KR101789658B1 - Manufacturing method of lower crank case for engine by hybrid die casting - Google Patents
Manufacturing method of lower crank case for engine by hybrid die casting Download PDFInfo
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- KR101789658B1 KR101789658B1 KR1020150170385A KR20150170385A KR101789658B1 KR 101789658 B1 KR101789658 B1 KR 101789658B1 KR 1020150170385 A KR1020150170385 A KR 1020150170385A KR 20150170385 A KR20150170385 A KR 20150170385A KR 101789658 B1 KR101789658 B1 KR 101789658B1
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- low
- water
- crankcase
- water tank
- cooling
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
- B22D17/20—Accessories: Details
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
- B22D17/20—Accessories: Details
- B22D17/22—Dies; Die plates; Die supports; Cooling equipment for dies; Accessories for loosening and ejecting castings from dies
- B22D17/24—Accessories for locating and holding cores or inserts
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D19/00—Casting in, on, or around objects which form part of the product
- B22D19/04—Casting in, on, or around objects which form part of the product for joining parts
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D30/00—Cooling castings, not restricted to casting processes covered by a single main group
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
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- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Cylinder Crankcases Of Internal Combustion Engines (AREA)
- Shafts, Cranks, Connecting Bars, And Related Bearings (AREA)
Abstract
The present invention relates to a method of manufacturing a low crankcase by hybrid die casting. The present invention relates to a method of manufacturing a die casting mold, comprising the steps of: charging an insert of an aluminum alloy material into a cavity of a die casting mold; A die casting step of filling molten metal in the mold cavity in which the insert is loaded to form a low crankcase; A takeout step of taking out the low crankcase from the mold; And a cooling step of rapidly cooling the taken-out low crankcase. The present invention can prevent the deterioration of physical properties due to annealing through rapid cooling.
Description
BACKGROUND OF THE
The engine is the most important part of the car, and the production of environmentally-friendly green vehicle engine products that meet the global environmental regulations and high oil prices is a prerequisite for the survival of the automobile industry. In Korea, it is rapidly being developed as a new engine that can meet high efficiency, environment friendly and high power demand from existing engines.
The
The aluminum
In recent years, the aluminum
The aluminum
Here, the above-mentioned main steel bearing insert can be applied to a product registered as a registered patent of Korean Patent Office No. 10-0802841 (applicant: Hyundai Motor Co., Ltd.). These prior art bearing inserts are made of cast iron and have protrusions on the surface to provide improved bondability at the insert.
However, in the above-described low crankcase, since the bearing insert is made of main steel and inserted, the vehicle fuel economy is lowered due to the high weight and the exhaust gas is increased. In addition, the cast iron and aluminum are simultaneously machined, There is a problem in that the productivity is lowered due to the post-processing that follows, and the processing roughness becomes difficult to manage, thereby increasing the manufacturing cost. If the same material is used in the case of a defective product, it can be used again by dissolving it, but it is practically impossible to regenerate due to the combination of dissimilar materials. In addition, there is a problem that the main steel bearing insert is exposed during long-term storage.
In recent years, Honda of Japan and BMW of Germany have developed a lightweight and lightweight material technology for engine to cope with exhaust gas regulations in response to high oil prices and remove the above-mentioned main steel bearing insert, A mono crankcase as shown in the drawing will be produced by applying a bearing insert made of a high strength aluminum alloy as shown. Such a mono crankcase is becoming a new eco-friendly vehicle because it can reduce the weight of engine parts by more than 20%. That is, in recent years, a technique of inserting an aluminum material bearing insert into an aluminum material crankcase will be developed and spread.
Here, the aluminum bearing insert described above can be manufactured by the technique disclosed in Korean Patent No. 10-1500012 (Applicant: Hyundai Motor Co., Ltd.). This prior art technique is based on an aluminum alloy composition consisting of 14 to 25 wt% silicon (Si), 2 to 7 wt% copper (Cu), 0.2 to 2.0 wt% magnesium (Mg) After the melt was dissolved as described above, the molten metal was maintained at a predetermined temperature in a warming furnace, and 50 to 500 ppm of phosphorus (P) was added thereto to stabilize the melt for a predetermined time. Thereafter, a round or rectangular round bar was produced through continuous casting, Is cut into a block-shaped preform, and then the preform is hot-forged to produce an aluminum bearing insert as a reinforcing material.
