Apparatus and method for centrifugal casting

Abstract

SOLUTION: An apparatus for centrifugal casting 10 which founds a casting by injecting melt L into a mold 18 while rotating the mold comprises: a control section 58 that controls the rotation speed of a mold; and a determining section 60 that determines whether or not the forefront of melt flowing in a direction of a rotation axis A of the mold reaches a predetermined position. The control section allows the mold to rotate at a first rotation speed and, when the determining section determines the forefront reaches the predetermined position, to rotate the mold at a second rotation speed.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a centrifugal casting apparatus and a centrifugal casting method. [Background technology]

[0002] Patent Document 1 below discloses a centrifugal casting method. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-276022 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, research and development has been conducted to contribute to energy efficiency in order to ensure that more people have access to affordable, reliable, sustainable, and advanced energy. However, there is a need in the art for better centrifugal casting equipment and methods.

[0005] The present invention aims to solve the above-mentioned problems. [Means for solving the problem]

[0006] A first aspect of the present disclosure is a centrifugal casting apparatus that casts a casting product by injecting molten metal into a casting mold while rotating the casting mold, and includes a control unit that controls the rotation speed of the casting mold, and a judgment unit that judges whether the leading position of the molten metal flowing in the direction of the rotation axis of the casting mold has reached a predetermined position, wherein the control unit rotates the casting mold at a first rotation speed, and when the judgment unit judges that the leading position has reached the predetermined position, the control unit rotates the casting mold at a second rotation speed.

[0007] A second aspect of the present disclosure is a centrifugal casting method for casting a casting product by injecting molten metal into a casting mold while rotating the casting mold, the centrifugal casting method comprising: a first rotation step for starting to inject the molten metal into the casting mold while rotating the casting mold at a first rotation speed; a determination step for determining whether the leading position of the molten metal flowing in the direction of the rotation axis of the casting mold has reached a predetermined position; and a second rotation step for rotating the casting mold at a second rotation speed if it is determined in the determination step that the leading position has reached the predetermined position. [Effects of the Invention]

[0008] The present disclosure provides a better centrifugal casting apparatus and centrifugal casting method. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view of a centrifugal casting machine according to one embodiment. [Figure 2] FIG. 2 is a partial cross-sectional view of the cylindrical member. [Figure 3] FIG. 3 is a partial cross-sectional view of the mold. [Figure 4] FIG. 4 is a control block diagram of the control device. [Figure 5] FIG. 5 is a flowchart showing the mold rotation control process executed by the control device. [Figure 6] 6A to 6D are schematic diagrams illustrating the mechanism of generation of an unhealthy layer in a cylindrical member. [Figure 7] FIG. 7 is a graph showing the relationship between the timing of switching from the first rotation speed to the second rotation speed and the length of the unhealthy layer. DETAILED DESCRIPTION OF THE INVENTION

[0010] [One embodiment] [Configuration of centrifugal casting equipment] 1 is a cross-sectional view of a centrifugal casting machine 10 according to one embodiment. The centrifugal casting machine 10 according to one embodiment casts, for example, a cylindrical member 12 as a casting.

[0011] FIG. 2 is a partial cross-sectional view of the cylindrical member 12. The cylindrical member 12 is cut to an appropriate length, and the cut cylindrical member 12 is used as a cylinder sleeve for an internal combustion engine. The cylinder sleeve is placed in the bore of a cylinder block. A reciprocating piston slides against the inner circumferential wall of the cylinder sleeve. The cylindrical member 12 is made of, for example, flake graphite cast iron. Flake graphite cast iron is a material with excellent vibration absorption, thermal shock resistance, and lubrication properties.

[0012] A large number of spinies 16 are formed on the outer peripheral surface 14 of the cylindrical member 12. The height of the spinies 16 from the outer peripheral surface 14 is set according to the outer diameter of the cylindrical member 12. For example, if the outer diameter of the cylindrical member 12 is 60 to 100 mm, the height of each spinie 16 is set within the range of 0.5 to 1.2 mm.

