Die casting machine, and die casting method using a die casting machine

Abstract

To provide a die-casting machine that maximizes the riser effect and improves the thickness and internal quality of the cast product. [Solution] The die-casting machine 10 consists of an injection plunger 44 for injecting and filling molten metal into the cavity 34, a clamping device 12 for clamping the movable mold 32, and a clamping force measuring device 27. Furthermore, the injection plunger 44 sets the casting pressure P so that the mold opening force Y on the movable mold 32 due to the molten metal is less than or equal to the clamping force X, and injects and fills the cavity 34 with an amount of molten metal equal to the volume of the cavity 34. Then, the casting pressure P is set so that the mold opening force Y is greater than the clamping force X, and an amount of molten metal exceeding the volume of the cavity 34 is injected. The clamping device 12 adjusts the initial clamping force so that the amount of molten metal supplied, calculated from the clamping force increase, which is the difference between the maximum clamping force and the initial clamping force, is equal to the solidification shrinkage amount, calculated from the clamping force decrease, which is the difference between the maximum clamping force and the clamping force after compression.

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 a die-casting method using the die-casting machine.

Background Art

[0002] In a conventionally used die-casting machine, molten metal such as an aluminum alloy melted in a melting furnace is measured and lifted by a ladle for each shot, the lifted molten metal is fed to the water inlet of an injection sleeve, and the molten metal is injected and filled into the cavity of the mold by the forward movement of an injection plunger provided to be movable forward and backward in the injection sleeve, thereby casting a casting. [

[0003] Generally, in the die-casting method using a die-casting machine, when the molten metal filled in the cavity is pressurized by the injection plunger, a force (mold-opening force) acts in the direction of opening the mold according to Pascal's principle. When mold opening occurs, casting defects and flash occur, so generally the force for clamping the mold (mold-clamping force) is set larger than the mold-opening force.

[0004] As defects of castings by the die-casting method using a die-casting machine, shrinkage cavities (solidification shrinkage cavities) generated when the volume of the molten metal filled in the cavity shrinks and solidifies are known. Castings with such defects are inferior in mechanical properties. Therefore, generally, after filling, a method is taken to reduce defects by replenishing the volume by which the molten metal has shrunk by pressurization from the injection plunger (pushing effect) (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems 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. As a result, the gate, which is the inlet to the cavity, is quite narrow and thin, causing the metal to solidify immediately after filling. Consequently, the supply of molten metal to compensate for the volume contraction due to pressure from the injection plunger is interrupted, resulting in the problem of not being able to obtain a sufficient riser effect.

[0007] This invention has been made in view of the above problems, and its purpose is to provide a die-casting machine and a die-casting method using a die-casting machine that can obtain a riser effect even after solidification has progressed and the gate has closed, and furthermore, can improve the internal quality of the casting by maximizing this riser effect, and can also make the thickness of the casting appropriate. [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, The cavity formed inside the mold, An injection plunger for injecting and filling the cavity with molten metal, A clamping device that opens and closes the movable mold relative to the fixed mold and clamps it, The system includes a clamping force measuring device for measuring the clamping force of the movable mold relative to the fixed mold. The injection plunger is, The casting pressure is set such that the initial clamping force of the movable mold relative to the fixed mold by the clamping device is equal to or less than the opening force of the movable mold caused by the molten metal injected into the cavity, and an amount of molten metal equal to the volume of the cavity is injected and filled. Thereafter, the casting pressure is set such that the mold opening force is greater than the mold clamping force, and an amount of molten metal exceeding the volume of the cavity is injected and filled. The clamping force measuring device is, The initial clamping force before the injection plunger injects and fills the cavity with an amount of molten metal equal to the volume of the cavity is measured, The maximum clamping force when the plunger injects and fills the cavity with an amount of molten metal exceeding its volume is measured, and the difference between the maximum clamping force and the initial clamping force is defined as the increase in clamping force. Furthermore, The clamping force after compression is measured at the stage when the solidification shrinkage of the molten metal is completed, and the difference between the maximum clamping force and the clamping force after compression is defined as the clamping force reduction. The clamping device is, The initial clamping force is adjusted so that the amount of molten metal supplied, calculated from the increase in clamping force, is equal to the amount of solidification shrinkage, calculated from the decrease in clamping force. A die-casting machine will be provided.