However, this prior art requires that the preforms should be forged at a pressure of about 49,000 tons during forging since block preforms must be hot-forged immediately. Thus, the above-described prior art is practically very difficult to implement.
Accordingly, the applicant of the present invention has developed and patented a technology capable of easily manufacturing a bearing insert of an aluminum material, and has been registered with the Korean Intellectual Property Office as registration No. 10-1258801. The invention of the present applicant of the present invention is to produce a preform by forming the billet from a molten aluminum alloy, then extruding the billet into an M-shape and then cutting it to a predetermined thickness. At this time, the preform is cut to a size corresponding to the size (thickness and width) of the bearing insert. Then, the preform is made of a finished bearing insert as a thin film flash protruded outwardly by forging after forging is removed by a trimming process.
Such a bearing insert is processed with a short blister to remove lubricant and oxidized foreign substances on the surface during forging, and fine unevenness is formed at the same time, so that the jointability at the time of insert is improved.
1, the
In order to manufacture the
Since the
On the other hand, in the case of a mono crank case to which the aluminum bearing insert is applied as described above, the hybrid die casting method of manufacturing the
However, this mono crank case is different from the primary metal bearing
When the mono crankcase is manufactured by the above-described hybrid die casting, the 'M' type aluminum bearing insert is preheated together with the cast iron insert and charged into the die casting die. Thereafter, aluminum molten metal of about 650 ° is pre- So that the aluminum bearing insert bonded to the hot molten aluminum metal in the preheated state is rapidly heated by the aluminum molten metal at a temperature of about 500 ° C. or more and at the same time, Because it is left at a temperature of about 200 ° C or higher (about 400-450 ° C) for a long time, it is left at a high temperature state near to melting due to the characteristic of aluminum alloy having a melting point of about 550-600 ° C lower than that of cast iron, Because of the long air cooling time, There is a problem that the cycle time is increased and the productivity is lowered.
Therefore, the applicant of the present invention has found that the hybrid die casting method satisfies only the merely bonding property as described above, and the modification and improvement of the manufacturing method according to the material of the insert can not be achieved. Therefore, .
The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a hybrid die casting capable of improving the productivity by shortening the molding cycle time of the die casting while minimizing the decrease in the mechanical properties of the aluminum bearing insert in the hybrid die casting integrated by casting To provide a method of manufacturing a low crankcase for an engine.
According to the present invention, there is provided a hybrid die casting method of inserting a bearing insert, which supports a crankshaft, into a low crankcase constituting a lower part of an engine, An insert charging step of charging an alloy bearing insert; A die casting step of injecting molten metal into the mold cavity at high speed and high pressure to mold the low crankcase after the insert charging step; A take-out step of taking out the low crank case from the mold cavity after the die casting step; And a cooling step of rapidly cooling the low crankcase after the taking out step, wherein the cooling step is characterized by rapid cooling of the taken-out low crankcase by water-cooling through the cooling water of the water tank.
Here, it is preferable that the bearing insert is charged into a cavity of the die casting mold at a normal temperature, for example.
The cooling step includes, for example, a water tank charging step of charging the taken-out low crankcase into the water tank in which cooling water is stored; A submerging step of submerging the low crankcase charged in the water tank into the cooling water of the water tank for a predetermined period of time; And a withdrawing step of withdrawing the low crank case from the water tank.
Preferably, the low crankcase is submerged in the cooling water of the water tank for a suitable time for cooling the low crankcase to 130 to 190 degrees.
A cooling water circulating step of circulating the cooling water in the water tank so that the water temperature of the cooling water stored in the water tank is suddenly increased or the water bubble is not generated in the cooling water due to the temperature of the taken out lower crankcase; .
The cooling water circulating step may include a step of circulating a part of the cooling water stored in the water tank to circulate the cooling water so that the cooling water is discharged to the outside of the water tank, And a cooling water replacement step of supplementing the water tank.
The cooling water circulation step may include a stirring step in which a stirring blade is provided in the water tank to circulate the cooling water in the water tank by stirring the cooling water.
The present invention further includes a vibration step of vibrating at least one of the low crankcase charged in the water tank and the elevator loading the low crankcase into the water tank to increase the heat exchange between the cooling water and the low crankcase .
