Die casting mold and die casting method for large-sized die casting

Abstract

The application discloses a die-casting die and a die-casting method for large-size die-casting parts, and has the structure of a double-feed mouth multi-section temperature control melting cup structure, cooperatively uses a double-reversing feeding mouth ladle, cooperatively uses a secondary pressurizing punch, the die is provided with a temperature control balance system, a die core inlaying and splicing structure of a large die, an improved far-end isolated column vertical type slag ladle structure, a tail adjustable type slag ladle structure, and the die-casting method comprises the steps of heating a hot die die-casting die, clamping, slag ladle forming inlaying fast withdrawal, feeding, slow injection, fast injection, mold opening and part taking, normal production die-casting comprises the steps of die heating, clamping, slag ladle forming inlaying fast insertion, feeding, slow injection, fast injection, first punch pressurization, second punch pressurization, die cooling, mold opening and part taking, and the application has the beneficial effects of die temperature balance in the production process, stable die structure, high product size precision, good product internal quality, high production efficiency and effective solution to the problem that large-size die-casting parts are difficult to be die-cast.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aluminum alloy die casting, in particular to a die casting die and a die casting method for large-size die castings BACKGROUND

[0002] Die casting is a precision forming process in which molten alloy liquid is cast into a pressure chamber, and the alloy liquid is pushed by a shot pin to fill the cavity at high speed, and then cools and solidifies under high pressure applied by the pin. This process has the advantages of low cost, high efficiency, light weight, good heat dissipation, etc., and is therefore widely used in the production of parts for automobiles and communications, such as automobile body structural parts, cylinder blocks and cylinder heads, gearbox housings, various brackets, boxes for communication base stations, shielding covers, filters, etc.

[0003] With the rapid development of intelligent networked new energy vehicles and new generation communication technologies, the design concept of automobile parts and communication base station parts has also undergone significant changes. Traditionally, multiple small and medium-sized parts are integrated into a large product or assembly through multiple integrations, but now the design concept has gradually changed to modular integration design, i.e., traditional multiple parts are integrated into a large-sized part, such as the front and rear floor skeletons of new energy vehicles, which are formed by integrating traditional multiple crossbeams and longitudinal beams into a large-sized die casting, and in the communication field, multiple small base stations or outer frames are integrated into a multi-in-one die casting. These changes have led to the development of die casting products from traditional single small parts (with sizes mostly less than 500*500mm) to multi-in-one and integrated products. Such products are usually large in size, such as the integrated body structural parts in new energy vehicles, which have an outer dimension of 1700*1500*700mm, and multi-in-one shielding covers and radiators in the communication field, which have an outer dimension of 1000*500*150mm. At the same time, such products usually require 4500T to 10,000T die casting machines for production, while traditional die casting dies and die casting processes in the die casting field are used to produce single parts below 3000T, so it is difficult to meet the requirements of internal and external quality, size and performance of such large-sized die castings using traditional die casting dies and die casting processes.

[0004] Die casting difficulties of large-sized die castings: the large size of the product leads to a long filling distance, making it difficult to ensure the quality of the far end; the complex structure of the product and the uneven wall thickness result in fast solidification and the inability to transmit pressure to the far end of the product, making it difficult to meet the requirements of the internal quality of the product; the large size of the die leads to slow temperature rise and difficulty in evenly controlling the die temperature; the large size of the product leads to large deformation and difficulty in accurately grasping the shrinkage size, making it difficult to ensure the dimensional accuracy of the product; the large size and weight of the product require a large amount of molten aluminum for single die casting, and the traditional feeding method takes a long time and the molten aluminum flows a long distance in the crucible, resulting in a rapid temperature drop and making it easy to form a poor filling. SUMMARY

[0005] In order to solve the above problems, the application provides a die casting die and a die casting method for large-size die casting parts.

[0006] In order to achieve the above purpose, the application adopts the following technical scheme:

[0007] A die casting die for large-size die casting parts, characterized in that: it comprises a movable die and a fixed die, a movable die core is arranged on the movable die, a fixed die core is arranged on the fixed die, the movable die core and the fixed die core form a cavity for forming a product, a sprue bushing and a melting cup are arranged on the fixed die, the melting cup has two feeding openings, the two feeding openings are spaced apart by a predetermined distance, a first heating channel is arranged below the feeding opening corresponding to the end of the melting cup, a second heating channel is arranged on the wall of the melting cup between the two feeding openings, a third heating channel is arranged below the feeding opening corresponding to the middle of the melting cup, a fourth heating channel is arranged on the wall of the melting cup between the feeding opening corresponding to the middle of the melting cup and the sprue bushing, the melting cup is used with a soup ladle with double pouring openings, a double-boosting type injection punch is arranged in the pressure chamber of the melting cup, the double-boosting type injection punch comprises a first punch and a second punch, the second punch is arranged in the first punch, and the second punch has a secondary boosting stroke compared with the first punch.

