Method and apparatus for manufacturing die casting

Abstract

To provide a die casting manufacturing method and a die casting manufacturing apparatus capable of satisfactorily manufacturing a die casting product by appropriately protecting a corner of a pressurizing pin tip when pressurizing a runner, thereby eliminating heat concentration to a drill and a tip corner part.SOLUTION: A die casting manufacturing apparatus includes second pressurizing means having a pin for pressurizing a passage directly connected to a cavity in addition to first pressurizing means for injecting molten metal into a die casting mold, and an inclined surface to be a chamfered part and a flat surface continuing to the inclined surface are formed on the outer peripheral part of the tip surface of the pressurizing pin.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a die casting method and apparatus, and more particularly to a die casting method and apparatus using a runner pressurization method or a local pressurization method. [Background technology]

[0002] The casting method for die-cast products is to fill the cavity made in the mold with molten metal such as aluminum using a plunger, and then remove the product that has solidified to a shape that matches the shape of the cavity. A pressure boosting mechanism is installed at the rear of the plunger to further boost the pressure on the plunger to prevent voids from forming when the product is formed. The plunger applies pressure to fill the cavity, producing a product that matches the shape of the cavity.

[0003] Recently, in order to further remove porosity from the product pressurized by the plunger, a structure has been proposed in which a separate pressurizing pin is arranged in the runner section leading to the product to press the product with a secondary high pressure after the primary pressurization by the plunger, and the product is pressed with a secondary high pressure. In particular, an orifice is provided at the sliding point of the pressurizing pin to prevent the molten metal from flowing back when high pressure is applied, and pressing is performed with high pressure (Patent Document 1). The pressurizing pin of the secondary pressurizing means is made smaller in diameter than the plunger in order to apply high pressure, and is set to apply a pressure of approximately 300 MPa, which exceeds the pressure limit of the plunger (70 MPa).

[0004] However, the sliding gap between the conventional pressure pin and the runner is small, and if the shape of the pressure pin is a simple cylinder, the gap formed also becomes a circular ring, which may cause galling at the insertion part of the molten metal and hinder the smooth movement of the pressure pin.In addition, the corners of the pressure pin may be damaged by galling or heat concentration. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 7090254 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention focuses on the above problems and aims to provide a die casting method and apparatus that can produce good die cast products by properly protecting the corners of the tip of the pressure pin when pressurizing the runner as a second injection after the molten metal is injected by the plunger, thereby eliminating galling and heat concentration at the tip corners. [Means for solving the problem]

[0007] In order to achieve the above object, the die-casting manufacturing method according to the present invention is configured as follows: In a manufacturing method for a die-casting product in which molten metal is injection molded into a die-casting mold by a first pressurizing means, and a passage directly connected to a cavity is pressurized by a second pressurizing means equipped with a pressurizing pin, the pressurizing means is characterized in that the second pressurizing means applies pressure using a pressurizing pin that has an inclined surface that forms a chamfer on the outer periphery of the tip of the pressurizing pin, and a flat surface that continues from the bottom of the inclined surface to the outer surface of the pin.

[0008] In this case, pressure may be applied by the second pressure means using a pressure pin having only an inclined surface that serves as a chamfer on the outer periphery of the tip of the pressure pin. Furthermore, in order to confirm the effect of runner pressurization in improving the quality of manufactured products, the casting can be performed without operating the runner pressurization pin, and the operation is characterized by an operation to avoid a state in which the product cannot be removed due to undercut that occurs when the runner pressurization is not in operation. In order to avoid the effect of undercut, when the pressurization by the second pressurization means is completed, the pressurization pin is pulled down to a depth greater than the undercut when the pressurization pin is pulled in.

[0009] Furthermore, the die-casting manufacturing apparatus according to the present invention is characterized in that, in addition to a first pressure applying means for injecting molten metal into a die-casting mold, a second pressure applying means having a pin for applying pressure to a passage directly connected to the cavity is provided, and a sloping surface that serves as a chamfer and a flat surface that continues from the sloping surface are formed on the outer periphery of the tip surface of the pressure pin.