[0013] The spinie 16 improves the adhesion between the cylinder sleeve and the cylinder block. In addition, the provision of the spinie 16 increases the surface area of ​​the cylinder sleeve, allowing heat generated in the cylinder sleeve by the sliding of the piston, etc., to be efficiently transferred to the cylinder block, thereby improving the heat dissipation performance of the cylinder sleeve.

[0014] Returning to FIG. 1 , centrifugal casting machine 10 includes a cylindrical mold 18. Annular grooves 22 and 24 are formed on the outer peripheral surface 20 of mold 18 by cutting out outer peripheral surface 20 in the circumferential direction. Rollers 26 contact annular groove 22, and rollers 28 contact annular groove 24. Motor 30 is connected to roller 26, and the driving force of roller 26 rotates mold 18 about rotation axis A. Rotation speed sensor 32 is connected to roller 28, and rotation speed sensor 32 measures the rotation speed of mold 18. Motor 30 is controlled by control device 34.

[0015] An annular closure member 36 is attached to the tip of the mold 18. A window 38 is provided in the closure member 36. A camera 40 provided outside the mold 18 photographs the interior of the mold 18 through the window 38. An annular frame 42 is attached to the base end of the mold 18. An opening 44 is provided in the frame 42. A melt filling pipe 48 of a trough 46 is inserted into the interior of the mold 18 through the opening 44. Melted material (molten metal L) is supplied from a pot 50 to the trough 46, and is poured from the trough 46 into the interior of the mold 18.

[0016] 3 is a partial cross-sectional view of the mold 18. When manufacturing the cylindrical member 12, a mold coat 53 is applied to the inner peripheral surface 52 of the heated mold 18. This mold coat 53 contains a heat insulating material, a binder, a mold release agent, a surfactant, and water.

[0017] The heat of the mold 18 causes the water contained in the mold coat 53 applied to the mold 18 to evaporate, forming bubbles, which cause the surface of the mold coat 53 to swell spherically, forming convex portions 55. A large number of convex portions 55 are formed on the surface of the mold coat 53, and concave portions 57 are formed between the convex portions 55. These concave portions 57 are transferred to the outer peripheral surface 14 of the cylindrical member 12, forming the spine 16.

[0018] After a coat 53 is applied to the inner peripheral surface 52 of the mold 18, the melt filling pipe 48 of the trough 46 is inserted into the mold 18 through the opening 44 of the frame 42. The motor 30 rotates the rollers 26, which in turn rotates the mold 18. The molten metal L is then supplied from the pot 50 to the trough 46 and poured from the trough 46 into the mold 18. The molten metal L contained within the mold 18 flows along the direction of the rotation axis A of the mold 18. The centrifugal force of the rotating mold 18 causes the molten metal L to be supplied all around the inner peripheral surface 52 of the mold 18.

[0019] As the rotation speed of the mold 18 increases and the centrifugal force increases, the contact pressure of the molten metal L with the inner circumferential surface 52 of the mold 18 increases, and the flow velocity of the molten metal L in the direction of the rotation axis A decreases. This can lead to the molten metal L solidifying before reaching the tip P1 (FIG. 1) of the inner circumferential surface 52 of the mold 18, potentially preventing the cylindrical member 12 from achieving the desired length and thickness. On the other hand, when the rotation speed of the mold 18 decreases and the centrifugal force decreases, the molten metal L does not reach the tip of the recess 57 on the inner circumferential surface 52 of the mold 18, and the height of the spine 16 decreases. This decreases the height of the spine 16, resulting in poor adhesion between the cylinder sleeve and the cylinder block. Furthermore, this decreases the height of the spine 16, resulting in poor heat dissipation from the cylinder sleeve.

[0020] [Control device configuration] 4 is a control block diagram of the control device 34. The control device 34 has a calculation unit 54 and a storage unit 56. The calculation unit 54 is a processor such as a central processing unit (CPU) or a graphics processing unit (GPU). The calculation unit 54 has a control unit 58 and a determination unit 60. The control unit 58 and the determination unit 60 are realized by the calculation unit 54 executing a program stored in the storage unit 56. At least a portion of the control unit 58 and the determination unit 60 may be realized by an integrated circuit such as an application specific integrated circuit (ASIC) or a field-programmable gate array (FPGA). At least a portion of the control unit 58 and the determination unit 60 may be realized by an electronic circuit including discrete devices.