[0008] Further, a vacuum system is arranged on the movable die and the fixed die at a position away from the sprue position, a vacuum A plate is arranged on the fixed die, a vacuum B plate is arranged on the movable die, the vacuum A plate and the vacuum B plate are arranged oppositely, a vacuum pipe is arranged above the vacuum A plate and the vacuum B plate, and a hydraulic valve core is arranged on the fixed die to block the vacuum pipe.

[0009] Further, a plurality of slag pocket openings are arranged on the upper part of the movable die core and the fixed die core, an adjustable slag pocket structure is arranged on the movable die, and the adjustable slag pocket structure comprises a slag pocket forming insert block, an insert block push-pull connecting block, a fixed column, and a built-in oil cylinder which are connected in sequence on the movable die.

[0010] Further, a rectangular oil temperature heating pipeline is arranged on the fixed die frame of the fixed die, an annular cooling water pipeline is arranged on the sprue bushing, and two groups of wire cooling water pipelines and four groups of oil temperature heating pipelines are arranged in sequence and uniformly on the fixed die core from bottom to top.

[0011] Further, a rectangular oil temperature heating pipeline is arranged on the movable die frame of the movable die, a U-shaped cooling water pipeline is arranged on the sprue plate of the movable die core, a runner conforming cooling water pipeline is arranged at the sprue position of the movable die core, and two groups of linear cooling water pipelines and four groups of oil temperature heating pipelines are arranged in sequence above the runner conforming cooling water pipeline.

[0012] Further, a casting system is also included, which is divided into two groups of runners from the end of the straight runner, each group of runners is divided into six branch runners, and the ends of the twelve branch runners are provided with centralized inner gates, an overall feeding table is arranged at the inner gate position along the product body, a drainage rib is arranged at the front end of the product end column, and a vertical ladle opening is arranged at the rear end of the drainage rib.

[0013] A die casting method for large-size die castings, characterized in that it comprises the following steps,

[0014] S1, mold heating, set the first section of the melting cup temperature to 150±10℃, the second section to 220±10℃, the third section to 150±10℃, and the fourth section to 250±10℃; the movable mold core oil temperature is set to 240±10℃; the movable mold frame oil temperature is set to 180±10℃;

[0015] S2, mold clamping, keep the movable and fixed mold parting surfaces completely adhered, and the double-layer sealing strip completely seals the mold cavity, keep the cavity sealed, and the vacuum degree is less than 100 mbar during the die casting process; when the vacuum degree of the cavity is greater than 100 mbar during the die casting, recheck the mold sealing property;

[0016] S3, feeding, use double pouring ladles to pour alloy liquid into different pressure chamber pouring ports respectively, after pouring is completed, use a sealing plug to close the feeding port 2, delay for 1-2 s, and wait for the aluminum liquid to mix stably;

[0017] S4, slow pressure injection, start the punch to push the alloy liquid forward, and start vacuum pumping when passing the feeding port 1;

[0018] S5, die casting, the die casting process is divided into first and second pressure increasing, the pressure increasing nodes are controlled by stroke, the punch low speed is 0.2 m / s, the high speed is 4-5 m / s, the high speed starting position is 700+ / -20 mm, the pressure starting position is 950±10 mm, the second punch starting position is 1000±10 mm, the cooling time is 15±2 s, the pressure injection time is 12±2 s, the vacuum starting position is 150±20 mm, the vacuum end position is 750±20 mm, the vacuum degree is 30-120 mbar, the holding temperature is 670±10℃, the pressure injection delay is 2 s, the first material cake thickness is 50±5 mm, the second material cake thickness is 30±5 mm, the mold temperature machine setting temperature (movable) is 230℃, the mold temperature machine setting temperature (fixed) is 230℃, the movable / fixed mold runner cooling delay is 2 (s), the casting pressure is 60-70 Mpa; the first punch pressure casting pressure P1=60 Mpa, and the second punch pressure casting pressure P2=16 Mpa;

[0019] S6, the mold is opened and the product is taken out. The product body or the cake is usually taken out by a mechanical hand. After taking out, the gate slag package is removed, and the product with residual heat is placed on a correction auxiliary tool. The residual heat of the casting is used, and the product and the auxiliary tool are placed in a water tank with a white agent for 5-10s by the mechanical hand. The demolding oil on the surface of the product is removed. After the surface oil is removed, the product and the auxiliary tool are transferred to the water tank with cooling water for cleaning and cooling, and the product is finally taken out and obtained.