[0009] According to another aspect of the present invention, A mold consisting of a fixed mold and a movable mold, The cavity formed inside the mold, An injection plunger for injecting and filling the cavity with molten metal, A clamping device that opens and closes the movable mold relative to the fixed mold and clamps it, A die-casting method using a die-casting machine equipped with a clamping force measuring device for measuring the clamping force of the movable mold relative to the fixed mold, In the injection plunger, The casting pressure is set such that the initial clamping force of the movable mold relative to the fixed mold by the clamping device is equal to or less than the opening force of the movable mold caused by the molten metal injected into the cavity, and an amount of molten metal equal to the volume of the cavity is injected and filled. Thereafter, the casting pressure is set such that the mold opening force is greater than the mold clamping force, and an amount of molten metal exceeding the volume of the cavity is injected and filled. In the aforementioned clamping force measuring device, The initial clamping force before the injection plunger injects and fills the cavity with an amount of molten metal equal to the volume of the cavity is measured, Measure the maximum clamping force when the injection plunger injects and fills the cavity with an amount of molten metal exceeding the volume of the cavity, and use the difference between the maximum clamping force and the initial clamping force as the amount of increase in the clamping force. Further, Measure the clamping force after compression at the stage when the solidification shrinkage of the molten metal has ended, and use the difference between the maximum clamping force and the clamping force after compression as the amount of decrease in the clamping force. With the clamping device, Adjust the initial clamping force so that the amount of molten metal replenishment calculated from the amount of increase in the clamping force is equal to the amount of solidification shrinkage calculated from the amount of decrease in the clamping force. A die-casting method using a die-casting machine is provided.

Advantages of the Invention

[0010] According to the die-casting machine and the die-casting method using the die-casting machine according to the present invention, even after solidification progresses and the gate is closed, a pushing effect of the molten metal can be obtained. Further, with the clamping device, by adjusting the initial clamping force so that the amount of molten metal replenishment calculated from the amount of increase in the clamping force is equal to the amount of solidification shrinkage calculated from the amount of decrease in the clamping force, it is possible to avoid the thickness of the cast product from becoming too thick and also avoid the molten metal from replenishing the solidification shrinkage and causing shrinkage cavities. Therefore, the internal quality of the cast product can also be improved.

Brief Description of the Drawings

[0011] [Figure 1] It is a diagram showing an example of a die-casting machine 10 according to an embodiment. [Figure 2] It is a graph showing changes in the casting pressure P (P'), the clamping force X (X'), and the mold opening force Y in the casting process using the die-casting machine 10. [Figure 3] It is a diagram showing the state of the mold 28 and the molten metal in the casting process using the die-casting machine 10, showing the state where the molten metal is injected and filled into the cavity. [Figure 4] It is a diagram showing the state of the mold 28 and the molten metal in the casting process using the die-casting machine 10, showing the state where the movable mold 32 is separated from the fixed mold 30. [Figure 5]It is a diagram showing the state of the mold 28 and the molten metal in the casting process using the die-casting machine 10, showing the state where the movable mold 32 is separated from the fixed mold 30 and the gate is closed. [Figure 6] It is a diagram showing the state of the mold 28 and the molten metal in the casting process using the die-casting machine 10, showing the state where the gap between the fixed mold 30 and the movable mold 32 has changed and the solidification of the molten metal has completed.

Mode for Carrying Out the Invention

[0012] (Configuration of Die-Casting Machine 10) As shown in FIG. 1, the die-casting machine 10 according to the present embodiment generally includes a clamping device 12, an injection device 14, and a control device 15.

[0013] The clamping device 12 includes a machine base 16, a fixed platen 18, a movable platen 20, a tailstock 22, a tie bar 24, a toggle mechanism 26, and a clamping force measuring device 27.

[0014] The machine base 16 is a member that constitutes the clamping device 12 and other members, and is a base member for the injection device 14.

