Centrifugal casting machine
By setting equidistant conical surfaces for contact positioning on the metal frame and core surfaces, the problem of misalignment between the metal frame and core under high temperature conditions was solved, achieving high-precision casting.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- KUBOTA CORP
- Filing Date
- 2024-11-29
- Publication Date
- 2026-06-10
AI Technical Summary
Under high-temperature conditions, existing technologies struggle to achieve precise alignment between the metal frame and the core, leading to uneven metal supply and potential casting defects.
The metal frame and core have first and second conical surfaces with equal angles on their inner and outer surfaces, which achieve precise positioning through contact, avoiding the need for complex sensor control.
High-precision alignment of the core was achieved under high-temperature conditions, preventing metal leakage and ensuring casting quality.
Smart Images
Figure 2026094942000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a centrifugal casting machine.
Background Art
[0002] To centrifugally cast a cast iron pipe, molten metal is poured into a centrifugal casting mold (hereinafter simply referred to as a mold), and the mold is rotated at high speed around the axis of the centrifugal casting mold.
[0003] Ductile iron pipes typically have a socket at one end with a larger diameter than the pipe body. Correspondingly, the mold is provided with a socket forming portion at one end having a larger diameter than the inner diameter of other portions. For example, Patent Document 1 discloses a mode of centrifugal casting by mounting a core ring on the socket side of the mold, and casting a pipe having a socket wall thickness corresponding to the inner diameter of the core ring.
[0004] In addition, the inner peripheral surface of the socket of a ductile iron pipe generally has a complex shape. In order to form such an inner peripheral surface of the socket, so-called cores such as sand cores may be used. The core is formed in a cylindrical shape, and concavo-convex portions for forming grooves on the inner periphery of the socket are formed on the outer periphery thereof. The core is supported by a core ring, and by mounting the core ring on the mold, the core is inserted into the socket forming portion of the mold, and a cast pipe having a complex shape on the inner peripheral surface of the socket is formed. Patent Document 2 discloses a casting method using a core.
Prior Art Documents
Patent Documents
[0005]
Patent Document 1
Patent Document 2
Summary of the Invention
Problems to be Solved by the Invention
[0006] When attaching the coring to the metal frame, insufficient alignment of the coring and the metal frame can result in variations in the gap between the frame and the core. This can also lead to variations in the amount of molten metal supplied during casting, potentially causing casting defects. Conventionally, alignment of the metal frame and core is achieved by controlling their position to a specified location. However, precise control using sensors is difficult in casting machines operating at high temperatures, and there was room for improvement in the need for a mechanism that can achieve more precise alignment.
[0007] Therefore, one embodiment of the present invention aims to provide a centrifugal casting machine and a pipe manufacturing method that can center the socket core with high precision even at high temperatures. [Means for solving the problem]
[0008] To solve the aforementioned problems, a centrifugal casting machine according to one aspect of the present invention is a centrifugal casting machine for manufacturing a tube having a socket by centrifugal casting, the centrifugal casting machine comprising a metal frame having an opening on the socket forming side, and a coring capable of fixing a socket core inserted into the metal frame, wherein the metal frame has an inner surface disposed opposite to the outer surface of the coring, the inner surface includes a first tapered surface, and the outer surface includes a second tapered surface, the first tapered surface and the second tapered surface have equal tapered angles, and the coring is centered and fixed to the metal frame by contact between the first tapered surface and the second tapered surface.
[0009] According to the above configuration, the coring is centered relative to the metal frame by bringing the first tapered surface and the second tapered surface into contact. Therefore, high-precision centering of the socket core is possible even at high temperatures without the need for complex control using sensors, and high-quality pipes can be cast.
[0010] In one aspect of the present invention, the centrifugal casting machine, in the above configuration, may have a reduced diameter surface extending from the end point on the inner side of the tube of the first tapered surface toward the central axis of the metal frame, and the coring may have a tip surface extending from the end point on the inner side of the tube of the second tapered surface toward the central axis of the coring, and in contact with the reduced diameter surface.
