head 30, a positioning flange 31, a sand core sand outlet 32 and a sand core closed end 33.

As shown in fig. 3 and 4, in the present embodiment, the shape of the sand core main body 19 is matched with the shape of the internal space of the casting, the upper end, the lower end and the side surfaces of the sand core main body 19 are respectively provided with an upper opening, a lower opening and side openings, and the upper opening, the lower opening and the side openings are respectively provided with positioning core heads 30 for positioning the relative positions of the sand core main body 19 and the metal mold 2. The positioning core heads 30 arranged at the lower opening and the side openings are provided with sand core closed ends 33 for closing the openings, and the positioning core heads 30 arranged at the upper opening are provided with sand core sand outlets 32. Wherein, the shape of the positioning core print 30 is matched with the shape of the inner wall of the corresponding positioning core slot 13 on the metal mold 2.

In a preferred embodiment, the outer side surface of the sand core outlet 32 is provided with a positioning flange 31 for positioning the sand core main body 19 relative to the metal mold 2.

Further, in the above embodiment, the sand core 3 is a hollow thin-walled resin sand body having an open end and an outer shape conforming to the shape of the internal space of the casting 4, and is mounted on the metal mold 2 before the casting is poured. The positioning core print 30 is matched with the inner wall shape of the corresponding positioning core groove 13 on the metal mold 2 in shape, and is used for fixing the relative position of the sand core 3 and the metal mold 2 so as to keep the clearance specified by design between the inner wall of the cavity 10 and the outer wall of the sand core main body 19. The positioning flange shape 21 is matched with the shape of the inner wall of the sand core positioning groove 17 in the metal mold 2 and is used for fixing the relative position of the sand core 3 and the metal mold 2 when the sand core is placed. The metal sand core structure and the characteristics are as follows:

in a preferred embodiment, the sand core body 19 is a hollow thin-walled thermosetting resin-coated sand shell core structure. For example: the structural form and the material of the thermosetting coated resin sand shell core sand core suitable for casting the thin-wall gray cast iron pipe fitting by a metal mold can be selected. The problems of poor air permeability of the sand core, rough appearance, casting precision grade, easy generation of air holes and sand holes of a casting and the like in the production efficiency of the traditional clay sand core are solved.

It should be noted that the sand core 3 can be processed by a sand core device and a hot core box core making die by adopting a thermosetting phenolic resin precoated sand hot core box sand core process. Therefore, the sand core 3 has the characteristics of high-temperature ablation resistance, no sand sticking to the casting, good air permeability and good collapsibility.

In the above embodiments, the resin sand core means a hollow sand core that can be used in various molding processes such as green sand, resin sand, etc., and the wall thickness of the sand core is generally selected to be in a range of 8 to 10mm, because the molding process is slow in cooling when molten iron is cast, if the sand core is too thin, the sand core is easily burnt through to cause molten iron leakage, and a casting cannot be molded. In the metal mold casting, because molten iron is rapidly cooled during casting, and most heat is absorbed by a metal mold, the wall thickness of the sand core is properly reduced, the sand core can be still prevented from being burnt out and burnt through, and the cost can be greatly reduced.

The improvement effects of the metal mold, the heat insulation coating and the sand shell core sand core of the embodiment are integrated, the defects of rough appearance quality, low size precision grade, large casting allowance and the like of the traditional casting process are overcome, the appearance quality of the produced thin-wall gray cast iron casting reaches the semi-precision casting grade, the size precision deviation is increased to +/-0.1 mm from +/-0.5 mm, the casting allowance is reduced, the weight of the similar product is reduced by about 15%, molten iron is saved, and the production cost is reduced.

Aiming at the structure of the sand core, the following introduces an embodiment of the core making process of the sand core:

the present embodiment selects the mature core-making process method in the casting process of metal thin-wall gray cast iron pipe fittings. The difference lies in that: the embodiment combines the characteristics of quick cooling of the metal mold and difficult burning of the resin sand core, and adopts a method for reducing the wall thickness of the sand core so as to reduce the cost. And therefore there is no convincing preference.

In the following, this embodiment will further describe the core making process of the resin sand core of the thin shell type sand core:

the sand core is a sand mold material for molding the pipe fitting casting cavity. The traditional sand casting and metal casting processes generally adopt solid clay sand cores, solid resin sand cores or hollow thick-wall coated sand cores. In the prior art, the sand core adopting the traditional casting process for the metal mold casting process of the thin-wall gray cast iron pipe fitting has the following problems:

1) the solid clay sand core is adopted, manual production is generally adopted, the production efficiency is low, the solid structure of the sand core is adopted, the exhaust performance is poor when the sand core is used for casting a metal casting, casting defects such as air holes and sand inclusion are easy to occur, the core sand inside the casting is difficult to clean, and the labor intensity is high;

2) the solid resin sand core is adopted, and although mechanical production can be adopted, the production efficiency is high, the problems of poor beating effect and difficult sand removal still exist, and the material cost is high;

3) in consideration of improving the casting process performance and the production efficiency, the traditional sand mold mechanical molding process also adopts thermosetting precoated sand to be shot and cured in a mold to form two half sand molds, and then the two half sand molds are combined into the hollow thick-wall sand core.