[0015] The fixed platen 18 is fixed on the machine base 16, and the fixed mold 30 that constitutes the mold 28 is attached thereto.

[0016] The movable platen 20 is a member that slides on the machine base 16 so as to approach and separate from the fixed platen 18, and the movable mold 32 that constitutes the mold 28 is attached thereto. When the movable mold 32 contacts the fixed mold 30, a cavity 34 into which the molten metal is filled is formed.

[0017] The tailstock 22 is a member placed on the machine base 16 on the side opposite to the fixed platen 18 when viewed from the movable platen 20.

[0018] The tie bar 24 is a round bar-shaped member with one end fixed to the fixed platen 18 and the other end fixed to the tailstock 22. The tie bar 24 is inserted through a tie bar insertion hole 36 formed in the movable platen 20, which is positioned between the fixed platen 18 and the tailstock 22. This allows the movable platen 20 to slide along the tie bar 24 on the machine base 16 in the left-right direction in the figure. Note that multiple tie bars 24 (for example, four) are used.

[0019] The toggle mechanism 26 is a mechanism for moving the movable platen 20 closer to, further away from, and holding the fixed platen 18, and the clamping drive mechanism 31 is attached to the tailstock 22.

[0020] The clamping force measuring device 27 is a device for measuring the clamping force X of the movable mold 32 relative to the fixed mold 30. For example, it could be attached to a tie bar 24 and measure the clamping force X based on the amount of strain (elongation) when the tie bar 24 is extended. Of course, the measurement method is not limited as long as it is possible to measure the clamping force X of the movable mold 32 relative to the fixed mold 30.

[0021] The movable platen 20 moves along the tie bar 24 (moves left to 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 to the left, the fixed mold 30 and the movable mold 32 are separated. On the other hand, when the movable platen 20 moves to the right, the fixed mold 30 and the movable mold 32 come into contact, forming a cavity (internal space) 34 inside the mold 28. When further pressure is applied in the direction that moves the movable platen 20 to the right, the fixed mold 30 and the movable mold 32 are clamped together.

[0022] 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 bar 24 begins to extend, and strain proportional to the tensile stress is generated in the tie bar 24. The tension in the tie bar 24 is applied to the fixed mold 30 and the movable mold 32 as a clamping force. When the toggle mechanism 26 is fully extended, the tie bar 24 is also fully extended, and when the movable mold 32 reaches the position where the clamping is complete, a specified clamping force is applied to the fixed mold 30 and the movable mold 32.

[0023] The injection device 14 generally comprises an injection mechanism 38 and a hydraulic operating mechanism 40.

[0024] The injection mechanism 38 includes an injection sleeve 42, an injection plunger 44, an injection piston 46, and an injection cylinder 48.

[0025] The injection sleeve 42 is a cylindrical member integrally provided with the fixed platen 18, with a molten metal inlet 50 formed at its upper part.

[0026] The injection plunger 44 is a roughly rod-shaped member that is provided to move back and forth within the injection sleeve 42.

[0027] The injection piston 46 is formed on the rear end side of the injection plunger 44 (the end opposite to the end that contacts the molten metal) and is the part that is pressed by the hydraulic fluid O.

[0028] The injection cylinder 48 is a cylindrical member through which the injection piston 46 moves back and forth, and is filled with hydraulic fluid O.

[0029] The hydraulic operating mechanism 40 is a mechanism that supplies hydraulic fluid 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 pressurized oil to the injection cylinder 48, a force (casting pressure P) in the forward direction shown on the left in the figure is applied to the injection plunger 44.

[0030] The control device 15, in order to perform the injection process and the return process of the injection plunger 44, detects the position information of the injection piston 46 and operates the hydraulic operating mechanism 40, as well as performing all the necessary controls for casting by the die-casting machine 10.

[0031] (Casting process of 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 explained with reference to Figures 2 to 6. Figure 2 is a graph showing the changes in clamping force X, mold opening force Y, and casting pressure P throughout the entire casting process using the die-casting machine 10, so it should be referred to throughout the entire casting process.

