Manufacturing method of housing pipe

Abstract

To manufacture a housing pipe formed with a joint projection extending along a circumferential direction, by centrifugal casting easily with accurate dimension.SOLUTION: A body side tapered surface 10 is formed on one end side of a mold body 5. An auxiliary side tapered surface 11 is formed in an auxiliary mold 6 fitted to one end side of the mold body 5. When the mold body 5 and the auxiliary mold 6 fit to each other, the body side tapered surface 10 and the auxiliary side tapered surface 11 surface-contact with each other and a peripheral groove 13 having a larger diameter than an inner diameter of the mold body 5 is formed in an inner peripheral side end portion 12 of a boundary between the mold body 5 and the auxiliary mold 6. By centrifugal casting by casting molten metal to the inside of the mold body 5 and the peripheral groove 13 in a state where the tapered surfaces 10, 11 surface-contact with each other, a straight pipe part 2 and a joint projection 3 extending along a circumferential direction in an outer peripheral surface of one end side of the straight pipe part 2 are integrally formed, while a joint projection 4 is also formed in the outer peripheral surface on the other end side of the straight pipe part 2, and thereby, a housing pipe 1 is manufactured.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] In a method for manufacturing a housing tube, auxiliary molds are provided at both ends of a cylindrical mold body to prevent leakage of molten metal, and molten metal is then poured into the mold body to manufacture the housing tube by centrifugal casting. For example, as shown in Figure 6(a) of Patent Document 1 below, an expanded diameter section with an expanded inner diameter is formed at one end of mold 1c (corresponding to the mold body), and a closure 8b (corresponding to the auxiliary mold) with a cylindrical section at its tip is fitted into the expanded diameter section, and molten metal is poured into a circumferential groove formed between the tip of the cylindrical section and the step of the expanded diameter section to form a joint ridge extending in the circumferential direction.

[0003] Also, as shown in FIG. 6(b) of Patent Document 1, for example, a circumferential groove is formed on one end side of the mold 1d, and then a closure 8c with a partially enlarged inner diameter is abutted against the end face of the mold 1d, and molten metal is poured into the circumferential groove formed between the mold 1d and the closure 8c, thereby forming a joint ridge extending in the circumferential direction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-148269 Summary of the Invention [Problem to be solved by the invention]

[0005] The configuration shown in Figure 6(a) of Patent Document 1 has the problem that it is difficult to adjust the clearance between the inner circumferential surface of the expanded diameter portion formed in the mold 1c and the outer circumferential surface of the cylindrical portion formed in the closure member 8b. If this clearance is small, it is difficult to fit the closure member 8b into the mold 1c, and if the clearance is large, the closure member 8b is likely to come off the mold 1c. Furthermore, the configuration shown in Figure 6(b) of Patent Document 1 has the problem that radial misalignment occurs between the mold 1d and the closure member 8c during high-speed rotation associated with centrifugal casting, resulting in a decrease in the dimensional accuracy of the cast housing tube. Thus, there is still room for improvement in the configurations of the molds 1c, 1d and the closure members 8b, 8c.

[0006] SUMMARY OF THE INVENTION An object of the present invention is to easily manufacture, by centrifugal casting, a housing pipe on which a circumferentially extending joint ridge is formed, with high dimensional accuracy. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides: A method for manufacturing a housing tube, comprising providing auxiliary molds at both ends of a cylindrical mold body to prevent leakage of molten metal, pouring molten metal into the mold body, and manufacturing the housing tube by centrifugal casting, comprising: a main body side tapered surface is formed on one end side of the mold main body, and an auxiliary side tapered surface is formed on the auxiliary mold that fits into the one end side of the mold main body, When the mold body and the auxiliary mold are fitted together, the body-side tapered surface and the auxiliary-side tapered surface come into surface contact with each other, and a circumferential groove having a diameter larger than the inner diameter of the mold body is formed at the inner peripheral end of the boundary separating the mold body and the auxiliary mold, A method for manufacturing a housing pipe (first configuration) has been constructed, characterized in that a straight pipe section and a joint ridge extending circumferentially on the outer peripheral surface of one end of the straight pipe section are integrally formed by centrifugal casting of molten metal into the mold body and the circumferential groove with both tapered surfaces in surface contact, while also forming a joint ridge on the outer peripheral surface of the other end of the straight pipe section, thereby manufacturing a housing pipe.