The present invention further includes a water removing step of removing moisture from the lower crankcase drawn out by cooling in the water tank.
The water removing step may include a step of allowing the low crank case to stand at room temperature for a period of time during which the water of the low crank case is dried so that the water is dried and removed from the low crank case taken out of the water tank have.
Alternatively, the water removing step may include, for example, an air blowing step of drawing the low crank case out of the water tank and spraying the compressed air onto the surface of the low crank case to remove moisture from the surface of the low crank case .
In addition, the water removing step may further include: a drying step of naturally drying the low crank case from which moisture has been removed by the compressed air after the air blowing step.
The present invention may further include a trimming step of removing the sprue formed in the lower crankcase after the cooling step.
Further, the present invention may further include an annealing step of annealing the low crankcase to remove internal stress after the cooling step.
According to the method of manufacturing a low crankcase for an engine by hybrid die casting according to the present invention, an aluminum material bearing insert which has not been preheated is charged into a die casting mold, and then the molten metal of aluminum is charged into the mold so that the temperature of the low crankcase is about 400 To 450 ° C and then rapidly cooling the low crankcase, the molten metal rapidly coagulates and is cooled by the bearing insert having a temperature lower than the normal preheating temperature of about 200 ° C., so that the molding time can be shortened In addition, the lowering of the forming temperature can minimize the exposure of the bearing insert to high temperature. In addition, since the low crank case with the bearing insert is rapidly cooled, the time for exposing the bearing insert to high temperature can be greatly reduced have. Therefore, it is possible to prevent the bearing insert from deteriorating in physical properties due to thermal stress.
Particularly, since the preheating process of the bearing insert, which is applied in the prior art, can be omitted, it is possible to shorten the time required for the entire production process due to the omission of the preheating time, thereby increasing the productivity and charging the low crankcase into the cooling water So that the low crank case can be cooled easily and quickly, and thus the creativity of the low crank case can be improved.
In addition, since the taken-out low crankcase is immersed in the cooling water of the water tank for a predetermined period of time to substantially reduce the cooling time, the overall production cycle of the low crankcase can be efficiently managed. In addition, Since the mechanical properties are reduced by softening, the lower crank case is cooled in the water tank at a temperature of about 130-190 DEG C, thereby preventing deterioration of the physical properties of the bearing insert and ensuring latent heat for the drying process.
In addition, since the cooling water in the water tank can be circulated, the water temperature stored in the water tank can be prevented from rising, water bubbles can be prevented from being generated in the cooling water and the low crank case can be cooled uniformly, It is possible to prevent the occurrence of bubble marks, and in addition, since new cooling water corresponding to the emission amount is replenished while part of the cooling water stored is discharged, not only can the water temperature of the stored cooling water be lowered again, It is possible to prevent water bubbles from being generated due to the descent, and furthermore, when the cooling water is stirred, the temperature rise of the cooling water and the water bubble phenomenon can be further prevented, and the low crankcase can be cooled even more.
In addition, since the elevator or the low crank case that immerses the low crank case in the water tank vibrates and the cooling water flows, the low crank case can be heat-exchanged smoothly with the cooling water, and water bubbles can be prevented from being generated.
In addition, it is possible to remove the water remaining on the surface of the low crank case by injecting the compressed air into the cooled low-crank case by the water-cooled method, so that the surface of the low crank case can be prevented from being contaminated by the residual water, In addition to this, it is possible to prevent water from remaining in the hollow portion or the complicated shape portion formed on the surface of the low crank case and shorten the drying time of the low crank case.
In addition, since the low crankcase is left standing to remove moisture from the low crankcase through the latent heat of the low crankcase, the low crankcase can be substantially completely dried as well as being able to perform the drying process easily.
In addition, since the hot sprue portion of the low crankcase is trimmed and removed, it is possible to provide a low crankcase having a beautiful outer appearance, and furthermore, the properties of the low crankcase and the bearing insert can be improved by annealing the low crankcase.
1 is a perspective view showing a conventional low crankcase for an engine and a primary metal bearing insert.
2 is a perspective view showing a low crankcase and an aluminum bearing insert for a lightweight insert type engine.