[0011] According to the above configuration, since the reduced diameter surface and the tip surface are in contact, molten metal does not leak out from between the coring and the metal frame, and a well-formed socket can be created using a predetermined amount of molten metal.
[0012] In one aspect of the present invention, the centrifugal casting machine, in the configuration described above, is provided with an adjacent inclined surface on the inner circumferential surface of the metal frame that is adjacent to the first tapered surface on the opening side of the first tapered surface, and the coring has a facing surface adjacent to the second tapered surface on the side further from the tip surface of the second tapered surface and facing the adjacent inclined surface, the adjacent inclined surface has a predetermined inclination angle, and the adjacent inclined surface and the facing surface are spaced apart, and the distance between them may gradually increase from the side closer to the first tapered surface and the second tapered surface to the side further away.
[0013] According to the above configuration, by reducing the contact area between tapered surfaces, the removal of the coring after casting can be made easier.
[0014] In one aspect of the present invention, the centrifugal casting machine, in the above configuration, may have a taper angle smaller than the inclination angle of the adjacent inclined surface.
[0015] According to the above configuration, the area near the opening of the metal frame (the area of the adjacent inclined surface) is wider than the area where the first tapered surface is located, making it easier to remove the coring after casting.
[0016] In one aspect of the present invention, the centrifugal casting machine, in the above configuration, may have an adjacent inclined surface that is a tapered surface having a different taper angle than the first tapered surface, and the opposing surface that is a tapered surface having a different taper angle than the second tapered surface.
[0017] According to the above configuration, when attaching the coring to the metal frame, the first tapered surface can be guided to the contact point with the second tapered surface while contacting the tapered surface that constitutes the opposing surface. Therefore, the coring can be smoothly attached to the metal frame.
[0018] In one aspect of the present invention, the centrifugal casting machine, in the above configuration, may have a configuration in which the adjacent inclined surface has a larger taper angle than the first tapered surface.
[0019] According to the above configuration, the diameter of the opening gradually widens from the region where the first tapered surface is formed on the inner circumferential surface of the metal frame toward the opening (of the metal frame). This makes it easy to remove the coring after casting. Furthermore, when attaching the coring to the metal frame, the second tapered surface of the coring can be guided to the contact point with the first tapered surface while contacting the tapered surface of the adjacent inclined surface. Therefore, the coring can be attached to the metal frame smoothly.
[0020] Furthermore, in order to solve the above-mentioned problems, a pipe manufacturing method according to one aspect of the present invention is a pipe manufacturing method for manufacturing a pipe having a socket by centrifugal casting, comprising: a preparation step of preparing a metal frame having an opening on the socket forming side and including a first tapered surface on its inner circumferential surface, and a coring capable of fixing a socket core inserted into the metal frame and including a second tapered surface on its outer circumferential surface having a taper angle equal to that of the first tapered surface; a fixing step of centering and fixing the coring with respect to the metal frame by contact between the first tapered surface and the second tapered surface; and a pouring step of pouring molten metal between the fixed coring and the metal frame.
[0021] According to the above configuration, the core ring is centered with respect to the metal frame by bringing the first tapered surface into contact with the second tapered surface. Therefore, it is possible to center the receiving core with high precision even at high temperatures without using complicated control using sensors, and it is possible to cast high-quality pipes.
Effects of the Invention
[0022] According to one aspect of the present invention, it is possible to provide a centrifugal casting machine and a pipe manufacturing method capable of centering a receiving core with high precision even at high temperatures.
Brief Description of the Drawings
[0023] [Figure 1] It is a view of a pipe centrifugally cast by a centrifugal casting machine according to an embodiment of the present invention, and is a side view with a part being a cross-sectional view. [Figure 2] It is a partial cross-sectional view showing the configuration of a part of a centrifugal casting machine according to an embodiment of the present invention. [Figure 3] It is an enlarged cross-sectional view of a part of the cross-sectional view shown in FIG. 2. [Figure 4] It is an enlarged cross-sectional view showing the details of the centrifugal casting machine shown in FIG. 2. [Figure 5] It is a view showing the flow of a method for manufacturing a pipe centrifugally cast by a centrifugal casting machine according to an embodiment of the present invention.
