Manufacturing method of bush

Abstract

To enhance heat transfer performance between a mold and a casting.SOLUTION: A bush manufacturing method for manufacturing a bush by pouring molten metal into a mold 11, includes: a first step of forming a portion corresponding to an interface between a solidified molten metal in the mold 11 and the mold 11 so as to have a predetermined surface roughness; a second step of disposing a core pin 21 in the mold 11; and a third step of pressing the core pin 21 into the mold 11 and applying pressure to the molten metal poured in the mold 11. Thus, the state of contact between the molten metal and the mold 11 formed to have a rough surface is maintained.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a bushing. [Background technology]

[0002] In recent years, a method of pouring molten metal into a mold to form a cylindrical or bag-shaped metal bush has been known. For example, a technology in this field is disclosed in JP 2020-006404 A. The method of manufacturing a bush described in this publication discloses a casting process for filling the mold with molten metal and a bush forming process for forming a bush from a casting. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-006404 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional bushing manufacturing method described above, when the molten metal is cooled in the casting process, shrinkage occurs inside the casting due to solidification shrinkage, and the volume of the molten metal decreases, which can lead to the formation of voids at the interface between the mold and the casting.

[0005] In particular, in a manufacturing method in which a bushing is cast by cooling after filling a mold with molten metal, the amount of solidification shrinkage is large. Furthermore, since gravity casting is performed in an as-cast state and the wall surface forming the cavity is smooth, voids are likely to occur at the interface between the casting and the mold. If voids occur at the interface between the casting and the mold, the heat transfer performance between the casting and the mold will decrease, the cooling of the casting will not be performed as planned, and the quality of the casting may decrease. The present invention provides a method for manufacturing a bushing that improves heat transfer between the mold and the casting. [Means for solving the problem]

[0006] The method for manufacturing a bushing according to the present invention is a method for manufacturing a bushing by pouring molten metal into a mold, and includes a first step of forming an area of ​​the mold corresponding to the interface between the solidified molten metal and the mold to a predetermined surface roughness, a second step of placing a core pin in the mold, and a third step of pressing the core pin into the mold and pressurizing the molten metal poured into the mold. This allows the molten metal to be pressurized by operating the core pin, and to maintain contact with the mold, which has a rough surface. Effect of the Invention

[0007] This improves the heat transfer performance between the mold and the casting. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a schematic cross-sectional view of a bushing manufacturing apparatus. [Diagram 2] FIG. 13 is a diagram showing the state in which the surface roughness of the inner wall surface has been reduced and made rough. [Diagram 3] FIG. 2 is a perspective view showing a typical cast-out device. [Figure 4] FIG. 2 is a side view showing a schematic diagram of the cast-out device. [Diagram 5] FIG. 1 is a diagram showing a manufacturing flow of a casting. [Figure 6] FIG. 13 is a diagram showing a detailed flow for setting up the cast-out device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a schematic cross-sectional view of a bushing manufacturing apparatus 1 having a cooling structure according to this embodiment. More specifically, the bushing manufacturing apparatus 1 includes a die 11 and a punching device 12 having a punching pin 21.

[0010] The mold 11 is made of a material having excellent resistance to high temperatures. The mold 11 has a mold body 11a and a cavity 11b into which molten metal is filled. The mold body 11a of the mold 11 is made of a material suitable for a die casting mold, which is unlikely to deform due to the heat of the molten metal when the molten metal is filled into the cavity 11b.

[0011] The mold body 11a may be provided with a flow path (not shown) for flowing a cooling medium such as cooling water.

[0012] As shown in FIG. 1, a cavity 11b provided in a mold body 11a is open at the top, and a casting pin 21 provided in a casting device 12 is inserted through the opening of the cavity 11b.

[0013] In the following, the up-down direction is defined as the Z direction, and the directions perpendicular to the Z direction and perpendicular to each other are defined as the X direction and the Y direction. Note that the X direction may be referred to as the left-right direction, and the Y direction may be referred to as the front-rear direction.

[0014] 2 is a diagram showing a state in which the surface roughness of the inner wall surface is reduced and made rough in the cavity 11b of the mold 11. Note that, although this diagram shows a state in which the surface roughness of the wall surface is reduced in a portion near the end in the Z direction, the surface roughness of the wall surface in other portions can also be reduced in a similar manner.

[0015] Next, the casting apparatus 12 will be described with reference to the perspective view shown in Fig. 3 and the side view shown in Fig. 4. Note that in part of Fig. 3, in order to make the invention easier to understand, some of the components are shown in a see-through manner.

[0016] The cast-out device 12 includes a cast-out pin 21, a pressure bolt (squeeze bolt) 22 arranged above the cast-out pin 21, a plurality of frame portions 23 supporting the cast-out pin 21, connecting portions 24 connecting the plurality of frame portions 23 together, a plurality of fixing bolts 25 fixing the frame portions 23 and the connecting portions 24, and a float spacer 26.