3 is a flowchart showing a method of manufacturing a low crankcase for an engine of a hybrid die casting type according to an embodiment of the present invention.
4 is a schematic view showing a cooling step in the manufacturing method according to the embodiment of the present invention.
5 is a schematic view showing an air blowing step in the manufacturing method according to the embodiment of the present invention.
Fig. 6 is a property table comparing physical properties of an aluminum insert of a low crankcase for an engine manufactured by an embodiment of the present invention with other examples. Fig.
The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary meanings and the inventor may properly define the concept of the term to describe its invention in the best possible way And should be construed in accordance with the principles and meanings and concepts consistent with the technical idea of the present invention.
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
3, the method for manufacturing a low crankcase for a hybrid die-casting engine according to an embodiment of the present invention includes steps S10, S10, S10, S30, S40, ).
That is, the present invention relates to a manufacturing method for inserting a bearing insert, which supports a crankshaft, into a low crankcase constituting a lower part of an engine, by casting, and integrally molding the bearing insert as described in the prior art.
For this purpose, an aluminum alloy composition consisting of 10 to 13 wt% silicon (Si), 3 to 6 wt% copper (Cu), 0.3 to 1.0 wt% magnesium (Mg), and balance aluminum (Al) To form a bearing insert.
The mechanical properties of the bearing insert are as follows: hardness HRB 80 to 85, tensile strength 400 to 450 MPa, and yield strength 350 to 380 MPa.
When the bearing insert is molded as described above, an insert charging step (S10) is performed in which the low crank case is charged into a cavity of the die casting mold. In this case, the bearing insert, which is charged into the cavity of the die casting mold, , And the robot can be used for charging the bearing insert.
Here, the above-mentioned bearing insert can be charged at a temperature of about 10 to 50 degrees, but is preferably charged at a normal temperature (about 15 to 35 degrees). When such a bearing insert is charged at a temperature of 50 ° C or higher, the temperature difference between the aluminum metal and the molten metal becomes small. As a result, (Molding time) can not be achieved.
After the insert charging step S10 is performed as described above, a die casting step S20 is performed in which the molten metal is injected into the cavity of the die casting mold at high speed and high pressure to mold the low crank case.
That is, in the die casting step S20, the bearing insert is precisely and quickly loaded into the cavity of the die casting mold using the robot. Before the bearing insert is loaded into the cavity of the die casting mold, After preheating at 250 ° C, the bearing insert is charged and the die casting mold is closed.
The molten metal is injected into the cavity of the die casting mold at a pitch speed of 40 m / s or higher and a pressing force of 800 bar to fill the cavity within 0.1 sec. At this time, the molten metal may be an aluminum or aluminum alloy composition, and the temperature of the molten metal is about 650 ° C.
Thus, when the molten metal is injected into the cavity of the die casting mold, the die casting mold and the bearing insert respectively contact the molten metal to absorb the heat of the molten metal, and the molten metal solidifies to conform to the cavity shape of the die casting mold.
Since the temperature difference between the die casting mold and the molten metal is about 450 ° C and the temperature difference between the bearing insert and the molten metal is about 630 ° C during the solidification process, the heat transfer near the bearing insert is accelerated and the cooling is accelerated, The time for forming the low crankcase is shortened by about 10% as compared with the time for preheating the bearing insert. At this time, the thermal stress caused by the molten metal is reduced in the bearing insert. Since the bearing insert is charged at a temperature of room temperature that is not preheated, the temperature difference between the metal and the molten metal is larger than that at the time of preheating. Since the temperature is the room temperature, the bearing insert is heated not only by the molten metal but also by the preheating The thermal stress is lowered at the time of preheating. Therefore, the bearing insert is suppressed as much as possible from change in physical properties due to high temperature of the molten metal, that is, strength reduction due to annealing. Particularly, as described above, since the time for solidifying the molten metal is shortened and the time for heating by the high temperature is minimized, the bearing insert is suppressed as much as possible.
On the other hand, after the die casting step S20 is completed, a take-out step S30 is taken out from the cavity of the die casting mold. The extraction step S30 uses the robot to take out the low crankcase solidified in the cavity of the die casting mold.
At this time, the temperature at the time of taking out the low crankcase from the cavity of the die casting mold is about 400 to 450 DEG C, so that the low crankcase has a low strength to push out the low crankcase from the die casting mold, Can be prevented.