Modes for Carrying Out the Invention
[0024] 〔Embodiment 1〕 〔Pipe to be Centrifugally Cast〕 First, the pipe 100 to be centrifugally cast according to the present embodiment will be described using FIG. 1. In FIG. 1, for convenience of explanation, a part is shown as a broken view, and the hatched part represents the cut surface of the pipe 100.
[0025] As shown in Figure 1, the pipe 100 has a socket 100b at one end and a spigot 100c at the other end. Between the socket 100b and the spigot 100c, there is a straight section 100a that extends in a nearly straight line and has an inner diameter that is nearly constant along the pipe axis XC. The spigot 100c has an inner diameter that is nearly constant along the pipe axis XC, and since this diameter is the same as the inner diameter of the straight section 100a, it can be included as part of the straight section 100a.
[0026] The socket 100b has a shape for inserting the spigot of another pipe. Furthermore, an annular groove 100n is formed on the inner circumferential surface of the socket 100b for attaching a locking ring to prevent the pipe 100 from detaching when connected to another pipe. The socket 100b and the spigot 100c allow the pipe 100 to be connected to another pipe.
[0027] Examples of pipes 100 with the above configuration include well-known ductile iron pipes used as earthquake-resistant pipes for water supply, etc. However, the pipes are not limited to these.
[0028] In this embodiment, a pipe 100 having such a socket 100b is manufactured by centrifugal casting in a pipe manufacturing line. Below, the centrifugal casting machine for centrifugal casting of the pipe and the pipe manufacturing method by centrifugal casting will be described.
[0029] [Centrifugal casting machine] Figure 2 is a partial cross-sectional view of a centrifugal casting machine 1, which is one embodiment of the present invention. Figure 2 is a cross-section of the portion of the centrifugal casting machine 1 that forms the receiving port 100b of the aforementioned pipe 100 (the portion enclosed by the dashed line A in Figure 1), and shows a cross-sectional view of a state in which the machine is cut vertically along the axis.
[0030] As shown in Figure 2, the centrifugal casting machine 1 has a metal frame 2 and a coring ring 5 to which the receiving core 3 is fixed.
[0031] The metal frame 2 is supported horizontally on the drive roller 4 and is capable of rotating at high speed around its central axis XC. With the receiving core 3 inserted into the receiving opening forming portion 21 of the metal frame 2, molten metal is poured into the metal frame 2, and the pipe 100 shown in Figure 1 is formed by centrifugal force.
[0032] The coring 5 can be mounted on the metal frame 2, and at this time it is mounted in a centered state. This will be described later. The coring 5 supports the receiving core 3. The receiving core 3, supported by the coring 5, is inserted into the receiving part 21 located on the opening 20 side of the metal frame 2 and set concentrically. There are no particular restrictions on the connection method between the coring 5 and the receiving core 3.
[0033] The socket core 3 is formed in a cylindrical shape and, in the state shown in Figure 2, extends along the axial direction from position 100x, which is the end of the socket of the pipe, toward the back of the pipe. Here, Figure 2 also shows a three-dimensional coordinate system of XYZ, with the direction along the pipe axis XC as the Y axis. The positive Y axis is defined as the direction toward the back of the pipe. The Z axis is the vertical direction, and the XY plane is defined as the horizontal plane. Note that the axis (central axis) of the metal frame 2 and the axis (central axis) of the socket core 3 can be considered to be coaxial with the pipe axis XC. Note that Figure 2 shows the state before molten metal has been poured into the metal frame 2.
[0034] On the outer circumferential surface of the extension portion of the socket core 3 that extends axially toward the back of the pipe, there are irregularities 31 formed to create an annular groove 100n (Figure 1) that is formed on the inner circumferential surface of the socket 100b.