[0010] In addition to the first pressurizing means for injecting molten metal into the die-casting mold, a second pressurizing means having a pin for pressurizing a passage directly connected to the cavity may be provided, and an inclined surface serving as a chamfer may be formed on the outer periphery of the tip face of the pressurizing pin.

[0011] In this device, the pressure pin of the second pressure means is slidable on the runner, and an orifice is provided on the sliding surface of the pressure pin, and the orifice serves as a backflow prevention portion. Furthermore, the pressure pin of the second pressure means may have a structure for cooling the inside. Effect of the Invention

[0012] According to the above configuration, the backflow of molten metal is prevented by the insertion of molten metal. That is, by machining and providing a groove with a chamfer on the tip of the pressure pin, the contact area of ​​the part that does not slide with the molten metal increases by the height of the groove, which enhances the cooling effect of the molten metal and forms a pool of molten metal in the groove, which, combined with the cooling effect, forms a metal seal of semi-solidified molten metal along the groove. Therefore, this metal seal suppresses the "insertion of molten metal" (backflow of molten metal) between the pressure pin and the sleeve.

[0013] This also has the effect of preventing pin breakage (extending the pin's life). The cooling effect reduces heat concentration at the corners of the pressure pin tips, and the corners are protected by a metal seal, preventing pin tip breakage and galling. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1(1) is an explanatory diagram of a pressure pin of a die-casting manufacturing apparatus according to an embodiment of the present invention, and FIG. 1(2) is a partially enlarged view thereof. [Diagram 2] 1 is a cross-sectional view of a main part of a die-casting manufacturing apparatus according to an embodiment of the present invention. [Diagram 3] 4 is a diagram showing an operation form of a pressure pin of the die casting manufacturing apparatus. FIG. [Figure 4] 11 is a cross-sectional view showing an operation mode when pressure is applied by the pressure pin. FIG. [Diagram 5] 1A and 1B are a side view and a plan view showing an example of a pressure pin. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, a die-casting manufacturing apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that the following description is merely one embodiment, and various modifications may be included in the present invention as long as they do not deviate from the gist of the present invention.

[0016] FIG. 2 is a cross-sectional view of the main part of the die-casting manufacturing apparatus according to this embodiment. The die-casting manufacturing apparatus 10 has main functional parts such as an injection part, a mold clamping part, and an extrusion part, and is composed of a base frame, a control panel, various oil and air pressure piping, safety devices, etc. The injection part is a mechanism for pouring molten metal such as aluminum into a mold, and the mold clamping part is a part for clamping the mold with the necessary force. The extrusion part is a part for pulling the product from the mold when removing it from the mold. The mold clamping part is mounted on the base frame, and is equipped with a movable plate that moves between the fixed plate using the tie bars as a guide and links the holding plate and the fixed plate fixed at fixed positions on the base frame with four tie bars. The holding plate is provided with a mold clamping cylinder, and the movable mold on the movable plate is pressed against the fixed mold on the fixed plate through a toggle mechanism interposed between the fixed plate and the movable plate to exert a mold clamping force.

[0017] 2, molten metal is injected into a cavity 38 formed by abutting a movable die 34 attached to the movable plate 28 and a fixed die 36 attached to the fixed plate 24, and a product having a shape that matches the cavity 38 is completed. The product can be removed from the cavity 38 by separating the dies 34, 36 and operating the ejection pin 40 of the ejection section 16 provided on the back side of the movable die 34.

[0018] A molten metal supply means 42 is disposed below the cavity 38 as the injection section 12 for supplying molten metal to the cavity 38 of such a die casting manufacturing apparatus 10. This is composed of a first pressurizing means 50 consisting of an injection sleeve 44 that is attached by penetrating horizontally through the fixed plate 24 and reaches the fixed mold 36, a plunger 48 disposed within the injection sleeve 44, and a pressurizing device that is disposed behind the plunger 48 and can push and pull the plunger 48.

[0019] A runner 52 is formed at the front end of the injection sleeve 44, serving as a passageway leading to the cavity 38. This runner 52 consists of a diverter runner portion 54 extending almost horizontally from the injection sleeve 44, and a rising runner portion 56 that turns upward so as to connect directly to the bottom of the cavity 38. The molten metal pushed out by the plunger 48 passes through the diverter runner portion 54, is turned upward by the rising runner portion 56, and is injected into the cavity 38.