[0032] The control device 15 operates the clamping drive mechanism 31 of the clamping device 12 to close the movable mold 32 against the fixed mold 30, and then clamps the mold with a predetermined initial clamping force X (Figure 2(1)). The clamping force measured at this time by the clamping force measuring device 27 is called the "initial clamping force".

[0033] Subsequently, the control device 15 injects and fills the cavity 34 of the mold 28 by advancing the injection plunger 44 (Figure 3). At this time, the control device 15 sets the casting pressure P such that the opening force Y on the movable mold 32 due to the molten metal injected into the cavity 34 is equal to or smaller than the clamping force X of the movable mold 32 relative to the fixed mold 30, thereby injecting and filling approximately the same amount of molten metal as the volume of the cavity 34 (Figure 2(2)).

[0034] After injecting and filling the cavity 34 with molten metal in an amount approximately equal to its volume, the control device 15 forms a chill layer on the surface of the cavity 34 (Figure 2(2)-(3)), then increases the casting pressure P to advance the injection plunger 44, injecting and filling the cavity 34 with an amount of molten metal exceeding its volume (Figure 2(3)).

[0035] When the mold opening force Y is less than or equal to the clamping force X (Y ≤ X), the injection plunger 44 cannot be advanced towards the cavity 34. However, when the casting pressure P is increased (let's call the increased casting pressure "casting pressure P'") and the mold opening force Y becomes greater than the clamping force X (Y > X), the injection plunger 44 can advance and inject and fill an amount of molten metal exceeding the volume of the cavity 34.

[0036] Furthermore, since the mold opening force Y is greater than the clamping force X, the movable mold 32 and movable platen 20 move slightly away from the fixed mold 30 due to the mold opening force Y, as shown in Figure 4 (Figure 2 (3)). This separation is not due to the bending of the toggle mechanism 26, but to the elongation due to the elastic deformation of the tie bar 24. When the tie bar 24 elongates, the clamping force X increases by the amount of elongation (the increased clamping force is called "clamping force X'"). The mold opening force Y due to the casting pressure P' through the molten metal causes the tie bar 24 to elongate by a predetermined length, and the clamping force X' rises until it becomes equal to the mold opening force Y. Thus, when the clamping force X' becomes equal to the mold opening force Y (Y=X'), the separation of the movable mold 32 and movable platen 20 stops (Figure 2 (4)). The clamping force X' measured at this time by the clamping force measuring device 27 is called the "maximum clamping force".

[0037] At this stage, the control device 15 calculates the difference between the "maximum clamping force" and the "initial clamping force" measured by the clamping force measuring device 27, and defines this difference as the "clamping force increase."

[0038] Here, the separation distance between the fixed mold 30 and the movable mold 32 can be expressed as "the elongation of the tie bar 24 × a coefficient (which is determined in advance through experiments, etc.)". The "elongation of the tie bar 24" can be calculated from the "amount of increase in clamping force" measured by the clamping force measuring device 27. Thus, the "separation distance" between the fixed mold 30 and the movable mold 32 can be determined from the "amount of increase in clamping force". The control device 15 then calculates the "elongation of the tie bar 24" from the calculated "amount of increase in clamping force", and further calculates the "separation distance" between the fixed mold 30 and the movable mold 32.

[0039] Then, once the "separation distance" between the movable mold 32 and the fixed mold 30 is known, the "molten metal supply amount" that can be secured can be calculated by multiplying this "separation distance" by the projected area of ​​the product portion of the cavity 34 (the "K" portion in Figure 4). The control device 15 then calculates the "molten metal supply amount" by multiplying the calculated "separation distance" by the projected area.

[0040] The chill layer (cooled and solidified film layer) mentioned above is a metallic structure formed when molten metal comes into contact with the surface of cavity 34 and is rapidly cooled. The chill layer formed on the surface of a casting is known to be beneficial in improving the strength of die-cast products because its metallic structure is fine and dense.

[0041] When the movable mold 32 separates from the fixed mold 30 and a gap W is created between them at the mold dividing surface, there is a concern that molten metal may flow into this gap, causing casting burrs and flash. 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 the casting pressure P'. Therefore, the chill layer on the surface of the cavity 34 acts as a lid on the gap W, preventing the remaining unsolidified molten metal from leaking out of the gap W. In other words, at the timing of "advancing the injection plunger 44 by the casting 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.