[0035] When forming a tube 100 by centrifugal force by pouring molten metal into a metal frame 2, using a coring ring 5 that supports the receiving core 3 with this configuration, the central axis of the coring ring 5 (coaxial with the central axis of the receiving core 3) needs to be centered so that it is coaxial with the central axis of the metal frame 2. As mentioned above, precise control using sensors as in the past is difficult in centrifugal casting machines that operate at high temperatures. Therefore, in this embodiment, the metal frame 2 and the coring ring 5 are provided with a configuration that allows them to be centered by contact with each other. This will be explained below.
[0036] Figure 3 is an enlarged view of the dashed-line-enclosed area B shown in Figure 2. Figure 3 also shows an enlarged cross-sectional view of a further portion of the enlarged view shown.
[0037] As shown in Figure 3, the metal frame 2 has an inner circumferential surface 24 that is positioned opposite the outer circumferential surface 52 of the coring 5. Furthermore, as shown in the enlarged view, the inner circumferential surface 24 includes a first tapered surface 24c, and the outer circumferential surface 52 includes a second tapered surface 52c.
[0038] The first tapered surface 24c and the second tapered surface 52c have equal taper angles. The taper angle is the angle between each tapered surface and the central axis XC (Y-axis). Furthermore, "equal taper angles" may mean perfectly equal, or substantially equal within a range that produces an effect equivalent to that of perfectly equal angles. The taper angles can be appropriately set within the range that allows the coring 5 to be inserted into the metal frame 2.
[0039] The taper angle is shown in Figure 4. Figure 4 is a magnified view of only a portion of Figure 3, illustrating the taper angle. The taper angle of the first tapered surface 24c is the taper angle θa shown in Figure 4, and represents the angle between the first tapered surface 24c of the metal frame 2 and the Y-axis. The taper angle of the second tapered surface 52c of the coring 5 is also considered to be the taper angle θa shown in Figure 4.
[0040] In this way, by setting the taper angles of the first tapered surface 24c of the metal frame 2 and the second tapered surface 52c of the coring ring 5 to be equal, the coring ring 5 is centered and fixed relative to the metal frame 2 by the contact between the first tapered surface 24c and the second tapered surface 52c. In other words, when attempting to fix the coring ring 5 to the metal frame 2, the centering is completed by inserting the coring ring 5 into the metal frame 2 and pushing it all the way in while bringing the first tapered surface 24c and the second tapered surface 52c into contact. That is, centering adjustment using sensors as in the past is unnecessary, and centering can be achieved simply by pushing the coring ring 5 in while bringing the tapered surfaces into contact.
[0041] As shown in Figure 3, the metal frame 2 has a reduced diameter surface 26 that extends from the end point 24m on the inner side of the pipe on the first tapered surface 24c toward the central axis XC of the metal frame 2. The coring 5 has a tip surface 56 that extends from the end point 52m on the inner side of the pipe on the second tapered surface 52c toward the central axis XC of the coring 5 and contacts the reduced diameter surface 26. Because the reduced diameter surface 26 and the tip surface 56 are in contact, molten metal does not leak out from between the coring 5 and the metal frame 2, and the receiving port 100b can be formed well using a predetermined amount of molten metal. In addition to the contact between the reduced diameter surface 26 and the tip surface 56, the prevention of molten metal leakage is also achieved by sealing the contact portion between the receiving port core 3 and the metal frame 2.
[0042] Furthermore, as shown in Figure 3, the inner circumferential surface 24 of the metal frame 2 is provided with an adjacent inclined surface 24p adjacent to the first tapered surface 24c on the opening 20 side of the first tapered surface 24c. The adjacent inclined surface 24p has a predetermined inclination angle. Here, the inclination angle refers to the angle made between the adjacent inclined surface 24p and the Y-axis, which is the angle θb shown in Figure 4. The taper angle θa of the first tapered surface is smaller than the inclination angle θb of the adjacent inclined surface 24p.