The traditional sand core is high in production efficiency, and the problem of difficulty in casting, exhausting and cleaning is solved, but the molten iron cooling and solidification speed is low in the traditional sand mold casting process, the depth of the surface of the sand core burnt by the high-temperature molten iron is usually 7-8 mm, in order to ensure that the hollow sand core is not burnt, the wall thickness of the hollow sand core is usually over 10mm, the precoated sand material is expensive, the weight of the thin-wall gray cast iron pipe fitting is light, the weight ratio of unit casting weight to sand weight is over 1: 1, the core manufacturing cost accounts for one third of the casting material cost, and the product cost lacks competitive advantages.

In order to solve the technical problems, the resin sand core process of the thin-shell type sand core is developed in the embodiment, thermosetting phenolic resin coated sand is selected as a sand core material, a hot core box sand core process is adopted for core making, and the whole thin-shell type structure of the sand core is designed. The reason for selecting the technical scheme is as follows:

1) the hot core box sand core process for the thermosetting phenolic resin precoated sand can adopt mechanized production, has high production efficiency, stable quality of the sand core, high dimensional precision and mature production equipment and process technology, and can effectively control the thickness of the sand core in a butting way.

2) The adoption of the integral shell type structure can ensure that the tubular sand core has a stable mechanical strength structure, and is convenient for storage, transportation and installation in a metal mold. Meanwhile, the integral shell mold structure can avoid the defect that burrs are easily formed at the combined gap part when the sand core with the combined structure is cast, and the casting polishing cost is increased

3) The core manufacturing cost can be greatly reduced by adopting a thin shell type structure. Repeated tests show that when the thin-wall gray cast iron pipe fitting metal mold casting process is used for casting molten iron, the cooling and solidification speed of the molten iron is far higher than that of the traditional sand mold casting, the burning depth of the cast sand core is only 2-3 mm, according to the experimental data, the thin-shell sand core with the wall thickness of 5-6 mm is adopted in the design of the embodiment, and an integral shell mold structure with certain strength is adopted, and the actual production verification proves that the thin-shell sand core can completely meet the requirements of the casting process and operation, and the core manufacturing cost is reduced by 45-50%.

4) In the embodiment, the core making process can also adopt double-component gas curing cold box resin sand for making the core by using medium-thickness wall phenolic resin and polyisocyanate, the process is suitable for making the sand core with a complex structure, although the process is slightly complex and the wall thickness is also thicker, the cold box resin sand is 40% cheaper than thermosetting precoated sand material, and the comprehensive cost is still lower than the comprehensive cost of the thermosetting precoated sand.

Therefore, the method for the resin sand core of the thin-shell sand core in the embodiment solves the problem that the sand core in the metal mold casting process of the thin-wall gray cast iron pipe fitting has influence on the casting quality and the production cost.

In the above embodiment, the gate 11 is disposed above the metal mold according to the casting process requirement of the casting 4, when the two molds are closed, the two molds have a cavity with a trumpet-shaped upper portion and a cylindrical lower portion, the runner 12 is a concave flat groove processed according to the casting process requirement of the casting 4, the upper portion is communicated with the gate 11 cylinder, the lower portion is communicated with the cavity 10 of the metal mold 2, when casting, molten iron is poured from the gate 11, and flows into and fills the gap between the cavity 10 and the sand core body 19 of the sand mold 3 through the runner 12, so as to form the solid body of the casting 4.

It should be noted that the first half mold 21 and the second half mold 22 are further provided with: and a positioning core groove 13 for fixing the relative position of the sand core in the cavity 10, wherein the positioning core groove 13 is arranged above the cavity 10. The shape of the positioning core head 30 on the sand core 3 is matched with the shape of the inner wall of the positioning core groove 13.

In this embodiment, the first mold half 21 and the second mold half 22 are relatively fixedly connected to the metal mold casting apparatus via respective fixing legs 16.

For example, the fixing legs 16 of the metal mold 2 are rectangular steel plates welded to both sides of the metal mold 2, and the two halves of the metal mold 2 are respectively fixed to the metal mold casting apparatus by fastening bolts or pressing the fixing legs 16 with a pressing plate.

In a preferred embodiment, the mold cavity 10 is a concave cavity that conforms to the shape of the outer surface of the casting 4 to shape the casting as it is cast. The positioning core slot 13 is a concave cavity matched with the shape of the outer surface of the positioning core head 30 of the sand core 3, and is used for fixing the relative position of the sand core 3 in the metal mold 2 so as to ensure that the casting 4 meets the wall thickness requirement specified by design.

Preferably, the first half-mould 21 and the second half-mould 22 are further provided with: a dowel hole 14 and a dowel pin 15 for keeping the relative positions of the two mold halves from shifting when the mold halves are closed. The positioning pin holes 14 on the first half die 21 are matched with the positioning pins 15 on the second half die 22 correspondingly in position and size. The positioning pins 15 on the first half die 21 are matched with the positioning pin holes 14 on the second half die 22 correspondingly in position and size.

For example, the metal mold 2 is provided with a positioning pin hole 14 and a positioning pin 15 for each mold half, and the position and size thereof are determined by design according to different castings. The positioning pin 15 of one half of the die is matched with the positioning hole 14 of the other half of the die correspondingly in position and size, so that the relative position is kept and the two half of the die are not shifted when the two half of the die of the metal die 2 are closed, and the external dimension of the casting is ensured to meet the design requirement.

