CN109290518B - V-method vertical modeling process and casting process - Google Patents
V-method vertical modeling process and casting process Download PDFInfo
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- CN109290518B CN109290518B CN201710613461.XA CN201710613461A CN109290518B CN 109290518 B CN109290518 B CN 109290518B CN 201710613461 A CN201710613461 A CN 201710613461A CN 109290518 B CN109290518 B CN 109290518B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/02—Sand moulds or like moulds for shaped castings
- B22C9/03—Sand moulds or like moulds for shaped castings formed by vacuum-sealed moulding
Abstract
The invention provides a V-method vertical modeling process, which comprises the following steps: respectively sucking and pasting films on the surfaces of the positive pressure plate and the negative pressure plate with the patterns and spraying paint; enabling the positive pressure plate, the back pressure plate and the sand box after film coating to form a closed molding chamber, enabling the sand box to be located between the positive pressure plate and the back pressure plate and to be compressed through a hydraulic system to enable a vertical cavity to be formed in the molding chamber, and enabling a sand shooting opening to be formed in the top surface of the sand box; injecting dry sand into the molding chamber vertically through a sand shooting device, and then carrying out vacuum pumping treatment on the molding chamber, wherein the sand shooting device is positioned above a sand shooting port; after the dry sand in the molding chamber is compacted, the positive pressure plate and the negative pressure plate are separated from the sand box to obtain a molding block with cavities on two sides; and (4) combining the mould blocks with the previous mould block to obtain a sand mould, and repeating the operation to prepare a moulding line formed by a plurality of sand moulds. The molding process has the advantages of high production speed, high efficiency, long service life of the mold and the sand box, and the prepared casting has smooth surface, clear outline and accurate size.
Description
Technical Field
The invention relates to the technical field of sand casting, in particular to a V-method vertical molding process and a casting process.
Background
Casting is a process of melting solid metal into liquid, pouring the liquid into a mold with a specific shape, and solidifying and molding the liquid. The sand casting is a common casting technology, the V-method modeling is a vacuum sealing modeling casting method, also called negative pressure modeling, and the V-method horizontal modeling is generally adopted at present, and the process flow is as follows: (1) sucking and sticking a preheated plastic film to the whole surfaces of the mould and the mould under the action of negative pressure, and then uniformly spraying quick-drying paint on the film; (2) putting a sand box with an air exhaust chamber on the sand box; (3) filling dry sand without adding a binder, moisture and additives, slightly vibrating the added sand to ensure that the dry sand is filled in the sand box, scraping, covering a film on the top, and vacuumizing through the wall of the sand box; (4) turning over the box and lifting the film, wherein the plastic film is uniformly adhered to the sand mold under the action of atmospheric pressure, so that the molding sand is in a compact state, and taking out the pattern to achieve the sand mold with the hardness of about 90 degrees; (5) mold assembling, wherein the negative pressure state of the casting mold is maintained until pouring, and the casting is solidified; (6) the negative pressure contacts, the casting mold automatically collapses, and the casting can be conveniently taken out from the casting mold dry sand.
The horizontal modeling by the V method adopts dry sand modeling, so that the sand treatment is simplified, and the recovery rate of used sand is high; the surface of the pattern is covered with a film, and the pattern is not in direct contact with the sand mould, so that the film is conveniently lifted, the dimensional precision of the casting is improved, and the abrasion to the pattern is reduced; pouring is carried out in a negative pressure state, the fluidity of the metal liquid is good, and a casting with the thickness of 2-3 mm can be prepared; vibration shakeout equipment is not needed, and the workshop environment is improved.
However, the horizontal modeling operation of the V method adopted by the prior art is complex, the production efficiency of small castings is low, and casting heads need to be machined secondarily; 4 films need to be covered by an upper box and a lower box in the preparation process, and the film covering times are more; moreover, the box needs to be turned over when being disassembled, and the upper box and the lower box need to be separated for shakeout. In addition, the controllability of the V-method horizontal modeling temperature field is poor, and more coatings are needed when the V-method horizontal modeling temperature field is used for manufacturing large castings.
Disclosure of Invention
In view of this, the invention aims to provide a V-method vertical modeling process and a casting process, and the modeling process provided by the invention is simple in method and high in efficiency.