[0020] The rising runner portion 56 of the runner 52 is provided with a second pressurizing means 58 for secondarily pressurizing the molten metal in the cavity 38. The second pressurizing means 58 is composed of an actuator 60 provided on the lower portion of the dies 34, 36, and a pressurizing pin 62 attached so as to move in and out from the lower portion to the upper portion of the rising runner portion 56 by the actuator. The diameter d of the pressurizing pin 62 is set smaller than the inner diameter D of the rising runner portion 56, allowing the pressurizing pin 62 to slide up and down on the rising runner portion 56. Therefore, the amount by which the pressurizing pin 62 is pressed into the rising runner portion 56 improves the density of the product formed by the cavity 38.

[0021] In this embodiment, as shown in Fig. 1, an orifice 64 is formed on the rising runner portion 56 side (part B in Fig. 1) above the intersection (section AB in Fig. 1) between the rising runner portion 56 and the diverter runner portion 54 to reduce the inner diameter. This is an annular protrusion 66 having a rectangular cross section formed on the inner diameter portion of the rising runner portion 56, and the height of the protrusion 66 (i.e., the inner diameter dimension of the rising runner portion 56) is adjusted as much as possible to the outer diameter d of the pressure pin 62 so that a metal seal can be formed here. Specifically, although it depends on the size of the mold cavity 38, the gap dimension Δ is 1 / 2 of the difference between the inner diameter D of the rising runner portion 56 and the outer diameter d of the pressure pin 62, and the height of the annular protrusion 66 is determined so that the gap dimension Δ is 1 / 2 to 1 / 3 or less. That is, the gap dimension δ of the metal seal portion is 1 / 2 the difference between the inner diameter of the annular protrusion 66 and the outer diameter d of the pressure pin 62, and δ = Δ × 1 / 2, preferably δ = Δ × 1 / 3, with the lower limit being the value at which the metal seal is damaged. Also, the axial length L of the annular protrusion 66 is set to about 10 mm to ensure that the metal seal is performed reliably.

[0022] The pin 62 that applies pressure to the molten metal discharged into the die-casting die is usually cylindrical, but in this embodiment, the outer periphery of the tip of the pressure pin 62 is formed with an inclined surface 70 that serves as a chamfer, and a flat surface 72 that continues to the inclined surface 70. This can be easily formed by cutting the tip of the tip of the pressure pin 62 to form a step surface (flat surface 72) and chamfering the inner small diameter part of the step surface. The chamfered portion is for providing a draft angle from the molten metal that adheres to it. As a result, two corners are formed on the outer periphery of the pressure pin 62, one of which is the corner formed by the outer periphery of the pressure pin 62 and the flat surface 72, and the other is the corner formed by the top end surface 62A of the pressure pin 62 and the inclined surface (inclined surface 70). As a result, the pressure pin 62 has two corners instead of one corner in the conventional case, and the cooling effect is more pronounced.

[0023] 1(2) is a diagram explaining the cooling function here, and when the diverter runner section 54 is cut off by the pressurizing action of the pressurizing pin 62 and reaches the rising runner section 56, the molten metal 74 is inserted between the outer periphery of the pressurizing pin 62 and the inner surface of the rising runner section 56, and solidifies in combination with the action of the internal cooling means 76 of the pressurizing pin 62, and the molten metal part immediately before solidification in the center of the cavity 38 before solidification is pressurized under high pressure and densified. At this time, the space sandwiched between the two corners on the outer periphery of the pressurizing runner 62 becomes a pool of molten metal, and in combination with the action of the internal cooling means 76 of the pressurizing pin 62, cooling begins early, and the molten metal shielding effect here is enhanced. The solidified part is shown at 78.

[0024] In this way, the pressure pin 62 of the second pressure means 58 is made slidable on the rising runner portion 56, and an orifice 64 is provided on the sliding surface of the pressure pin 62, which serves as a backflow prevention portion. The orifice 64 serves as a backflow prevention portion, enabling the pressure pin 62 to pressurize the molten metal 74 in the cavity. At this time, since an inclined surface 70 and a flat surface 72 continuing thereto are provided on the outer circumferential corner portion of the pressure pin 62, the cooling function is enhanced at this corner portion, and the surrounding molten metal 74 solidifies more quickly. Therefore, the pressure blocking effect of this solidification portion 78 facilitates the subsequent pressurizing operation.