In a preferred embodiment, the positioning core groove 13 is further provided with: and a core positioning slot 17 for positioning the core in the first mold half 21 and the second mold half 22. The sand core positioning groove 17 is matched with a positioning flange arranged on the sand core. That is, the inner wall shape of the core positioning groove 17 matches the outer shape of the positioning flange 31 provided on the core 3.

In this embodiment, the sand core positioning slot 17 is a concave cavity matched with the outer surface shape of the positioning flange 31 of the sand core 3, and is used for preventing the sand core 3 installed in the metal mold 2 from shifting during casting so as to ensure the casting dimensional accuracy of the casting.

In the above embodiment, the metal mold 2 is used for casting a thin-wall gray cast iron pipe, and a vertical parting structure is adopted, that is, the parting surface 18 of the metal mold 2 is kept vertical, and when the first half mold 21 and the second half mold 22 are closed, the parting surfaces 18 are attached to each other.

For example, when the mold halves 2 are closed, the parting plane 18 completely conforms to form a cavity of the mold 2. The parting surface 18 is a plane or a curved surface formed by an outline closed line projected according to a parting direction of the casting design. Therefore, the parting surfaces 18 of the first half mold 21 and the second half mold 22 are completely jointed when the two half molds are closed, so that the molten iron does not leak during casting of the casting and the casting 4 is smoothly demoulded after being formed.

In this embodiment, as shown in fig. 1, the metal mold casting apparatus may include: the device comprises a frame 5, a fixed template 6, a movable template 7, a movable template guide shaft 8, a pneumatic mold closing device 9 and a metal mold 2. The metal mold 2 is a pair of two half molds, which are respectively and correspondingly arranged on the fixed mold plate 6 and the movable mold plate 7. The fixed template 6 is arranged on the frame 5, and the movable template guide shaft 8 is arranged between the frame 5 and the fixed template 6 and penetrates through the movable template 7. One end of the mold closing device is fixed on the frame 5, and the other end is connected to the movable mold plate 7; driven by a pneumatic die assembly device 9, the movable die plate 7 reciprocates on a movable die plate guide shaft 8 to complete die opening and closing actions.

Here, the metal mold 2 will be further described by taking an example in which a metal mold is applied to the above-described metal mold casting apparatus:

the metal mold 2 comprises a pair of two half molds, namely a first half mold 21 and a second half mold 22, and comprises a cavity 10, a sprue 11, a pouring gate 12, a positioning core groove 13, a positioning pin hole 14, a positioning pin 15, a fixed support leg 16, a sand core positioning groove 17 and a parting surface 18, wherein the metal mold 2 is fixedly arranged on a fixed mold plate 6 and a movable mold plate 7 on the metal mold casting equipment 1 respectively through the fixed support leg 16, the movable mold plate 7 enables the two half molds of the metal mold 2 to be closed together under the horizontal pushing of a pneumatic mold closing device 9, the opposite positioning pin hole 14 and the positioning pin 15 on the metal mold 2 are matched when the two half molds are closed, the opposite positions of the two half molds are fixed, and the parting surfaces 18 of the two half molds are kept in a completely-jointed state when the two half molds.

In summary, in the above embodiments, the metal mold 2 is composed of a pair of two mold halves, and is divided vertically, the gate 11 is disposed above the mold, and the runner 12 extends from the upper portion of the cavity 10 into the cavity 10. When the two halves are closed, the parting surfaces 18 are completely attached to form a cavity for molding the casting. The vertical parting and pouring system arrangement mode of the metal mold is beneficial to the rapid filling and forming of molten iron in the narrow gap between the cavity and the sand core under the action of gravity. Compared with the existing upper part rain type pouring gate, the metal mold 2 of each embodiment can shorten the casting time, avoid the phenomenon of insufficient casting caused by overlong mold filling time, and improve the yield.

In addition, the metal mold 2 of each embodiment adopts an integral structure, and the metal mold 2 adopts a positioning core slot and a sand core positioning slot dual positioning mode for positioning the metal mold core so as to ensure the positioning precision and the casting size precision.

It should be noted that, in the existing mold adopting the assembly structure, when the mold is heated at a high temperature, the mold is easily deformed, so that the position of the mold during assembly is changed, the mold closing is difficult, and the positioning accuracy of the mold during mold closing is affected. In addition, the heated state of the parts is inconsistent, the parting surface of the die can be formed to be arched and deformed, the die assembly gap is increased, molten iron leaks, and the rejection rate of castings is increased. Compared with the prior art, the metal mold 2 of the present embodiment has the advantages of no resistance to heat conduction and uniform thermal deformation by adopting an integral mold structure, and the above problems are prevented.

Metal mold casting apparatus embodiment

Referring to fig. 1, there is shown the structure of the metal mold casting apparatus of the present embodiment. The metal mold casting apparatus of the present example includes: the device comprises a frame 5, a fixed template 6, a movable template 7, a movable template guide shaft 8, a mold closing device and a metal mold 2. The metal mold 2 is a pair of two half molds, which are respectively and correspondingly arranged on the fixed mold plate 6 and the movable mold plate 7. The fixed template 6 is arranged on the frame 5, and the movable template guide shaft 8 is arranged between the frame 5 and the fixed template 6 and penetrates through the movable template 7. One end of the mold closing device is arranged on the frame 5, and the other end of the mold closing device is arranged on the movable mold plate 7. Driven by the mold closing device, the movable mold plate 7 reciprocates on the movable mold plate guide shaft 8 to complete the mold opening and closing action.