[0020] S7, spraying, two groups of special-shaped micro-spraying tools are used for spraying demolding agent. One group of mechanical hands carries a fixed mold spraying tool to spray the fixed mold side, and the other group of mechanical hands carries a movable mold spraying tool to spray the movable mold side. First, blow along the mold cavity from top to bottom for 3-6s, then uniformly spray along the mold cavity for 10-15s, and finally blow along the spray path in reverse order for 8-12s to keep the surface of the cavity dry, and wait for the next cycle of die casting production.

[0021] Further, the first and second pressurization in the die casting process of step S5 is controlled by time. The low speed is 0.2m / s, the high speed is 4-5m / s, the injection delay is 1-2s, the high speed start time is 4±0.5s, the first punch pressurization time start time is 6±0.2s, the first punch pressurization start time is 6.3±0.2s, and the rest is the same as the stroke control.

[0022] The beneficial effects of the present application include: mold temperature balance in production process, stable mold structure, high product size precision, good product internal quality, high production efficiency, and effective solution to the problem of difficult die casting of large-size die castings. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a mold structure schematic diagram of the present application;

[0024] Figure 2 is a structure schematic diagram of the melting cup heating system of the present application;

[0025] Figure 3 is a movable mold core temperature control structure diagram of the present application;

[0026] Figure 4 is a fixed mold core temperature control structure diagram of the present application;

[0027] Figure 5 is a runner random cooling waterway structure of the present application;

[0028] Figure 6 is a fixed mold frame temperature control structure diagram of the present application;

[0029] Figure 7is a movable die frame temperature control structure diagram of the present application;

[0030] Figure 8 is a normal die casting pouring system diagram of the present application;

[0031] Figure 9 is a hot die casting pouring system diagram of the present application;

[0032] Figure 10 is a second punch pressurized die casting schematic diagram of the present application. DETAILED DESCRIPTION

[0033] The present application will be further described in detail below in conjunction with specific embodiments and drawings.

[0034] A large-size die casting die as Figure 1 shown, comprising a movable die 1 and a fixed die 2, a sprue bushing 3 is arranged in the fixed die frame, the sprue bushing 3 and the fixed die core 4 and the movable die core 5 jointly form a product cavity; the fixed die core 4 is composed of a fixed die inner core and a fixed die outer core, and similarly, the movable die core 5 is composed of a movable die inner core and a movable die outer core. Four groups of locking pins are symmetrically arranged on the back side of the fixed die frame, and the die can be provided with 6 groups or 8 groups of locking pins according to tonnage, size and weight. A rectangular sprue bushing 3 is arranged below the fixed die core 4, the sprue bushing 3 is provided with a circulating water cooling system, and the diameter of the sprue bushing 3 is 10-20mm larger than the inner diameter of the melting cup 6 on one side. The sprue bushing 3 cooperates with the melting cup 6. A fixed die vacuum A plate 7 is arranged above the fixed die core 4, two groups of hydraulic vacuum valve mounting holes are arranged in the fixed die vacuum A plate 7, and a hydraulic vacuum valve core 8 and an oil cylinder 9 and other components are arranged on the back of the fixed die frame to form a vacuum system. The front of the fixed die frame is provided with a die frame sealing structure, and the fixed die outer core is provided with a die core sealing structure, and the number of vacuum valve groups can be set to multiple groups and set to different positions according to product size, mass, structure, etc.

[0035] The movable die direction is from bottom to top in turn, the gate plate 10 is arranged in the gate plate 10, the circulating water cooling structure is arranged in the gate plate 10, and the movable die core 5 is arranged upward, which is composed of a movable die inner core and a movable die outer core, the movable die inner core is sleeved on the movable die outer core, and the outer core is sleeved in the movable die frame. A plurality of slag pocket openings are arranged above the movable die inner core and the outer core, and the slag pocket opening is outwardly provided with an adjustable slag pocket structure, which comprises a slag pocket forming insert 11, an insert push-pull connecting block 12, a fixed column 13, and an embedded oil cylinder 14. The rear part of the die frame is supported by four cushion blocks 15 from top to bottom and left to right, a center pin, a center pin fixing plate, a center pin plate, a support block 16, a reset rod, a limiting column and the like are installed, an upper cover plate 22 is installed on the outside, the same positions of the copper fixed die frame on the outside are provided with locking pins, which are used for installation and fixation of the movable die on the die casting machine, and a vacuum B plate 23 is arranged above the movable die core.

[0036] The movable and fixed die frames are provided with die feet 24 below, and a plurality of cooling and heating pipe joints, oil cylinder joints and the like are arranged on the outside.

