Die casting method for ensuring high compactness of multi-oil-duct DHT shell

Abstract

The invention relates to a die-casting method for ensuring high compactness of a multi-oil-duct DHT shell. The method comprises the steps that materials are poured; carrying out injection delay; injection and cooling: the stroke of an injection rod is 0 mm, injection is started, and the injection speed is low; when the stroke of the injection rod is 350mm, vacuumizing and starting to act; the stroke of an injection rod is 590 mm, and injection is started at a high speed; when the stroke of the injection rod is 850 mm, injection pressurization is started; when the stroke of the injection rod is 910 mm, vacuumizing is stopped; the stroke of the injection rod is 930 mm, and injection is finished; the total time of the whole injection and cooling is 25 seconds, the external extrusion pin machine starts timing while the injection is started, the lower sliding block extrusion pin starts to be started 18 seconds after the injection is started, pressurization is performed for 3 seconds, and retreating is performed for 2 seconds to achieve rear limiting; opening the mold; pulling out the core; taking the workpiece; spraying is conducted; core pulling in; and closing the mold. According to the invention, the compactness of multiple oil ducts is ensured through a process that one oil cylinder is used for extruding multiple oil ducts at one time and the diameters of multiple extrusion pins are different.

Description

TECHNICAL FIELD

[0001] The application relates to the field of DHT (hybrid power dedicated gearbox) shell die casting processes, and relates to a high-density die casting method for ensuring a DHT aluminum alloy shell with multiple oil channels. BACKGROUND

[0002] The hybrid power automobile transmission is a new type of transmission form rising with the development of new energy vehicles. The DHT shell, as one of important components of the hybrid power automobile transmission, has the important functions of supporting internal transmission and storing lubricating oil. In order to realize the high-efficiency lubrication and cooling functions, the DHT shell oil channel is designed to be multiple and extremely complex. However, the oil leakage in the oil channel area will affect the performance of the gear, bearing, clutch, motor and other parts in the transmission shell. Therefore, the high density of the DHT shell oil channel area becomes an important index for developing the transmission shell.

[0003] The DHT shell oil channel is multiple and complex in angle, and most of the oil channels cannot be removed from the core needle on the casting, which means that the density of the oil channel cannot be ensured by local pinhole extrusion. At present, a commonly used method is to increase a small boss in the oil channel area, set an extrusion pin on the small boss, and then perform local surface extrusion on the small boss surface to ensure the density of the oil channel. However, due to the large number of oil channels and limited space of the mold, the number of extrusion pins that can be arranged on the mold is limited, so the high density of the multiple oil channels cannot be ensured. Three extrusion pins with the same diameter are arranged on three oil channels, the diameter of the oil cylinder the extrusion stroke is 20 mm, the center of the oil cylinder is at the center of the circumcircle of the triangle, and through X-ray flaw detection verification of the casting, the first extrusion pin and the second extrusion pin are internally dense, and the third extrusion pin area of the meat thickness structure is still not dense, and has a shrinkage hole. SUMMARY

[0004] The application aims to overcome the above shortcomings and provide a high-density die casting method for ensuring a DHT shell with multiple oil channels.

[0005] The application is achieved by the following technical scheme: a high-density die casting method for ensuring a DHT shell with multiple oil channels, comprising the following steps:

[0006] A, pouring: the molten metal liquid is automatically scooped into the cylinder of the die casting equipment by the die casting equipment;

[0007] B, pressure delay: the delay time between the pouring action and the pressure action of the die casting machine is 5 seconds;

[0008] C. Injection and cooling: the plunger stroke is at 0mm, the injection starts, the slow stage; the plunger stroke is at 350mm, the vacuum extraction starts to act; the plunger stroke is at 590mm, the injection high speed starts; the plunger stroke is at 850mm, the injection pressure boosting starts; the plunger stroke is at 910mm, the vacuum extraction is closed; the plunger stroke is at 930mm, the injection ends; the whole injection and cooling time is 25 seconds, the external extrusion pin machine starts to count at the same time when the injection starts, the injection starts for 18 seconds, the lower slide extrusion pin starts to start, the pressure boosting is 3 seconds, and the retreat is 2 seconds to reach the rear limit;