The mold clamping device described in the above embodiment may be a pneumatic mold clamping device 9, a manual or electric screw mold clamping device. The manual screw mold closing device can be used for small-batch production, and the electric screw mold closing device can be used under the condition without an air source. Here, the mold clamping device of the present embodiment may preferably employ a pneumatic mold clamping device 9.

The metal mold casting equipment designed by the embodiment adopts pneumatic drive control to supply air to the pouring pipeline in a centralized manner, only needs an air source and does not need a power supply, has the characteristics of simple structure, small occupied area of the equipment, high action speed of the equipment, high production efficiency, rapidness in loading and unloading molds and the like, and is particularly suitable for production of mechanized casting production lines. In addition, the metal mold casting equipment designed by the invention is convenient to maintain and simple and convenient to operate, the failure rate of the metal mold casting equipment is greatly reduced, the production operation cost is reduced, and the mechanical automatic casting production line is very convenient to form.

Therefore, the metal mold casting equipment designed and developed in the embodiment is suitable for pneumatic operation of a mechanized casting production line, and can effectively solve the problems of complex structure, high manufacturing cost, low action speed, low production efficiency and the like of the currently used gravity casting machine.

In the above embodiment, the frame 5 includes: a horizontal steel frame 51 and a vertical reinforcing steel plate 52 for fixing the pneumatic mold clamping device 9; wherein, the horizontal steel frame 51 and the vertical reinforced steel plate 52 are welded or integrally formed. In the above embodiment, the fixed die plate 6 is vertically connected to the horizontal steel frame 51.

In a preferred embodiment, reinforcing ribs are provided between the outer sides of the vertical reinforcing steel plates 52 and the horizontal steel frame 51.

In the above embodiment, the four corners of the fixed die plate 6 and the vertical reinforcing steel plate 52, and the two opposite corners of the movable die plate 7 are respectively provided with the shaft holes for mounting the guide shafts 8 of the movable die plate. The position of the shaft hole formed in the movable template 7 and used for installing the guide shaft 8 of the movable template corresponds to the position of the shaft hole in the fixed template 6.

It should be noted that the number of the movable die plate guide shafts 8 is at least two, and the movable die plate guide shafts 8 are installed by selecting any two or more diagonally distributed shaft holes according to the requirement of convenient operation and are fastened by nuts.

In the above embodiment, one end of the guide shaft 8 of the movable platen is installed in two diagonally distributed shaft holes of the vertically reinforcing steel plate 52, and the other end is installed in a shaft hole of the fixed platen 6 corresponding to a selected shaft hole of the vertically reinforcing steel plate 52. Wherein, the movable mould plate 7 is arranged on the guide shaft 8 of the movable mould plate through a shaft hole.

In the above embodiment, the center of one side of the fixed die plate 6 is provided with an installation screw hole for fixedly connecting the pneumatic die clamping device 9. The center of one side of the movable mould plate 7 is provided with a mounting hole connected with a cylinder shaft head of the pneumatic mould closing device 9, and the mounting hole of the center of one side of the movable mould plate 7 is tightly connected with the cylinder shaft head of the pneumatic mould closing device 9 through bolts. Wherein, the fixed template 6 and the movable template 7 are respectively provided with more than two through holes for fixing the metal mold 2. In the above embodiment, the metal mold 2 has a vertically parted structure, and the gate of the metal mold 2 is disposed above the gate, and the runner thereof enters the cavity from the upper portion of the cavity.

Therefore, the metal mold casting equipment 1 has the characteristics of simple structure, high action speed, high production efficiency, quick mold loading and unloading, convenience in maintenance, simplicity and convenience in operation, low production and operation cost and the like, and only needs an air source and does not need to be electrified. Can conveniently form a mechanical automatic casting production line.

The traditional hydraulic gravity casting machine is additionally provided with a hydraulic workstation, a hydraulic pipeline, an electromagnetic control valve and a hydraulic oil cylinder, has complex structure, slow operation action, poor adaptability to high-temperature severe environment, large floor area and high manufacturing cost, and is more than 10 times of the manufacturing cost of metal casting equipment 1.

The mold casting apparatus of the above embodiment is further described below with reference to an example:

in this example, as shown in fig. 1, the metal mold casting apparatus 1 includes a frame 5, a fixed platen 6, a movable platen 7, two movable platen guide shafts 8, and a pneumatic mold clamping device 9, the fixed platen is vertically welded to the frame 5, the two movable platen guide shafts 8 are installed on the frame 5 and the fixed platen 6, and the movable platen 7 is installed on the two movable platen guide shafts 8 and connected to the pneumatic mold clamping device 9 for horizontal reciprocating motion.

The metal mold casting equipment is used for manufacturing thin-wall gray cast iron pipe fittings, and a rack 5 of the metal mold casting equipment 1 is formed by welding a horizontal steel section frame 51 and a vertical reinforcing steel plate 52 for fixing a pneumatic mold closing device 9; and shaft holes for installing the guide shafts 8 of the movable template are processed at four corners of the vertical reinforcing steel plate 52.