If the take-out temperature of the low crankcase is lower than 400 to 450 占 폚, the molding cycle time of the die casting increases and the productivity is lowered. Therefore, the takeout temperature of the low crankcase in the die casting mold is preferably 400 to 450 占 폚.
When the take-out step S30 is completed, a cooling step S40 for cooling the low crankcase is performed. The cooling step S40 is a step in which the low crankcase taken out of the die at a temperature of 400 to 450 DEG C is cooled as quickly as possible to minimize the deterioration of the physical properties of the aluminum material, Likewise, it is charged into a water tank containing cooling water and rapidly cooled by water-cooling. That is, in the cooling step (S40), the low crank case at 400 to 450 deg. C is cooled rapidly in a water-cooled manner so that the temperature of the aluminum crushing case is lowered to about 200 deg.
The cooling step S40 includes, for example, a water tank charging step of charging the taken-out low crankcase into the cooling water of the water tank; The lower crankcase charged in the water tank is immersed in the cooling water of the water tank for a predetermined period of time; And a withdrawing step of withdrawing the low crank case from the water tank. That is, the cooling step S40 may be constituted of a water tank charging step, a sinking step, and a drawing step.
In the water tank charging step, the taken-out low crankcase is deeply charged into the lower part of the water tank through a device such as a normal robot. When the low crankcase taken out at 400 to 450 ° C is charged into the water tank, the temperature of the cooling water contacting with the surface of the low crankcase rises sharply so that large air bubbles, such as boiling water, Water bubbles are formed in the water tank. As a result, the low crankcase is partially prevented from contacting with water due to the water bubbles, and cooling is delayed. Especially, the water bubbles of the formed hollow part and the complicated shape part are not smoothly discharged, The uneven cooling which is slowly cooled becomes intensified. As a result, the low crankcase has a partially large cooling difference, and the temperature is not uniform, thereby increasing the thermal deformation, increasing the residual stress in the product, and decreasing the cooling rate. Therefore, in the water tank charging step, the low crank case taken out so as to suppress the rapid water temperature rise of the cooling water and the occurrence of the water bubble as much as possible is deeply charged into the lower part of the water tank as shown in FIG.
The submerging step submerges the low crankcase into the cooling water of the water tank for a time set to cool the low crankcase to below 200 degrees, in particular from 130 to 190 degrees. At this time, the predetermined settling time is preferably about 15 seconds to 32 seconds, and most preferably about 20 seconds. When the silent period is less than 15 seconds, the low crank case can not be cooled to the above-mentioned temperature, and when the silent period is longer than 32 seconds, the production time is excessively required, thereby causing a trouble in the production cycle. Therefore, the silting time needs to be limited within about 15 seconds to 32 seconds.
Particularly, the silencing time is about 20 seconds according to the experiment of the applicant of the present invention. This is because the settling time of the low crankcase is typically 60 to 90 seconds, and the working robot loads the bearing insert into the mold, loads the tubular insert into the tub, and then performs the related tasks up to the trimming This is because 20 seconds is most suitable.
The withdrawing step is such that the lower crankcase, which has been immersed in the water tank for the aforementioned time and cooled to the above-mentioned temperature, is removed from the water tank. At this time, the low crankcase is quickly removed from the water tank so that the above-mentioned cooling time is not exceeded. Since the low crank case is removed from the water tank by a conventional method using a device such as a robot, the drawing step is not described in detail.
On the other hand, the water tank needs to maintain the water temperature of the cooling water at about 20 to 50 ° C to cool down the low crankcase. However, as described above, the water tank can be heated by the charging of the low crankcase at about 400 to 450 ° C. It is difficult for the water tank to rapidly cool the low crankcase to the above-mentioned temperature when the cooling water is heated and the water temperature rises. Further, in the water tank, when the other low crankcase is charged while the cooling water is heated, more water bubbles may be generated as described above. 4, the low-
The
The cooling water circulation step circulates the cooling water stored in the
In the cooling water exchanging step, some of the cooling water in the
According to the experiment of the applicant of the present invention, when the cooling water is exchanged as described above, the water temperature of the cooling water rises by at least about 1 degree to about 12 degrees maximum depending on the amount of supply and discharge of the cooling water , The water temperature rises within a range of 1 degree to 3 degrees within most cases (for example, when the room temperature is high due to the summer and the heat), so that the cooling of the
In this
The
And, when the low crankcase is cooled down to 130 degrees or less, the drying time is excessively excessive in natural drying, which will be described later. More specifically, the low crank case evaporates and removes the water through the heat of itself, that is, the latent heat, during natural drying, which will be described later. However, when the low crankcase is cooled below 130 degrees, latent heat is weak and it is not possible to smoothly evaporate the water, and it is difficult to remove residual water by air blowing, which will be described later. Therefore, it is preferable that the low crankcase is cooled to a temperature of 130 degrees or more.
