Low pressure casting device

Abstract

The low-pressure casting device forms a cavity (7) between the lower mold (1), the upper mold (2), and a plurality of side molds 3 to 6 arranged on the holding furnace (50). The lower mold (1) has: a lower mold core (1A) which forms the inner bottom surface of the cavity (7); and a lower mold base (1B). The lower mold core (1A) has a sprue bushing (8). At least one of the side molds 3 to 6 can move forward and backward relative to the mold center. The lower mold base (1B) has a guide pillar (10) that restricts the forward position of the side molds 3 to 6 that can move forward and backward. A horizontal adjustment gap S is provided between the lower mold core (1A) and the lower mold base (1B) to prevent excessive gaps between the molds caused by thermal expansion of the lower mold (1) and to improve the mold closing accuracy.

Description

Technical Field

[0001] This invention relates to improvements in low-pressure casting equipment. Background Technology

[0002] As a current low-pressure casting apparatus, for example, there is the structure described in Patent Document 1. The low-pressure casting apparatus described in Patent Document 1 includes: a lower mold disposed on a holding furnace; an upper mold capable of rising and falling relative to the lower mold; and a plurality of transverse molds capable of advancing and retracting relative to the mold center on the lower mold. The low-pressure casting apparatus forms a cavity between the lower mold, the descending upper mold, and the advancing transverse molds. The lower mold has a gating section communicating with a riser pipe (stalk).

[0003] Furthermore, after the mold is closed, the low-pressure casting apparatus pressurizes the holding furnace, thereby filling the mold cavity with molten metal from the holding furnace through the riser pipe and the gating section. Then, after the molten metal in the mold cavity solidifies due to cooling, the low-pressure casting apparatus opens the mold to demold the casting.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2007-319891 Summary of the Invention

[0005] Typically, in low-pressure casting apparatuses with a lower mold, upper mold, and cross mold, a guide pillar is positioned in the lower mold to restrict the forward movement of the cross mold. Furthermore, the temperature of the lower mold, which has a gate, is relatively high. Therefore, in current low-pressure casting apparatuses, the lower mold is prone to thermal expansion in the horizontal direction. If thermal expansion occurs, the guide pillar shifts outward from the mold, causing the cross mold's forward movement to deviate towards the front. As a result, in current low-pressure casting apparatuses, a gap exceeding the slit width is particularly likely to form between the upper mold and the cross mold. Solving this problem has become a challenge.

[0006] This invention addresses the aforementioned current issues and aims to provide a low-pressure casting device that can prevent excessive gaps between molds caused by thermal expansion of the lower mold, thereby improving mold closing accuracy.

[0007] The low-pressure casting apparatus of the present invention comprises: a lower mold disposed on a holding furnace; an upper mold capable of being raised and lowered relative to the lower mold; and a plurality of side molds disposed on the lower mold, forming a cavity between the lower mold, the upper mold, and the side molds. The lower mold comprises: a lower mold core forming the inner bottom surface of the cavity; and a lower mold base holding the lower mold core. The lower mold core has a sprue bushing at the cavity opening. At least one of the side molds is capable of advancing and retracting relative to the mold center, and the lower mold base has a guide pillar that limits the advancing position of the retractable side mold. Furthermore, the low-pressure casting apparatus is characterized by a horizontal adjustment gap provided between the lower mold core and the lower mold base.

[0008] Regarding the low-pressure casting apparatus with the above structure, during casting, the temperature of the lower mold core, which has a gating bushing, rises relatively, primarily due to thermal expansion in the horizontal direction. In contrast, the low-pressure casting apparatus divides the lower mold into a lower mold core and a lower mold base, with an adjustment gap between them. This adjustment gap absorbs the thermal expansion of the lower mold core and suppresses thermal deformation of the lower mold base. Consequently, the low-pressure casting apparatus prevents displacement of the guide pillars of the lower mold base, ensuring the correct forward and backward movement of the side molds and preventing excessively large gaps (greater than or equal to the slit) between the side molds and the upper mold.

[0009] The effects of the invention

[0010] The low-pressure casting apparatus of the present invention, by adopting the above-described structure, can prevent excessive gaps between the molds caused by the thermal expansion of the lower mold, thereby improving the mold closing accuracy. Attached Figure Description

[0011] Figure 1 This is a top view of the mold in the open state in the first embodiment of the low-pressure casting apparatus of the present invention.

[0012] Figure 2 It is a vertical cross-sectional view showing the mold opening state.

[0013] Figure 3 Is Figure 1 The following is a top view of the mold in the closed state.

[0014] Figure 4 Is Figure 2 The following is a vertical cross-sectional view showing the mold-closed state.

[0015] Figure 5 This is a vertical cross-sectional view showing the mold-opening state in the second embodiment of the low-pressure casting apparatus of the present invention.