The fixed die plate 6 is vertically welded on a section steel frame of the frame 5, shaft holes for mounting a guide shaft 8 of the movable die plate are processed at four corners of the fixed die plate 6, a mounting screw hole for fixing a pneumatic die closing device 9 is processed at the center of one side of the fixed die plate 6, and a plurality of through holes for fixing the metal die 2 are processed on the fixed die plate 6;

one ends of the two movable template guide shafts 8 are arranged in two diagonally distributed shaft holes on the vertical reinforced steel plate 52 of the frame 5 and are fastened by nuts, and the other ends of the two movable template guide shafts are arranged in shaft holes corresponding to the selected shaft holes on the fixed template 6 and the vertical reinforced steel plate 52 and are fastened by nuts. Wherein, two movable mould plate guide shafts 8 can be installed by selecting any two shaft holes which are distributed diagonally according to the operation convenience requirement of the metal mold casting equipment 1.

Two opposite corners of the movable mould plate 7 are provided with shaft holes for installing a guide shaft 8 of the movable mould plate, the center of one side of the movable mould plate 7 is provided with an installation hole connected with a cylinder shaft head of a pneumatic mould closing device 9, and the movable mould plate 7 is provided with a plurality of through holes for fixing the metal mould 2. The shaft hole position of the movable template 7 corresponds to the shaft hole position of the fixed template 6 on which the movable template guide shaft 8 is installed, the movable template 7 is installed on the movable template guide shaft 8 through the shaft hole, a central installation hole in one side of the movable template 7 is tightly connected with a pneumatic die closing device 9 cylinder shaft head through a bolt, and the pneumatic die closing device 9 cylinder drives the movable template 7 to reciprocate on the movable template guide shaft 8 to complete the die opening and closing action.

It should be noted that, in this embodiment, the metal mold 2 is composed of a pair of two half molds, including a cavity 10, a gate 11, a runner 12, a positioning core groove 13, a positioning pin hole 14, a positioning pin 15, a fixing leg 15, a sand core positioning groove 17 and a parting surface 18, the metal mold 2 is respectively and fixedly installed on the fixed mold plate 6 and the movable mold plate 7 on the metal mold casting device 1 by the fixing leg 16, the movable mold plate 7 is pushed horizontally by the pneumatic mold closing device 9 to close the two half molds of the metal mold 2 together, the opposite positioning pin hole 14 and the positioning pin 15 on the metal mold 2 are engaged when the two half molds are closed, so that the relative positions are fixed, and the parting surfaces 18 of the two half molds are kept in a completely fitted state when the two half molds are closed.

The metal mold 2 is of a vertical parting structure, that is, the parting surface of the metal mold 2 is kept vertical. The metal mold 2 is composed of a pair of two half molds, and when the two half molds are closed, the parting surfaces are completely attached to form a cavity of the metal mold 2. Wherein, the cavity 10 is a concave cavity matched with the shape of the outer surface of the casting and is used for forming the shape of the casting during casting. Two half dies of the metal mold 2 are respectively installed and fixed on a fixed die plate 6 and a movable die plate 7 of the metal mold casting equipment 1.

In an embodiment, a sand core 3 is arranged in the metal mold 2, and a positioning core slot of the metal mold 2 is a concave cavity matched with the shape of the outer surface of a positioning core head of the sand core 3, so as to fix the relative position of the sand core 3 in the metal mold 2 and ensure that the casting 4 meets the wall thickness requirement specified by design.

Preferably, the metal mold 2 is vertically divided, a gate is arranged above the mold, and a pouring channel enters the cavity from the upper part of the cavity. The setting mode of the parting and pouring system is beneficial to the rapid filling and forming of molten iron in the narrow gap between the cavity and the sand core under the action of gravity, the pouring time is shortened, the phenomenon of insufficient casting due to overlong filling time is avoided, and the yield is improved.

The metal mold 2 is a thin-wall gray cast iron pipe metal mold, and the metal mold 2 adopts a vertical parting structure, namely, a parting surface 18 of the metal mold 2 keeps a vertical state. The metal mold 2 is composed of a pair of two half molds, and when the two half molds are closed, the parting surface 18 is completely attached to form a cavity of the metal mold 2.

Wherein, the cavity 10 is a concave cavity matched with the shape of the outer surface of the casting 4 and is used for forming the shape of the casting during casting. The pouring gate 11 is arranged above the metal mold according to the casting process requirement of the casting 4, when the two molds are closed, the upper parts of the two molds are horn-shaped cavities, the lower parts of the two molds are cylindrical cavities, the pouring gate 12 is a concave flat groove processed according to the casting process requirement size of the casting 4, the upper parts of the two molds are communicated with the cylinder of the pouring gate 11, the lower parts of the two molds are communicated with the cavity 10 of the metal mold 2, when in casting, molten iron is poured in from the pouring gate 11 and flows into and fills the gap between the cavity 10 and the sand core main body 19 of the sand mold 3 through the pouring gate 12.

In an alternative embodiment, the positioning core slot 13 is a concave cavity matching the shape of the outer surface of the positioning core head 30 of the sand core 3 to fix the relative position of the sand core 3 in the metal mold 2 to ensure that the casting 4 meets the wall thickness requirement specified by the design. The sand core positioning groove 17 is a concave cavity matched with the shape of the outer surface of the positioning flange 31 of the sand core 3, and is used for preventing the sand core 3 arranged in the metal mold 2 from shifting during casting so as to ensure the casting size precision of a casting.