[0009] D. Mold opening: the mold is separated after solidification;

[0010] E. Core pulling out: the movable core is opened under the driving of the oil cylinder, and the casting can be smoothly pushed out from the mold and separated;

[0011] F. Part taking: the part taking robot receives the taking permission instruction, enters the cavity, and takes out the casting from the mold;

[0012] G. Spraying: the mold cavity is cleaned, and the movable and fixed molds and the slide are uniformly sprayed with the release agent;

[0013] H. Core pulling in: the movable core is closed under the driving of the oil cylinder, and is restored to the original position, so that the next die casting operation can be carried out;

[0014] I. Mold closing: after the molten metal is prepared, the mold is closed.

[0015] Further improvement of the application is that the extrusion pin single side gap in step C is controlled at 0.02-0.05mm.

[0016] Further improvement of the application is that the extrusion pin sleeve in the extrusion pin machine in step C is made of SKD61 material, and the hardness of the sleeve is 50-52HRC.

[0017] Further improvement of the application is that the extrusion pin sleeve in the extrusion pin machine in step C is made of SKD61 material, and the hardness of the sleeve is 50-52HRC.

[0018] Further improvement of the application is that the extrusion pin sleeve in the extrusion pin machine in step C is made of SKD61 material, and the hardness of the sleeve is 50-52HRC. 2 Further improvement of the application is that the extrusion pin sleeve in the extrusion pin machine in step C is made of SKD61 material, and the hardness of the sleeve is 50-52HRC.

[0019] A further improvement of the present invention is that: the diameter φ of the first extrusion pin and the second extrusion pin is 10mm, the diameter φ of the third extrusion pin is 12mm, the extrusion stroke is 20mm, the diameter φ of the hydraulic cylinder is 100mm, and the center of the hydraulic cylinder moves from the center of the circumcircle of the triangle to near the third extrusion pin until the hydraulic cylinder fixing plate extrudes smoothly without local tilting, which would cause unilateral wear of the extrusion pin needle sleeve. This position is the final center of the hydraulic cylinder.

[0020] A further improvement of the present invention is that the extrusion stress is the reaction force on the extrusion pin during the extrusion process of the molten aluminum;

[0021] The extrusion force is the extrusion force exerted by the hydraulic cylinder on the extrusion pin. The extrusion force is generally taken with a safety factor of K = 3 to 5.

[0022] Extrusion stress × k = Extrusion force;

[0023] Extrusion stress = Injection specific pressure × 3.14 × (Extrusion pin radius) 2 ;

[0024] Extrusion pressure = System pressure × 3.14 × (cylinder radius) 2 ;

[0025] The center line connecting the three extrusion pins forms an equilateral triangle. The extrusion stress of the first extrusion pin is F1, the extrusion stress of the second extrusion pin is F2, and the extrusion stress of the third extrusion pin is F3. The diameters of the first and second extrusion pins are both 10mm, and the diameter of the third extrusion pin is 12mm. F1 = F2 = F, the extrusion stress remains constant, and F3 = 1.44 × F. At this point, the equivalent point of force application (x...) p ,y p In the equation, according to the resultant moment theorem: the equivalent point of application P(x) p ,y p The torque of all forces about any axis is equal to the torque of the resultant force about the same axis.

[0026] Resultant force F 合 =F1+F2+F3=F+F+1.44F=3.44F;

[0027] Torque balance about the x-axis (calculated in the horizontal direction): F1·x1 + F2·x2 + F3·x3 = F 合 ·x p Substituting, we get:

[0028] The torque is balanced about the y-axis. For calculations in the vertical direction, since the forces are in the same direction, the formula is:

[0029] The cylinder center, calculated theoretically, is (0, ...). ).

