JP2005270984A - Core forming inner surface of receiving hole in centrifugal casting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely prevent the occurrence of such accident that molten metal invades during casting into the inner part of a core having repeatedly usable metal-made dividing structure. <P>SOLUTION: This core is composed of; a flange part 22 fitted to the end part of a receiving hole side of a metallic frame 1; cylindrical separation core parts 28 which is arranged on the same axis toward the deep side of the receiving hole in the metallic frame 1 from the flange part 22 and separated into a plurality of portions along the peripheral direction, and in which the normal shape can be formed by expanding the size with centrifugal force at the casting time and the size of the normal shape can be reduced when the centrifugal force disappears; a cylindrical body 41 arranged in the inner part of the separated core part 28; and a flange-like body 48 which is fitted to the outer periphery of the cylindrical body 41 and can close the opening hole at the deep end side of the receiving hole of the separated core part 28 on the outer side in the diameter direction from this cylindrical body 41. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a receiving port inner surface forming core in a centrifugal casting apparatus.

  An apparatus shown in FIG. 5 is known as an apparatus for centrifugally casting a cast iron pipe such as a ductile cast iron pipe. In FIG. 5, reference numeral 1 denotes a centrifugal cast metal frame, which is supported on the drive roller 2 in the horizontal direction so that it can rotate around the axis 3 at a high speed.

  A ductile cast iron pipe usually has a receiving port having a diameter larger than that of the tube body at one end. Correspondingly, the metal frame 1 also has a larger diameter at one end than the inner diameter of other portions. A receiving port forming portion 4 having a diameter is provided.

  In general, the inner peripheral surface of the receiving port of the cast iron pipe has a complicated shape. In order to form such an inner peripheral surface of the receiving port, a sand core, that is, a core 5 as shown in the figure is used. (Patent Document 1, Patent Document 2). The core 5 is formed in a cylindrical shape, and has a concave and convex portion (not shown) for forming a groove on the inner periphery of the receiving port on the outer periphery, and the diameter increases toward the inner side of the receiving port on the inner periphery of the receiving port. An enlarged diameter portion 6 for forming a tapered surface is formed. The core 5 is supported by the core ring 7 by being fitted to the core ring 7 of the core setter, and the core ring 7 is attached to the metal frame 1 by the flange portion 8, thereby It is configured to be inserted into the opening forming portion 4 and set concentrically.

When the metal frame 1 fitted with the core 5 is rotated at a high speed by the roller 2 while the molten metal is supplied from the pouring trough to the inside and cooled and solidified, the cast iron pipe 9 becomes as shown in the figure. Centrifugal casting. Reference numeral 10 denotes a receiving port of the cast iron tube 9, and the inner surface thereof is formed in a complicated shape corresponding to the outer surface shape of the core 5.
Japanese Patent Laid-Open No. 62-124060 JP 2001-150114 A

  When the cast iron pipe 9 is taken out from the metal frame 1 after casting the cast iron pipe 9 by centrifugal casting, first, the core ring 7 is pulled away from the opening forming portion 4 of the metal frame 1 in the direction of the axis 3. At this time, since the core 5 has a complicated outer shape as described above, the core 5 remains inside the receiving port 10 of the cast iron pipe 9 and cannot be extracted from the cast iron pipe 9 when the core ring 7 is pulled away. For this reason, after that, the casting tube 8 is pulled out from the metal frame 1 with the core 5 attached, and then the core 5 is broken and removed from the interior of the receiving port 10. Therefore, each time one pipe 9 is manufactured, one core 5 is consumed, and there is a problem that the use of the core 5 becomes uneconomical.

  In order to solve such a problem, it is possible to consider introducing a heat-resistant metal core that can be used repeatedly. However, in this case, a metal core having a complicated shape corresponding to the inner surface shape of the cast iron pipe 9 is cast like the core 5 made of sand, after the pipe 9 is cast, It is necessary to devise so that it can be extracted from the mouth 10 without hindrance. For this reason, the metal cylindrical core is divided into a plurality of parts along the circumferential direction, for example, and is integrated by being expanded by the centrifugal force during casting to become a regular shape, and the centrifugal It is preferable if the diameter can be reduced from the regular shape when the force disappears.

  However, with such a configuration, the distal end portion of the cylindrical metal core having a divided structure which is expanded and integrated is opened toward the back of the metal frame. For this reason, when there is a variation in the flow of molten metal flowing in the pouring trough during centrifugal casting, a phenomenon called so-called “fogging”, in which the molten metal enters the inside of a metal cylindrical core May occur. There is a problem that such molten metal enters, and when the molten metal solidifies on the inner surface of the core having a divided structure, the core cannot be reduced in diameter and demolded.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to reliably prevent the occurrence of an accident in which a molten metal enters a core of a metal divided structure that can be used repeatedly during casting.