Meanwhile, as shown in FIG. 4, the cooling water stirring step is performed while stirring the cooling water through a
Here, the above-described
The
In the meantime, the present invention can be implemented by at least one of a water removing step, a trimming step (S70), and an annealing step (S80) after the cooling step (S40) is performed.
The water removing step is a step of removing water from the
5, the air blowing step S50 is a step in which the
The drying step (S60) is a step after the air blowing step (S50) is performed. In the drying step S60, the
The trimming step S70 removes the gate of the
The annealing step S80 is a step of strengthening the strength of the
The annealing step S80 transfers the
The annealing step S80 is performed at a temperature of 200 DEG C for about 2 hours in the
The physical properties of a bearing insert provided in the engine crankcase for engine manufactured by the above-described manufacturing method will be described with reference to FIG.
As shown, the "insert before die casting " shown in the property table is the property of the aluminum insert bearing insert, that is, the bearing insert before being loaded into the die casting die. "Example insert" is the physical property of an aluminum material bearing insert bonded to the low crankcase by the manufacturing method of the present invention. The "comparative example insert" is the physical property of an aluminum material bearing insert which is precooled by an aluminum reamer insert, charged into a die casting die, die cast and cooled by air cooling as described in the prior art.
As shown in Fig. 6, the material has a mechanical property of hardness of 80 to 85 HRB, tensile strength of 400 to 450 MPa and yield strength of 350 to 380 MPa in the case of "material insert before die casting". In the case of the "comparative insert", it has mechanical properties of 50 to 55 HRB in hardness, 250 to 300 MPa in tensile strength, and 220 to 250 MPa in yield strength. On the other hand, the bearing insert produced by the manufacturing method of the present invention has mechanical properties of 70 to 75 HRB hardness, 350 to 380 MPa tensile strength, and 3000 to 330 MPa yield strength.
According to these results, the bearing insert of the "comparative insert" reduces the material properties by about 35% compared to the "insert prior to die casting ", whereas the" It was found that the quality limit of the bearing insert manufactured by the present invention was satisfied and the function as a product was sufficiently performed.
Herein, the above-mentioned "comparative insert" refers to an aluminum insert bearing insert which is preheated at a temperature of about 200 degrees and is contacted with the molten metal, and is left at room temperature for a long time at a temperature of about 400 to 500 degrees for air cooling, It is considered that the mechanical properties are weaker than the " example insert "according to the embodiment of the present invention. However, in the "example insert" according to the embodiment of the present invention described above, the temperature of the molten metal injected into the mold by the non-preheated bearing insert is lowered so that the bearing insert is not substantially exposed to high temperatures unlike the " , The molding time was shortened due to the lowering of the temperature of the molten metal, the duration of the high temperature state of the bearing insert was shortened, and the holding time at the high temperature state was drastically shortened by the water cooling type, .
In the meantime, although not shown in the illustrated property table, the aluminum reamer insert is charged into a mold at a normal temperature as in the embodiment of the present invention, and is molded in a mold with molten metal as described above, In the case of the low-crankcase which was slowly cooled to the above-mentioned "Comparative Example Insert". Therefore, the mechanical properties of the low crankcase, which was molded in the same manner as in the embodiment of the present invention and then slowly cooled by air cooling, were weaker than the "example insert" according to the present invention. It is considered that the lower crank case was left at room temperature for a long time at a temperature close to the melting point of the aluminum alloy, and the property was deteriorated by the loosening phenomenon.
