Die cast machine and die cast method with die cast machine

Abstract

To provide a die casting machine that improves the internal quality of a casting by achieving a feeding head effect even after the gate solidifies and closes.SOLUTION: A die casting machine 10 comprises a mold 28 composed of a fixed mold 30 and a movable mold 32, a cavity 34 formed inside the mold 28, an injection plunger 44 for injecting molten metal into the cavity 34, and a mold clamp device 12 for opening and closing the mold and clamping the movable mold 32 relative to the fixed mold 30. Further, using the injection plunger 44, the injection pressure P is set such that the mold opening force Y exerted on the movable mold 32 by the molten metal injected into the cavity 34 is equal to or less than the mold clamping force X set for the movable mold 32 relative to the fixed mold 30. This allows molten metal equal to the volume of the cavity 34 to be injected and filled. Subsequently, the injection pressure P is set such that the mold opening force Y becomes greater than the mold clamping force X, and molten metal in an amount exceeding the volume of the cavity 34 is injected.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a die-casting machine that injects molten metal into a mold to cast a casting, and to a die-casting method using the die-casting machine. [Background technology]

[0002] In conventional die-casting machines, molten metal such as aluminum alloy melted in a melting furnace is measured and pumped up with a ladle for each shot, and the pumped molten metal is supplied to a feed port of an injection sleeve. The molten metal is then injected and filled into the cavity of a mold by the forward movement of an injection plunger that is movably mounted within the injection sleeve, thereby casting a cast product.

[0003] Generally, in die casting using a die casting machine, when the molten metal filled in the cavity is pressurized with the injection plunger, a force (mold opening force) acts in the direction of opening the mold according to Pascal's principle.If the mold opens, flash and flash will occur, so the force tightening the mold (mold clamping force) is generally set greater than the mold opening force.

[0004] One known defect in cast products produced by die casting using a die casting machine is shrinkage cavities (solidification shrinkage cavities), which occur when the molten metal filled into the cavity shrinks in volume as it cools and solidifies. Cast products with such defects have poor mechanical properties. Therefore, a common method of reducing defects is to replenish the volume of the molten metal that has shrunk by applying pressure from the injection plunger after filling (the feeder effect) (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-065062 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in conventional die casting methods using die casting machines, the molten metal is injected and filled into the cavity at high speed, so the gate that is the inlet to the cavity is quite narrow and thin, and solidification occurs quickly after filling. As a result, the supply of molten metal to make up for the contracted volume due to pressure from the injection plunger is cut off, and there is a problem in that a sufficient feeder effect cannot be obtained.

[0007] The present invention has been made in view of the above-mentioned problems, and its object is to provide a die-casting machine and a die-casting method using the die-casting machine that can improve the internal quality of a casting by obtaining a feeder effect even after solidification has progressed and the gate has closed. [Means for solving the problem]

[0008] According to one aspect of the present invention, a mold consisting of a fixed mold and a movable mold; a cavity formed inside the mold; an injection plunger that injects and fills the cavity with molten metal; a mold clamping device that opens, closes, and clamps the movable mold relative to the fixed mold, The injection plunger is an injection pressure is set so that the mold opening force exerted on the movable mold by the molten metal injected into the cavity is equal to or smaller than the clamping force of the movable mold against the fixed mold set by the mold clamping device, and the molten metal is injected and filled in an amount equal to the volume of the cavity; Thereafter, the injection pressure is set so that the mold opening force is greater than the mold clamping force, and the molten metal is injected and filled in an amount that exceeds the volume of the cavity. A die casting machine is provided.

[0009] Preferably, The injection plunger injects and fills the molten metal in an amount equal to the volume of the cavity, and then, with a chill layer of the molten metal formed on the surface of the cavity, increases the injection pressure to inject and fill an amount of the molten metal that exceeds the volume of the cavity.

[0010] According to another aspect of the present invention, a mold consisting of a fixed mold and a movable mold; a cavity formed inside the mold; an injection plunger that injects and fills the cavity with molten metal; a die-casting method using a die-casting machine including a die-clamping device that opens, closes, and clamps the movable die relative to the fixed die, The injection plunger, The injection pressure is set so that the mold opening force of the molten metal injected into the cavity on the movable mold is equal to or smaller than the mold clamping force set on the movable mold relative to the fixed mold by the mold clamping device, and the molten metal is injected and filled in an amount equal to the volume of the cavity, and thereafter The injection pressure is set so that the mold opening force is greater than the mold clamping force, and the molten metal is injected and filled in an amount that exceeds the volume of the cavity. A die casting method using a die casting machine is provided.