[0016] Figure 6 This is a top view of the lower mold in the mold-open state.

[0017] Figure 7 Is Figure 5 The following is a vertical cross-sectional view showing the mold-closed state.

[0018] Figure 8 This is a vertical cross-sectional view showing the mold-closed state in the third embodiment of the low-pressure casting apparatus of the present invention.

[0019] Figure 9 It means Figure 8 The circuit diagram of the suction mechanism of the low-pressure casting device is shown. Detailed Implementation

[0020] <First Embodiment>

[0021] Figure 1 and Figure 2 The low-pressure casting apparatus shown includes: a lower mold 1, which is disposed on a holding furnace 50; an upper mold 2, which is movable relative to the lower mold 1; and a plurality of (four in the illustrated example) side molds 3 to 6, which are disposed on the lower mold 1. Furthermore, as... Figure 3 and Figure 4 As shown, the low-pressure casting apparatus forms a cavity 7 as a casting space between the lower mold 1, the upper mold 2, and multiple side molds 3-6. Furthermore, in Figure 2 and Figure 4 Only the side molds 3 and 5, which are configured on the left and right sides, are shown in the image.

[0022] For the holding furnace 50, detailed illustrations are omitted, but it has a well-known structure such as storing molten metal and having a riser pipe that serves as a filling path for the molten metal, and an internal pressurization mechanism.

[0023] The lower mold 1 has: a lower mold core 1A, which forms the inner bottom surface of the cavity 7; and

[0024] The lower mold base (mold base) 1B holds the aforementioned lower mold part 1A. In the illustrated example, the lower mold part 1A is square when viewed from above, with four gate bushings 8 arranged longitudinally and transversely in its center. Each gate bushing 8 has its lower part connected to the riser pipe of the holding furnace 50, and its upper part open into the cavity 7.

[0025] Regarding the lower mold 1 in the illustrated example, the lower mold core 1A has a downward-facing stepped portion on its outer periphery, and the lower mold base 1B has an upward-facing stepped portion on the inner periphery of the receiving portion of the lower mold core 1A, with the stepped portions of the two engaging with each other. Thus, the upper surfaces of the lower mold core 1A and the lower mold base 1B are connected to each other in a plane, and a horizontal adjustment gap S is provided between them.

[0026] The upper mold 2 integrally comprises: an upper mold core 2A, which forms the inner upper surface of the cavity 7; and an upper mold base 2B. The upper mold 2 can be raised and lowered using a drive mechanism not shown in the figure, and has a ejector plate 9 having a plurality of ejector pins 9A that pass through the upper mold core 2A in the vertical direction. The ejector plate 9 can be raised and lowered using a drive mechanism different from that of the upper mold.

[0027] At least one of the side molds 3 to 6 of the low-pressure casting apparatus of the present invention is capable of moving forward and backward relative to the mold center. The illustrated example of side molds 3 to 6 includes: side mold portions 3A to 6A forming the inner side surface of a cavity 7; and plates 3B to 6B disposed on its back surface. The side molds 3 to 6 are arranged in four directions relative to the cavity 7, and each is capable of moving forward and backward relative to the mold center using a drive mechanism not shown in the figures. The side molds 3 to 6 are positioned corresponding to each side of the lower mold portion 1A forming a square.

[0028] In contrast, in the lower mold base 1B of the lower mold 1, at the outer corners of the four corners of the square lower mold base 1A, and between adjacent side molds 3-6, there is a guide pillar 10 that restricts the forward movement of the side molds 3-6. This guide pillar 10... Figure 1 The state shown indicates that when each side mold 3-6 moves towards the center of the mold, as... Figure 3 The plates 3B to 6B of the side molds 3 to 6 are brought into contact, thereby restricting the forward movement of each side mold 3 to 6.

[0029] The low-pressure casting device with the above structure is from Figure 1 and Figure 2 The mold opening state shown causes the side molds 3-6 to advance and the upper mold 2 to descend, thereby forming a mold. Figure 3 and Figure 4 The mold cavity 7 is formed in the closed state shown. Then, the low-pressure casting apparatus appropriately pressurizes the holding furnace 50 and depressurizes the mold cavity 7, thereby filling the mold cavity 7 with molten metal from the holding furnace 50 through riser pipes and each gating bushing 8. Moreover, after the molten metal solidifies, as shown... Figure 1 and Figure 2 The mold is opened as shown, so that the demolding plate 9 is lowered relative to the upper mold 2, and the demolding pin 9A protrudes from the upper mold 2 to demold the casting.