[0037] As Figure 1 and 2 Large size die casting parts due to the large projection area, casting weight, need to use large tonnage die casting machine, such as 4500T, 6000T, 8800T, 9000T even ten tons level, and the die casting machine configuration of the die chamber specification is usually large in diameter, long, and the traditional aluminum liquid feeding method takes a long time, which makes the aluminum liquid oxidation serious, on the other hand, the die chamber fullness is low, and finally the aluminum liquid flows from the melting cup feeding end to the melting cup discharging end, which makes the aluminum liquid temperature drop fast, the aluminum liquid oxidation is serious, and finally the internal forming quality of the product cannot be guaranteed; To solve the above problems, the application uses a double pouring spout ladle and a melting cup and a double booster type injection punch structure, the double pouring spout ladle structure includes an inlet, two pouring ports, and two groups of feeding ports are arranged according to the distance between the two ladles, and the distance between the two pouring ports needs to meet the following conditions:

[0038] L is the total length of the die chamber; L1 is the distance between the center of the feeding port 1 and the end of the die chamber; L2 is the distance that the product high-speed soup material completely pours into the die chamber to maintain fullness of 100%; L3 is the center distance of the two feeding ports of the die chamber (the center distance of the two pouring ports of the ladle); D is the buffer distance (usually 100-300mm);

[0039] L3=L-L2-L1-D;

[0040] L4 is the flowing distance of the alloy liquid poured by the first feeding port;

[0041] L5 is the flowing distance of the alloy liquid poured by the second feeding port;

[0042] L4≈L-L5;

[0043] L5≈L-L3-L1;

[0044] Satisfy the above conditions, the second pouring port must fall in the low speed area, ensure that the alloy liquid poured into the die chamber will not overflow from the rear feeding port in the low speed stage, and at the same time, a certain implementation distance is reserved for the vacuum air extraction;

[0045] After the ladle feeding, the aluminum liquid poured by the first feeding port flows to the front end of the melting cup (L4), and the aluminum liquid poured by the second feeding port flows to the rear end of the melting cup (L5). After pouring, the injection delay is 1s, so that the soup 1 and the soup 2 are mixed smoothly.

[0046] The large size of the punch in the die casting process causes the die cake to be thin and large (usually more than 150mm, 30-50mm thick), which is prone to rapid solidification (and unilateral increase in the thickness of the die cake will cause the die cake to burst, resulting in product sticking to aluminum, and the cooling time is prolonged, which slows down the production rhythm, and finally wastes the back furnace material, reducing the process yield of the product), which causes the pressure to be unable to be transmitted to the product during pressure increase, making it difficult to meet the requirements of the internal quality of such products; to solve such problems, a double pressure increasing process is provided, and the thickness of the die cake during production can reach 80-100mm, effectively solving the problem that the pressure cannot be transmitted to the product due to the rapid solidification of the die cake, the double pressure increasing punch is composed of a first punch and a second punch, the second punch does not work in the hot mold stage, which is the same as the conventional die casting process; during normal production, the first punch is pressurized by the pressure increasing system of the die casting machine after the fast injection is completed, and after the pressure increasing is completed, the second punch is started to pop out to pressurize the center position of the die cake for the second time according to the set distance or time delay, the two times of pressure increasing make the internal organization of the product dense, and at the same time, the die cake center forms a concave cavity under the action of the second punch, and problems such as die cake burst do not occur, and the gate of the double pressure increasing punch is arranged in the thick wall thick area of the product during mold design, and the inner gate is connected into an integrated type as much as possible, and the thickness of the inner gate is 3-6mm, so that the implementation effect is optimal.

[0047] The large size of the punch in the die casting process causes the die cake to be thin and large (usually more than 150mm, 30-50mm thick), which is prone to rapid solidification (and unilateral increase in the thickness of the die cake will cause the die cake to burst, resulting in product sticking to aluminum, and the cooling time is prolonged, which slows down the production rhythm, and finally wastes the back furnace material, reducing the process yield of the product), which causes the pressure to be unable to be transmitted to the product during pressure increase, making it difficult to meet the requirements of the internal quality of such products; to solve such problems, a double pressure increasing process is provided, and the thickness of the die cake during production can reach 80-100mm, effectively solving the problem that the pressure cannot be transmitted to the product due to the rapid solidification of the die cake, the double pressure increasing punch is composed of a first punch and a second punch, the second punch does not work in the hot mold stage, which is the same as the conventional die casting process; during normal production, the first punch is pressurized by the pressure increasing system of the die casting machine after the fast injection is completed, and after the pressure increasing is completed, the second punch is started to pop out to pressurize the center position of the die cake for the second time according to the set distance or time delay, the two times of pressure increasing make the internal organization of the product dense, and at the same time, the die cake center forms a concave cavity under the action of the second punch, and problems such as die cake burst do not occur, and the gate of the double pressure increasing punch is arranged in the thick wall thick area of the product during mold design, and the inner gate is connected into an integrated type as much as possible, and the thickness of the inner gate is 3-6mm, so that the implementation effect is optimal.

