Degassing structure of mold

Abstract

To make a product molding cycle into a high cycle.SOLUTION: A degassing structure of a mold 10 includes a degassing passage 20 formed between a parting plane 11a of a fixation mold 11 and a parting plane 12a of a movable mold 12 and communicating with a cavity 17. A fitting part 60 is provided between the parting plane 11a of the fixation mold 11 and the parting plane 12a of the movable mold 12, the fitting part 60 composed of a fitting projection 61 and a fitting recess 62 capable of fitting to each other so as to make a creepage distance between the degassing passage 20 and the outside long. Jetting out of molten metal from the parting plane 11a of the fixation mold 11 and the parting plane 12a of the movable mold 12 in a peripheral part of the degassing passage 20 is suppressed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a venting structure for a mold, and more particularly to a venting structure for discharging gas from a cavity during molding in a die-casting mold or an injection molding mold. [Background technology]

[0002] A conventional gas venting structure for an injection molding machine is described in Patent Document 1. This gas venting structure is configured with a chill vent consisting of a box-shaped case equipped with a cooling chamber through which cooling water can flow and a cooling plate equipped in the case, with the surfaces of the cooling plates facing each other. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-212693 Summary of the Invention [Problem to be solved by the invention]

[0004] When trying to shorten the time required for one molding cycle, such as casting, shortening the cooling time of the mold itself is an effective way to do this. However, as the temperature difference between the periphery of the cavity in the mold and the periphery of the gas vent passage increases, mold deformation increases, making it easier for molten metal to spray out from the mold parting surface. This makes it difficult to increase the product molding cycle (shortening the time required for one molding cycle).

[0005] The problem that the technology disclosed in this specification aims to solve is to increase the product molding cycle. [Means for solving the problem]

[0006] In order to solve the above problems, the technology disclosed in this specification takes the following measures.

[0007] The first means is a venting structure for a mold, which has a venting passage formed between the parting surface of the fixed mold and the parting surface of the movable mold of the mold and which communicates with the cavity, and between the parting surface of the fixed mold and the parting surface of the movable mold, there is provided a fitting portion consisting of a fitting convex portion and a fitting concave portion which can be fitted together to increase the surface distance between the venting passage and the outside.

[0008] According to the first aspect, the engagement between the convex and concave fitting portions of the fitting portion provided between the parting surfaces of the fixed mold and the parting surface of the movable mold can lengthen the creepage distance between the vent passage and the outside. This makes it possible to suppress the molten metal from spraying out from between the parting surfaces of the fixed mold and the movable mold around the vent passage of the mold. This allows for a high-speed product molding cycle.

[0009] The second means is the venting structure of the mold of the first means, in which the fitting portion has a shape that surrounds the venting passage.

[0010] According to the second means, a fitting portion having a shape that surrounds the vent passage can more effectively suppress the ejection of molten metal from between the parting surfaces of the fixed mold and the movable mold in the peripheral area of ​​the vent passage of the mold, compared to a fitting portion having a shape that does not surround the vent passage.

[0011] The third means is a venting structure for a mold according to the first or second means, in which at least one of the fixed mold and the movable mold is provided with a cooling passage adjacent to the venting passage and through which a cooling fluid flows.

[0012] According to the third aspect, the cooling fluid flowing through the cooling passage cools the periphery of the degassing passage, thereby accelerating the solidification of the molten metal that has reached the degassing passage, thereby effectively suppressing the molten metal from spraying out from between the parting surfaces of the fixed mold and the movable mold in the periphery of the degassing passage of the mold.

[0013] The fourth means is a venting structure for a mold of the first or second means, which is provided with an extrusion pin that extrudes the excess portion that has solidified in the venting passage, and a boss forming hole that integrally forms a boss portion on the excess portion is formed on the tip surface of the extrusion pin.