The invention provides a V-method vertical modeling process, which comprises the following steps:
1) respectively sucking and pasting films on the surfaces of the positive pressure plate and the back pressure plate with the patterns and spraying paint to obtain the positive pressure plate and the back pressure plate after film coating;
2) the positive pressure plate, the back pressure plate and the sand box with the air exhaust chamber form a closed molding chamber after film coating,
the sand box is positioned between the positive pressure plate and the negative pressure plate and is pressed tightly through a hydraulic system, so that a vertical cavity is formed in the molding chamber, and a sand shooting opening is formed in a top panel of the sand box;
3) after dry sand is vertically injected into the molding chamber through the sand injection device, the sand injection port is sealed by a film, then the molding chamber is vacuumized,
the sand shooting device is positioned above the sand shooting port;
4) after the dry sand in the molding chamber is compacted, the positive pressure plate and the negative pressure plate leave the sand box to obtain a molding block with cavities on two sides;
5) performing mould assembling on the mould block and the previous mould block to obtain a sand mould, and vertically parting the sand mould;
6) and repeating the operations of the steps 1) to 5) to obtain a molding line formed by a plurality of sand molds.
Preferably, the method for sealing the sand shooting port by using the film in the step 3) comprises the following steps:
sealing the sand shooting port by adopting a film on the surface of the positive pressure plate or the negative pressure plate in the step 1); or
And cutting the film again according to the size and the shape of the sand shooting opening to seal the sand shooting opening.
Preferably, the front side plate and/or the rear side plate of the sand box are/is provided with a vacuum channel.
Preferably, the film is selected from one or more of polyethylene film, polyvinyl chloride film, ethylene-vinyl acetate copolymer film, polypropylene film and polyvinyl alcohol film.
Preferably, the pressure of the sand shooting is 0.02-0.06 MPa;
the sand shooting time is 0.1-0.4 seconds.
Preferably, the fineness of the dry sand is 70-120 meshes.
Preferably, the vacuum degree of the vacuumizing treatment is 30-70 KPa.
Preferably, the surface strength of the mould block is 85-95 g/mm2。
Preferably, the precision of the mould assembling is within 0.1 mm.
The invention provides a casting process, which comprises the following steps:
pouring molten metal into a sand mold of the molding line to obtain a casting;
the moulding line is prepared by the moulding process in the technical scheme.
Compared with the prior art, the V-method horizontal molding process is optimized and improved, a vertical V-method molding method is adopted, the two surfaces of the mold block are provided with the mold cavities, the casting mold is composed of the mold cavities between the two mold blocks, one mold block is equivalent to one casting mold, the pouring system is arranged on the vertical parting surface, secondary processing on the casting head is not needed, the number of times of film covering is few, the unpacking process cannot be turned over, and the upper box and the lower box do not need to be separated for sand falling.
In addition, the molding blocks continuously manufactured by the molding method provided by the invention are mutually pushed to form a long molding block row, the molding blocks are mutually pushed, the friction force between the molding blocks and the casting platform can resist the casting pressure during casting, the molding blocks can keep close fit, and a clamping device is not needed.
The molding process provided by the invention effectively overcomes the defects of horizontal molding by a V method, and the prepared casting has smooth surface, clear outline, accurate size, high production speed and long service life of a mold and a sand box.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is a schematic illustration of the positions of a flask, a sand shooting device, a positive platen and a negative platen before molding according to an embodiment of the present invention;
FIG. 2 is a schematic illustration of the positions of the flask, the sand shooting device, the positive platen and the negative platen after the mold clamping of the embodiment of the invention;
FIG. 3 is a front view of a molding line according to an embodiment of the present invention;
FIG. 4 is a top view of a styling line according to an embodiment of the present disclosure;
FIG. 5 is a fireplace plate casting made in accordance with example 1 of the present invention;
FIG. 6 is a cast hob made according to example 2 of the present 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.
The invention provides a V-method vertical modeling process, which comprises the following steps:
1) respectively sucking and pasting films on the surfaces of the positive pressure plate and the back pressure plate with the patterns and spraying paint to obtain the positive pressure plate and the back pressure plate after film coating;
2) the positive pressure plate, the back pressure plate and the sand box with the air exhaust chamber form a closed molding chamber after film coating,
the sand box is positioned between the positive pressure plate and the negative pressure plate and is pressed tightly through a hydraulic system, so that a vertical cavity is formed in the molding chamber, and a sand shooting opening is formed in a top panel of the sand box;
3) after dry sand is vertically injected into the molding chamber through the sand injection device, the sand injection port is sealed by a film, then the molding chamber is vacuumized,
the sand shooting device is positioned above the sand shooting port;
4) after the dry sand in the molding chamber is compacted, the positive pressure plate and the negative pressure plate leave the sand box to obtain a molding block with cavities on two sides;
5) performing mould assembling on the mould block and the previous mould block to obtain a sand mould, and vertically parting the sand mould;
6) and repeating the operations of the steps 1) to 5) to obtain a molding line formed by a plurality of sand molds.