[0030] Compared with the prior art, the present application has the following advantages:

[0031] The present application realizes one extrusion of multiple extrusion pins and the process of multiple extrusion pins with different diameters to ensure the density of multiple oil channels, and solves the problem of insufficient space for arranging multiple extrusion pin molds. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a schematic view of three extrusion pins;

[0033] Reference numerals in the figure: 1 - first extrusion pin, 2 - second extrusion pin, 3 - third extrusion pin. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments. The elements and features described in one embodiment of the present application can be combined with the elements and features shown in one or more other embodiments. It should be noted that, for the purpose of clarity, the representations and descriptions of components and processes unrelated to the present application and known to those of ordinary skill in the art are omitted in the description. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0035] A high-density die casting method for ensuring multiple oil channels DHT shell, comprising the following steps:

[0036] 1. Pouring: the molten metal liquid after melting is automatically scooped into the cylinder of the die casting machine by the die casting equipment.

[0037] 2. Pressure delay: the delay time between the pouring action and the pressure action of the die casting machine is 5 seconds.

[0038] 3. Pressure + cooling: the stroke of the ejector rod is 0mm, the pressure starts, and the slow stage; the stroke of the ejector rod is 350mm, the vacuum starts to act; the stroke of the ejector rod is 590mm, the high-speed pressure starts; the stroke of the ejector rod is 850mm, the pressure boosting starts; the stroke of the ejector rod is 910mm, the vacuum is closed; the stroke of the ejector rod is 930mm, the pressure ends. The whole pressure + cooling is 25 seconds. At the same time when the pressure starts, the external extrusion pin machine starts timing, the pressure starts 18 seconds, the lower slide extrusion pin starts to start, and the pressure is 3 seconds, and the retreat is 2 seconds to reach the rear limit.

[0039]

[0040]

[0041] 4. Open the mold: the mold is separated after solidification.

[0042] 5. Core pulling: the movable core is opened under the drive of the oil cylinder, and the casting can be smoothly separated from the mold.

[0043] 6. Take out the part: the take-out robot receives the take-out permission instruction, enters the cavity, and takes out the casting from the mold.

[0044] 7. Spraying: clean the mold cavity, and uniformly spray the release agent on the movable mold and the slide.

[0045] 8. Core insertion: the movable core is closed under the drive of the oil cylinder, and returns to the original position for the next die casting operation.

[0046] 9. Close the mold: the mold is closed after the molten metal is ready.

[0047] The single-sided gap of the extrusion pin is controlled at 0.02-0.05mm, ensuring the coaxiality of the extrusion pin during extrusion, and the extrusion pin will not be stuck;

[0048] 2. The needle sleeve of the extrusion pin is made of SKD61 material, and the hardness of the needle sleeve is improved from 46-48HRC to 50-52HRC, thereby improving the wear resistance of the extrusion pin needle sleeve;

[0049] 3. First, determine the solidification sequence of the three oil channels and whether there is a hot spot through mold flow analysis, set the extrusion pin in the area where the shrinkage hole is easy to produce or the hot spot area, the diameter of the extrusion pin and the extrusion stroke can be calculated theoretically

first calculate the volume of shrinkage hole after solidification = extrusion area volume before extrusion × (1-2.4 / 2.64), then calculate the theoretical extrusion amount = volume of shrinkage hole after solidification / (3.14× extrusion pin radius2), extrusion stroke > calculated theoretical extrusion amount

[0050] Extrusion stress is the reaction force of the extrusion pin during the extrusion of the liquid aluminum.