[0030] During the casting process described above, the temperature of the lower mold section 1A with the gating bushing 8 in the low-pressure casting apparatus rises relatively, and the lower mold section 1A thermally expands in the horizontal direction. In contrast, the low-pressure casting apparatus divides the lower mold 1 into the lower mold section 1A and the lower mold base section 1B, and an adjustment gap S is provided between the two. Therefore, the thermal expansion of the lower mold section 1A can be absorbed by the adjustment gap S, and the thermal deformation of the lower mold base section 1B can be suppressed.

[0031] Therefore, the low-pressure casting device prevents the displacement of the guide pillar 10 in the lower mold base 1B. The guide pillar 10 ensures the correct forward position of the side molds 3-6 that can move forward and backward, and no excessive gaps greater than or equal to the gap are generated between the lower mold 1 and the side molds 3-6, or between the side molds 3-6 and the upper mold 2.

[0032] Therefore, the low-pressure casting device can prevent excessive gaps between molds caused by the thermal expansion of the lower mold 1, thus improving mold closing accuracy. Consequently, the low-pressure casting device can improve the dimensional accuracy of the castings as the mold closing accuracy improves, especially in castings using aluminum as the material, reducing defects such as piercing.

[0033] Figures 5-9 These figures illustrate the second and third embodiments of the low-pressure casting apparatus according to the present invention. In the following embodiments, structural parts that are the same as in the first embodiment are labeled with the same reference numerals and detailed descriptions are omitted.

[0034] <Second Implementation>

[0035] Figure 5 and Figure 6 The low-pressure casting apparatus shown has various combinations (two sets are shown in the illustrated example) of a lower mold 1, an upper mold 2, and multiple side molds 3 to 6. In this case, the lower mold 1 has two lower mold parts 1A, but the lower mold base part 1B is common. On the other hand, the upper mold 2 is divided into an upper mold part 2A that forms the inner upper surface of the cavity 7, and an upper mold base part 2B. The upper mold base part 2B holds the upper mold part 2A in a way that allows it to move back and forth in the arrangement direction of the side molds 3 to 6.

[0036] The upper mold assembly 2A in the example diagram can move back and forth in the left-right direction, i.e., the direction in which the side molds 3 and 5 are arranged. The upper mold assembly 2A is connected to the upper mold base assembly 2B using a sliding concave-convex structure such as grooves and protrusions, or an elastic body. At this time, the range of reciprocating movement of the upper mold assembly 2A only needs to be within the range that allows the mold to close. In addition, in order to allow relative movement with the ejector pin 9A, the upper mold assembly 2A and the upper mold base assembly 2B have the through hole of the ejector pin 9A formed into an elongated hole shape in cross-section.

[0037] Furthermore, the low-pressure casting apparatus has a central base 11 for positioning at least one of the side molds. The central base 11 is a structure extending from between the two upper mold base portions 2B, 2B to the lower mold 1, positioning the two side molds 3, 5 whose back surfaces are opposite to each other. Figure 5 Position the right side mold 5 of the right group in the figure and the left side mold 3 of the left group in the figure.

[0038] In addition, the central base 11 can be configured to be raised and lowered by a drive mechanism not shown, or it can be positioned horizontally by engaging the recess 11A at its lower end with the protrusion 1C of the lower mold base portion 1B.

[0039] Furthermore, the central base 11 of the low-pressure casting device and the side molds 5 and 3 positioned by the central base 11 are separated in such a way that adjustment shims 12 can be clamped between them. That is, the opposing surfaces of the central base 11 and the side molds 3 and 5 are flat, and flat adjustment shims 12 can be clamped between the opposing surfaces.

[0040] Here, the aforementioned central base 11 can also form a central mold including side molds 3 and 5. In this case, similar to the lower mold 1 and upper mold 2, the side molds 3 and 5 correspond to the side mold components (3A, 5A) that form the internal side surfaces of the cavity 7, and the central base 11 corresponds to the central mold base component. Thus, the central mold is constructed such that it is divided into the side mold components (3, 5) and the central mold base component (11), and an adjustment shim 12 can be clamped between the two.

[0041] Similar to the first embodiment, the low-pressure casting apparatus having the above structure can absorb the thermal expansion of the lower mold parts 1A and 1A and suppress the thermal expansion of the lower mold base 1B by utilizing the adjustment gap S provided between the lower mold parts 1A and 1A and the lower mold base 1B, thereby preventing the position of the guide pillar 10 and the forward position of the side molds 3, 4 and 6 that can move forward and backward from shifting, and maintaining good mold closing accuracy.

[0042] In addition, the above-mentioned low-pressure casting device divides the upper mold 2 into an upper mold base 2A and an upper mold base 2B, presses the upper mold base 2B against the central base 11, and the upper mold base 2A can move back and forth relative to the upper mold base 2B.

[0043] Therefore, regarding low-pressure casting equipment, such as Figure 7 As shown, during mold closing, each upper mold element 2A can move in the opposite direction (arrow direction) with the central base 11 as a reference, thus enabling each upper mold element 2A to be corrected to an accurate mold closing position, thereby further improving the mold closing accuracy.