[0008] In this way, the tapered surfaces formed on the mold body and the auxiliary mold are in surface contact with each other, allowing for smooth positioning between the mold body and the auxiliary mold. Furthermore, the surface contact between the mold body and the auxiliary mold at the tapered surfaces increases the contact area, minimizing wobble when the mold body is rotated at high speed. This allows for easy, highly dimensionally accurate production of a housing pipe with circumferentially extending joint ridges by centrifugal casting.

[0009] In the first configuration, the main body side tapered surface can be a tapered surface formed on the inner surface of the mold main body, the inner diameter of which decreases from the pipe end toward the rear in the pipe axis direction, and the auxiliary side tapered surface can be a tapered surface formed on the outer surface of the auxiliary mold, the outer diameter of which decreases from the pipe end toward the rear in the pipe axis direction (second configuration).

[0010] Furthermore, the main body side tapered surface may be a tapered surface formed on the outer peripheral surface of the mold main body, the outer diameter of which increases from the pipe end toward the rear in the pipe axis direction, and the auxiliary side tapered surface may be a tapered surface formed on the inner peripheral surface of the mold, the inner diameter of which increases from the pipe end toward the rear in the pipe axis direction (third configuration).

[0011] In both the second and third configurations, the tapered surfaces can be reliably brought into surface contact with each other, and as with the first configuration, a housing pipe having circumferentially extending joint ridges formed thereon can be easily manufactured with high dimensional accuracy by centrifugal casting. [Effects of the Invention]

[0012] In this invention, by bringing the tapered surfaces formed on the mold body and the auxiliary mold into surface contact with each other, it is possible to smoothly position the mold body and the auxiliary mold, and to minimize core wobble when the mold body is rotated at high speed.As a result, a housing pipe with circumferentially extending joint ridges can be easily manufactured by centrifugal casting with high dimensional accuracy. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a partial cross-sectional view showing a housing tube manufactured by the housing tube manufacturing method according to the present invention. [Figure 2] 1 is a cross-sectional view showing one embodiment of a manufacturing method for a housing tube according to the present invention; [Figure 3] (a) is a cross-sectional view showing the main part of FIG. 2, and (b) is a cross-sectional view showing the main part of (a). [Figure 4] (a) is a cross-sectional view of a first modified example of FIG. 3, (b) is a cross-sectional view showing a main part of (a), (c) is a cross-sectional view of a second modified example of FIG. 3, (d) is a cross-sectional view showing a main part of (c), (e) is a cross-sectional view of a third modified example of FIG. 3, and (f) is a cross-sectional view showing a main part of (e). [Figure 5] A first example of a joint rib on the other end of a housing pipe is shown, where (a) is a perspective view during assembly and (b) is a cross-sectional view after assembly. [Figure 6] A second example of a joint rib on the other end of the housing pipe is shown, where (a) is a perspective view during assembly and (b) is a cross-sectional view after assembly. [Figure 7] A third example of a joint protrusion on the other end of the housing pipe is shown. (a) is a perspective view after buildup welding, and (b) is a cross-sectional view after grinding. [Figure 8] (a) is a cross-sectional view showing the joint between the housing tubes, and (b) is a cross-sectional view along line bb in (a). DETAILED DESCRIPTION OF THE INVENTION