The invention preferably sucks and attaches the preheated plastic film to the surfaces of the positive pressure plate and the back pressure plate with patterns under the action of negative pressure. In the invention, an EVA film is preferably used as a vertical V-method casting plastic film, the film is placed under a heater for 150-200 mm during film covering and forming, the heating temperature is 80-120 ℃, the heating time is generally 20-50 s, the film is quickly dropped into the film when being heated to be in a mirror surface shape, after film covering, whether the film is tightly attached to a model surface or not and whether cavities or damages exist or not need to be checked, and for some parts which are difficult to absorb the film and form, local strengthening vacuum pumping measures are adopted, and the air pumping speed is adjusted to realize film covering and forming.
In the invention, the surfaces of the positive pressure plate and the negative pressure plate are provided with patterns, and the patterns preferably comprise patterns of a pre-obtained casting and pouring gate patterns communicated with the casting patterns; the positive platen surface preferably carries a left half pattern and the counter platen surface preferably carries a right half pattern.
In the invention, the positive pressure plate, the negative pressure plate and the surface pattern of the pressure plate are preferably made of aluminum alloy; the processing precision of the surface patterns of the positive pressure plate, the negative pressure plate and the pressure plate is preferably 0.1 mm.
In the present invention, the film is preferably a film which has high strength and elongation, stable quality, easy handling of the remaining film, small gas evolution during combustion, and low cost. In the present invention, the film is preferably a plastic film. The material of the plastic film is not particularly limited, and the plastic film known to those skilled in the art may be used, such as one or more of Polyethylene (PE) film, polyvinyl chloride (PVC) film, ethylene-vinyl acetate copolymer (EVA) film, polypropylene (PP) film, and polyvinyl alcohol (PVA) film. In the invention, the thickness of the EVA film is preferably 0.06-0.15 mm, and the thickness of the PP film is preferably 0.05-0.07 mm. The source of the film is not particularly limited in the present invention and is commercially available.
The present invention preferably uniformly sprays the quick-drying coating on the surface of the film. The present invention is not particularly limited in the kind and source of the coating, and the coating in the V-process molding process, which is well known to those skilled in the art, may be used. In the present invention, the components of the quick-drying coating used preferably include:
25 parts of 320-mesh corundum powder;
18 parts of 200-mesh silicon jade powder;
2 parts of attapulgite;
1 part of lithium bentonite;
polyvinyl butyral;
a thermoplastic phenolic resin;
a solvent.
In the invention, the mass content of the polyvinyl butanol in the quick-drying paint is preferably 1%; the mass content of the thermoplastic phenolic resin in the quick-drying paint is preferably 1.5%; the solvent is preferably process ethanol. In the present invention, the quick-drying paint preferably further comprises a surfactant for paint and a coupling agent.
According to the invention, a closed molding chamber is formed by the positive pressure plate, the back pressure plate and the sand box with the air exhaust chamber after film coating, the sand box is positioned between the positive pressure plate and the back pressure plate and is compressed by a hydraulic system, a vertical cavity is formed in the molding chamber, and a sand shooting opening is formed on the top panel of the sand box.
In the present invention, the flask is located between the positive and negative platens to form a molding chamber. The positive pressure plate, the counter pressure plate and the sand box are preferably matched by a matching device to form a molding chamber, and the sand box is fastened and kept unchanged in position in the whole process of matching; the moving speed of the positive pressure plate and the negative pressure plate in the mold closing process is preferably less than 1 mm/s. In the invention, after the die assembly, the patterns on the positive pressure plate and the negative pressure plate are positioned in the molding chamber, so that a cavity in the molding chamber is a vertical cavity.
In the invention, the sand box is preferably a vacuum casting sand box, the material of the sand box is preferably cast iron, and the cast iron sand box has high strength and is not easy to deform. In the present invention, the processing accuracy of the sand box is preferably 0.1 mm. In the present invention, the shape of the flask is preferably a hollow square frame having front and rear sides and a top surface without left and right sides (the positive and negative pressure plates are filled to positions of the left and right sides of the flask to close the flask in the process of forming the molding chamber). The invention is not particularly limited to the size of the flask, and those skilled in the art can select a flask of an appropriate size according to the size of the cast product actually produced. In the invention, the front and/or the back of the sand box are/is preferably provided with a vacuum channel.