[0051] Extrusion force is the extrusion force of the extrusion pin brought by the oil cylinder. The extrusion force is generally taken as a safety factor K = 3-5

[0052] Extrusion stress x k = extrusion force

[0053] Extrusion stress = injection specific pressure x 3.14 x (extrusion pin radius) 2

[0054] Extrusion force = system pressure x 3.14 x (cylinder radius) 2

[0055] The center lines of the three extrusion pins in this implementation are an equilateral triangle, the extrusion stress of the first extrusion pin is F1, the extrusion stress of the second extrusion pin is F2, and the extrusion stress of the third extrusion pin is F3. Before the diameter of the third extrusion pin is changed, the diameters of the three extrusion pins are all 10 mm, i.e. F1 = F2 = F3 = F, and the coordinates of the centers of the three extrusion pins are A(x1, y1), B(x2, y2), and C(x3, y3).

[0056] The force equivalent point (xp, yp) of the three extrusion pins is the center of gravity of the equilateral triangle, i.e. xp = (x1+x2+x3) / 3, yp = (y1+y2+y3) / 3

[0057] Assume that the equilateral triangle A(0, ), B(-a, 0), C(a, 0), and the diameters of the three extrusion pins are φ10, i.e. F1 = F2 = F3 = F.

[0058]

[0059] When the diameter of the third extrusion pin is changed to φ12, F1 = F2 = F extrusion stress remains unchanged, and F3 = 1.44 x F. At this time, the force equivalent point (xp, yp) is

[0060] According to the theorem of the distance of the resultant force: the equivalent point P(xp, yp) satisfies the moment of all forces on any axis equal to the moment of the resultant force on the same axis.

[0061] The resultant force F 合 = F1 + F2 + F3 = F + F + 1.44F = 3.44F

[0062] The moment balance on the x-axis (horizontal direction coordinate calculation): F1 x1 + F2 x2 + F3 x3 = F 合 x p Substituting, we get:

[0063] The moment of y axis is balanced (vertical direction coordinate calculation, because the force direction is same, the formula is similar):

[0064] Conclusion: when the diameter of three extrusion pins is φ10, the center of the original oil cylinder is (0, ), when the diameter of the third extrusion pin is changed to φ12, the diameters of the first extrusion pin and the second extrusion pin are φ10, and the new center of the oil cylinder is (0, ) through theoretical calculation. When the diameter of the third extrusion pin is changed to φ12, the center of the oil cylinder needs to be moved along the line connecting the center of the original oil cylinder and the center of the third extrusion pin to the direction close to the third extrusion pin (see Figure 1 ).

[0065] The application can realize high density performance of DHT die-casting aluminum alloy casting shell complex multi-oil channel.

[0066] Finally, it should be noted that: although the application and its advantages have been described in detail above, it should be understood that various changes, substitutions and modifications can be made without exceeding the spirit and scope of the application defined by the appended claims. Moreover, the scope of the application is not limited to the specific embodiments of the processes, devices, means, methods and steps described in the specification. Those skilled in the art will readily understand from the disclosure of the application that processes, devices, means, methods or steps that perform substantially the same function or obtain substantially the same result as the corresponding embodiments described herein can be used according to the application. Therefore, the appended claims are intended to include such processes, devices, means, methods or steps within their scope.

Claims

1. A method for ensuring high density in die casting of multi-channel DHT shells, characterized in that: Includes the following steps: A. Pouring: The molten metal is automatically scooped into the die-casting machine's cylinder by the die-casting equipment; B. Injection delay: The delay time between the start of the material pouring action and the injection action of the die casting machine is 5 seconds; C. Injection and Cooling: Injection begins at 0mm, slow speed phase; vacuuming begins at 350mm; high-speed injection starts at 590mm; pressurization starts at 850mm; vacuuming stops at 910mm; injection ends at 930mm. The entire injection and cooling process takes 25 seconds. Simultaneously with the start of injection, the external extrusion pin machine begins timing. 18 seconds into injection, the lower slide extrusion pin starts, pressurizing for 3 seconds, and then retracts for 2 seconds to reach the rear limit. D. Mold opening: The mold is separated after solidification; E. Core pulling: The movable core opens under the drive of the hydraulic cylinder, allowing the casting to be smoothly ejected and separated from the mold; F. Retrieval: After receiving the retrieval permission command, the retrieval robot enters the cavity and retrieves the casting from the mold; G. Spraying: Clean the mold cavity thoroughly, and spray the moving and fixed molds and sliders evenly with release agent; H. Core insertion: The movable core closes under the drive of the hydraulic cylinder and returns to its original position so that the next die-casting operation can be carried out. I. Mold Closure: After the molten metal is ready, the mold will be closed.