[0042] After the separation of the movable mold 32 and the movable platen 20 from the fixed mold 30 stops, the injection plunger 44 also stops (Figure 2 (4) to (5)). Then, as shown in Figure 5, the solidification of the molten metal at the gate G proceeds first, and the gate G closes (Figure 2 (5) to (6)). As a result, the pressurization and supply of molten metal from the injection plunger 44 to the cavity 34 is cut off, and the pushing effect of the injection plunger 44 ceases thereafter.

[0043] Because the gate G is blocked, even if the injection plunger 44 pressurizes the molten metal filling the cavity 34, the mold opening force Y according to Pascal's principle does not act on it. Also, as the molten metal begins to cool, it simultaneously begins to solidify and shrink, so the mold opening force Y, which had been kept constant, begins to decrease rapidly (Figure 2 (5)~(6)). On the other hand, since the tie bar 24 is extended in advance, as the mold opening force Y decreases, the tie bar 24 shrinks, causing the movable mold 32 and movable platen 20 to move closer to the fixed mold 30. However, since the molten metal in the cavity 34 (some of which is solidified, but this solidified portion is also included and 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 move closer in accordance with the volume reduction due to the solidification shrinkage of the molten metal. Therefore, the molten metal is constantly subjected to a clamping force X' or X (compressive force) 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, molten metal is supplied that is pre-filled in a quantity greater than the volume of the cavity 34 (= "molten metal supply amount"). As the tie bar 24 shrinks during the molten metal supply process, the clamping force X' or X decreases (Figure 2 (5)~(7)).

[0044] Then, as shown in Figure 6, once the solidification of the molten metal in the cavity 34 is complete, a gap W' narrower than the gap W at (4) to (5) in Figure 2 exists between the fixed mold 30 and the movable mold 32. In this way, a clamping force X' or X (compressive force) is constantly applied from the movable mold 32 and the fixed mold 30 until the solidification of the molten metal in the cavity 34 is complete, so that pressure can be continuously generated in the molten metal, and a riser effect can be obtained even after the gate is closed. This is shown by the fact that the clamping force at (7) to (8) in Figure 2 is greater than the clamping force X at (1) when clamping is complete.

[0045] Once the solidification of the molten metal in the cavity 34 is complete, the clamping force X measured by the clamping force measuring device 27 is called the "compression clamping force". The control device 15 then calculates the difference between the "maximum clamping force" measured by the clamping force measuring device 27 and the "compression clamping force" and defines this as the "clamping force reduction amount".

[0046] As described above, the "elongation of the tie bar 24" can be calculated from the calculated "increase in clamping force," and further, the "separation distance" of the movable mold 32 from the fixed mold 30 can be calculated. Therefore, the "contraction of the tie bar 24" can be calculated from the "decrease in clamping force," and further, the "approach distance" of the movable mold 32 relative to the fixed mold 30 can be calculated.

[0047] Once this "approach distance" is known, the "solidification shrinkage amount," which is the amount of shrinkage (= amount of molten metal supplied) before the molten metal solidifies, can be calculated by multiplying this "approach distance" by the projected area of ​​the product portion of the cavity 34 (the "K" portion in Figure 4). The control device 15 then calculates the "solidification shrinkage amount" by multiplying the "approach distance" calculated from the "clamping force reduction amount" by the projected area.

[0048] Then, 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) (Figure 2 (8)), and the casting is removed from the cavity 34 using an ejector pin or the like (not shown). This completes the casting of the product by the die casting machine 10.

[0049] As explained above, the die-casting machine 10 according to this embodiment is capable of calculating the "molten metal supply amount" and the "solidification shrinkage amount" based on the clamping force X measured by the clamping force measuring device 27. The ideal state is when the "molten metal supply amount" and the "solidification shrinkage amount" are equal. If the "molten metal supply amount" is greater than the "solidification shrinkage amount," the excess molten metal will increase the thickness of the finished casting. Conversely, if the "molten metal supply amount" is less than the "solidification shrinkage amount," the supply of molten metal to compensate for the solidification shrinkage will be insufficient, resulting in shrinkage cavities within the finished casting.