[0014] According to the fourth aspect, a boss is integrally formed in the excess portion through the boss-forming hole of the ejector pin. This prevents the excess portion from falling by maintaining the boss of the excess portion engaged with the boss-forming hole of the ejector pin when the excess portion is pushed out by the ejector pin. In other words, by holding an intermediate product including the excess portion on the ejector pin, the intermediate product can be easily grasped by a robot hand. This allows for a high-speed product molding cycle. [Effects of the Invention]

[0015] According to the technology disclosed in this specification, the product molding cycle can be increased. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 2 is a cross-sectional view showing a gas venting structure of a mold according to one embodiment. [Figure 2] FIG. 10 is a cross-sectional view showing the gas vent structure in a state where the molten metal has been completely filled. [Figure 3] FIG. 10 is a cross-sectional view showing the gas vent structure in a state where the excess portion is extruded. [Figure 4] FIG. 10 is a diagram showing a dividing surface of a fixed mold. [Figure 5] FIG. 2 is a cross-sectional view taken along the line VV in FIG. [Figure 6] FIG. 10 is a diagram showing a dividing surface of a movable mold. [Figure 7] FIG. 7 is a cross-sectional view taken along the line VII-VII in FIG. [Figure 8] FIG. 10 is a perspective view showing an excess portion of the intermediate product. DETAILED DESCRIPTION OF THE INVENTION

[0017] An embodiment for carrying out the technology disclosed in this specification will be described below with reference to the drawings. In this embodiment, a venting structure for a die-casting mold is illustrated. FIG. 1 is a cross-sectional view showing the venting structure for the mold. For convenience of explanation, the up, down, left, and right directions are determined based on FIG. 1.

[0018] (Outline of mold gas venting structure) As shown in Figure 1, the mold 10 includes a fixed mold 11 and a movable mold 12. A venting passage 20 is formed between a parting surface 11a of the fixed mold 11 and a parting surface 12a of the movable mold 12. The venting passage 20 is connected to a cavity 17 for molding a product. The venting passage 20 is located above the cavity 17.

[0019] The gas vent passage 20 has a pressure-receiving chamber 21, an exhaust chamber 23, and a bypass passage 22. The pressure-receiving chamber 21 is formed between the dividing surface 11a of the fixed mold 11 and the dividing surface 12a of the movable mold 12 in the shape of a hollow short cylinder with its axial direction extending in the left-right direction. The left wall surface 21a of the pressure-receiving chamber 21 is formed as an inclined surface that shortens the axial length of the pressure-receiving chamber 21 from bottom to top. The volume of the pressure-receiving chamber 21 increases as the pressure-receiving pin 30 moves backward (see Figure 2).

[0020] The exhaust chamber 23 is disposed above the pressure-receiving chamber 21. The exhaust chamber 23 is formed in the shape of a hollow short cylinder with its axial direction extending in the left-right direction between the dividing surface 11a of the fixed mold 11 and the dividing surface 12a of the movable mold 12. The volume of the exhaust chamber 23 increases as the shut-off pin 40 retracts (see FIG. 2).

[0021] Fig. 4 is a diagram showing the dividing surface 11a of the fixed mold 11, and Fig. 6 is a diagram showing the dividing surface 12a of the movable mold 12. As shown in Fig. 4, two bypass paths 22 are arranged symmetrically about a straight line L connecting the center of the pressure receiving chamber 21 and the center of the exhaust chamber 23. The two bypass paths 22 branch off from the pressure receiving chamber 21, bypass the pressure receiving chamber 21 and the exhaust chamber 23, and merge into the exhaust chamber 23.

[0022] The detour path 22 is divided between the dividing surface 11a of the fixed mold 11 and the dividing surface 12a of the movable mold 12. The detour path 22 is divided into six passage sections 22a to 22f, numbered first to sixth, from the upstream side to the downstream side. A first passage section 22a, a third passage section 22c, and a fifth passage section 22e are each formed in a groove shape on the dividing surface 11a of the fixed mold 11. As shown in FIG. 6, a second passage section 22b, a fourth passage section 22d, and a sixth passage section 22f are each formed in a groove shape on the dividing surface 12a of the movable mold 12. In FIG. 4, the second passage section 22b, the fourth passage section 22d, and the sixth passage section 22f on the dividing surface 12a are indicated by two-dot chain lines. The first to sixth passage sections 22a to 22f form the detour path 22, which is continuous when the molds are closed.

[0023] 1, the movable mold 12 is formed with a hollow cylindrical first guide hole 13 that is coaxially connected to the pressure-receiving chamber 21 and a hollow cylindrical second guide hole 14 that is coaxially connected to the exhaust chamber 23, and these holes are parallel to each other. The movable mold 12 is also formed with an exhaust port 15 that is perpendicular to the second guide hole 14 and connects the second guide hole 14 to the outside. A vacuum pump (not shown) is connected to the exhaust port 15.