[0017] Here, the multiple frame parts 23 each have a shape extending in the X direction and are provided continuously in the Z direction. Specifically, the multiple frame parts 23 are composed of a first frame part 31 provided below, a second frame part 32 provided above the first frame part 31, and a third frame part 33 provided above the second frame part 32.

[0018] The connecting portion 24 is composed of connecting portions 41 and 42 which are two connecting portions arranged between the first frame portion 31 and the second frame portion 32, and connecting portions 43 and 44 which are two connecting portions arranged between the second frame portion 32 and the third frame portion 33. Each of the connecting portions 41 to 44 can be a rectangular parallelepiped block.

[0019] The first frame portion 31 includes a frame 31a, a core pin hole portion 31b that passes through the frame 31a in the vertical direction, and a gate block 31c provided on the frame 31a.

[0020] The frame 31a is a substantially rectangular parallelepiped extending in the X-direction. A core pin hole 31b through which the core pin 21 passes is formed in the frame 31a. A spout block 31c, which is a spout for pouring molten metal into a pouring caddy disposed below the casting device 12, is provided near the core pin hole 31b.

[0021] Furthermore, a pouring jig leg 31d is provided on the side surface of the frame 31a. The pouring jig leg 31d comes into contact with the die 11 provided below during pouring, and fixes the casting device 12 in place.

[0022] Typically, two grooves are formed on the upper surface of the frame 31a for inserting parts of the connecting parts 41, 42 when providing the connecting parts 41, 42. Furthermore, the two grooves are provided with fixing bolt holes into which the tips of the fixing bolts 25 that pass through the connecting parts 41, 42 are inserted.

[0023] The second frame portion 32 includes a frame 32a, a core pin hole portion 32b that passes through the frame 32a in the vertical direction, and a plurality of fixing bolt holes that pass through the frame 32a in the vertical direction.

[0024] The frame 32a is a substantially rectangular parallelepiped extending in the X-direction. A thick portion 32c that is thickened in the vertical direction is formed in a part of the frame 32a. The core pin hole 32b is provided so as to penetrate the thick portion 32c in the vertical direction. The core pin 21 is inserted into the core pin hole 32b.

[0025] The third frame portion 33 includes a frame 33a, a squeeze bolt hole 33b that passes through the frame 33a in the vertical direction, and a fixing bolt hole that passes through the frame 32a in the vertical direction.

[0026] The frame 33a is a substantially rectangular parallelepiped extending in the X-direction. Furthermore, the squeeze bolt 22 is inserted into the squeeze bolt hole 33b.

[0027] As described later, the squeeze bolt 22 is arranged above the cast pin 21, and the cast pin hole 31b, the cast pin hole 32b, and the squeeze bolt hole 33b are arranged so as to be aligned in the XY direction.

[0028] The connecting parts 41, 42 are disposed between the first frame part 31 and the second frame part 32 and are spaced apart from each other in the X direction. The lower parts of the connecting parts 41, 42 abut against the upper surface of the frame 31a, and the upper parts of the connecting parts 41, 42 abut against the lower surface of the frame 32a. The connecting parts 41, 42 each have a hole for a fixing bolt that penetrates in the vertical direction.

[0029] The connecting parts 43, 44 are disposed between the second frame part 32 and the third frame part 33, spaced apart from each other in the X direction. The lower parts of the connecting parts 43, 44 abut against the upper surface of the frame 32a, and the upper parts of the connecting parts 43, 44 abut against the lower surface of the frame 33a. The connecting parts 43, 44 each have a hole for a fixing bolt that penetrates in the vertical direction. The connecting part 43 is disposed above the connecting part 41, and the connecting part 44 is disposed above the connecting part 42.

[0030] The core pin 21 includes a pin body 21a formed in a long, generally cylindrical shape, and a flange portion 21b provided at an end of the pin body 21a.

[0031] The pin body 21a is disposed so as to extend in the vertical direction. The pin body 21a also penetrates the first frame portion 31 and the second frame portion 32. The lower portion of the pin body 21a is inserted into a molten metal insert of the die 11 disposed below the cast-out device 12.

[0032] The flange portion 21b is provided at an end of the pin body 21a and is formed to have a larger diameter than the pin body 21a. The flange portion 21b is disposed above the second frame portion 32 and below the third frame portion 33. Typically, the lower surface of the flange portion 21b abuts against the upper surface of the second frame portion 32 via the float spacer 26.

[0033] Furthermore, a squeeze bolt hole 21c into which an end of a squeeze bolt 22 is inserted is formed in the approximate center of the upper surface of flange portion 21b.

[0034] The squeeze bolt 22 includes a long bolt body 22a and a bolt head 22b formed at the end of the bolt body 22a.

[0035] Specifically, bolt body 22a is disposed so as to extend in the vertical direction and penetrates third frame portion 33. Squeeze bolt 22 is disposed above cast pin 21, and the lower end of bolt body 22a is inserted into squeeze bolt hole 21c provided in flange portion 21b.

[0036] The bolt head 22b is disposed above the third frame portion 33. An external force is applied to the bolt head 22b to rotate about an axis whose axis is the vertical direction of the squeeze bolt 22, causing the bolt head 22b to rotate. When a rotational force is applied to the squeeze bolt 22, the squeeze bolt 22 presses the core pin 21 downward.