[0011] Preferably, After the molten metal is injected and filled in an amount equal to the volume of the cavity, a chill layer of the molten metal is formed on the surface of the cavity, and then the injection pressure is increased to inject and fill the molten metal in an amount exceeding the volume of the cavity. [Effects of the Invention]

[0012] According to the die-casting machine and the die-casting method using the die-casting machine of the present invention, the internal quality of the casting can be improved by obtaining a riser effect even after solidification has progressed and the gate has closed. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a diagram showing an example of a die-casting machine 10 according to an embodiment. [Figure 2] 1 is a graph showing changes in mold clamping force X (X') and injection pressure P (P') in a casting process using a die-casting machine 10. [Figure 3] FIG. 2 is a diagram showing the state of a die 28 and molten metal in a casting process using a die-casting machine 10, showing the state in which the molten metal has been injected and filled into the cavity. [Figure 4] 1 is a diagram showing the state of the mold 28 and molten metal in a casting process using the die-casting machine 10, showing the state in which the movable mold 32 is separated from the fixed mold 30. FIG. [Figure 5] FIG. 1 is a diagram showing the state of the mold 28 and molten metal in a casting process using the die-casting machine 10, showing the state in which the movable mold 32 is separated from the fixed mold 30 and the gate is closed. [Figure 6] This figure shows the state of the mold 28 and molten metal during the casting process using the die-casting machine 10, and shows the state in which the gap between the fixed mold 30 and the movable mold 32 has changed and the solidification of the molten metal has been completed. DETAILED DESCRIPTION OF THE INVENTION

[0014] (Configuration of die casting machine 10) As shown in FIG. 1, the die-casting machine 10 according to this embodiment generally includes a mold clamping device 12, an injection device 14, and a control device 15.

[0015] The mold clamping device 12 includes a machine base 16, a fixed platen 18, a movable platen 20, a tailstock 22, tie bars 24, and a toggle mechanism 26.

[0016] The machine base 16 is a member that serves as a base for the other members that make up the mold clamping device 12 and the injection device 14.

[0017] The fixed platen 18 is fixed on the machine base 16, and a fixed mold 30 that constitutes the mold 28 is attached to it.

[0018] The movable platen 20 is a member that slides on the machine base 16 so as to approach and move away from the fixed platen 18, and has a movable mold 32 attached thereto that constitutes the mold 28. When the movable mold 32 comes into contact with the fixed mold 30, a cavity 34 is formed that is filled with molten metal.

[0019] The tailstock 22 is a member placed on the machine base 16 on the opposite side of the fixed platen 18 as viewed from the movable platen 20 .

[0020] The tie bars 24 are round bar-shaped members having one end fixed to the fixed platen 18 and the other end fixed to the tailstock 22. The tie bars 24 are inserted into tie bar insertion holes 36 formed in the movable platen 20 disposed between the fixed platen 18 and the tailstock 22. This allows the movable platen 20 to slide along the tie bars 24 on the machine base 16 in the left-right direction in the drawing. A plurality of tie bars 24 (for example, four) are used.

[0021] The toggle mechanism 26 is a mechanism for moving the movable platen 20 toward and away from the fixed platen 18 and for holding the movable platen 20 in place, and the mold clamping drive mechanism 31 is attached to the tailstock 22 .

[0022] The movable platen 20 moves along the tie bars 24 (moves left and right in the figure) as the driving force of the mold clamping drive mechanism 31 is transmitted through the toggle mechanism 26. When the movable platen 20 moves leftward, the fixed mold 30 and the movable mold 32 move away from each other. On the other hand, when the movable platen 20 moves rightward, the fixed mold 30 and the movable mold 32 come into contact with each other, and a cavity (internal space) 34 is formed inside the mold 28. Then, when pressure is further applied in a direction that moves the movable platen 20 rightward, the fixed mold 30 and the movable mold 32 are clamped.

[0023] At this time, the toggle mechanism 26 gradually extends from its bent state. When the movable mold 32 comes into contact with the fixed mold 30, the tie bars 24 begin to extend, and strain proportional to the tensile stress is generated in the tie bars 24. The tension of the tie bars 24 is applied to the fixed mold 30 and the movable mold 32 as a clamping force. When the toggle mechanism 26 extends to its maximum, the tie bars 24 also extend to its maximum, and when the movable mold 32 reaches a position where clamping is completed, a specified clamping force is applied to the fixed mold 30 and the movable mold 32.

[0024] The injection device 14 generally includes an injection mechanism 38 and a hydraulic operation mechanism 40 .