[0025] A pool of molten metal is formed around the corner of the tip of the pressure pin 62 in the direction of travel, and the molten metal becomes semi-solidified when the pool comes into contact with the pressure pin 62. The pressure pin 62 is easily brought into a semi-solidified state by externally and internally cooling it. The semi-solidified pool is formed around the sliding part between the sleeve and the pressure pin 62, and penetrates into the sliding gap to act as a metal seal, preventing molten metal backflow and galling. In addition, the semi-solidified molten metal acting as a metal seal for the height of the pool protects the area around the tip of the pressure pin 62 and prevents damage to the area around the tip of the pressure pin 62.

[0026] In order to achieve the above, the peripheral portion of the tip of the pressure pin 62 is machined into a shape that makes it easy to obtain a metal seal effect. The metal seal effect can be achieved by chamfering the periphery of the pressure pin tip, but a greater effect can be achieved by chamfering with a step. The processing around the tip of the pressure pin is done by chamfering or stepped chamfering, but the optimum dimensions vary depending on the size and shape of the die-cast product, and the shape and pressure conditions of the pressure pin, so consideration is required each time.

[0027] The second pressurizing means 58 thus configured starts pressurizing from the position shown in Fig. 3(1) after the injection by the plunger 48 of the first pressurizing means 50 is completed, and when the pressurizing pin 42 reaches the annular protrusion 46 (Fig. 3(2)), the molten metal from above enters the orifice 64 to form a metal seal, which exerts a shielding function. Therefore, the metal seal at the orifice 64 increases the amount of molten metal filled in the cavity 38, and the pushing action of the pressurizing pin 62 lengthens the stroke, completing the operation (Fig. 3(3)).

[0028] The annular projection 66 forming the orifice 64 may have a rectangular cross section as in the embodiment, but may also have a V-shaped or arc-shaped cross section. In this case, if the tip of the V-shaped or arc-shaped projection is sharp, the metal seal cannot be removed, so it is preferable to have a shape with the tip cut off.

[0029] In addition, a cooling means can be placed on the annular protrusion 46 that forms the orifice 64. This can be a horizontal type / water-cooling type or an oil-cooling type, and it is recommended to cool it when injection by the first pressurizing means 50 is completed and pressure is applied to the annular protrusion 66 by the second pressurizing means 58 (FIG. 3(2)). This makes it easier to form a metal seal.

[0030] Thus, according to this embodiment, injection into the cavity 38 is performed by the first pressurizing means 50, and the second pressurizing means 58 is operated when the runner 52 is filled with molten metal. Then, while the pressurizing pin 62 reaches the intersection (FIG. 3A→B) of the diverter runner portion 54 and the rising runner portion 56, it performs a normal pushing action, but as soon as the diverter runner portion 54 breaks and reaches the rising runner portion 56, the annular protrusion 66 reaches the portion, and the molten metal solidifies in the gap δ by the metal seal, where the pressure is shut off (FIG. 3(2)). Therefore, the runner molten metal on the cavity 38 side that is not yet solidified and located above the pressurizing pin 62 is pushed toward the cavity 38 side against the background of the shut-off pressure.

[0031] At this time, when the diverter runner portion 54 is blocked by the pressurizing action of the pressurizing pin 62 and reaches the rising runner portion 56, the molten metal 74 is inserted between the outer circumferential surface of the pressurizing pin 62 and the inner surface of the rising runner portion 56 and solidifies in combination with the action of the internal cooling means 76 of the pressurizing pin 62, and the molten metal portion immediately before solidification in the center of the cavity 38 before solidification is pressurized under high pressure and densified. At this time, the space sandwiched between the two corners on the outer circumferential portion of the pressurizing runner 62 becomes a pool of molten metal, which in combination with the action of the internal cooling means 76 of the pressurizing pin 62 begins to cool early, and the molten metal shielding effect in the early solidification portion 78 is enhanced. Furthermore, this technique is not limited to the configuration shown in the figure, but can also be applied to devices that perform localized pressure application.