In the present invention, sand is shot vertically into the molding chamber from above the molding chamber. The sand shooting device is used for shooting sand, and the sand shooting device is preferably a sand silo. In the invention, the sand shooting device is arranged above the sand shooting opening of the sand box, the molding sand falls vertically in the sand shooting process, and the sand shooting device is connected with the sand shooting opening in a sealing way to realize the sealing of the sand box; and after the sand shooting is finished, the sand shooting device is separated from the sand shooting port. In the invention, the pressure of the sand shooting is preferably 0.02-0.06 MPa, more preferably 0.03-0.05 MPa, and most preferably 0.04 MPa. In the present invention, the sand shooting time is preferably 0.1 to 0.4 seconds, and more preferably 0.2 to 0.3 seconds.
In the present invention, the sand for shooting is preferably a sand without adding a binder, water and additives, and the sand is dry sand. In the invention, the fineness (AFS fineness value) of the molding sand (dry sand) is preferably 70-120 meshes, and more preferably 80-100 meshes. In the invention, the molding sand (dry sand) is preferably three-screen sand, and the effect is better. In the present invention, the water content of the molding sand (dry sand) is preferably not more than 0.2% (mass percentage content).
In the present invention, after the sand shooting is completed, the molding sand in the molding chamber is preferably compacted by a hydraulic system and sealed by an inflatable sealing ring. The vertical sand box is preferably vibrated continuously in the sand shooting process, and the molding sand is compacted through the sand shooting port and the hydraulic machine (or the hydraulic pump) after the sand shooting is finished.
In the invention, after the sand shooting is finished, the sand shooting device is preferably separated from the sand box, the sand shooting opening is sealed by adopting a film, and then the molding chamber is vacuumized to compact the molding sand. According to the invention, the cavity surface and the back surface of the sand mold are sealed by using the film, and the molding sand is tightly molded by using the pressure difference between the inside and the outside of the sand mold caused by negative pressure generated by air suction of the vacuum pump. In the invention, the sand shooting opening of the top surface of the sand box can be covered by the residual part of the film covering the surfaces of the positive pressure plate and the negative pressure plate, or the film with proper size can be cut according to the size and shape of the sand shooting opening to cover the surface of the sand shooting opening for sealing. The invention only needs to carry out film covering twice, and has simple film covering process and higher production efficiency.
Before the vacuumizing treatment, the vibration treatment is preferably carried out on the molding chamber after the sand shooting; the time for the vibration treatment is preferably 8-12 seconds, and more preferably 10 seconds; the acceleration of the vibration treatment is preferably 1 g. In the present invention, it is preferable to perform the vacuum-pumping process of the molding chamber through the vacuum passage in the flask by using a vacuum pump. In the present invention, the vacuum-pumping treatment is performed so that the degree of vacuum is maintained at preferably 30 to 70KPa, more preferably 40 to 60KPa, and most preferably 50 KPa.
And after the vacuum pumping treatment is finished, the positive pressure plate and the negative pressure plate are separated from the sand box, and a mould block with cavities on two sides is formed in the sand box. In the present invention, the positive and negative platens preferably exit the flask from both the left and right sides. In the invention, after the vacuum-pumping treatment, the strength of the surface of the briquette is preferably 85-95 g/mm2More preferably 90g/mm2。
The method comprises the steps of moving the prepared mould block and combining the mould block with the previous mould block to obtain a sand mould; repeating the operations of steps 1) to 5) to obtain a molding line formed of a plurality of sand molds continuously manufactured. In the present invention, the flask is preferably moved under vacuum to close the flask, and the vacuum can be continued without the flask leaving the flask during the movement of the flask. In the present invention, the degree of vacuum under the vacuum condition is preferably 30 to 50KPa, more preferably 35 to 45KPa, and most preferably 40 KPa. In the invention, a positioning mechanism is preferably adopted for positioning in the process of combining the molding block and the previous molding block, and the positioning mechanism preferably adopts a unilateral reference positioning technology, so that the box combining precision is preferably within 0.1 mm.
The molding process provided by the invention has the advantages of high production speed and long service life of the pressing plate and the sand box.