[0021] The memory unit 56 is a computer-readable, non-transitory, tangible storage medium. The memory unit 56 is composed of a volatile memory (not shown) and a non-volatile memory (not shown). The volatile memory is, for example, a random access memory (RAM). The non-volatile memory is, for example, a read-only memory (ROM) or a flash memory. Data, for example, is stored in the volatile memory. Programs, tables, maps, for example, are stored in the non-volatile memory. At least a portion of the memory unit 56 may be provided in the processor, integrated circuit, or the like described above. At least a portion of the memory unit 56 may be installed in a device connected to the centrifugal casting machine 10 via a network.

[0022] The control unit 58 acquires the rotation speed of the mold 18 measured by the rotation speed sensor 32. The control unit 58 performs feedback control of the motor 30 so that the rotation speed of the mold 18 becomes a predetermined rotation speed.

[0023] The determination unit 60 acquires an image of the inside of the mold 18 taken by the camera 40. The determination unit 60 analyzes the acquired image and determines whether the leading edge of the molten metal L flowing along the direction of the rotation axis A of the mold 18 has reached a predetermined position. The determination unit 60 may determine whether the leading edge of the molten metal L has reached a predetermined position based on the elapsed time from when the molten metal L began to be poured into the mold 18.

[0024] [Mold rotation control processing] 5 is a flowchart showing the rotation control process of the mold 18 executed by the control device 34. The rotation control process is executed when the molten metal L is poured into the mold 18.

[0025] In step S1, the control unit 58 controls the motor 30 to rotate the mold 18 at a first rotation speed. The first rotation speed is set to a rotation speed at which the relative centrifugal acceleration of the mold 18 is, for example, 90 to 100 G. The first rotation speed is set based on the flow rate (pouring rate) of the molten metal L when the molten metal L is poured into the mold 18 from the trough 46.

[0026] In step S2, the determination unit 60 determines whether the leading edge of the molten metal L flowing along the direction of the rotation axis A of the mold 18 has reached a predetermined position. The predetermined position is set, for example, to the leading edge P1 (FIG. 1) of the inner peripheral surface 52 of the mold 18. The predetermined position is not limited to the leading edge P1. If it is determined that the leading edge of the molten metal L flowing along the direction of the rotation axis A of the mold 18 has reached the predetermined position (step S2: YES), the process proceeds to step S3. If it is determined that the leading edge of the molten metal L has not reached the predetermined position (step S2: NO), the process of step S2 is repeated.

[0027] In step S3, the control unit 58 controls the motor 30 to rotate the mold 18 at a second rotation speed. The second rotation speed is set to a rotation speed at which the relative centrifugal acceleration of the mold 18 becomes a value of, for example, 100 [G] to 130 [G]. After the process of step S3 has been performed for a predetermined time, the rotation control process ends.

[0028] [Mechanism of unhealthy layer formation] When a cylindrical member 12 is cast using a centrifugal casting machine 10, an unsound layer forms at the tip of the cylindrical member 12. Because the portion with the unsound layer cannot be used as a cylinder sleeve, the tip of the cylindrical member 12 is cut off and discarded. To reduce the amount of discarded material, it is necessary to shorten the length of the unsound layer in the cylindrical member 12.

[0029] 6A to 6D are schematic diagrams illustrating the mechanism of generation of an unhealthy layer in the cylindrical member 12. FIG.

[0030] The molten metal L (hereinafter referred to as the first group L1) that is first poured into the mold 18 flows along the inner circumferential surface 52 of the mold 18 in the direction of the rotation axis A. At this time, because the mold 18 is rotating, centrifugal force acts on the first group L1, and the flow speed of the first group L1 in the direction of the rotation axis A decreases. The molten metal L contains impurities (slag). Because the specific gravity of the impurities is lighter than that of the flake graphite cast iron that is the material of the cylindrical member 12, the impurities float to the inner circumferential side of the first group L1 (FIG. 6A).