[0014] A method for manufacturing a housing pipe according to the present invention will be described with reference to the drawings. The housing pipe 1 manufactured by this manufacturing method is a cast iron pipe body. As shown in FIG. 1, the housing pipe 1 has a straight pipe section 2 with a constant inner diameter along its entire length. Both ends of the straight pipe section 2 are formed with joint ridges 3, 4 that protrude radially outward. These joint ridges 3, 4 have a rectangular cross section and are formed around the entire circumferential direction of the straight pipe section 2. The joint ridge 3 on one end (left side in FIG. 1) is formed integrally with the straight pipe section 2 by centrifugal casting, which will be described later. Meanwhile, the joint ridge 4 on the other end (right side in FIG. 1) is formed separately after centrifugal casting is completed. Hereinafter, the joint ridge 3 on one end will be referred to as the one-end joint ridge 3, and the joint ridge 4 on the other end will be referred to as the other-end joint ridge 4.

[0015] This housing pipe 1 is manufactured by centrifugal casting, in which auxiliary molds 6 and 7 are provided at both ends of a cylindrical mold body 5 to prevent leakage of molten metal, molten metal is poured into the mold body 5, and the mold body 5 and auxiliary molds 6 and 7 are rotated at high speed around their axis to cast the housing pipe. Hereinafter, the auxiliary mold 6 provided at one end of the mold body 5 will be referred to as the one-end auxiliary mold 6, and the auxiliary mold 7 provided at the other end of the mold body will be referred to as the other-end auxiliary mold 7.

[0016] As shown in Figures 2 and 3(a), the mold body 5 is a substantially cylindrical mold with a constant inner diameter throughout its entire length except for one end. One end of the mold body 5 is formed with a thick-walled section 8 that has an increased radial thickness. In addition, two axial locations of the mold body 5 are formed with expanded diameter sections 9 that come into contact with rotation mechanisms (not shown) such as rollers that rotate the mold body 5 around its axis. One end of the mold body 5 is formed with a body-side tapered surface 10. The body-side tapered surface 10 is a tapered surface formed on the inner peripheral surface of the mold body 5, with the inner diameter decreasing from the pipe end toward the inner side in the axial direction of the pipe.

[0017] As shown in Figures 2 and 3(a), the one-end auxiliary mold 6 is a generally disk-shaped mold with a through-hole formed in the center, which is fitted into the inner periphery of one end of the mold body 5. An auxiliary-side tapered surface 11 is formed on the side of the one-end auxiliary mold 6 that fits into the mold body 5. The auxiliary-side tapered surface 11 is a tapered surface formed on the outer circumferential surface of the one-end auxiliary mold 6, the outer diameter of which decreases from the pipe end of the mold body 5 toward the inner side in the axial direction of the pipe. The inclination angles of both tapered surfaces 10, 11 with respect to the axial direction of the pipe are the same.

[0018] When the one-end auxiliary mold 6 is pressed toward the mold body 5 by a pressing means (not shown), the mold body 5 and the one-end auxiliary mold 6 fit together, and the main body tapered surface 10 and the auxiliary side tapered surface 11 come into surface contact, preventing leakage of molten metal from the one end. In addition, with the main body tapered surface 10 and the auxiliary side tapered surface 11 in surface contact, a circumferential groove 13 with a larger diameter than the inner diameter of the part of the mold body 5 other than the one end side is formed at the inner peripheral end 12 of the boundary separating the mold body 5 and the one-end auxiliary mold 6.

[0019] 2, the other-end auxiliary mold 7 is a generally disk-shaped mold with a through-hole formed in the center, which is abutted against the side surface of the other end of the mold main body 5. When the other-end auxiliary mold 7 is pressed against the mold main body 5 by a pressing means (not shown), the other-end end face of the mold main body 5 and the end face of the other-end auxiliary mold 7 facing the mold main body 5 come into surface contact, preventing leakage of molten metal from the other end side.