[0024] A cylindrical pressure-receiving pin 30 is inserted into the first guide hole 13 so as to be slidable in the axial direction (mold opening / closing direction). A cylindrical shut-off pin 40 is inserted into the second guide hole 14 so as to be slidable in the axial direction (mold opening / closing direction).

[0025] At the end (tip portion) of shutoff pin 40 on the exhaust chamber 23 side, a valve portion 41, a two-face width portion 42, and a thin shaft portion 43 are formed from the tip to the base. When shutoff pin 40 is in the forward position (the position shown in FIG. 1), valve portion 41 is located within exhaust chamber 23, and the opening surface of second guide hole 14 on the exhaust chamber 23 side is open. In addition, thin shaft portion 43 is located at a position perpendicular to exhaust port 15, and a gap between second guide hole 14 and thin shaft portion 43 and exhaust port 15 are in communication. The gap between second guide hole 14 and width-across-flat portion 42 communicates the opening of second guide hole 14 on the exhaust chamber 23 side with the gap between second guide hole 14 and thin shaft portion 43. That is, exhaust chamber 23 and exhaust port 15 are in communication. When shut-off pin 40 retracts from the forward position, valve portion 41 closes the opening of second guide hole 14 on the exhaust chamber 23 side (see FIG. 2).

[0026] A connecting arm 32 is fitted onto the pressure-receiving pin 30. The connecting arm 32 is fixed by screwing a joint 34 onto the pressure-receiving pin 30. A cylindrical first pushing pin 36 is connected to the joint 34 so as to be movable within a predetermined range in the axial direction. The first pushing pin 36 is supported by the ejection plate 19 of the mold 10. The maximum movement distance between the joint 34 and the first pushing pin 36 is set to a distance S1.

[0027] A shut-off pin 40 is slidably inserted into the connecting arm 32. The shut-off pin 40 has a flange portion 45 against which the connecting arm 32 abuts when the pressure-receiving pin 30 retracts. A cylindrical second pushing pin 47 is connected to the shut-off pin 40 so as to be movable within a predetermined range in the axial direction. A spring (not shown) that urges the shut-off pin 40 forward (to the left in FIG. 1) is installed between the shut-off pin 40 and the second pushing pin 47. The second pushing pin 47 is supported by the ejection plate 19 of the mold 10. The maximum movement distance between the shut-off pin 40 and the second pushing pin 47 is set to a distance S2. The distance S2 is greater than the distance S1.

[0028] (Operation of the gas venting structure of the mold 10) Assume now that the pressure-receiving pin 30 and the shut-off pin 40 are both in their forward positions (original positions) (see FIG. 1). Also, the exhaust chamber 23 and the exhaust passage 15 are in communication. In this state, when molten metal is supplied to the cavity 17, the gas in the cavity 17 is sucked by the vacuum pump through the exhaust path including the gas vent passage 20 and the exhaust port 15 and is exhausted to the outside.

[0029] Furthermore, the molten metal that has filled the cavity 17 reaches the pressure-receiving chamber 21 of the gas vent passage 20 and flows into the exhaust chamber 23 via the bypass 22. At this time, the molten metal retracts the joint 34 of the pressure-receiving pin 30 until it abuts against the first pushing pin 36 (see FIG. 2). Accordingly, the flange portion 45 of the shut-off pin 40 is retracted (see the two-dot chain line 45 in FIG. 2) against the bias of the built-in spring via the connecting arm 32, and the valve portion 41 closes the exhaust chamber 23 (see the two-dot chain line 41 in FIG. 2). This prevents the molten metal from spraying out of the exhaust chamber 23.

[0030] Subsequently, the molten metal that reaches the exhaust chamber 23 moves the shut-off pin 40 backward until the flange portion 45 abuts against the second pushing pin 47 (see FIG. 2). The amount of movement of the shut-off pin 40 at this time is the difference S3 between the distance S2 and the distance S1.

[0031] After the molten metal has solidified, the mold is opened. At this time, as shown in Fig. 3, the pusher plate 19 moves the pressure-receiving pin 30 in the advancing direction via the first pushing pin 36 and the joint 34, and moves the shut-off pin 40 in the advancing direction via the second pushing pin 47. This causes the excess portion 52 that has solidified in the gas vent passage 20 to be pushed out. Also, the product portion 51 that has solidified in the cavity 17 is pushed out. This causes the intermediate product 50, which has the product portion 51 and the excess portion 52, to be removed. Fig. 8 is a perspective view showing the excess portion 52 of the intermediate product 50.