In a preferred embodiment, the two halves of the metal mold 2 are each provided with a registration pin hole 14 and a registration pin 15, the location and size of which are determined by design for each casting. The positioning pin 15 of one half of the die is matched with the positioning hole 14 of the other half of the die correspondingly in position and size, so that the relative position is kept and the two half of the die are not shifted when the two half of the die of the metal die 2 are closed, and the external dimension of the casting is ensured to meet the design requirement.

In the above embodiment, the fixing legs 16 of the metal mold 2 are rectangular steel plates welded to two sides of the metal mold 2, and the two halves of the metal mold 2 are respectively fixed on the fixed mold plate 6 and the movable mold plate 7 of the metal mold casting device 1 by fastening bolts or pressing the fixing legs 16 with a pressing plate.

The parting surface 18 of the metal mold 2 is a plane or a curved surface formed by an outline closed line projected according to the parting direction designed by the casting 4, and the parting surfaces 18 of the two halves of the metal mold 20 are completely attached when the two halves of the mold are closed, so that the molten iron is prevented from leaking during casting of the casting and the casting 4 is smoothly demoulded after being formed.

In summary, the metal mold 2 is vertically divided, the gate 11 is disposed above the mold, and the runner 12 enters the cavity 10 from the upper part of the cavity 10. The setting mode of the parting and pouring system is beneficial to the rapid filling and forming of molten iron in the narrow gap between the cavity and the sand core under the action of gravity, the pouring time is shortened, the phenomenon of insufficient casting caused by overlong filling time is avoided, and the yield is improved.

Compared with the prior art, the embodiments of the invention have the following advantages:

the metal mold casting equipment designed by the embodiments of the invention adopts pneumatic drive control to supply gas to the pouring pipeline in a centralized way, only needs a gas source and does not need a power supply, has the characteristics of simple structure, small occupied area of the equipment, high action speed of the equipment, high production efficiency, quick mold loading and unloading and the like, and is particularly suitable for the production of a mechanized casting production line. In addition, the metal mold casting equipment designed by the invention is convenient to maintain and simple and convenient to operate, the failure rate of the metal mold casting equipment is greatly reduced, the production operation cost is reduced, and the mechanical automatic casting production line is very convenient to form.

Therefore, the pneumatic metal mold casting equipment which is designed and developed and is suitable for a mechanized casting production line can effectively solve the problems of complex structure, high manufacturing cost, low action speed, low production efficiency and the like of the currently used gravity type casting machine.

The technical problems solved by the invention have the interrelated comprehensive effects of reducing the production cost, improving the product quality, realizing convenient and efficient mechanical production, reducing the dependence of the traditional casting process on high-salary modeling technicians and the like. The implementation of the achievement of the invention is that the metal mold casting technology greatly advances the economy and the practicability, and the comprehensive cost of the product is far lower than that of the traditional mechanical casting mode and that of the manual casting mode with low cost. The product quality also reaches the semi-precision casting grade level which cannot be achieved by the two production modes. The metal mold casting production line of the thin-wall gray cast iron pipe fitting established by the technical scheme of the invention becomes the production base of the cast iron drainage pipe fitting with the best quality, the lowest cost, the highest production efficiency and the largest scale at present in China.

In addition, the present invention also provides a method of manufacturing the metal mold according to each of the above embodiments, the method including: selecting low-carbon structural steel with uniform metal structure as a hot-rolled section for manufacturing a metal mold; manufacturing a fashionable metal mold according to the shape and the structure of the casting; during blanking, setting the fiber direction of the metal structure of the metal mold processed in the rolling direction of the hot-rolled section to be in a horizontal state; the total weight of the finished metal mold is not less than 75 times of the weight of the casting.

As described above, the inventors have repeatedly tested the material of the metal mold 2 to determine that the thick plate material of the hot rolled ordinary low carbon structural steel Q235 is used for processing. The selected Q235 hot-rolled common low-carbon structural steel has the carbon content generally selected within the range of 0.12-0.22%, has the characteristic of low hardenability, is not easy to form a hardening layer which is easy to generate cracks on the surface of a metal mold cavity under the impact of high-temperature molten iron, and has good hot cracking resistance. The selected Q235 hot-rolled common low-carbon structural steel adopts a general thick plate profile, has good material uniformity, avoids the internal defects and casting stress which are easily caused by selecting a heat-resistant alloy casting blank for a traditional metal mold, has better welding performance, and is convenient for welding repair when the local burning loss of the mold occurs.

In order to further prevent the phenomenon of white cast caused by chilling when high-temperature molten iron contacts with a metal mold, the invention also provides an embodiment of molten iron components suitable for the metal mold casting process of the thin-wall gray cast iron pipe fitting and a method for controlling the white cast. In the embodiment, the cooling speed in metal mold casting is tens of times to hundreds of times of that of the traditional sand mold, and particularly, a thin-wall gray cast iron pipe fitting casting is easy to form a white structure due to high cooling speed. In order to eliminate the white structure in the casting, besides selecting a proper heat-insulating coating to reduce the cooling speed of molten iron, selecting a proper molten iron Carbon Equivalent (CE) and an inoculation method are important links for promoting graphitization and preventing white cast. According to typical chemical components and metallographic structure performance of gray cast iron, Carbon Equivalent (CE) is an important parameter influencing the formation of the metallographic structure form during solidification and crystallization of the cast iron, the Carbon Equivalent (CE) of the common molten iron in the traditional sand casting is controlled to be about 4.3 percent, and the molten iron is easily white when used for metal mold casting. The introduction of data shows that the carbon equivalent of molten iron for metal mold casting is controlled to be 4.9-5.0%, and in practice, more carburant and ferrosilicon are required to be added when the molten iron is smelted to reach the control range, so that the material cost of the molten iron is increased, and the too high carbon equivalent easily generates cold brittleness of castings, so that the mechanical strength of the castings is reduced, and the pipe fittings are easy to damage.