The invention also provides a casting process, comprising:
and pouring molten metal into the sand mold of the molding line in the technical scheme to obtain a casting.
The present invention preferably conveys the obtained molding line to a casting station for molten metal casting. In the pouring process, the invention still keeps the vacuum-pumping treatment of the sand mold, the cavity is in a negative pressure state, and the pouring metal liquid has good fluidity under the negative pressure condition, so that a thin-wall casting with the thickness of 2-3 mm can be poured.
According to the invention, after the casting is preferably finished, the box is opened after cooling to obtain a casting; according to the invention, the vacuum pumping treatment on the sand mold is preferably stopped to relieve the negative pressure in the box opening process, the sand mold automatically collapses after the negative pressure is relieved, and a casting can be conveniently taken out from the collapsed dry sand.
The molding process provided by the invention comprises the processes of film coating, dry sand injection and vacuum pumping, and adopts a vertical molding method to cast a casting without dividing a sand box into an upper sand box and a lower sand box. In the invention, because the left and right surfaces of one sand box (which becomes a molding block after sand shooting) are contacted with the pattern, the left and right surfaces of the formed molding block are both provided with cavity molds, a plurality of molding blocks are contacted in sequence, the mold is composed of the cavities between the two molding blocks, and the parting plane is vertical; one mould block is equivalent to one casting mould and can be cast into a casting piece, the utilization rate of the mould block is high, and the film coating times can be reduced by one time. In addition, the invention does not need to adopt green sand modeling.
Compared with the prior art, the invention adopts the processes of film covering, dry sand injection and vacuumizing to carry out vertical molding to prepare the molding block with the cavities on both sides, one module is equivalent to the molding process of one casting mold, only one casting head needs to be processed once, the whole molding and pouring process is finished in a vertical state, the sand box does not need to be turned over, and only one sand box does not need to be separated for sand mold preparation. The production level of the molding process provided by the invention can reach 220 sand boxes per hour, and the production efficiency is high.
The position schematic diagram of a sand box, a sand shooting device, a positive pressure plate and a negative pressure plate used before molding of the following embodiment of the invention is shown in fig. 1, wherein 1 is the positive pressure plate made of aluminum alloy, and comprises: the positive pressure plate comprises a positive pressure plate body 101, a left half die pattern 102 (the rightmost side of the top is provided with a left half sprue gate) on the surface of the positive pressure plate, and the machining precision is 0.1 mm; 2 is back pressure plate of aluminum alloy material, includes: the machining precision of the counter pressure plate body 201 and the right half pattern 202 (the leftmost side of the top is provided with a right half pouring gate) on the surface of the counter pressure plate is 0.1 mm; the shape and size of a cavity formed after the left half pattern 102 and the right half pattern 202 are matched with those of a prefabricated casting; the shape and size of a cavity formed after the left half sprue gate and the right half sprue gate are assembled are the same as those of a sprue gate required in the pouring process; 3, the sand box is a hollow square frame without a left side surface and a right side surface and only with a top surface, a front side surface and a rear side surface, a round sand shooting port 301 is arranged on the top surface of the sand box, a round pipe vacuum channel 302 is arranged on the front side surface of the sand box, the sand box is provided with an air exhaust chamber, the air exhaust chamber is vacuumized through the vacuum channel, and the processing precision of the sand box is 0.1 mm; and 4, the sand shooting device is a sand silo.
Example 1
The method comprises the following steps of sucking and pasting a preheated mirror-like polyethylene plastic film on the surface of one side, provided with a left half mold, of a positive pressure plate under the action of negative pressure, and then uniformly spraying a quick-drying paint on the surface of the plastic film (103 in the figure 1 is the plastic film), wherein the spraying thickness is 0.4mm, and the quick-drying paint comprises the following components: 25 parts of 320-mesh corundum powder, 18 parts of 200-mesh silicon jade powder, 2 parts of attapulgite, 1 part of lithium bentonite, polyvinyl butanol, thermoplastic phenolic resin, a surfactant for paint, a coupling agent and industrial ethanol; the mass content of the polyvinyl butanol in the quick-drying paint is 1%, and the mass content of the thermoplastic phenolic resin in the quick-drying paint is 1.5%.