2. The method for ensuring high density in die casting of multi-channel DHT shells according to claim 1, characterized in that: In step C, the clearance on one side of the extrusion pin is controlled to be 0.02 to 0.05 mm.

3. The die-casting method for ensuring high density of multi-oil-channel DHT shells according to claim 1, characterized in that: In step C, the extrusion pin sleeve in the extrusion pin machine is made of SKD61 material, and the hardness of the sleeve is 50-52HRC.

4. The method for ensuring high density in die casting of multi-channel DHT shells according to claim 1, characterized in that: First, determine the solidification sequence and hot spots of the three oil channels through mold flow analysis. Set extrusion pins for areas prone to shrinkage cavities or hot spots during solidification. The diameter and stroke of the extrusion pins can be calculated theoretically: first, calculate the volume of shrinkage cavities after solidification = volume of the extrusion area before extrusion × (1-2.4 / 2.64), then calculate the theoretical extrusion amount = volume of shrinkage cavities after solidification / (3.14 × extrusion pin radius 2). The extrusion stroke > the calculated theoretical extrusion amount. The selected cylinder pressure, cylinder diameter, extrusion pin length, and extrusion pin diameter must meet the calculation formula for the stability of the ejector pin.

5. The method for ensuring high density in die casting of multi-channel DHT shells according to claim 4, characterized in that: The diameter φ of the first and second extrusion pins is 10mm, the diameter φ of the third extrusion pin is 12mm, the extrusion stroke is 20mm, the diameter φ of the hydraulic cylinder is 100mm, the center of the hydraulic cylinder moves from the center of the circumcircle of the triangle to near the third extrusion pin, until the hydraulic cylinder fixing plate extrudes smoothly without local tilting, thus preventing one-sided wear of the extrusion pin needle sleeve. This position is the final center of the hydraulic cylinder.

6. The method for ensuring high density in die casting of multi-channel DHT shells according to claim 5, characterized in that: Extrusion stress is the reaction force on the extrusion pin during the extrusion process of molten aluminum; The extrusion force is the extrusion force exerted by the hydraulic cylinder on the extrusion pin. The extrusion force is generally taken with a safety factor of K = 3 to 5. Extrusion stress × k = Extrusion force; Extrusion stress = Injection specific pressure × 3.14 × (Extrusion pin radius) 2 ; Extrusion pressure = System pressure × 3.14 × (cylinder radius) 2 ; The center line connecting the three extrusion pins forms an equilateral triangle. The extrusion stress of the first extrusion pin is F1, the extrusion stress of the second extrusion pin is F2, and the extrusion stress of the third extrusion pin is F3. The diameters of the first and second extrusion pins are both 10mm, and the diameter of the third extrusion pin is 12mm. F1 = F2 = F, the extrusion stress remains constant, and F3 = 1.44 × F. At this point, the equivalent point of force application (x...) p ,y p In the equation, according to the resultant moment theorem: the equivalent point of application P(x) p ,y p The torque of all forces about any axis is equal to the torque of the resultant force about the same axis. Resultant force F 合 =F1+F2+F3=F+F+1.44F=3.44F; Torque balance about the x-axis (calculated in the horizontal direction): F1·x1 + F2·x2 + F3·x3 = F 合 ·x p Substituting, we get: The torque is balanced about the y-axis. For calculations in the vertical direction, since the forces are in the same direction, the formula is: The center of the hydraulic cylinder is calculated theoretically as follows:

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