[0031] The molten metal L (hereinafter referred to as the second group L2) poured into the mold 18 after the first group L1 flows along the inner circumferential surface of the first group L1 in the direction of the rotation axis A. Because the second group L2 is poured after the first group L1, the flow velocity of the second group L2 is faster than that of the first group L1 immediately after the second group L2 is poured. Therefore, the second group L2 overtakes the first group L1 and becomes the leading group. As the second group L2 overtakes the first group L1, it sweeps away impurities floating on the inner circumferential side of the first group L1 (FIG. 6B). Furthermore, the leading second group L2 sweeps away inclusions adhering to the inner circumferential surface 52 of the mold 18 (FIG. 6B). The inclusions may be, for example, peeled mold coat 53.

[0032] Because the centrifugal force caused by the rotation of the mold 18 also acts on the second group L2, the flow velocity of the second group L2 in the direction of the rotation axis A also decreases. The molten metal L (hereinafter referred to as the third group L3) poured into the mold 18 after the second group L2 pushes the first group L1 and the second group L2 toward the tip of the mold 18. As a result, the first group L1 and the second group L2 flow together in the direction of the rotation axis A (FIG. 6C). An oxide film forms all over the inner periphery of the molten metal L (FIG. 6C).

[0033] When the second group L2 reaches the tip of the mold 18, the portion of the second group L2 located ahead of the first group L1 (hereinafter referred to as the leading portion LH) is compressed, and the oxide film on the leading portion LH of the second group L2 is folded. The leading portion LH of the second group L2 has a relatively high proportion of impurities, inclusions, and oxide film, and an unhealthy layer is generated (FIG. 6D).

[0034] As the rotation speed of the mold 18 increases, the flow velocity of the first group L1 decreases, and therefore the length of the leading portion LH of the second group L2 increases, and the length of the unsound layer also increases. In other words, to shorten the length of the unsound layer, the rotation speed of the mold 18 can be reduced to slow the decrease in the flow velocity of the first group L1. On the other hand, reducing the rotation speed of the mold 18 reduces the height of the spine 16, as described above. Therefore, in one embodiment, when the pouring of the molten metal L into the mold 18 begins, the rotation speed of the mold 18 is set to a first rotation speed, and when the leading position of the molten metal L reaches a predetermined position, the rotation speed of the mold 18 is set to a second rotation speed.

[0035] [Timing for switching between the first and second rotation speeds] 7 is a graph showing the relationship between the timing of switching from the first rotation speed to the second rotation speed and the length of the unsound layer. The switching timing is shown with 0 [s] being the time when the leading edge of the molten metal L reaches the tip P1 (FIG. 1) of the inner circumferential surface 52 of the mold 18.

[0036] As shown in FIG. 7, it can be seen that the length of the unhealthy layer can be shortened by switching from the first rotation speed to the second rotation speed at the timing of -2 [s] to 3 [s].

[0037] 7, if the timing of switching from the first rotation speed to the second rotation speed is too late, the length of the unhealthy layer becomes long because the molten metal L that hits the blocking member 36 returns toward the base end of the mold 18 together with impurities and inclusions.

[0038] According to the above embodiment, the length of the unhealthy layer can be shortened while ensuring the height of the spine 16 of the cylindrical member 12. This also contributes to energy efficiency.

[0039] The following additional notes are further disclosed regarding the above embodiment.

[0040] (Appendix 1) The centrifugal casting machine (10) of the present disclosure is a centrifugal casting machine that casts a casting by injecting molten metal (L) into a rotating mold (18), and includes a control unit (58) that controls the rotation speed of the mold, and a determination unit (60) that determines whether the leading edge of the molten metal flowing along the rotation axis (A) of the mold has reached a predetermined position. The control unit rotates the mold at a first rotation speed, and when the determination unit determines that the leading edge has reached the predetermined position, rotates the mold at a second rotation speed. This allows the length of the unsound layer to be shortened while maintaining the height of the spine.

[0041] (Appendix 2) In the centrifugal casting machine described in Appendix 1, the second rotation speed may be higher than the first rotation speed, thereby making it possible to shorten the length of the unsound layer while ensuring the height of the spine.