  In order to solve the above-described problems, the present invention provides a core mounted to form an inner surface of the receiving port at an end portion on the receiving side of a metal frame for centrifugally casting a tube having a receiving port at one end. A flange portion attached to an end portion on the receiving side of the metal frame, and is arranged coaxially from the flange portion toward the back of the receiving port in the metal frame, and is divided into a plurality along the circumferential direction. In addition, a cylindrical divided core portion that can have a regular shape by being expanded by a centrifugal force during casting, and can be reduced in diameter from the regular shape when the centrifugal force disappears, and the divided core portion A tubular body provided inside the tubular body, and can be fitted to the tubular body so as to close the opening on the rear end side of the receiving portion of the divided core portion on the radially outer side than the tubular body. And a rod-shaped body.

  With such a configuration, a cylindrical body provided inside the split core portion, and a receptacle core of the split core portion that is fitted on the cylindrical body and radially outside of the cylindrical body. Since it has a brim-like body capable of closing the opening on the end side, the opening on the back end side of the receiving end of the split core part can be reliably closed with the tubular body and the brim part. Even if the molten metal flows into the metal frame and the molten metal bounces inside the metal frame, the molten metal may enter the inside of the cylindrical body even if it enters the inside of the cylindrical body. Therefore, it is possible to reliably prevent the molten metal from entering the split core portion during casting. Moreover, in general, the metal frame is inserted with a pouring trough from the insertion port forming part opposite to the receiving port forming part, and the molten metal is supplied from the receiving port forming part side, and the supply state of the molten metal to this metal frame is Although it is customary to control the casting process by detecting with an optical sensor arranged outside the receiving part of the metal frame, a cylindrical body is provided inside the split core part. Since the cylindrical body secures an optical path from the inside of the metal frame to the outside of the receiving port forming portion beyond the receiving port forming portion, the molten metal enters the inside of the split core portion during casting as described above. In addition to being able to reliably prevent the molten metal, the detection of the molten metal by the optical sensor can be performed without any trouble.

  In FIG. 1, 1 is a centrifugal cast metal frame, and 4 is a receiving port forming portion. On the inner periphery of the opening of the receiving port forming portion 4, an outwardly opening tapered surface 15 and a radially inner end surface 16 following the inner end of the tapered surface 15 are formed. 9 is a cast iron pipe formed by supplying molten metal into the metal frame 1, and 10 is a receiving port thereof. On the inner periphery of the receiving port 10, an outwardly open tapered surface 17 is formed at the opening, and gradually toward the back side of the receiving port 10 on the back side of the receiving port 10 with respect to the tapered surface 17. A so-called reverse-tapered tapered surface 18 that expands in diameter and a receiving end end surface 19 are formed.

  1 to 4, reference numeral 21 denotes a core for forming an inner surface of a receiving opening according to the present invention. In this core 21, 22 is an annular flange made of a heat-resistant metal, and is in contact with the tapered surface 15 on the inner periphery of the metal frame 1 to position the core 21 concentrically with the metal frame 1. The outer peripheral taper surface 23 and the outer peripheral taper surface 23 are pressed against the inner end surface 16 of the metal frame 1 in a state where the outer peripheral taper surface 23 is in contact with the taper surface 15 of the metal frame 1, thereby positioning the core 21 in the axial direction with respect to the metal frame. And an end face 20 for the purpose. Reference numeral 24 denotes a space formed in the central portion of the flange portion 22. A cylindrical fixed core portion 25 is formed integrally with the flange portion 22. The fixed core portion 25 is used for forming an outwardly opening tapered surface 17 in the casting tube 9.

  The flange portion 22 has a pair of brackets at a plurality of positions along the circumferential direction on the surface opposite to the surface on which the fixed core portion 25 is formed, that is, the surface facing the outside of the metal frame 1. 26 and 26 are provided so as to protrude in the axial direction of the metal frame 1. A plurality of shafts 27 oriented in the direction of the tangent to the pitch circle on which the brackets 26 are arranged, that is, a plurality of shafts 27 provided in a direction perpendicular to the axis of the metal frame 1 on the pitch circle. These are supported by a pair of brackets 26 and 26, respectively.

  28 is a cylindrical division | segmentation core part formed with the heat-resistant metal. The divided core portion 28 is divided into a plurality of portions along the circumferential direction, and as shown in FIG. 4, a long divided portion 29 having a long circumferential length, and a short divided portion 30 having a short circumferential length, However, it is set as the structure arrange | positioned alternately along the circumferential direction.