[0032] The intermediate product 50 is conveyed to the next process by having the excess portion 52 and other excess portions grasped by a robot hand. After that, as the mold is closed, the ejector plate 19 returns to its original position, and the pressure-receiving pin 30 and the shut-off pin 40 also return to their original positions (see FIG. 1).

[0033] (Characteristic configuration of the embodiment) As shown in FIG. 1, a fitting portion 60 consisting of a fitting protrusion 61 and a fitting recess 62 that can be fitted together is provided between the parting surface 11a of the fixed mold 11 and the parting surface 12a of the movable mold 12 to increase the creeping distance between the gas vent passage 20 and the outside.

[0034] As shown in Fig. 4, the fitting protrusion 61 is formed on the dividing surface 11a of the fixed mold 11. The fitting protrusion 61 is formed in a rectangular C-ring shape that surrounds the pressure-receiving chamber 21, the exhaust chamber 23, and the first passage portion 22a, the third passage portion 22c, and the fifth passage portion 22e of the detour path 22 of the gas vent passage 20. Both ends of the fitting protrusion 61 extend forward at the front lower part of the dividing surface 11a. The fitting protrusion 61 is formed to have a trapezoidal cross section (see Fig. 1).

[0035] As shown in FIG. 6, the fitting recess 62 is formed in the dividing surface 12a of the movable mold 12. The fitting recess 62 is formed in a rectangular C-shaped ring shape that surrounds the pressure receiving chamber 21 of the gas vent passage 20, the exhaust chamber 23, and the second passage portion 22b, the fourth passage portion 22d and the fourth passage portion 22d of the bypass path 22. Both ends of the fitting recess 62 extend forward at the front lower part of the dividing surface 12a. The fitting recess 62 is formed so that it can be fitted into the fitting protrusion 61 with almost no gap (see FIG. 1). In other words, the fitting portion 60 has a shape that surrounds the gas vent passage 20,

[0036] As shown in FIG. 4, the fixed mold 11 is provided with a fixed-mold-side cooling passage 70 adjacent to the degassing passage 20 and through which a cooling fluid flows. The fixed-mold-side cooling passage 70 has two linear vertical passage sections 71, one at the front and one at the back, extending vertically, and a linear horizontal passage section 72 communicating with the lower ends of both vertical passage sections 71. As shown in FIG. 5, both vertical passage sections 71 are open at one end (upper end). The horizontal passage section 72 is open at one end (front end) and the other end (rear end). Cooling water as a cooling fluid flows through the fixed-mold-side cooling passage 70.

[0037] As shown in Fig. 6, the movable mold 12 is provided with a movable mold-side cooling passage 80 adjacent to the degassing passage 20 and through which a cooling fluid flows. The movable mold-side cooling passage 80 has two linear vertical passage sections 81, one at the front and one at the back, extending vertically, and a linear horizontal passage section 82 communicating with the lower ends of both vertical passage sections 81. As shown in Fig. 7, both vertical passage sections 81 are open at one end (upper end). The horizontal passage section 82 is open at one end (rear end) and closed at the other end (front end). Cooling water as a cooling fluid flows through the movable mold-side cooling passage 80.

[0038] As shown in Figure 1, a hollow, truncated cone-shaped boss-forming hole 38 is formed in the tip surface of the pressure-receiving pin 30. When the molten metal filled in the boss-forming hole 38 solidifies, a truncated cone-shaped boss 52a is integrally formed in the excess portion 52 of the intermediate product 50 (see Figures 3 and 8). The pressure-receiving pin 30 corresponds to the "extrusion pin" referred to in this specification.

[0039] (Advantages of the characteristic configuration of the embodiment) According to this embodiment, the fitting protrusion 61 of the fitting portion 60 provided between the parting surface 11a of the fixed mold 11 and the parting surface 12a of the movable mold 12 fits into the fitting recess 62, thereby making it possible to increase the creeping distance between the vent passage 20 and the outside. This makes it possible to suppress the molten metal from spraying out from between the parting surface 11a of the fixed mold 11 and the parting surface 12a of the movable mold 12 around the vent passage 20 of the mold 10. This makes it possible to increase the product molding cycle.