[0020] As shown in detail in Figure 3(b), the circumferential groove 13 is composed of a bottom surface portion 14 and a side surface portion 15. In this embodiment, an extension of the inner peripheral edge portion 12 of the boundary separating the mold body 5 and the one-end auxiliary mold 6 overlaps with the side surface portion 15, but as shown in Figures 4(a) to 4(d) described later, it is also possible to configure the extension of the inner peripheral edge portion 12 to overlap with the bottom surface portion 14.

[0021] As shown in Figures 4(a) to (f), the shape of the vicinity of the mating portion between the mold body 5 and the one-end auxiliary mold 6 can be changed as appropriate, as long as the housing tube 1 can be smoothly released when the one-end auxiliary mold 6 is removed from the mold body 5. In addition, in the embodiment shown in Figures 3(a)(b) and 4(a) to (d), the inner surface of the mold body 5 is formed with a main body side tapered surface 10 whose inner diameter decreases as it moves from the pipe end to the rear in the pipe axial direction, and the outer surface of the one-end auxiliary mold 6 is formed with an auxiliary side tapered surface 11 whose outer diameter decreases as it moves from the pipe end of the mold body 5 to the rear in the pipe axial direction.However, as shown in Figures 4(e)(f), it is also possible to form a main body side tapered surface 10 whose outer diameter increases as it moves from the pipe end to the rear in the pipe axial direction on the outer surface of the mold body 5, and an auxiliary side tapered surface 11 whose inner diameter increases as it moves from the pipe end of the mold body 5 to the rear in the pipe axial direction on the inner surface of the one-end auxiliary mold 6.

[0022] In the manufacturing method of this housing pipe 1, as shown in Figure 2, each auxiliary mold 6, 7 is attached to the mold body 5, and then molten metal is poured into the mold body 5 while the mold body 5 is rotated at high speed around its axis using a rotation mechanism (not shown) to perform centrifugal casting, thereby integrally forming the straight pipe section 2 of the housing pipe 1 and the one-end joint rib 3 extending circumferentially on the outer peripheral surface of one end of the straight pipe section 2.

[0023] After the straight pipe section 2 and the one-end joint ridge 3 are integrally formed by centrifugal casting, the mold body 5 and both auxiliary molds 6, 7 are removed. Then, the other-end joint ridge 4 is formed on the other end side of the straight pipe section 2. As a method for forming this other-end joint ridge 4, for example, as shown in Figures 5(a) and 5(b), a circumferential groove 16 of a predetermined depth is formed on the other end side of the cast straight pipe section 2, and a ring-shaped other-end joint ridge 4 (4a) with a partial circumferential cutout is fitted into this circumferential groove 16, and both axial ends of this other-end joint ridge 4 (4a) are fixed with welds 17.

[0024] 6(a)(b), a method can also be employed in which a ring-shaped other-end joint rib 4 (4b) is directly attached to the outer peripheral surface of the other end of the cast straight pipe section 2, and both axial sides of this other-end joint rib 4 (4b) are fixed with welds 17. Also, as shown in Figures 7(a)(b), a method can also be employed in which an overlay weld 18 is formed circumferentially on the other end of the cast straight pipe section 2, and this overlay weld 18 is then processed, such as by grinding, to form the other-end joint rib 4 (4c).

[0025] The housing pipes 1 manufactured as described above are aligned in the axial direction as shown in Figures 8(a) and 8(b) and joined by a housing joint 19. The housing joint 19 has a pair of semicircular couplings 20 split in half in the circumferential direction, fastening fittings 21 provided on both ends of the semicircular couplings 20, fastening members 22 (bolts and nuts) that fasten the fastening fittings 21 together, and a rubber ring 23.

[0026] First, rubber rings 23 are provided so as to straddle the ends of the adjacently arranged housing pipes 1. Next, a pair of semicircular couplings 20 are provided so as to straddle the one-end joint ridge 3 formed on one housing pipe 1 and the other-end joint ridge 4 formed on the other housing pipe 1, and the fastening fittings provided on both ends of the semicircular couplings 20 are fastened together with fastening members 22. This joins the adjacent housing pipes 1 together, ensuring a watertight state between the two housing pipes 1.