According to the method for manufacturing a low crankcase for an engine according to the present invention, when the temperature of the low crankcase in the die casting mold is 400 to 450 ° C, it is charged into the cooling water of the tank, When the temperature is 150 [deg.] C, the die-casting cycle time is shortened and the productivity can be improved.
Further, the present invention can prevent the bearing insert from being softened because the cold crank case is drawn out from the water tank when the temperature of the low crank case is 150 캜 in the cooling step, and the water can be evaporated by the latent heat of the low crank case, The occurrence of contamination on the surface of the crankcase can be prevented.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. .
1: Low crank case 10: Bearing insert
20:
20b: drain pipe 21: elevator
22: Vibrating device 23: stirring blade
30: Conveyor 40: Blower
Claims (9)
An insert charging step of charging an aluminum alloy bearing insert into a cavity of a die casting mold;
A die casting step of injecting molten metal into the mold cavity at high speed and high pressure to mold the low crankcase after the insert charging step;
A take-out step of taking out the low crank case from the mold cavity after the die casting step; And
And a cooling step of rapidly cooling the low crank case after the taking out step,
The cooling step includes:
The extracted low crankcase is rapidly cooled in a water-cooled manner through cooling water in a water tank,
The cooling step includes:
A water tank loading step of loading the taken-out low crankcase into the water tank in which cooling water is stored;
A submerging step of submerging the low crankcase charged in the water tank into the cooling water of the water tank for a predetermined time; And
And withdrawing the low crankcase from the water tank,
Wherein,
Wherein the low crank case is submerged for 15 to 32 seconds so that the low crank case is cooled to 130 to 190 degrees.
And a cooling water circulating step of circulating the cooling water in the water tank so that the water temperature of the cooling water stored in the water tank is prevented from rising due to the temperature of the taken-out low crankcase, or water bubbles are prevented from being generated in the cooling water, A method of manufacturing a crankcase.
A part of the cooling water stored in the water tank is exchanged so that the cooling water is circulated and a part of the cooling water in the water tank is discharged to the outside of the water tank while exchanging the cooling water for supplementing the new cooling water corresponding to the amount of the discharged cooling water to the water tank Wherein the low crank case is made of a synthetic resin.
And stirring the cooling water in the water tank to circulate the cooling water in the water tank.
And a vibrating step of vibrating at least one of the low crankcase charged in the water tank and the elevator loading the low crank case into the water tank to increase the heat exchange between the cooling water and the low crank case, A method of manufacturing a case.
And blowing the compressed air to the surface of the low crankcase to remove water from the surface of the low crankcase.
And drying the low crank case, from which moisture has been removed by the compressed air, in a natural drying process.
And an annealing step of annealing the low crank case to remove internal stress. ≪ RTI ID = 0.0 > 11. < / RTI >
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KR1020150170385A KR101789658B1 (en) | 2015-12-02 | 2015-12-02 | Manufacturing method of lower crank case for engine by hybrid die casting |
PCT/KR2016/013495 WO2017095057A1 (en) | 2015-12-02 | 2016-11-22 | Production method of low crank case for engine by hybrid die casting |
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KR1020150170385A KR101789658B1 (en) | 2015-12-02 | 2015-12-02 | Manufacturing method of lower crank case for engine by hybrid die casting |
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JP2008248283A (en) * | 2007-03-29 | 2008-10-16 | Kobe Steel Ltd | Method for quenching forged material of aluminum alloy |
JP2009243797A (en) * | 2008-03-31 | 2009-10-22 | Mitsubishi Electric Corp | Water heater |
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US7182825B2 (en) * | 2004-02-19 | 2007-02-27 | Alcoa Inc. | In-line method of making heat-treated and annealed aluminum alloy sheet |
DE102007023060A1 (en) * | 2007-05-16 | 2008-11-20 | Daimler Ag | Method for producing a cylinder crankcase |
KR101500012B1 (en) * | 2009-12-01 | 2015-03-09 | 현대자동차주식회사 | Reinforce low crankcase and method for manufacturing the same, low crankcase |
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JP2008248283A (en) * | 2007-03-29 | 2008-10-16 | Kobe Steel Ltd | Method for quenching forged material of aluminum alloy |
JP2009243797A (en) * | 2008-03-31 | 2009-10-22 | Mitsubishi Electric Corp | Water heater |
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