[0025] The injection mechanism 38 includes an injection sleeve 42 , an injection plunger 44 , an injection piston 46 , and an injection cylinder 48 .

[0026] The injection sleeve 42 is a cylindrical member that is provided integrally with the fixed platen 18 and has a molten metal supply port 50 formed at the top thereof for supplying molten metal.

[0027] The injection plunger 44 is a generally rod-shaped member that is provided within the injection sleeve 42 so as to be able to advance and retreat.

[0028] The injection piston 46 is formed on the rear end side of the injection plunger 44 (the end opposite to the end that comes into contact with the molten metal), and is the part that is pressed by the hydraulic oil O.

[0029] The injection cylinder 48 is a cylindrical member in which the injection piston 46 advances and retreats, and is filled with hydraulic oil O.

[0030] The hydraulic operating mechanism 40 is a mechanism for supplying hydraulic oil O used in the injection process of the injection plunger 44 to the injection cylinder 48 to act on the injection piston 46. In addition, by supplying pressure oil to the injection cylinder 48, a force (injection pressure P) in the forward direction shown on the left in the drawing is applied to the injection plunger 44.

[0031] When performing the injection process and the return process of the injection plunger 44, the control device 15 detects the position information of the injection piston 46, etc., and operates the hydraulic operating mechanism 40, as well as performing all controls necessary for casting by the die-casting machine 10.

[0032] (Casting process of the die-casting machine 10 according to this embodiment) Next, the procedure for casting a molded body using the die-casting machine 10 according to this embodiment will be described with reference to Figures 2 to 6. Note that Figure 2 is a graph showing changes in the mold clamping force X, injection pressure P, and mold opening force Y throughout the entire casting process using the die-casting machine 10, and will therefore be referred to throughout the entire casting process.

[0033] The control device 15 operates the mold clamping drive mechanism 31 to close the movable mold 32 against the fixed mold 30, and further clamps the mold with a predetermined mold clamping force X ((1) in FIG. 2).

[0034] Thereafter, the control device 15 moves the injection plunger 44 forward to inject and fill the molten metal into the cavity 34 of the mold 28 (FIG. 3). At this time, the control device 15 sets the injection pressure P so that the mold opening force Y on the movable mold 32 by the molten metal injected into the cavity 34 is the same as or smaller than the mold clamping force X of the movable mold 32 against the fixed mold 30, thereby injecting and filling an amount of molten metal that is approximately the same as the volume of the cavity 34 ((2) in FIG. 2).

[0035] Next, the control device 15 injects and fills the cavity 34 with an amount of molten metal approximately equal to the volume of the cavity 34, and then forms a chill layer on the surface of the cavity 34 ((2) to (3) of Figure 2), and then increases the injection pressure P of the injection plunger 44 to move it forward, and injects and fills an amount of molten metal that exceeds the volume of the cavity 34 ((3) of Figure 2).

[0036] The chill layer (cooled solidified film layer) is a metal structure formed when the molten metal comes into contact with the surface of the cavity 34 and is rapidly cooled. The chill layer formed on the surface of the casting has a fine and dense metal structure and is therefore known to be beneficial for improving the strength of the die-cast product.

[0037] When the mold opening force Y is equal to or less than the mold clamping force X (Y≦X), the injection plunger 44 cannot be advanced toward the cavity 34. However, when the injection pressure P is increased (the increased injection pressure is referred to as "injection pressure P'") and the mold opening force Y becomes greater than the mold clamping force X (Y>X), the injection plunger 44 can advance and inject and fill an amount of molten metal that exceeds the volume of the cavity 34.

[0038] Furthermore, because the mold opening force Y is greater than the mold clamping force X, as shown in FIG. 4, the movable mold 32 and the movable platen 20 are slightly separated from the fixed mold 30 by the mold opening force Y ((3) in FIG. 2). This separation is not due to bending of the toggle mechanism 26, but is caused by extension of the tie bars 24 due to elastic deformation. When the tie bars 24 are extended, the mold clamping force X increases by the amount of extension (the increased mold clamping force is referred to as "mold clamping force X'"). The mold opening force Y due to the injection pressure P' via the molten metal extends the tie bars 24 by a predetermined length, and the mold clamping force X' increases until it becomes equal to the mold opening force Y. As a result, when the mold clamping force X' becomes equal to the mold opening force Y (Y = X'), the separation of the movable mold 32 and the movable platen 20 stops ((4) in FIG. 2).