[0027] In the method for manufacturing the housing pipe 1 described above, the tapered surfaces 10, 11 formed on the mold body 5 and the auxiliary mold 6 (one-end auxiliary mold 6), respectively, are in surface contact with each other, which allows smooth positioning between the mold body 5 and the auxiliary mold 6 (one-end auxiliary mold 6). Furthermore, by bringing the mold body 5 and the auxiliary mold 6 (one-end auxiliary mold 6) into surface contact at the tapered surfaces 10, 11, the contact area is increased, making it possible to minimize wobbling when the mold body 5 is rotated at high speed. This allows the housing pipe 1, on which the joint ridge 3 (one-end joint ridge 3) extending in the circumferential direction is formed, to be manufactured easily and with high dimensional accuracy by centrifugal casting.

[0028] Furthermore, in the manufacturing method for the housing pipe 1, an extension line of the inner peripheral end 12 of the boundary separating the mold body 5 and the one-end auxiliary mold 6 overlaps with either the bottom surface 14 or the side surface 15, so that after the centrifugal casting is completed, the one-end auxiliary mold 6 can be smoothly released from the mold body 5 and the cast housing pipe 1. This prevents chipping of the one-end joint ridge 3 and allows the one-end joint ridge 3 to be formed with good dimensional accuracy.

[0029] The embodiments disclosed herein are to be considered in all respects as illustrative and not restrictive. Therefore, the scope of the present invention is defined by the claims, not by the above description, and is intended to include meanings equivalent to the claims and all modifications thereof. [Explanation of symbols]

[0030] 1 Housing tube 2 Straight pipe section 3 Joint ridge (joint ridge on one end) 4 (4a, 4b, 4c) Joint protrusion (other end joint protrusion) 5 Mold body 6 Auxiliary mold (one end auxiliary mold) 7 Auxiliary mold (other end auxiliary mold) 8 Thick part 9 Expanded diameter part 10 Tapered surface on the body side 11 Auxiliary side tapered surface 12 Inner circumference end 13, 16 Circumferential groove 14 Bottom part 15 Side part 17 Welded parts 18 Overlay weld 19 Housing joint 20 Semicircular Coupling 21 Fasteners 22 Fastening members 23 Rubber ring

Claims

1. A method for manufacturing a housing pipe (1) by centrifugal casting, comprising providing auxiliary molds (6) at both ends of a cylindrical mold body (5) to prevent leakage of molten metal, and then pouring molten metal into the mold body (5), comprising: A main body side tapered surface (10) is formed on one end side of the mold main body (5), and an auxiliary side tapered surface (11) is formed on the auxiliary mold (6) that fits into one end side of the mold main body (5), When the mold body (5) and the auxiliary mold (6) are fitted together, the body-side tapered surface (10) and the auxiliary-side tapered surface (11) are in surface contact with each other, and a circumferential groove (13) having a diameter larger than the inner diameter of the mold body (5) is formed at the inner peripheral end (12) of the boundary separating the mold body (5) and the auxiliary mold (6). A method for manufacturing a housing pipe, characterized in that a straight pipe section (2) and a joint ridge (3) extending circumferentially on the outer peripheral surface of one end of the straight pipe section (2) are integrally formed by pouring molten metal into the mold body (5) and the circumferential groove (13) with both tapered surfaces (10, 11) in surface contact, and centrifugal casting is performed to manufacture a housing pipe (1).

2. 2. A method for manufacturing a housing tube according to claim 1, wherein the main body-side tapered surface (10) is a tapered surface formed on the inner peripheral surface of the mold main body (5) such that the inner diameter decreases from the tube end toward the rear in the tube axial direction, and the auxiliary-side tapered surface (11) is a tapered surface formed on the outer peripheral surface of the auxiliary mold (6) such that the outer diameter decreases from the tube end toward the rear in the tube axial direction.

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