[0048] The die casting die and the die casting process of the large size die casting part set the shrinkage rate according to the product size, the product structure and the product process, the product size is 500-1000mm, and the shrinkage rate is set to 4.5-5 thousandths; the product size is more than 1000mm, and the shrinkage rate is set to 4-4.5 thousandths; the shrinkage rate of the product requiring heat treatment is usually the lower limit value, and the shrinkage rate of the embodiment is 4.8 thousandths.

[0049] The die casting die of the large size die casting part can be embedded into multiple insert blocks according to the product size and the die structure, the insert blocks are designed to be consistent in material and consistent in thermal expansion rate, so as to maintain the size accuracy of the product, and the movable and fixed die cores are embedded into corresponding inner and outer die cores according to the product size and structure in the embodiment, which is convenient for die machining and meets the sealing requirements of the die, and when the product design is changed, the die can be repaired at low cost.

[0050] In order to ensure the product size precision, the die movable and fixed mold frame back sides of the large-size die casting die are uniformly provided with multiple sets of support blocks, the area of the support blocks supporting the contact mold frame back sides is not less than 50% of the mold frame, the mold strength and rigidity are ensured, and the mold is effectively prevented from being concave when the mold is impacted by high speed and high pressure, thereby causing the product wall thickness to be poor.

[0051] In order to ensure the internal quality of multiple high columns of the product tail, the die is provided with a drainage rib on the front side of the column and a vertical rib slag pocket on the back side to guide the slag into the slag pocket, the front side drainage rib and the column have an oblique angle of 30-45 DEG, and the back side drainage rib and the column have an oblique angle of 45-60 DEG, which is removed through subsequent machining, thereby effectively ensuring the internal quality of the threaded column.

[0052] The punch 18 of the present application adopts a double-pressurized punch structure, the rear end of the structure is connected with a plunger rod, the front end pushes the alloy liquid to fill the cavity and pressurizes, a second punch piston cylinder is arranged in the interior, corresponding to an oil inlet cylinder and an oil outlet cylinder, oil inlet holes and oil outlet holes are arranged in the oil inlet cylinder and the oil outlet cylinder respectively, when the second punch pressurization is not started, the first punch and the second punch cooperate to form the first punch structure, when the second punch is started, the piston pushes the second punch to move forward and separate from the first punch, and corresponding secondary pressurization is carried out, when the pressurization is completed, the piston ring drives the second punch to move backward until the second punch and the first punch are combined into a group, the second punch is composed of copper alloy material, and the first punch is composed of H13 steel material, the oil way driving mechanism of the second punch is connected to the die casting machine and can be triggered according to the position or triggered with time delay, the diameter of the second punch is usually greater than the diameter of the first punch by more than 40mm, which is to ensure the wall thickness of the first punch and to facilitate the pressurization effect of the second punch.

[0053] As shown in Figure 2 As shown in FIG. 1, the large-size die casting of the present application needs large die casting equipment, the pressure chamber is usually large and long, and the fullness of the pressure chamber is low, and the temperature of the aluminum liquid drops quickly, in order to solve the problems, the present application adopts a multi-section type pressure chamber heating system, through the multi-section setting, one is to keep the alloy liquid temperature in the melting cup balanced after pouring into the melting cup, and two is to keep the temperature drop to a minimum during the plunger process, the melting cup is internally provided with two groups of spiral type and two groups of U-shaped oil temperature heating structures, each group of oil temperature heating structure has corresponding oil inlets and outlets, the heating temperature of each group of heating systems can be individually set during the plunger process, and the alloy liquid temperature is accurately controlled, a first heating channel 31 is arranged below the corresponding lower part of the soup feeding port at the end of the melting cup, a second heating channel 32 is arranged on the melting cup wall between the two soup feeding ports, a third heating channel 33 is arranged below the corresponding lower part of the soup feeding port at the middle part of the melting cup, and a fourth heating channel 34 is arranged on the melting cup wall between the soup feeding port at the middle part of the melting cup and the sprue bushing.

[0054] AsFigure 4 and 6 As shown in FIGS. 1, 2, 3, 4, 5, 6, 7 and 8, to ensure constant mold temperature and improve casting quality, the present application sets a rectangular oil temperature heating system for the fixed mold frame, with a pipe center distance of 35 mm from the surface depth of the mold frame, keeping the mold frame temperature uniform and controllable, and keeping constant during the die casting process; the fixed mold gate sleeve sets a ring-shaped water cooling, with a pipe center distance of 25 mm from the surface depth, and the fixed mold core is sequentially and uniformly set with 2 groups of linear cooling from bottom to top, and 4 groups of oil temperature heating pipes, with a pipe center distance of 40 mm from the surface depth of the mold core, cooling is implemented near the gate, and heating is implemented at the far end, ensuring mold temperature balance, during the die casting process, the far end mold temperature heating is set to be constantly on, and the cooling near the gate is intermittently cooled (water cooling is performed after the pressure increase is completed, and is closed before starting the pressure injection).