And (2) sucking and attaching a polyethylene plastic film which is heated to be in a mirror surface shape to the surface of one side of the back pressure plate with the right half-mould under the action of negative pressure, and then uniformly spraying a quick-drying paint on the surface of the plastic film (203 in figure 1 is the plastic film), wherein the spraying thickness is 0.4mm, and the components of the quick-drying paint are the same as the components.
Placing the sand box between the positive pressure plate and the negative pressure plate, and closing the positive pressure plate, the negative pressure plate and the sand box through a closing mechanism to form a molding chamber, wherein the sand box is fastened in the whole process and is kept unchanged in position, the instantaneous speed of closing the mold is lower than 1mm/s, the positive pressure plate is positioned at the left side plate of the sand box after closing the mold, the negative pressure plate is positioned at the right side plate of the sand box, so that the sand box is closed, and the patterns on the left pressure plate and the right pressure plate are positioned in the molding chamber; the position of the sand bin is located above the sand shooting port on the sand box and is connected with the sand shooting port in a sealing mode, and the schematic position diagram of the sand box, the sand shooting device, the positive pressure plate and the negative pressure plate after the mold is closed is shown in figure 2.
Taking three-screen dry sand without adding a binder, moisture and additives in a sand bin as molding sand and vertically injecting the molding sand into a molding chamber; the AFS fineness value of the molding sand is 70 meshes, and the mass content of water in the molding sand is less than or equal to 0.2%; the pressure in the sand shooting process is 0.02MPa, and the sand shooting time is 0.4 s;
and continuously vibrating the vertical sand box (vibrating at the acceleration of 1g for 10 seconds) in the sand shooting process, compacting the molding sand through a sand shooting port and a hydraulic machine after the sand shooting is finished, and sealing by adopting an inflatable sealing ring. Separating the sand bin from the sand box, and covering the surface of a sand shooting opening of the sand box with a polyethylene plastic film with the thickness of 0.05-0.15 mm; then, a vacuum pump is used for vacuumizing the molding chamber through a vacuum channel in the sand box to compact the molding sand, the vacuum degree in the vacuumizing process is 30KPa, and the molding sand is pumpedThe strength of the sand mould surface in the moulding chamber is 85g/mm under vacuum2。
Separating the positive pressure plate and the negative pressure plate from the sand box from the left side and the right side to obtain a molding block with cavities on two sides;
slowly moving the obtained molded block under the condition of keeping the vacuum degree of 30KPa (continuing the operation of the vacuumizing treatment) to be combined with the previous molded block, and positioning by adopting a PID positioning mechanism in a unilateral reference scheme in the process of combining the molded blocks, so as to ensure that the precision of combining the molded blocks is within 0.1 mm; repeating the above operations of preparing and assembling the mold blocks to form a molding line composed of a plurality of mold blocks, as shown in fig. 3 and 4 (fig. 3, 5 is molten metal);
conveying the sand mold on the molding line to a casting working section, casting molten metal, and keeping a negative pressure state in the sand mold in the casting process, wherein the vacuum degree is 30KPa (continuing the vacuum pumping treatment operation);
and (4) cooling after the pouring is finished, relieving the negative pressure in the sand mould (stopping the vacuumizing operation), automatically collapsing the sand mould, and opening the box to take out the casting.
The casting prepared in example 1 of the present invention was a furnace wall plate, and the shot blasting treatment was performed on the obtained casting as shown in fig. 5. The obtained casting is subjected to scribing measurement, the measurement number is not less than 50 pieces, the measurement precision is 0.02, the measurement repeatability of a non-inclined plane is 0.05, and the measurement result is approximately 0.1 mm. The dimensional deviation (nominal size of the casting-actual size of the casting) of the casting prepared by the method provided by the embodiment 1 of the invention reaches the CT4 grade in GB/T6414-1999 casting dimensional tolerance and machining allowance, and the surface roughness grade of the casting is 18S.
Example 2
The polyvinyl chloride plastic film which is heated to be mirror-like in advance is sucked and pasted on the surface of the left half-mold-shaped side of the positive pressure plate under the action of negative pressure, and then the quick-drying paint is uniformly sprayed on the surface of the plastic film (103 in figure 1 is the plastic film), the spraying thickness is 0.5mm, and the components of the quick-drying paint are the same as those of the example 1.
A polyvinyl chloride plastic film which is heated to be in a mirror surface shape in advance is sucked and attached to the surface of one side of the back pressure plate with the right half-mould under the action of negative pressure, and then quick-drying paint is uniformly sprayed on the surface of the plastic film (203 in figure 1 is the plastic film), wherein the spraying thickness is 0.5mm, and the components of the quick-drying paint are the same as those in example 1.