[0037] The fixing bolts 25 are bolts that fix the plurality of frame portions 23 and the connecting portion 24. More specifically, the fixing bolts 25 are inserted into fixing bolt holes provided in the plurality of frame portions 23 and the connecting portion 24, respectively, and fix the plurality of frame portions 23 and the connecting portion 24.

[0038] More specifically, at least one fixing bolt 25 can be used to fix the first frame portion 31, the second frame portion 32, the third frame portion 33, the connecting portion 41, and the connecting portion 43 disposed above the connecting portion 41. Similarly, at least one fixing bolt 25 can be used to fix the first frame portion 31, the second frame portion 32, the third frame portion 33, the connecting portion 42, and the connecting portion 44 disposed above the connecting portion 42.

[0039] The float spacer 26 is a spacer that is thin in the Z direction and is disposed at a position between the upper surface of the second frame portion 32 and the lower surface of the flange portion 21b of the core pin 21. The float spacer 26 is detachable from the core device 12.

[0040] When the float spacer 26 is inserted into the casting device 12, the core pin 21 is in a state of being moved slightly upward. On the other hand, when the float spacer 26 is in a state of being removed from the casting device 12, the core pin 21 can be lowered by a distance equal to the thickness of the float spacer 26 in the Z direction.

[0041] Next, with reference to Figs. 5 and 6, an example of a procedure for pouring molten metal into the die 11 while utilizing the cast-out device 12 to form a casting will be described.

[0042] First, a portion of the mold 11 that corresponds to the interface between the solidified molten metal and the mold 11 is formed to have a predetermined surface roughness. Typically, the mold 11 in which a portion that corresponds to the interface between the molten metal and the mold 11 is formed to have a predetermined surface roughness is prepared in advance (S1).

[0043] A core pin is placed in the die 11 (S2).

[0044] Specifically, as shown in FIG. 6, the cast-out device 12 is set in a state in which the float spacer 26 is inserted and the cast-out pin 21 is floated upward (S21).

[0045] The core device 12 is set in the mold 11. At this time, the lower end of the core pin 21 is inserted into the molten metal insert to be poured. Thereafter, pouring of molten metal into the molten metal insert to be poured is started from the gate block 31c (S22).

[0046] Next, the float spacer 26 is removed from the casting device 12 (S23), which allows the casting pin 21 to move downward.

[0047] 5, the core pin 21 is pressed downward by rotating the squeeze bolt 22 (S3). At this time, the core pin 21 is pressed in without contacting the inner wall surface of the molten metal core to be poured.

[0048] Thereby, by lowering the core pin 21 inserted into the core to be poured, the adhesion of the molten metal to the inner wall surface of the cavity 11b can be improved.

[0049] In particular, when the molten metal solidifies and shrinks due to cooling, the molten metal tends to separate from the inner wall surface of the cavity 11b, but by pressurizing the molten metal by deeply inserting the core pin 21, the molten metal can be pressed against the inner wall surface of the cavity 11b. This makes it difficult for a gap to occur at the interface between the die 11 and the solidified molten metal. Therefore, the heat transfer performance between the solidified molten metal and the die 11 can be improved.

[0050] 2, the surface roughness of the inner wall surface of the pouring insert that comes into contact with the molten metal is made rough, so that the contact area between the molten metal and the cavity 11b can be increased, thereby improving the heat transfer performance between the die 11 and the molten metal.

[0051] The present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit of the present invention. In other words, the above description has been omitted or simplified as appropriate for the purpose of clarity, and a person skilled in the art can easily modify, add, or convert each element of the embodiment within the scope of the present invention.

[0052] For example, the squeeze bolt 22 is not limited to rotating the bolt head 22b, but may be configured to press the core pin 21 downward by pressing the bolt head 22b downward, and to insert it deeply into the liner to be poured, thereby pressurizing the molten metal. [Explanation of symbols]

[0053] 1 Bush manufacturing equipment 11 Mold 11a Mold body 11b Cavity 12 Casting equipment 21 Cast pin 21a Pin body 21b flange 21c Squeeze bolt hole 22 Pressure bolt (squeeze bolt) 22a Bolt body 22b Bolt head 23 Frame section 24 Connecting part 25 Fixing bolt 26 Float spacer 31 First frame section 31a Frame 31b Hole for cast pin 31c Gate block 31d pouring jig legs 32 Second frame section 32a Frame 32b Cast pin hole 32c thick part 33 Third frame section 33a Frame 33b Squeeze bolt hole 41,42,43,44 Connection part

Claims

[Claim 1] A method for manufacturing a bushing by pouring molten metal into a die, comprising the steps of: A first step of preparing a mold in which a surface roughness of a portion corresponding to an interface between the solidified molten metal and the mold is higher than that of other portions; a second step of placing a core pin within the die; and a third step of pushing the core pin into the die and pressurizing the molten metal poured into the die. A method for manufacturing a bush.

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