[0055] As shown in FIGS. 1, 2, 3, 4, 5, 6, 7 and 8, to ensure constant mold temperature and improve casting quality, the present application sets a rectangular oil temperature heating system for the fixed mold frame, with a pipe center distance of 35 mm from the surface depth of the mold frame, keeping the mold frame temperature uniform and controllable, and keeping constant during the die casting process; the fixed mold gate sleeve sets a ring-shaped water cooling, with a pipe center distance of 25 mm from the surface depth, and the fixed mold core is sequentially and uniformly set with 2 groups of linear cooling from bottom to top, and 4 groups of oil temperature heating pipes, with a pipe center distance of 40 mm from the surface depth of the mold core, cooling is implemented near the gate, and heating is implemented at the far end, ensuring mold temperature balance, during the die casting process, the far end mold temperature heating is set to be constantly on, and the cooling near the gate is intermittently cooled (water cooling is performed after the pressure increase is completed, and is closed before starting the pressure injection). Figure 3 、 5 As shown in FIGS. 1, 2, 3, 4, 5, 6, 7 and 8, to ensure constant mold temperature and improve casting quality, the present application sets a rectangular oil temperature heating system for the fixed mold frame, with a pipe center distance of 35 mm from the surface depth of the mold frame, keeping the mold frame temperature uniform and controllable, and keeping constant during the die casting process; the fixed mold gate sleeve sets a ring-shaped water cooling, with a pipe center distance of 25 mm from the surface depth, and the fixed mold core is sequentially and uniformly set with 2 groups of linear cooling from bottom to top, and 4 groups of oil temperature heating pipes, with a pipe center distance of 40 mm from the surface depth of the mold core, cooling is implemented near the gate, and heating is implemented at the far end, ensuring mold temperature balance, during the die casting process, the far end mold temperature heating is set to be constantly on, and the cooling near the gate is intermittently cooled (water cooling is performed after the pressure increase is completed, and is closed before starting the pressure injection).

[0056] As shown in FIGS. 1, 2, 3, 4, 5, 6, 7 and 8, to ensure constant mold temperature and improve casting quality, the present application sets a rectangular oil temperature heating system for the fixed mold frame, with a pipe center distance of 35 mm from the surface depth of the mold frame, keeping the mold frame temperature uniform and controllable, and keeping constant during the die casting process; the fixed mold gate sleeve sets a ring-shaped water cooling, with a pipe center distance of 25 mm from the surface depth, and the fixed mold core is sequentially and uniformly set with 2 groups of linear cooling from bottom to top, and 4 groups of oil temperature heating pipes, with a pipe center distance of 40 mm from the surface depth of the mold core, cooling is implemented near the gate, and heating is implemented at the far end, ensuring mold temperature balance, during the die casting process, the far end mold temperature heating is set to be constantly on, and the cooling near the gate is intermittently cooled (water cooling is performed after the pressure increase is completed, and is closed before starting the pressure injection). Figure 8 、 9The product size of the embodiment is shown as 940*450*160mm, the product quality is 10kg, multiple mounting columns are arranged at the end, a fan-shaped casting system is arranged, the pouring system is divided into two groups of runners from the end of the straight sprue, each group of runners is divided into six branch runners upwards, centralized inner gates are arranged at the ends of the twelve branch runners, an integral feeding table is arranged along the product body at the inner gate position, the alloy liquid is ensured to be pushed forward integrally and stably, sequential and stable filling is realized, a drainage rib is arranged at the front end of the product end column, and a vertical ladle opening is arranged at the rear end, so that the cold material flowing through the column flows into the ladle along the vertical ladle, an adjustable ladle structure is arranged at the tail of the ladle overflow port, when the hot mold is completed, the built-in oil cylinder drives the ladle forming insert to retreat, the tail of the ladle is integrally formed, the mold temperature of the tail area is ensured to be quickly increased, when the hot mold is completed, the built-in oil cylinder drives the ladle forming insert to advance, multiple ladles are independently formed, the slag collection and exhaust of the tail of the product are accurately realized, two groups of large hydraulic vacuum valves are connected to the tail of the ladle, the valve core cross-sectional area of the vacuum valve suction port is 360mm2; S cake = 13266.5mm2, S straight runner = 3850mm2, S runner = 2516mm2, S inner gate = 2352.5mm2, the first punch diameter is 160mm, the inner diameter of the gate sleeve is 180mm (the cake position cross-sectional area is increased, the solidification time before the cake position is increased in pressure is delayed, and the second pressurization effect of the second punch is better implemented), the second punch diameter is 100mm (according to the cake diameter of 160mm, the position with a center of 100mm is slowly solidified, and the requirement of the double-punch structure on the minimum wall thickness is met), the gate ratio is 8.5V, the internal pressure is 4.5*8.5=38.25m / s, the cold mold filling degree is 36.74%, and the normal filling degree is 34.31%; the pouring temperature is 660℃.