[0044] Furthermore, the aforementioned low-pressure casting device, by employing a central base 11 for positioning the two side molds 3 and 5 and an adjustment shim 12, can adjust the position of the side molds 3 and 5, and, with the fixed side molds 3 and 5 as a reference, can perform mold closing of other side molds and the upper mold part 2A, thus achieving further improvement in mold closing accuracy.

[0045] Furthermore, the aforementioned low-pressure casting device, through the adoption of a central base 11 and a drive mechanism for side molds 3 and 5 that do not require positioning, can achieve miniaturization of the entire device compared to the case where multiple casting devices are arranged in parallel.

[0046] <Third Implementation>

[0047] Figure 8 The low-pressure casting apparatus shown has the same characteristics as the second embodiment ( Figures 5-7 It has the same basic structure as the upper mold 1 and the side molds 3 and 5, with an exhaust passage P for venting air from the cavity 7, and an attraction mechanism 60 for attracting air from the cavity 7 to the outside through the exhaust passage P.

[0048] In the exhaust path P, a well-known cooling vent can be used. For example... Figure 9 As shown, the suction mechanism 60 has two sets of exhaust pipes 61A and 61B connected to the exhaust paths P of each group of low-pressure casting devices. Each exhaust pipe 61A and 61B is connected to the suction source 62, which consists of a vacuum pump and a vacuum container, and has pressure regulating valves V1 and V2 and an exhaust valve V3 in between. The suction source 62 and each valve V1 to V3 are controlled based on the measured values ​​of pressure gauges M1 and M2 of each cavity 7.

[0049] As described in the first and second embodiments, the low-pressure casting apparatus with the above structure has good mold-closing accuracy, thus enabling differentiation of the usual gaps between molds and the venting path P. Therefore, the low-pressure casting apparatus has no unnecessary gaps between molds, allowing air in the cavity 7 to be effectively and efficiently drawn out using the venting path P, improving the vacuum level of the cavity 7 even without the entire casting apparatus being surrounded by a large housing. Furthermore, the low-pressure casting apparatus can perform low-pressure casting using multiple ejector molds, enabling the efficient manufacture of thin-walled castings.

[0050] The structure of the low-pressure casting apparatus involved in this invention is not limited to the above-described embodiments, and can be appropriately modified within the scope of the spirit of this invention. Of course, it can also be applied to casting using a core, etc.

[0051] Explanation of the label

[0052] 1 Lower mold

[0053] 1A Lower Casting Mold Key Parts

[0054] 1B Lower mold base

[0055] 2 upper mold

[0056] 2A Upper Casting Mold Key Parts

[0057] 2B Upper Mold Base

[0058] 3-6 side molds

[0059] 7-type cavity

[0060] 8. Gating bushing

[0061] 10 Guiding Pillars

[0062] 11 Central Base

[0063] 12 Adjustment shims

[0064] 50 holding furnace

[0065] 60 Attraction Agencies

[0066] P exhaust path

[0067] S Adjustment gap

Claims

1. A low-pressure casting apparatus comprising: a lower mold disposed on a holding furnace; an upper mold movable relative to the lower mold; and a plurality of side molds disposed on the lower mold. A cavity is formed between the lower mold, the upper mold, and the side mold. The lower mold includes: a lower casting core, which forms the inner bottom surface of the cavity; And the lower mold base portion, which holds the lower mold core portion. The lower mold portion has a sprue bushing that opens into the cavity. At least one of the side molds is capable of moving forward and backward relative to the mold center, and the lower mold base has guide pillars that limit the forward movement of the side molds. A horizontal adjustment gap is provided between the lower mold core and the lower mold base. Its features are, It has multiple combinations of the lower mold, the upper mold, and multiple side molds. The upper mold includes: an upper casting part, which forms the inner upper surface of the cavity; And the upper mold base portion, which holds the upper mold portion so that it can move back and forth in the arrangement direction of the side molds. The low-pressure casting apparatus has a central base for positioning at least one of the side molds. The central base and the side mold positioned by the central base are separated in a manner that allows for the clamping and adjustment of shims.

2. The low-pressure casting apparatus according to claim 1, characterized in that, An exhaust passage for venting air from the cavity is provided between the upper mold and the side mold. The low-pressure casting apparatus has a suction mechanism that draws air from the cavity to the outside through the exhaust path.

3. The low-pressure casting apparatus according to claim 1, characterized in that, The lower mold portion has a downward-facing stepped portion on its outer periphery, and the lower mold base portion has an upward-facing stepped portion on the inner periphery of the receiving portion of the lower mold portion. The lower mold core and the stepped portion of the lower mold base engage with each other.

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