[0050] Here, assuming the movement of the casting pressure P by the injection plunger 44 is the same, the "molten metal supply amount" can be changed by changing the initial clamping force of the clamping device 12. For example, if the initial clamping force is lowered, the "amount of increase in clamping force" when the injection plunger 44 increases the casting pressure to P' increases, and thus the "molten metal supply amount" increases. Therefore, if the "molten metal supply amount" is less than the "amount of solidification shrinkage", the initial clamping force of the clamping device 12 will be adjusted to be lower.

[0051] Conversely, increasing the initial clamping force reduces the "amount of increase in clamping force" when the injection plunger 44 increases the casting pressure to P', thus reducing the "amount of molten metal supplied". Therefore, if the "amount of molten metal supplied" is greater than the "amount of solidification shrinkage", the clamping device 12 will be adjusted to increase the initial clamping force.

[0052] Thus, in the die-casting machine 10 according to this embodiment, the riser effect can be obtained even after solidification has progressed and the gate G has closed. Furthermore, by adjusting the initial clamping force of the clamping device 12 so that the "molten metal supply amount" calculated from the increase in clamping force is equal to the "solidification shrinkage amount" calculated from the decrease in clamping force, it is possible to avoid the casting becoming too thick while also preventing the formation of shrinkage cavities by supplying the solidification shrinkage amount with molten metal, thereby improving the internal quality of the casting.

[0053] (Variation 1) The fixed mold 30 and movable mold 32 in the above-described embodiment show an example where the mold dividing surface is flat to the periphery, but the present invention is not limited to this, and a shear edge structure can be adopted. A shear edge structure refers to a fitting structure formed between the fixed mold 30 and the movable mold 32 that can be inserted and removed from each other while sliding against each other. By adopting a shear edge structure, it is effective in preventing the molten metal injected into the cavity 34 from leaking out of the mold. In particular, in the present invention, the effect of preventing molten metal leakage by adopting a shear edge structure allows for further widening of the gap W (further extending the tie bar 24), so the riser effect can be made more pronounced by increasing the clamping force X applied to the molten metal and increasing the amount of molten metal supplied. A shear edge structure is also called a spigot structure or a spigot structure.

[0054] (Modification 2) The molten metal in the embodiments described above is assumed to consist only of a liquid phase above the melting point of the metal, but the present invention is not limited to this. For example, the present invention can apply to metals that have been cooled from a molten metal consisting only of a liquid phase to a semi-solid state, or to metals that have been heated in a solid phase to generate a liquid phase, resulting in a semi-molten state with both solid and liquid components. In the present invention, molten metal consisting only of a liquid phase and metals in a semi-solid state are collectively referred to as molten metal.

[0055] (Variation 3) The injection device 14 in the above-described embodiment is assumed to be operated by hydraulic drive, but the present invention is not limited thereto. For example, the injection device 14 may be configured as an electric cylinder driven by a motor. Since it is possible to achieve higher operating precision of the plunger compared to a hydraulic cylinder, it is preferable to apply the present invention to a die-casting machine 10 that provides a more stable variable casting pressure P.

[0056] (Modification 4) Although an example of a die-casting machine 10 configured horizontally has been shown, the present invention is not limited to this. In the present invention, the die-casting machine 10 may also be configured vertically.

[0057] (Variation 5) In this embodiment, the mold opening force Y change process shown in Figures 2(2) to (6) is shown as a two-stage example, but the mold opening force Y in Figures 2(3) to (5) is the minimum number of stages for mold opening force in the present invention. In other words, the mold opening force Y may be changed by varying the casting pressure P(P') in three or four or more stages.

[0058] (Experimental variation 6) Furthermore, the present invention can also be applied to multi-cavity molds that have multiple cavities in a single mold. In the case of multi-cavity molds, there is variation in the timing of closing each gate G, and conventional methods using only pressurization by an injection plunger result in variations in the riser effect, leading to variations in internal quality. However, as described above, in the present invention, a clamping force X' or X (compression force) is always applied from the movable mold 32 and the fixed mold 30, and a riser effect is obtained even after the gate G has closed, so the present invention is also suitable for multi-cavity molds.