[0057] The die casting process of the application comprises:

[0058] Mold heating:

[0059] Melt cup temperature setting: first section heating temperature 150±10℃, second section heating temperature 220±10℃, third section heating temperature 150±10℃, fourth section heating temperature 250±10℃; movable and fixed mold core oil temperature heating temperature setting 240±10℃; movable and fixed mold frame oil temperature heating temperature setting 180±10℃;

[0060] Gate sleeve position cooling is always on, mold core and runner cooling is turned on after the pressurization is completed in the normal production process, to realize rapid cooling of the product and the runner position, and the cooling is turned off after the product is taken out of the mold, and the cycle is repeated in turn;

[0061] Mold clamping: the movable and fixed mold parting surfaces are kept completely adhered, the double-layer sealing strips completely seal the mold cavity, the cavity is kept sealed, and the vacuum degree is less than 100mbar during the die casting process; when the vacuum degree of the cavity is greater than 100mbar during the die casting, the mold sealing property is rechecked.

[0062] The slag pot forming insert performs different actions depending on the hot mold and normal die casting. During hot mold, the slag pot forming insert retracts, keeping the entire slag pot fully open and forming an integral slag pot. During normal production, the slag pot forming insert retracts, keeping the slag pot disconnected and forming a single isolated slag pot structure.

[0063] Serve soup:

[0064] The double-pouring ladle pours the molten alloy into different pressure chamber pouring ports. After pouring, the pouring port 2 is sealed with a sealing plug and left for 1-2 seconds to allow the molten aluminum to mix steadily.

[0065] Slow injection:

[0066] The punch starts and pushes the alloy liquid forward. After passing the feed port 1, the vacuum is activated.

[0067] Die casting:

[0068] like Figure 10 As shown, the die-casting process has two control methods: the first is to control the punch to perform the first and second pressurizations by stroke control, and the second is to control the first and second pressurizations by time.

[0069] The stroke control process is as follows:

[0070] Low speed 0.2m / s, high speed 4-5m / s, high speed start position 700+ / -20mm, pressure start position 950±10mm, second punch start position 1000±10mm, cooling time 15±2s, injection time 12±2s, vacuum start position 150±20mm, vacuum end position 750±20mm, vacuum degree 30-120mbar, heat preservation temperature 670±10℃, injection delay 2s, first cake thickness 50±5mm, second cake thickness 30±5mm (second cake pressurization forms 20±5mm), mold temperature controller set temperature (dynamic) 230℃, mold temperature controller set temperature (fixed) 230℃, dynamic / fixed mold runner cooling delay 2 (s), casting pressure 60-70Mpa;

[0071] The first punch pressurization casting pressure P1 = 60 MPa

[0072] The second punch pressure boosting casting pressure P2 = P (pressure of the second punch boosting system) * D2 (size of the second punch boosting cylinder) / D2 (diameter of the second punch) = 160 * 100 * 100 / 100 * 100 = 16 MPa;

[0073] The time control process is as follows:

[0074] Low speed 0.2 m / s, high speed 4-5 m / s, injection delay 1-2 s, high speed start time 4±0.5 s, first punch pressurization time start time 6±0.2 s, first punch pressurization start time 6.3±0.2 s, the rest is consistent with the stroke control;

[0075] Mold opening and taking out cooling:

[0076] The product is usually taken out by a mechanical hand grabbing the product body or the cake, and after taking out, the sprue slag package is removed, the product with residual heat is placed on a correction auxiliary tool, the residual heat of the casting is utilized, and then the product and the auxiliary tool are placed in a water tank with a white agent for 5-10 s by the mechanical hand grabbing the correction auxiliary tool, the residual demolding oil on the surface of the product is removed (to prevent chemical corrosion between the demolding agent and the riveting screw in the subsequent riveting of the product), after the surface oil is removed, the product and the auxiliary tool are transferred to a water tank containing cooling water for cleaning and cooling, and until the product is completely cooled, the product is finally taken out and obtained, which is a product without deformation, stable size, and no oil on the surface;

[0077] Spraying:

[0078] Two groups of special shape micro-spraying tools are used for spraying the demolding agent, one group of mechanical hand carries the fixed mold spraying tool to spray the fixed mold side, and the other group of mechanical hand carries the movable mold spraying tool to spray the movable mold side, first, air is blown along the mold cavity from top to bottom for 3-6 s (to remove the adhered aluminum scraps and sundries on the surface of the mold), then uniform spraying is performed along the mold cavity for 10-15 s, and finally, the cavity is sequentially swept in reverse along the spraying path for 8-12 s to keep the surface of the cavity dry.