Placing the sand box between the positive pressure plate and the negative pressure plate, closing the positive pressure plate, the negative pressure plate and the sand box through a closing mechanism to form a molding chamber, wherein the sand box is fastened in the whole process and is kept unchanged in position, the instantaneous speed of closing the mold is lower than 1mm/s, the positive pressure plate is positioned at the left side plate of the sand box after closing the mold, the negative pressure plate is positioned at the right side plate of the sand box, so that the sand box is closed, and the patterns on the left pressure plate and the right pressure plate are positioned in the molding chamber; the position of the sand bin above the sand shooting opening of the sand box is sealed and connected with the sand shooting opening, and the schematic position diagram of the sand box, the sand shooting device, the positive pressure plate and the negative pressure plate after the mold is closed is shown in figure 2.
Taking three-screen dry sand without adding a binder, moisture and additives in a sand bin as molding sand and vertically injecting the molding sand into a molding chamber; the AFS fineness value of the molding sand is 120 meshes, and the mass content of water in the molding sand is less than or equal to 0.2%; the pressure in the sand shooting process is 0.06MPa, and the sand shooting time is 0.1 s;
and continuously vibrating the vertical sand box (vibrating at the acceleration of 1g for 10 seconds) in the sand shooting process, compacting the molding sand through a sand shooting port and a hydraulic machine after the sand shooting is finished, and sealing by adopting an inflatable sealing ring. Separating the sand bin from the sand box, and covering the surface of a sand shooting opening of the sand box with a polyvinyl chloride film with the thickness of 0.1 mm; then, a vacuum pump is used for vacuumizing the molding chamber through a vacuum channel in the sand box to compact the molding sand, the vacuum degree in the vacuumizing process is 50KPa, and the vacuumizing is carried out to ensure that the strength of the surface of the sand mold in the molding chamber is 95g/mm2。
Separating the positive pressure plate and the negative pressure plate from the sand box from the left side and the right side to obtain a molding block with cavities on two sides;
slowly moving the obtained mould block under the condition of keeping the vacuum degree at 50KPa (continuing the operation of the vacuumizing treatment) to mould together with the previous mould block, and positioning by adopting a PID positioning mechanism in a unilateral reference scheme in the mould-combining process to ensure that the mould-combining precision is within 0.1 mm; repeating the above operations of preparing the mold blocks and assembling the mold boxes to form a molding line as shown in fig. 3 and 4 (5 in fig. 3 is molten metal);
conveying the sand mold on the molding line to a casting working section, casting molten metal, and keeping a negative pressure state in the sand mold in the casting process, wherein the vacuum degree is 50KPa (continuing the vacuum pumping treatment operation);
and (4) cooling after the pouring is finished, relieving the negative pressure in the sand mould (stopping the vacuumizing operation), automatically collapsing the sand mould, and opening the box to take out the casting.
The casting prepared in the embodiment 2 of the invention is a furnace frame, and the shot blasting treatment is performed on the obtained casting as shown in fig. 6. The obtained casting is subjected to scribing measurement, the measurement number is not less than 50 pieces, the measurement precision is 0.02, the measurement repeatability of a non-inclined plane is 0.05, and the measurement result is approximately 0.1 mm. The dimensional deviation (nominal size of the casting-actual size of the casting) of the casting prepared by the method provided by the embodiment 2 of the invention reaches the CT4 grade in GB/T6414-1999 casting dimensional tolerance and machining allowance, and the surface roughness grade of the casting is 25S.
The casting preparation method provided by the embodiment of the invention adopts the processes of vertical film covering, spraying, sand shooting and molding, mold lifting and box closing and pouring, and all molding actions are completed at the same station; the processes of covering a bottom film, turning over a box, assembling and the like are reduced, and the production efficiency is high; in addition, the fine dry sand molding sand is used, the investment of sand mixing equipment and sand mixing auxiliary materials is reduced, and the prepared casting has better surface roughness and size precision.