[0059] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0060] 10…Die casting machine, 12…Clamping device, 14…Injection device, 15…Control device, 16…Machine stand, 18…Fixed platen, 20…Movable platen, 22…Tailstock, 24…Tie bar, 26…Toggle mechanism, 27…Clamping force measuring device, 28…Mold, 30…Fixed mold, 31…Clamping drive mechanism, 32…Movable mold, 34…Cavity, 36…Tie bar insertion hole, 38…Injection mechanism, 40…Hydraulic operating mechanism, 42…Injection sleeve, 44…Injection plunger, 46…Injection piston, 48…Injection cylinder, 50…Hot water inlet O...hydraulic fluid, P...casting pressure, Q...mold pressure, X...clamping force, Y...mold opening force, G...gate, W...gap

Claims

1. A mold consisting of a fixed mold and a movable mold, The cavity formed inside the mold, An injection plunger for injecting and filling the cavity with molten metal, A clamping device that opens and closes the movable mold relative to the fixed mold and clamps it, The system includes a clamping force measuring device for measuring the clamping force of the movable mold relative to the fixed mold. The injection plunger is, The casting pressure is set such that the initial clamping force of the movable mold relative to the fixed mold by the clamping device is equal to or less than the opening force on the movable mold caused by the molten metal injected into the cavity, and an amount of molten metal equal to the volume of the cavity is injected and filled. Thereafter, the casting pressure is set such that the mold opening force is greater than the mold clamping force, and an amount of molten metal exceeding the volume of the cavity is injected and filled. The clamping force measuring device is, The initial clamping force before the injection plunger injects and fills the cavity with an amount of molten metal equal to the volume of the cavity is measured, The maximum clamping force when the injection plunger injects and fills the cavity with an amount of molten metal exceeding its volume is measured, and the difference between the maximum clamping force and the initial clamping force is defined as the increase in clamping force. Furthermore, The clamping force after compression is measured at the stage when the solidification shrinkage of the molten metal is completed, and the difference between the maximum clamping force and the clamping force after compression is defined as the clamping force reduction. The clamping device is, The initial clamping force is adjusted so that the amount of molten metal supplied, calculated from the increase in clamping force, is equal to the amount of solidification shrinkage, calculated from the decrease in clamping force. Die-casting machine.

2. A mold consisting of a fixed mold and a movable mold, The cavity formed inside the mold, An injection plunger for injecting and filling the cavity with molten metal, A clamping device that opens and closes the movable mold relative to the fixed mold and clamps it, A die-casting method using a die-casting machine equipped with a clamping force measuring device for measuring the clamping force of the movable mold relative to the fixed mold, In the injection plunger, The casting pressure is set such that the initial clamping force of the movable mold relative to the fixed mold by the clamping device is equal to or less than the opening force on the movable mold caused by the molten metal injected into the cavity, and an amount of molten metal equal to the volume of the cavity is injected and filled. Thereafter, the casting pressure is set such that the mold opening force is greater than the mold clamping force, and an amount of molten metal exceeding the volume of the cavity is injected and filled. In the aforementioned clamping force measuring device, The initial clamping force before the injection plunger injects and fills the cavity with an amount of molten metal equal to the volume of the cavity is measured, The maximum clamping force when the injection plunger injects and fills the cavity with an amount of molten metal exceeding its volume is measured, and the difference between the maximum clamping force and the initial clamping force is defined as the increase in clamping force. Furthermore, The clamping force after compression is measured at the stage when the solidification shrinkage of the molten metal is completed, and the difference between the maximum clamping force and the clamping force after compression is defined as the clamping force reduction. In the aforementioned clamping device, The initial clamping force is adjusted so that the amount of molten metal supplied, calculated from the increase in clamping force, is equal to the amount of solidification shrinkage, calculated from the decrease in clamping force. Die casting method using a die casting machine.

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