  As shown in FIG. 1, the split core portion 28 composed of the long split portion 29 and the short split portion 30 is a portion on the deeper side of the receiving port 10 than the tapered surface 17 of the outer opening in the cast iron pipe 9, that is, A core forming portion 31 for forming a portion including the tapered surface 18 on the back side of the receiving port 10 with respect to the tapered surface 17 is formed integrally with the core forming portion 31, and the core forming portion 31 is made of gold. The arm portion 32 is disposed along the axial direction of the metal frame 1 toward the opening side of the frame 1. The core forming portion 31 includes an inner flange portion 33 for forming the back end surface 19 of the receiving port 10 of the cast iron pipe 9. The arm portion 32 is formed in an L shape, and the tip portion is supported by the shaft 27. In other words, each of the long divided portion 29 and the short divided portion 30 of the divided core portion 28 has an arm portion 32 and is supported by the shaft 27, as shown by a solid line and a virtual line in FIG. 1. The metal frame 1 can be swung in the radial direction about the shaft 27. Thereby, the split core part 28 can take the diameter-expanded state shown by the solid line in FIG. 1, that is, the normal state for forming the inner surface of the cast iron pipe 9, and the diameter-reduced state shown by the phantom line in FIG. .

  As shown in FIG. 4, the cross-sectional shapes of the long divided portion 29 and the short divided portion 30 are both trapezoidal. Specifically, the long divided portion 29 is formed in a trapezoidal shape with the inner peripheral side being the upper bottom and the outer peripheral side being the lower bottom, and the short divided portion 30 is a trapezoid having the inner peripheral side being the lower bottom and the outer peripheral side being the upper bottom. Is formed. Thereby, it is comprised so that the diameter expansion and contraction of the division | segmentation core part 28 can be performed without hindrance. And when it expands in diameter and it will be in a regular state, it is set as the cross-sectional shape which each elongate division part 29 and the short division part 30 contact | connect without the clearance gap of the circumferential direction.

  Further, as shown in FIG. 1, the split core portion 28 is configured to be able to come into contact with the tip of the fixed core portion 25 when the diameter is expanded to a normal state. Thereby, the fixed core part 25 and the division | segmentation core part 28 are positioned mutually, and can cast the inner surface of the receiving port 10 of the cast iron pipe 9 correctly.

  A metal annular core ring 35 protruding from the position of the flange portion 22 toward the outside of the metal frame 1 is concentrically attached to the flange portion 22. Reference numeral 36 denotes a fixing bolt. The core ring 35 is formed with a notch portion 37 for avoiding interference with the bracket 26, the shaft 27, and the arm portion 32 of the split core portion 28 when the core ring 35 is attached to the flange portion 22. A sleeve 38 is formed concentrically at the center of the core ring 35, and this sleeve 38 is rotatably supported by a core setter (not shown) by a bearing portion 39. The core ring 35 has an outer peripheral flange 34. The outer peripheral flange 34 is pressed in the axial direction of the metal frame 1 by the core setter, so that the entire core 21 is attached to the metal frame 1 in a pressed state during casting. The The sleeve 38 has a space 40 therein.

  In FIG. 1 and FIG. 2, reference numeral 41 denotes a cylindrical body having a space 42 inside and disposed in the axial direction at the center of the metal frame 1, and its base end 43 is connected to the sleeve 38 of the core ring 35. It is fitted concentrically and fixed by bolts 44. The cylindrical body 41 has a main body portion 45 disposed inside the split core portion 28, and a distal end portion 46 at the back side of the metal frame 1 with respect to the inner flange portion 33 at the distal end of the split core portion 28. Protrudes into position. By providing the cylindrical body 41 in this way, the split core portion 28 is reduced in diameter until the inner peripheral end of the inner flange portion 33 reaches a position where it contacts the cylindrical body 41 as indicated by a virtual line in FIG. It is possible.

  An external screw 47 is formed on the outer periphery of the distal end portion 46 of the cylindrical body 41. An annular metal cover 48 is screwed onto the external screw 47. The cover 48 protrudes from the cylindrical body 41 in a brim shape, and the outer peripheral end thereof is positioned on the outer peripheral side of the inner peripheral end of the inner flange portion 33 of the split core portion 28 when the diameter is expanded. It is comprised so that the opening of the back | inner side of the metal frame 1 in the division | segmentation core part 28 when expanding the diameter between the inner periphery of the inner flange part 33 and the outer periphery of the cylindrical body 41 can be plugged up. . Reference numeral 49 denotes a metal nut, which is similarly screwed to the external screw 47 so that the cover 48 can be fixed to a predetermined position along the axial direction with a double nut. The outer periphery of the cover 48 gradually shrinks from the portion corresponding to the split core portion 28 toward the distal end side of the cylindrical body 41 so as not to hinder the molten metal from flowing into the receiving port forming portion 4 of the metal frame 1. A tapered surface 50 is formed.