[0043] Furthermore, as shown in Figure 3, the coring 5 has an opposing surface 52p that is adjacent to the second tapered surface 52c and faces the adjacent inclined surface 24p, on the side further from the tip surface 56 than the second tapered surface 52c.
[0044] Here, the adjacent inclined surface 24p and the opposing surface 52p are spaced apart. The distance between them gradually increases from the side closer to the first tapered surface 24c and the second tapered surface 52c to the side further away.
[0045] As described above, the adjacent inclined surface 24p and opposing surface 52p are provided, reducing the contact area between the tapered surfaces 24c and 52c. This makes it easier to remove the coring 5 after casting, i.e., to remove it from the metal frame 2. Furthermore, even if the taper angle θa of the first tapered surface 24c is smaller than the inclination angle θb of the adjacent inclined surface 24p, the area close to the opening 20 of the metal frame 2 (the area of the adjacent inclined surface 24p) is wider than the area where the first tapered surface 24c is located, thus making it easier to remove the coring 5 after casting.
[0046] Here, the adjacent inclined surface 24p may be a tapered surface having a different taper angle than the first tapered surface 24c. And the opposing surface 52p may be a tapered surface having a different taper angle than the second tapered surface 52c.
[0047] Furthermore, if the adjacent inclined surface 24p is a tapered surface, the taper angle may be larger than that of the first tapered surface 24c. The inner circumferential surface 24 of the metal frame 2 is configured such that the opening diameter gradually widens from the region where the first tapered surface 24c is formed toward the opening 20 (of the metal frame 2). This makes it easy to remove the coring 5 after casting. Also, when attaching the coring 5 to the metal frame 2, the second tapered surface 52c of the coring 5 can be guided to the contact point with the first tapered surface 24c while contacting the tapered surface of the adjacent inclined surface 24p. Therefore, it is possible to attach the coring 5 to the metal frame 2 smoothly.
[0048] However, the adjacent inclined surface 24p and the opposing surface 52p are not limited to tapered surfaces; they may also be curved surfaces in the same cross-sectional view as in Figures 3 and 4.
[0049] Furthermore, if the opposing surface 52p is a tapered surface having a different taper angle than the second tapered surface 52c, then, as shown in Figure 4, the taper angle θc of the opposing surface 52p is smaller than the taper angle θa of the second tapered surface 52c.
[0050] The first tapered surface 24c is provided along the entire circumference of the inner circumferential surface 24. Similarly, the second tapered surface 52c is provided along the entire circumference of the outer circumferential surface 52. However, the first tapered surface 24c may be provided intermittently along the circumference of the inner circumferential surface 24. Likewise, the second tapered surface 52c may be provided intermittently along the circumference of the outer circumferential surface 52.
[0051] Furthermore, similar to these tapered surfaces 24c and 52c, the adjacent inclined surface 24p is provided along the entire circumference of the inner circumferential surface 24, but it may also be provided intermittently along the circumference of the inner circumferential surface 24. Similarly, the opposing surface 52p is provided along the entire circumference of the outer circumferential surface 52, but it may also be provided intermittently along the circumference of the outer circumferential surface 52.
[0052] Next, we will describe the centrifugal casting of a tube using the centrifugal casting machine 1 equipped with the above-described configuration.
[0053] [Pipe manufacturing method] Figure 5 is a diagram showing the flow of the pipe manufacturing method of this embodiment. The pipe manufacturing method S10 of this embodiment is a method for manufacturing pipes by centrifugal casting and includes a preparation step S11, a fixing step S12, and a pouring step S13. Each step will be described below.
[0054] In preparation step S11, the coring 5 supporting the aforementioned receiving core 3 and the gold frame 2 are prepared.
[0055] In the fixing step S12, following the preparation step S11, the coring 5 is centered and fixed to the metal frame 2 by the contact between the first tapered surface 24c of the metal frame 2 and the second tapered surface 52c of the coring 5. The process of inserting the coring 5 into the metal frame 2 may be done manually or using a machine called a core setter.