[0040] Furthermore, the fitting portion 60 having a shape that surrounds the vent passage 20 can more effectively suppress the spraying of molten metal from between the parting surface 11a of the fixed mold 11 and the parting surface 12a of the movable mold 12 in the peripheral area of ​​the vent passage 20 of the mold 10, compared to a fitting portion having a shape that does not surround the vent passage 20.

[0041] Furthermore, by cooling the periphery of the vent passage 20 with the cooling fluid flowing through the fixed-mold-side cooling passage 70 and the movable-mold-side cooling passage 80, it is possible to promote solidification of the molten metal that has reached the vent passage 20. This makes it possible to effectively suppress the molten metal from spraying out from between the parting surface 11a of the fixed mold 11 and the parting surface 12a of the movable mold 12 in the periphery of the vent passage 20 of the mold 10. Furthermore, by cooling the periphery of the vent passage 20, it is possible to suppress thermal expansion of the mold 10 and ensure the operability (slidability) of the pressure-receiving pin 30 and the shut-off pin 40.

[0042] Furthermore, the boss portion 52a is integrally formed with the excess portion 52 by the boss portion forming hole 38 of the pressure-receiving pin 30. As a result, when the excess portion 52 is pushed out by the pressure-receiving pin 30, the boss portion 52a of the excess portion 52 remains engaged with the boss portion forming hole 38 of the pressure-receiving pin 30, thereby preventing the excess portion 52 from falling. In other words, by having the pressure-receiving pin 30 hold the intermediate product 50 including the excess portion 52, the intermediate product 50 can be easily grasped by a robot hand. This allows the product molding cycle to be increased.

[0043] [Other embodiments] The technology disclosed in this specification is not limited to the above-described embodiment and can be implemented in various other forms. For example, the technology disclosed in this specification is not limited to die-casting molds, and may also be used in injection molding molds for plastics, etc. Furthermore, the fitting portion 60 may be formed intermittently in the circumferential direction surrounding the vent passage 20. Furthermore, the fitting portion 60 may be formed in a non-annular shape that does not surround the vent passage 20. Furthermore, the fitting protrusion 61 and the fitting recess 62 of the fitting portion 60 may be arranged in reverse, i.e., the fitting protrusion 61 may be formed in the movable mold 12 and the fitting recess 62 may be formed in the fixed mold 11.

[0044] Furthermore, the cooling fluid may be other liquids or gases such as cooling air instead of cooling water. At least one of the fixed mold side cooling passage 70 and the movable mold side cooling passage 80 may be omitted. The shapes of the fixed mold side cooling passage 70 and the movable mold side cooling passage 80 are not limited. The boss forming hole 38 of the pressure-receiving pin 30 may be formed in the shut-off pin 40. The boss forming hole 38 may be formed in both the pressure-receiving pin 30 and the shut-off pin 40. In this case, the shut-off pin 40 corresponds to the "extrusion pin" as referred to in this specification. The vacuum pump may be omitted. [Explanation of symbols]

[0045] 10. Mold 11 Fixed type 11a Split plane 12 Movable type 12a Split plane 17 Cavity 20 Gas vent passage 30 Pressure receiving pin (extrusion pin) 38 Boss forming hole 40 Shut-off pin 50 Intermediate products 51 Product Department 52 Surplus 52a boss part 60 Fitting part 61 mating protrusion 62 Fitting recess 70 Fixed type side cooling passage 80 Movable mold side cooling passage

Claims

1. A venting structure for a mold, comprising a venting passage formed between a parting surface of a fixed mold and a parting surface of a movable mold of the mold and communicating with a cavity, A mold venting structure in which a fitting portion consisting of a fitting convex portion and a fitting concave portion that can be fitted to each other is provided between the parting surface of the fixed mold and the parting surface of the movable mold to increase the surface distance between the gas venting passage and the outside.

2. The mold venting structure according to claim 1, The fitting portion has a shape that surrounds the gas vent passage.

3. The gas venting structure of a mold according to claim 1 or 2, At least one of the fixed mold and the movable mold has a cooling passage adjacent to the gas venting passage and through which a cooling fluid flows.

4. The gas venting structure of a mold according to claim 1 or 2, a push-out pin for pushing out the solidified excess portion in the gas vent passage; The gas venting structure of the mold, wherein a boss forming hole for integrally forming a boss portion on the excess portion is formed on the tip surface of the ejector pin.

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