[0042] (Appendix 3) In the centrifugal casting machine described in Appendix 1, the first rotation speed may be set according to a pouring speed, which is a flow rate of the molten metal when the molten metal is poured into the mold, thereby shortening the length of the unhealthy layer.

[0043] (Appendix 4) In the centrifugal casting machine according to any one of Supplementary Notes 1 to 3, the inner peripheral surface 52 of the mold may be formed with a plurality of recesses 57, thereby forming a spine on the outer peripheral surface of the casting.

[0044] (Appendix 5) The centrifugal casting method disclosed herein is a centrifugal casting method for casting a casting product by injecting molten metal into a rotating mold, the method comprising: a first rotation step of starting to inject the molten metal into the mold while the mold is rotating at a first rotation speed; a determination step of determining whether the leading edge of the molten metal flowing in the direction of the rotation axis of the mold has reached a predetermined position; and a second rotation step of rotating the mold at a second rotation speed if it is determined in the determination step that the leading edge has reached the predetermined position. This allows the length of the unsound layer to be shortened while maintaining the height of the spine.

[0045] (Appendix 6) In the centrifugal casting method described in Supplementary Note 5, the second rotation speed may be higher than the first rotation speed, thereby making it possible to shorten the length of the unsound layer while ensuring the height of the spine.

[0046] (Appendix 7) In the centrifugal casting method described in Appendix 5, the first rotation speed may be set according to a pouring speed, which is a flow speed of the molten metal when the molten metal is poured into the mold, thereby making it possible to shorten the length of the unhealthy layer.

[0047] (Appendix 8) In the centrifugal casting method according to any one of Supplementary Notes 5 to 7, a plurality of recesses may be formed in the inner peripheral surface of the mold, thereby forming a spine on the outer peripheral surface of the casting.

[0048] Although the present disclosure has been described in detail, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the gist of the present disclosure or the spirit of the present disclosure derived from the content of the claims and their equivalents. These embodiments can also be implemented in combination. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these. The same applies when numerical values ​​or mathematical expressions are used in the description of the above-described embodiments. [Explanation of symbols]

[0049] 10...Centrifugal casting device 18...Mold 52...inner peripheral surface 57...recess 58...control unit 60...determination unit A: Rotation axis L: Molten metal

Claims

1. A centrifugal casting apparatus that casts a casting product by injecting molten metal into a mold while rotating the mold, a control unit that controls the rotation speed of the mold; a determination unit that determines whether a leading edge of the molten metal flowing in the direction of the rotation axis of the mold has reached a predetermined position; Equipped with The control unit rotates the mold at a first rotation speed, and when the determination unit determines that the leading position has reached the predetermined position, rotates the mold at a second rotation speed.

2. The centrifugal casting apparatus according to claim 1, The second rotation speed is greater than the first rotation speed.

3. The centrifugal casting apparatus according to claim 1, a centrifugal casting machine in which the first rotation speed is set in accordance with a pouring speed, which is a flow speed of the molten metal when the molten metal is poured into the mold;

4. The centrifugal casting machine according to any one of claims 1 to 3, A centrifugal casting machine, wherein a plurality of recesses are formed on the inner peripheral surface of the mold.

5. A centrifugal casting method for casting a casting product by injecting molten metal into a rotating mold, comprising: a first rotation step of starting to pour the molten metal into the mold while rotating the mold at a first rotation speed; a determining step of determining whether or not a leading edge of the molten metal flowing in the direction of the rotation axis of the mold has reached a predetermined position; a second rotation step of rotating the mold at a second rotation speed when it is determined in the determination step that the leading position has reached the predetermined position; A centrifugal casting method comprising the steps of:

6. The centrifugal casting method according to claim 5, The centrifugal casting method, wherein the second rotation speed is greater than the first rotation speed.

7. The centrifugal casting method according to claim 5, A centrifugal casting method, wherein the first rotation speed is set in accordance with a pouring speed, which is a flow speed of the molten metal when the molten metal is poured into the mold.

8. The centrifugal casting method according to any one of claims 5 to 7, A centrifugal casting method, wherein a plurality of recesses are formed on the inner peripheral surface of the mold.

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