[0056] In the pouring step S13, following the fixing step S12, molten metal is poured between the fixed coring 5 (more specifically, the receiving core 3 supported by the coring 5) and the metal frame 2. The molten metal is poured from the insertion opening 100a side. Once the pouring is complete, the centrifugal casting machine 1 (the fixed coring 5 and the metal frame 2) is rotated by the drive roller 4 (Figure 1), and the tube 100 is formed by the centrifugal force. As the centrifugal casting machine 1 rotates, the molten metal flows in the direction of the arrow shown in Figure 3 and fills the space between the receiving core 3 and the metal frame 2. The machine continues to rotate for a while to cool and solidify the molten metal. After solidification, the coring 5 is removed from the metal frame 2 and the tube 100 is taken out.
[0057] The tube 100 is manufactured through the above series of steps. The coring 5 is centered relative to the metal frame 2 by bringing the first tapered surface 24c and the second tapered surface 52c into contact, so that the socket core can be centered with high precision even at high temperatures without using complicated control using sensors. Therefore, according to the tube manufacturing method of this embodiment, high-quality tubes can be cast.
[0058] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]
[0059] 1. Centrifugal casting machine 2 gold frame 3 socket core 4 drive rollers 5 Coring 21 Socket forming part 24 Inner peripheral surface 24c First tapered surface 24m Endpoint of the first tapered surface 24p Adjacent Inclined Surface 26 Reduced diameter surface 31 Uneven part 52 Outer surface 52c Second tapered surface 52m End point of the second tapered surface 52p Opposing surface 56 Tip surface 100 tubes 100b socket 100n annular groove 100x position
Claims
1. A centrifugal casting machine for manufacturing tubes having sockets by centrifugal casting, The centrifugal casting machine comprises a metal frame having an opening on the socket forming side, and a core ring capable of fixing a socket core inserted into the metal frame, The metal frame has an inner surface that is positioned opposite to the outer surface of the coring, The inner circumferential surface includes a first tapered surface, The outer circumferential surface includes a second tapered surface, The first tapered surface and the second tapered surface have equal taper angles, and the coring is centered and fixed to the metal frame by contact between the first tapered surface and the second tapered surface. A centrifugal casting machine characterized by the following features.
2. The metal frame has a reduced diameter surface that extends from the end point on the inner side of the tube in the first tapered surface toward the central axis of the metal frame, The coring extends from the inner end point of the second tapered surface toward the central axis of the coring and has a tip surface that contacts the reduced diameter surface. The centrifugal casting machine according to feature 1.
3. The inner circumferential surface of the metal frame is provided with an adjacent inclined surface adjacent to the first tapered surface on the opening side of the first tapered surface, The coring has a facing surface adjacent to the second tapered surface and facing the adjacent inclined surface, on the side further from the tip surface than the second tapered surface. The adjacent inclined surface has a predetermined inclination angle, The adjacent inclined surface and the opposing surface are spaced apart, and the distance between them gradually increases from the side closer to the first tapered surface and the second tapered surface towards the side further away. The centrifugal casting machine according to feature 2.
4. The taper angle of the first tapered surface is smaller than the inclination angle of the adjacent inclined surface. The centrifugal casting machine according to feature 3.
5. The adjacent inclined surface is a tapered surface having a different taper angle than the first tapered surface. The opposing surface is a tapered surface having a different taper angle than the second tapered surface. The centrifugal casting machine according to feature 3.
6. The adjacent inclined surface has a larger taper angle than the first tapered surface. The centrifugal casting machine according to feature 5.
7. A method for manufacturing a pipe having a socket by centrifugal casting, A preparation step of preparing a metal frame having an opening on the socket forming side and including a first tapered surface on its inner circumferential surface, and a coring capable of fixing a socket core to be inserted into the metal frame and including a second tapered surface on its outer circumferential surface having the same taper angle as the first tapered surface, A fixing step in which the coring is centered and fixed to the metal frame by the contact between the first tapered surface and the second tapered surface, A pouring step of pouring molten metal between the fixed coring and the metal frame, including, A method for manufacturing pipes characterized by the following features.