[0079] The production process of the application is as follows:

[0080] The hot mold process is as follows:

[0081] Mold heating-mold closing-slag package forming insert fast withdrawal-giving soup-slow injection-fast injection-mold opening and taking out; usually after 5-12 molds of hot mold, the mold temperature reaches the requirement, normal production is stopped, and the normal production mode is switched;

[0082] Mold heating-mold closing-slag package forming insert fast insertion-giving soup-slow injection-fast injection-first punch pressurization-second punch pressurization-mold cooling-mold opening and taking out.

[0083] The technical solutions provided by the embodiments of the application are described in detail above, specific examples are applied in this paper to describe the principles and implementation modes of the embodiments of the application, and the above description of the embodiments is only applicable to help understand the principles of the embodiments of the application; meanwhile, for those skilled in the art, the specific implementation modes and application ranges of the embodiments of the application will be changed, and the content of the description should not be understood as a limitation of the application.

Claims

1. A die-casting mold for large-size die-cast parts, characterized in that: It includes a moving mold and a fixed mold. The moving mold is provided with a moving mold core, and the fixed mold is provided with a fixed mold core. The moving mold core and the fixed mold core form a cavity for forming the product. Multiple sets of slag bag openings are provided on the upper part of the moving mold core and the fixed mold core. An adjustable slag bag structure is provided outward from the slag bag openings. The adjustable slag bag structure is provided on the moving mold. The adjustable slag bag structure includes a slag bag forming insert, an insert push-pull connecting block, a fixing column, and a built-in hydraulic cylinder, which are connected in sequence on the moving mold. The fixed mold is provided with a sprue bushing and a melting cup. The melting cup has two inlet ports, and the two inlet ports are spaced apart by a predetermined distance. The predetermined distance needs to meet the following conditions: L is the total length of the pressure chamber; L1 is the distance from the center of the soup inlet to the end of the pressure chamber; L2 is the distance from which the high-speed soup is poured into the pressure chamber to maintain 100% fullness; L3 is the center distance between the two soup inlets on the pressure chamber; D is the buffer distance, with a value of 100-300mm; L3 = L - L2 - L1 - D; A first heating channel is provided below the soup inlet at the end of the melting cup, a second heating channel is provided on the melting cup wall between the two soup inlets, a third heating channel is provided below the soup inlet in the middle of the melting cup, and a fourth heating channel is provided on the melting cup wall between the soup inlet in the middle of the melting cup and the sprue sleeve. The melting cup is used in conjunction with a double pouring ladle, wherein the pouring port corresponding to the soup inlet needs to fall in the low speed zone. A double-pressure injection punch is provided in the pressure chamber of the melting cup. The double-pressure injection punch includes a first punch and a second punch. The second punch is located inside the first punch and has a second pressure boosting stroke compared to the first punch.

2. The die-casting mold for a large-size die-casting part according to claim 1, characterized in that: Vacuum systems are provided on the moving mold and the fixed mold at the far end relative to the gate position. The fixed mold is provided with a vacuum plate A and the moving mold is provided with a vacuum plate B. The vacuum plates A and B are arranged opposite to each other. Vacuum tubes are provided above the vacuum plates A and B. The fixed mold is provided with a hydraulic valve core to block the vacuum tubes.

3. The die-casting mold for a large-size die-casting part according to claim 1, characterized in that: The fixed mold frame on the fixed mold is equipped with rectangular oil temperature heating pipes, and the gate bushing is equipped with annular cooling water channels. The fixed mold core is evenly equipped with two sets of linear cooling water channels and four sets of oil temperature heating pipes from bottom to top.

4. The die-casting mold for a large-size die-casting part according to claim 1, characterized in that: The moving mold frame is provided with a rectangular oil temperature heating pipe, the sprue plate on the moving mold core is provided with a U-shaped cooling water channel, the sprue position on the moving mold core is provided with a sprue-following cooling water channel, and two sets of linear cooling water channels and four sets of oil temperature heating pipes are arranged in sequence above the sprue-following cooling water channel.

5. The die-casting mold for a large-size die-casting part according to claim 1, characterized in that: It also includes a casting system, which is divided into two groups of horizontal runners from the end of the sprue. Each group of horizontal runners is divided into six branch horizontal runners. The ends of the twelve branch horizontal runners are equipped with centralized ingates. The ingates are located along the product body and an integral feeding platform is set. A guide rib is set at the front end of the product end column and a vertical slag pot opening is set at the rear end of the end column so that the cold material flowing through the end column flows into the slag pot along the vertical slag pot opening.

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