[0039] When the movable mold 32 separates from the fixed mold 30 and a gap W is formed between them at the mold parting surface, there is a concern that molten metal may flow into this gap, causing flashing and other problems. However, in the die-casting machine 10 according to this embodiment, as described above, a chill layer is formed on the surface of the cavity 34 before the injection plunger 44 is advanced by injection pressure P'. This means that the chill layer on the surface of the cavity 34 serves to cover the gap W, preventing any remaining unsolidified molten metal from leaking out of the gap W. In other words, at the timing when "the injection plunger 44 is advanced by injection pressure P'," the molten metal on the surface of the cavity 34 has solidified, but most of the molten metal inside the cavity 34 has not yet solidified.

[0040] After the movable mold 32 and movable platen 20 stop moving away from the fixed mold 30, the injection plunger 44 also stops ((4) to (5) in FIG. 2). Then, as shown in FIG. 5, solidification of the molten metal at the position of gate Z first progresses, and the gate closes ((5) to (6) in FIG. 2). This blocks the pressurization and replenishment of molten metal from the injection plunger 44 to the cavity 34, and thereafter the feeder effect of the injection plunger 44 ceases.

[0041] Because the gate is closed, the mold opening force Y according to Pascal's principle does not act on the molten metal filled in the cavity 34, even when pressurized by the injection plunger 44. As a result, the mold opening force Y, which had been kept constant, begins to decrease rapidly (see (5) in Figure 2). On the other hand, because the tie bars 24 have been extended in advance, the tie bars 24 contract as the mold opening force Y decreases, causing the movable mold 32 and the movable platen 20 to approach the fixed mold 30. However, because the molten metal in the cavity 34 (part of it has solidified and is not molten, but this solidified portion will continue to be referred to as "molten metal") is sandwiched between the movable mold 32 and the fixed mold 30, the movable mold 32 and the fixed mold 30 approach each other while adjusting to the decrease in volume due to the solidification and shrinkage of the molten metal. Therefore, the mold clamping force X' or X (compression force) is always applied to the molten metal from the movable mold 32 and the fixed mold 30, and pressure is generated in the molten metal according to Pascal's principle. Furthermore, to compensate for the volume reduction due to solidification shrinkage, the cavity 34 is replenished with molten metal that has been previously filled in an amount greater than the volume of the cavity 34. As the molten metal is replenished, the tie bars 24 contract, and the clamping force X' or X decreases ((5) to (7) in FIG. 2).

[0042] 6, when solidification of the molten metal in the cavity 34 is complete, a gap W' narrower than the gap W at (4) to (5) in FIG. 2 exists between the fixed mold 30 and the movable mold 32. By doing this, a clamping force X' or X (compressive force) is constantly applied from the movable mold 32 and the fixed mold 30 until solidification of the molten metal in the cavity 34 is complete, and pressure can continue to be generated in the molten metal, so that a feeder effect can be obtained even after the gate is closed. This is represented by the fact that the clamping force at (7) to (8) in FIG. 2 is greater than the clamping force X at (1) when clamping is complete.

[0043] After the molten metal has solidified, the clamping drive mechanism 31 of the clamping device 12 is operated to separate the movable mold 32 from the fixed mold 30 (mold opening) ((8) in FIG. 2), and the casting is removed from the cavity 34 with an ejector pin or the like (not shown). This completes the casting of the casting by the die-casting machine 10.

[0044] Furthermore, as explained above, in the die-casting machine 10 according to this embodiment, by controlling the injection plunger 44 to adjust only the injection pressure P(P') (related to the mold opening force) of the molten metal in the cavity 34, it is possible to freely adjust the separation distance (gap W) of the dies 28 during the casting process and the mold clamping force X at the time when the molten metal has completely solidified ((7) in Figure 2) without controlling the mold clamping drive mechanism 31 during the casting process.

[0045] (Variation 1) While the stationary mold 30 and movable mold 32 in the above-described embodiment have flat mold parting surfaces extending to their peripheries, the present invention is not limited to this configuration and may employ a shear edge structure. A shear edge structure is a fitting structure formed between the stationary mold 30 and the movable mold 32 that allows them to slide relative to each other while inserting and removing. The shear edge structure effectively prevents the molten metal injected and filled into the cavity 34 from leaking out of the mold. In particular, in the present invention, the shear edge structure prevents molten metal from leaking, allowing the gap W to be further widened (by further extending the tie bars 24). This increases the clamping force X applied to the molten metal and the amount of replenished molten metal, thereby enhancing the riser effect. The shear edge structure is also known as a spigot structure or a spigot structure.