As can be seen from the above embodiments, the present invention provides a molding process, comprising: respectively sucking and pasting films on the surfaces of the positive pressure plate and the negative pressure plate with the patterns and spraying paint; enabling the positive pressure plate, the back pressure plate and the sand box after film coating to form a closed molding chamber, enabling the sand box to be located between the positive pressure plate and the back pressure plate and to be compressed through a hydraulic system to enable a vertical cavity to be formed in the molding chamber, and enabling a sand shooting opening to be formed in the top surface of the sand box; injecting dry sand into the molding chamber vertically through a sand shooting device, and then carrying out vacuum pumping treatment on the molding chamber, wherein the sand shooting device is positioned above a sand shooting port; after the dry sand in the molding chamber is compacted, the positive pressure plate and the negative pressure plate are separated from the sand box to obtain a molding block with cavities on two sides; and (4) combining the mould blocks with the previous mould block to obtain a sand mould, and repeating the operation to prepare a moulding line formed by a plurality of sand moulds. The molding process has the advantages of high production speed, high efficiency, long service life of the mold and the sand box, and the prepared casting has smooth surface, clear outline and accurate size.
Claims (9)
1. A V-method vertical modeling process comprises the following steps:
1) respectively sucking and pasting films on the surfaces of the positive pressure plate and the back pressure plate with the patterns and spraying paint to obtain the positive pressure plate and the back pressure plate after film coating;
2) the positive pressure plate, the back pressure plate and the sand box with the air exhaust chamber form a closed molding chamber after film coating,
the sand box is positioned between the positive pressure plate and the negative pressure plate and is pressed tightly through a hydraulic system, so that a vertical cavity is formed in the molding chamber, and a sand shooting opening is formed in a top panel of the sand box;
3) after dry sand is vertically injected into the molding chamber through the sand injection device, the sand injection port is sealed by a film, then the molding chamber is vacuumized,
the sand shooting device is positioned above the sand shooting port;
4) after the dry sand in the molding chamber is compacted, the positive pressure plate and the negative pressure plate leave the sand box to obtain a molding block with cavities on two sides;
5) performing mould assembling on the mould block and the previous mould block to obtain a sand mould, and vertically parting the sand mould;
6) repeating the operations of the steps 1) to 5) to obtain a moulding line formed by a plurality of sand moulds;
and a vacuum channel is formed on the front side plate and/or the rear side plate of the sand box.
2. The molding process according to claim 1, wherein the step 3) of sealing the sand shooting port with the film comprises the following steps:
sealing the sand shooting port by adopting a film on the surface of the positive pressure plate or the negative pressure plate in the step 1); or
And cutting the film again according to the size and the shape of the sand shooting opening to seal the sand shooting opening.
3. The molding process according to claim 1, wherein said film is one or more selected from the group consisting of a polyethylene film, a polyvinyl chloride film, an ethylene-vinyl acetate copolymer film, a polypropylene film and a polyvinyl alcohol film.
4. The molding process according to claim 1, wherein the pressure of the sand shooting is 0.02 to 0.06 MPa;
the sand shooting time is 0.1-0.4 seconds.
5. The molding process according to claim 1, wherein the fineness of the dry sand is 70-120 mesh.
6. The molding process according to claim 1, wherein a degree of vacuum of the vacuum treatment is 30 to 70 KPa.
7. The molding process according to claim 1, wherein the surface strength of said block is 85 to 95g/mm2。
8. The molding process according to claim 1, wherein said precision of said mold assembling is within 0.1 mm.
9. A casting process, comprising:
pouring molten metal into a sand mold of the molding line to obtain a casting;
the molding line is prepared by the molding process of claim 1.
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| CN111604475B (en) * | 2020-06-05 | 2022-01-11 | 王振升 | Short-flow V-method modeling process |
| CN112846079B (en) * | 2021-01-05 | 2022-11-18 | 中国第一重型机械股份公司 | Modeling control method for large water turbine blade sand mold |
| CN113996758B (en) * | 2021-10-29 | 2023-07-21 | 苏州明志科技股份有限公司 | V-method vertical modeling process and production line thereof |
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| CN1099576C (en) * | 1996-03-29 | 2003-01-22 | 中国建筑材料工业建设邯郸建材机械厂 | Vacuum forming technology for lining plate of heat-resisting steel hanging used inside cement kiln |
| CN1074951C (en) * | 1997-01-10 | 2001-11-21 | 北京科技大学 | Roller vacuum sealing moulding technique |
| CN102554122A (en) * | 2012-01-29 | 2012-07-11 | 姜玉飞 | Novel modeling method for casting large-sized and ultra large-sized alloy steel track shoes |
| CN104550848A (en) * | 2013-10-24 | 2015-04-29 | 青岛和德隆机械有限公司 | V-method vacuum casting technology |
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