  When the cast iron pipe 9 is centrifugally cast by the metal frame 1 using the core 21 having such a configuration, first, the split core portion 28 of the core 21 not attached to the metal frame 1 is attached with an appropriate jig or the like. After expanding the diameter, a coating material is applied to the outer peripheral surface.

  Next, the diameter-expanded state of the split core portion 28 is released, and the core 21 is attached to the metal frame 1 with a core setter. When the metal frame 1 is rotated around the axis at a high speed, the core 21 is also rotated integrally, and the divided core portion 28 is expanded in diameter to a regular shape as shown in FIG. 1 by centrifugal force. Therefore, while maintaining this state, the pouring trough is inserted from the insertion forming portion of the metal frame 1 to the vicinity of the receiving port forming portion 4, and the molten metal is supplied from the tip of the pouring trough to the inner periphery of the metal frame 1. To do.

  At this time, an optical sensor 51 is provided as shown in FIG. 1, and the optical sensor 51 passes through the space 40 inside the sleeve 38 of the core ring 35 and the space 42 inside the cylindrical body 41. By detecting the supply state of the molten metal from the outside, the casting process can be appropriately controlled. In addition, since the optical path to the optical sensor 51 is ensured by the spaces 38 and 42 inside the core 21 as described above, the core 21 having a complicated configuration is attached to the end of the metal frame 1. The detection of the molten metal by the optical sensor 51 can be performed without hindrance.

  The molten metal supplied to the receptacle forming part 4 of the metal frame 1 enters into the space formed between the inner periphery of the metal frame 1 and the outer periphery of the core 21 by centrifugal force. A mouth 10 is formed. At this time, even when the molten metal flow in the pouring trough varies and the molten metal splashes inside the metal frame 1, the inner flange portion of the split core portion 28 is covered by the cover 48. Between the inner periphery of 33 and the outer periphery of the cylindrical body 41, that is, the opening on the back side of the metal frame 1 in the divided core portion 28 is closed, so that it is ensured that the molten metal enters the inside of the divided core portion 28. Can be prevented.

  For this reason, it is possible to prevent the occurrence of a situation in which the diameter of the split core portion 28 is hindered by solidification of the molten metal that has entered. In some cases, the molten metal may enter the inside of the cylindrical body 41 and solidify. However, even if this happens, no particular problem occurs.

  When casting of the cast iron pipe 9 by the pouring operation is completed, the rotation of the metal frame 1 is stopped. Then, the divided core portion 28 can be reduced in diameter by gravity or other action, and by reducing the diameter, the core 21 can be easily extracted from the cast iron pipe 9 having the so-called reverse tapered tapered surface 18. It can be removed from the metal frame 1.

It is sectional drawing of the core for receptacle inner surface shaping | molding in the centrifugal casting apparatus of embodiment of this invention. FIG. 2 is a perspective view of a receiving port inner surface forming core in FIG. 1. FIG. 3 is a rear view of the receiving port inner surface forming core of FIG. 2. It is the perspective view which showed the detail of the division | segmentation core part, without drawing the cylindrical body in the core of FIG. It is sectional drawing which shows schematic structure of the core for receptacle inner surface shaping | molding in the conventional centrifugal casting apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Centrifugal casting metal frame 4 Receptacle formation part 9 Cast iron pipe 10 Receptacle 21 Receptacle inner surface formation core 22 Flange part 28 Divided core part 41 Cylindrical body 48 Cover

Claims (1)

A core mounted to form an inner surface of the receiving port at an end of the receiving side of a metal frame for centrifugally casting a tube having a receiving port at one end;
A flange portion to be attached to an end portion on the receiving side of the metal frame;
It is arranged coaxially from the flange part toward the inner side of the receiving port in the metal frame, divided into a plurality along the circumferential direction, and becomes a regular shape by being expanded by centrifugal force during casting. In addition, when the centrifugal force disappears, a cylindrical divided core portion that can be reduced in diameter from the regular shape,
A cylindrical body provided inside the split core portion;
A collar-like body that is fitted over the tubular body and can close the opening on the rear end side of the receiving end of the split core portion on the radially outer side than the tubular body;
A core for forming an inner surface of a receiving port in a centrifugal casting apparatus.

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