Therefore, in this embodiment, a method for controlling the chemical composition of molten iron and white cast iron used in the metal mold casting process of the thin-wall gray cast iron pipe fitting was developed through experiments in combination with the use of the metal mold heat-insulating coating.

1) The molten iron comprises five main chemical components:

3.5-3.8% of carbon C, 2.5-2.8% of silicon Si, 0.3-0.5% of manganese MnP, less than or equal to 0.6% of phosphorus P and less than or equal to 0.1% of sulfur S; wherein the content of Mn, P and S in the original molten iron before the components are not adjusted is not more than the upper limit value; when the content of C does not reach the lower limit value, adding a carburant into the furnace burden for adjustment; when the content of Si does not reach the lower limit value, the content of Si is adjusted by adding inoculant ferrosilicon in the inoculation process; it should be noted that the content of P in the chemical components of the molten iron is higher than the control index of less than or equal to 0.3 percent in the traditional process, and the control index has the functions of properly increasing the content of P in the metal mold casting, contributing to improving the fluidity of the molten iron and improving the hot cracking resistance of the casting.

2) Control of carbon equivalent CE:

in this example, the carbon equivalent is controlled as follows: CE ═ C +0.3(Si + P) ]% > is more than or equal to 4.5%; in the embodiment, the adoption of the metal-type heat-insulating coating reduces the carbon equivalent control value by 0.3-0.5% compared with the carbon equivalent control value required by the conventional metal mold casting, reduces the use amount of the carburant and the ferrosilicon, and saves the material cost (because each increase of 0.1% of the carbon equivalent requires that approximately 0.45% of 75 silicon is added, and the material cost can be reduced by 120-200 yuan per ton of molten iron according to the reduction of 0.3-0.5% of the carbon equivalent).

3) Inoculation of molten iron:

in the inoculation of the molten iron in the embodiment, a certain amount of ferrosilicon (inoculant) is added into the molten iron before the molten iron is discharged from a furnace and poured into a ladle and a ladle, and the three inoculation modes are respectively called as follows: the method comprises the steps of furnace inoculation, large ladle inoculation and casting ladle inoculation, and aims to further adjust the carbon equivalent to be more than or equal to 4.5%, promote graphitization and prevent white cast from being generated.

Inoculation in a furnace: adopt 75 ferrosilicon that silicon content is 75%, the bulk size is 20 ~ 50mm, when the interior molten iron temperature of smelting electric stove reaches 1350 ~ 1380 ℃, add ferrosilicon according to the content of C and Si in the molten iron assay composition, the addition is according to satisfying that carbon equivalent CE equals 4.5% and the absorption rate 90% calculation of silicon in the ferrosilicon.

Large ladle inoculation: firstly, 75 ferrosilicon is added into a ladle according to 0.1 percent of the weight of molten iron contained in the ladle, and when the inoculated molten iron in a furnace reaches the tapping temperature of 1400-1420 ℃, high-temperature molten iron is flushed into the ladle to finish ladle inoculation. The particle size of the ferrosilicon should be within the range of 1-5 mm during inoculation of the large ladle so that the ferrosilicon can be rapidly melted and the absorption rate is improved.

And (3) inoculation in a small bag: firstly, 75 ferrosilicon is added into a molten iron casting ladle according to 0.1 percent of the weight of molten iron contained in the casting ladle, and the molten iron in the molten iron casting ladle is poured into the casting ladle before casting, so that the inoculation of a small ladle is completed. And during inoculation of the small bags, the particle size of the ferrosilicon should be within the range of 1-3 mm, so that the ferrosilicon is rapidly melted, and the inoculation effect is improved.

In summary, in the embodiment, the molten iron composition and the method for controlling white cast iron suitable for the metal mold casting process of the thin-wall gray cast iron pipe fitting enable a more economical molten iron capable of ensuring the material property of the pipe fitting casting to be applied to the metal mold casting process of the thin-wall gray cast iron pipe fitting.

The present invention is not limited to the above preferred embodiments, and any modifications, equivalent substitutions, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A thermal barrier coating, comprising: kaolin, diatomite, polyvinyl alcohol, lithium bentonite and water, wherein the weight percentages are as follows:

11-12% of kaolin

3.6 to 4.0 percent of diatomite

0.09-0.11 percent of polyvinyl alcohol

0.50-0.60% of lithium bentonite

The rest proportion of water;

the coating comprises a coating, a lithium bentonite, a polyvinyl alcohol, a coating suspending agent, a binder and a dispersant, wherein the polyvinyl alcohol is used as a coating binder component, and the lithium bentonite is used as a coating suspending agent, a binder and a dispersant component;

the preparation method of the heat insulation coating comprises the following steps:

preparing polyvinyl alcohol paste;

preparing lithium bentonite paste;

adding powdery diatomite, kaolin and water into a low-speed stirrer, and stirring to completely mix the powdery diatomite, the kaolin and the water with the aqueous solution;

after fully stirring without agglomeration, sequentially adding the lithium bentonite paste and the polyvinyl alcohol paste, continuously stirring and fully mixing uniformly, and filtering by a filter screen for later use;

wherein the method for preparing the polyvinyl alcohol paste comprises the following steps:

taking the polyvinyl alcohol and the water according to the proportion of 1: 25;

adding polyvinyl alcohol and water into the interlayer electric heating kettle in a fixed amount according to the ratio of 1: 25 to enable the polyvinyl alcohol and the water to be transparent paste;

the method for preparing the lithium-based bentonite paste comprises the following steps:

taking lithium bentonite and water according to the proportion of 1: 10;

quantitatively adding lithium bentonite and water into a container according to the proportion of 1: 10, standing for more than 24 hours until the bentonite fully absorbs water and swells;

adding the fully swelled lithium bentonite into a stirrer for fully stirring before use.

2. The thermal barrier coating of claim 1, further comprising: dispersants, defoamers and/or rust inhibitors for improving coating performance.

3. The method for preparing the thermal barrier coating material according to claim 1 or 2, comprising:

preparing polyvinyl alcohol paste;

preparing lithium bentonite paste;

after fully stirring without agglomeration, sequentially adding the lithium bentonite paste and the polyvinyl alcohol paste, continuously stirring and fully mixing uniformly, and filtering by a filter screen for later use.

4. The method for preparing a thermal barrier coating according to claim 3, wherein the method for preparing a polyvinyl alcohol paste comprises:

adding polyvinyl alcohol and water into the electric heating kettle in the ratio of 1: 25 to make polyvinyl alcohol and water into transparent paste.

5. The method for preparing a heat-insulating coating according to claim 4, wherein the method for preparing the lithium-based bentonite paste comprises:

taking lithium bentonite and water according to the proportion of 1: 10;

6. A metal mold is arranged on a metal mold casting device and is characterized by comprising a first half mold (21) and a second half mold (22) which are processed by low-carbon structural steel with uniform metal structure;

the first half mould (21) and the second half mould (22) are respectively and correspondingly provided with: a cavity (10) for forming the appearance of a casting during casting, a pouring gate (11), a pouring channel (12), a fixed leg (16) which can be fixedly connected to the metal mold casting device, and a parting surface (18) which can be mutually jointed when the first half mold (21) and the second half mold (22) are closed;

the die cavity (10) is a concave cavity matched with the shape of the outer surface of the casting, and is provided with a sand core (3) for limiting the shape and the wall thickness of the inner surface of the casting; a positioning part for positioning the relative position between the sand core (3) and the cavity (10) is arranged above the cavity (10);

the gates (11) are respectively and correspondingly arranged above the first half mould (21) and the second half mould (22); the pouring channel (12) is communicated with the pouring gate (11) and extends into the cavity (10) from the upper part of the cavity (10);

wherein the inner surface of the mould cavity (10) is coated with a thermal barrier coating according to claim 1 or 2.

7. The metal-type die of claim 6,

the positioning part comprises a positioning core groove (13) and a sand core positioning groove (17), and the positioning core groove (13) is used for positioning the relative position between a positioning core head (30) of the sand core (3) and the cavity (10); the sand core positioning groove (17) is used for positioning the relative position between the main body of the sand core (3) and the cavity (10);

a positioning flange (31) is arranged on the sand core (3), and the shape of the positioning flange (31) is matched with the shape of the inner wall of the sand core positioning groove (17);

wherein the low-carbon structural steel is Q235 hot-rolled common low-carbon structural steel, and the carbon content of the low-carbon structural steel is within the range of 0.12-0.22%.

8. The metal-type die of claim 7,

the first half-mould (21) and the second half-mould (22) are further provided with: a positioning pin hole (14) and a positioning pin (15) which are used for keeping the relative positions of the two half moulds from shifting when the two half moulds are closed;

the positioning pin holes (14) on the first half die (21) are matched with the positioning pins (15) on the second half die (22) in position and size;

the positioning pins (15) on the first half die (21) are matched with the positioning pin holes (14) on the second half die (22) in position and size.

9. The metal-type die of claim 8,

when the first half mould (21) and the second half mould (22) are closed, the sprue (11) is in a cavity with a horn-shaped upper part and a cylindrical lower part; and/or the presence of a gas in the gas,

the upper part of the pouring gate (12) is communicated with the cylinder of the pouring gate (11), and the lower part of the pouring gate is communicated with the cavity (10); wherein the pouring channel (12) is a concave flat groove processed according to the size required by the casting process of the casting.

10. A metal mold casting apparatus, comprising: -a frame (5), -a stationary platen (6), -a movable platen (7), -a movable platen guide shaft (8), -a clamping unit, and-a metal mold (2) according to any one of claims 6 to 9; wherein,

the first half mould (21) and the second half mould (22) are respectively and correspondingly arranged on the fixed mould plate (6) and the movable mould plate (7);

the fixed template (6) is arranged on the rack (5), and the movable template guide shaft (8) is arranged between the rack (5) and the fixed template (6) and penetrates through the movable template (7);

one end of the mold closing device is arranged on the rack (5), and the other end of the mold closing device is arranged on the movable mold plate (7); and under the drive of the mold closing device, the movable mold plate (7) reciprocates on the movable mold plate guide shaft (8) to complete the mold opening and closing action.