[0046] (Variation 2) The molten metal in the above-described embodiment is assumed to consist solely of a liquid phase above the melting point of the metal, but the present invention is not limited to this. For example, the molten metal may be a metal that has been semi-solidified by cooling a molten metal consisting solely of a liquid phase, or may be a metal that has been semi-molten in a solid-liquid coexistence state by heating a solid metal to generate a liquid phase. In the present invention, the molten metal refers to both a molten metal consisting solely of a liquid phase and a metal that has been semi-solidified.

[0047] (Variation 3) Although the injection device 14 in the above-described embodiment is assumed to be hydraulically driven, the present invention is not limited to this. For example, the injection device 14 may be configured as an electric cylinder driven by a motor. Since this allows for higher plunger operation accuracy compared to a hydraulic cylinder, it is preferable to apply the present invention to a die-casting machine 10 that can vary the injection pressure P more stably.

[0048] (Variation 4) Although the die-casting machine 10 is configured as a horizontal type in the above example, the present invention is not limited to this. In the present invention, the die-casting machine 10 may be configured as a vertical type.

[0049] (Variation 5) In this embodiment, the mold opening force Y is changed in two steps as shown in (2) to (6) of Fig. 2, but the mold opening force Y in (3) to (5) of Fig. 2 is the minimum number of steps of mold opening force in the present invention. In other words, the mold opening force may be changed by varying the injection pressure P (P') in three or four or more steps.

[0050] (Variation 6) Furthermore, the present invention can also be applied to a multi-cavity mold having multiple cavities in one mold. In the case of a multi-cavity mold, there is variation in the timing of gate closure for each gate, and conventional methods of applying pressure only with an injection plunger result in variation in the feeder effect, which in turn results in variation in internal quality. However, as described above, in the present invention, the clamping force X' or X (compression force) is always applied from the movable mold 32 and the fixed mold 30, and the feeder effect is obtained even after the gates are closed, so the present invention is also suitable for a multi-cavity mold.

[0051] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0052] 10...Die casting machine, 12...Mold clamping device, 14...Injection device, 15...Control device, 16...Machine base, 18...Fixed platen, 20...Moveable platen, 22...Tailstock, 24...Tie bar, 26...Toggle mechanism, 28...Mold, 30...Fixed mold, 31...Mold clamping drive mechanism, 32...Movable mold, 34...Cavity, 36...Tie bar insertion hole, 38...Injection mechanism, 40...Hydraulic operation mechanism, 42...Injection sleeve, 44...Injection plunger, 46...Injection piston, 48...Injection cylinder, 50...Feed port O...hydraulic oil, P...injection pressure, X...mold clamping force, Y...mold opening force, Z...gate, W...gap

Claims

1. a mold consisting of a fixed mold and a movable mold; a cavity formed inside the mold; an injection plunger that injects and fills the cavity with molten metal; a mold clamping device that opens, closes, and clamps the movable mold relative to the fixed mold, The injection plunger is an injection pressure is set so that the mold opening force exerted on the movable mold by the molten metal injected into the cavity is equal to or smaller than the clamping force of the movable mold against the fixed mold set by the mold clamping device, and the molten metal is injected and filled in an amount equal to the volume of the cavity; Thereafter, the injection pressure is set so that the mold opening force is greater than the mold clamping force, and the molten metal is injected and filled in an amount that exceeds the volume of the cavity. Die casting machine.

2. The injection plunger injects and fills the molten metal in an amount equal to the volume of the cavity, and then, in a state in which a chill layer of the molten metal is formed on the surface of the cavity, increases the injection pressure to inject and fill the molten metal in an amount exceeding the volume of the cavity. The die casting machine according to claim 1 .

3. a mold consisting of a fixed mold and a movable mold; a cavity formed inside the mold; an injection plunger that injects and fills the cavity with molten metal; a die-casting method using a die-casting machine including a die-clamping device that opens, closes, and clamps the movable die relative to the fixed die, The injection plunger, The injection pressure is set so that the mold opening force of the molten metal injected into the cavity on the movable mold is equal to or smaller than the mold clamping force set on the movable mold relative to the fixed mold by the mold clamping device, and the molten metal is injected and filled in an amount equal to the volume of the cavity, and thereafter The injection pressure is set so that the mold opening force is greater than the mold clamping force, and the molten metal is injected and filled in an amount that exceeds the volume of the cavity. Die casting method using a die casting machine.

4. After the molten metal is injected and filled in an amount equal to the volume of the cavity, a chill layer of the molten metal is formed on the surface of the cavity, and then the injection pressure is increased to inject and fill the molten metal in an amount exceeding the volume of the cavity. A die casting method using the die casting machine according to claim 3.

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