[0032] Figure 4 shows how to deal with the situation when the product cannot be removed due to undercut. An inclined surface 70 and a flat surface 72 are formed on the outer periphery of the pressure pin 62, and when the lowering limit S of the pressure pin 62 is aligned with the lower end position of the diverter runner section 54 when the product is completed, the top surface 80 will be higher than the flat surface 72 by the amount of the inclined surface 70. Therefore, when an attempt is made to remove the product, the inclined surface will become an undercut. Therefore, the pressure pin 62 is pulled down beyond the undercut as shown in Figure 4(2). This makes it easier to remove the die-cast product (Figure 4(3)).

[0033] In addition, the outer peripheral surface shape of the tip end of the pressure pin 62 is composed of an inclined surface 70 and a flat surface 72 on the outside thereof, as shown in FIG. 5(1). However, the same effect can be obtained even if only the inclined surface 70 is provided, without the flat surface 70, as shown in FIG. 5(2). [Industrial Applicability]

[0034] The present invention relates to a die casting method and apparatus in which the molten metal is extruded and molded into the cavity by the plunger pressure action of the first pressure means, and then the runner is pressurized by the second pressure means, in which the molten metal already formed in the cavity is pressurized by a pressure pin with a sloped or stepped portion on the outer periphery of the tip, thereby eliminating galling and providing a structure with a high cooling effect. [Explanation of symbols]

[0035] 10...die casting manufacturing apparatus, 24...fixed plate, 28...movable plate, 34...movable mold, 36...fixed mold, 38...cavity, 40...ejector pin, 42...melt water supply means, 44...injection sleeve, 48...plunger, 50...first pressure means, 52...runner, 54...diverter runner portion, 56...rising runner portion, 58...second pressure means, 60...actuator, 62...pressure pin, 64...orifice, 66...annular protrusion, 70...inclined surface, 72...flat surface, 74...molten metal, 76...cooling means, 78...solidification portion.

Claims

1. A method for manufacturing a die-cast product, comprising the steps of: injecting molten metal into a die-casting die by a first pressurizing means; and pressurizing a passage directly connected to a cavity by a second pressurizing means provided with a pressurizing pin, A die casting manufacturing method, characterized in that pressure is applied by the second pressure means using a pressure pin having a chamfered inclined surface on the outer periphery of the tip of the pressure pin and a flat surface continuing from the bottom of the inclined surface to the outer surface of the pin.

2. A method for manufacturing a die-cast product, comprising the steps of: injecting molten metal into a die-casting die by a first pressurizing means; and pressurizing a passage directly connected to a cavity by a second pressurizing means provided with a pressurizing pin, A die casting manufacturing method, characterized in that pressure is applied by the second pressure means using a pressure pin having a chamfered inclined surface formed on the outer periphery of the tip of the pressure pin.

3. 3. The die casting manufacturing method according to claim 1, wherein, in order to enable casting without operating a runner pressure pin, when pressure is applied by the second pressure means, the pressure pin is pulled down to a depth greater than the undercut when the pressure pin is pulled in.

4. A die casting manufacturing device characterized in that, in addition to a first pressurizing means for injecting molten metal into a die casting mold, a second pressurizing means having a pin for pressurizing a passage directly connected to a cavity is provided, and a sloping surface that serves as a chamfer and a flat surface continuing from the sloping surface are formed on the outer periphery of the tip face of the pressurizing pin.

5. A die casting manufacturing device characterized in that, in addition to a first pressure applying means for injecting molten metal into a die casting mold, a second pressure applying means having a pin for applying pressure to a passage directly connected to a cavity is provided, and an inclined surface that serves as a chamfer is formed on the outer periphery of the tip face of the pressure pin.

6. 6. The die casting manufacturing apparatus according to claim 4, wherein the pressure pin of the second pressure means is capable of sliding on a runner, and an orifice is provided on the sliding surface of the pressure pin, the orifice serving as a backflow prevention section.

7. 6. The die casting manufacturing apparatus according to claim 4, wherein the pressure pin of the second pressure means is structured so as to be cooled inside.

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