JP2006122942A - Insert casting method of cylindrical member, and induction heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an insert casting method for inserting a cylindrical member, which exerts excellent fusing property in casting, and to provide an induction heating device. <P>SOLUTION: A cylindrical member 2 is mounted on a predetermined position of a casting mold 10. An induction heating coil 21 is inserted in the inner periphery of the cylindrical member 2. Casting is conducted by pouring molten metal into the casting mold 10 after heating the cylindrical member 2 to a predetermined temperature by induction heating from the inner periphery. The coil pitches at both end parts of the induction heating coil 21 are made to be smaller than the pitch at the central part of the coil 21. The coil length in the axial direction of the induction heating coil 21 is made to be longer than the length of the cylindrical member. The induction heating coil 21 is arranged in the cylindrical member 2 in such a way that each of both end parts of the coil is protruded by a predetermined length in the axial direction from both ends of the cylindrical member 2 arranged in the casting mold. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a casting method in which a cylindrical member such as a cylinder liner is cast into a cast product in casting of a cylinder block of, for example, an engine or a compressor, and an induction heating apparatus for heating the cylindrical member.

  In the manufacture of cylinder blocks such as engines and compressors, casting is performed by casting a cylindrical member into a cast product, such as casting a liner at the same time when casting the cylinder block. It is desirable to pour hot water in a state where the temperature is raised by heating the cylindrical member so as to increase the fusion property between the cast product and the cylindrical member during casting. For this purpose, the cylindrical member is heated in a heating furnace and placed in a mold, or the cylindrical member placed in the mold is heated by a burner.

  However, in the casting method in which the cylindrical member taken out from the conventional heating furnace is placed in the mold and poured into the mold, it takes time to place the high-temperature cylindrical member in the mold, and the temperature of the cylindrical member is lowered and the casting is performed. It is difficult to maintain the cylindrical member temperature at a constant temperature. Further, the method of heating a cylindrical member arranged in a mold with a burner has a problem that it is difficult to heat a large number of cylindrical members to a uniform temperature.

For this reason, the invention which heats a cast member by induction heating is disclosed (patent documents 1 and 2). However, these conventional methods involve induction heating from the outside of the mold, and are difficult to apply to large molds.
JP-A-53-88628 Japanese Patent Laid-Open No. 54-10228

  Therefore, in the present invention, with a cylindrical member installed in a casting mold, a heating coil is inserted into the inner periphery of the cylindrical member to be cast, and the cylindrical member is induction-heated from the inner periphery. It is an object of the present invention to provide a casting method and an induction heating device for casting a cylindrical member that can be uniformly heated and has improved the fusion property between the cylindrical member and a cast product.

  In order to achieve the above object, a casting method for casting a cylindrical member according to the present invention includes mounting a cylindrical member at a predetermined position of a casting mold, inserting an induction heating coil on the inner periphery of the cylindrical member, and The member is induction-heated from the inner periphery to a predetermined temperature, and then poured into a casting mold to cast the cylindrical member.

  That is, in the casting method of the present invention, the cylindrical member is heated by induction heating from the inner periphery in a state where the cylindrical member is mounted on the casting mold, so that it is heated more uniformly than the conventional method of heating the cylindrical member with a burner or the like. In addition to being able to do so, a large number of cylindrical members can be easily and evenly heated simultaneously with a small amount of electric power as compared with a known method in which induction heating is performed from the outside of a mold that is far from the cylindrical member. Since the cylindrical member is poured into the mold in a state where the cylindrical member is uniformly heated, it is possible to perform casting with good fusion between the cast product and the cylindrical member even in the case of casting in which a large number of cylindrical members are cast. .

  In the casting method for casting the cylindrical member of the present invention, the cylindrical member is positioned on the casting mold by inserting a hollow core having a predetermined thickness on the inner periphery thereof, and the cylindrical member is interposed by interposing the core. It is desirable to perform induction heating from the inner periphery. If it does in this way, there exists an advantage which can position a some cylindrical member reliably and can prevent that hot water leaks to the inner side of a cylindrical member.

  In the induction heating coil according to the present invention, the coil pitch at both ends is smaller than the central pitch, the axial coil length is longer than the length of the cylindrical member, and both ends of the coil are disposed in the casting mold. It is desirable that the cylindrical member is disposed in the cylindrical member so as to protrude from the both ends of the cylindrical member by a predetermined length in the axial direction. That is, the cylindrical member to be heated is in contact with the mold at the end portion, and heat is taken away from this portion, so that the coil pitch near the end portion is narrowed and the end of the coil is projected from the cylindrical member to facilitate heating the end portion. Is. The appropriate coil pitch interval and the amount of protrusion at the coil end are determined experimentally.

  An induction heating apparatus for casting a cylindrical member according to the present invention heats the inner circumference of a cylindrical member disposed at the center position of each cylindrical member in casting for casting one or more cylindrical members. Or two or more induction heating coils, and induction heating coil moving means for inserting / extracting the one or more induction heating coils to / from a predetermined position on the inner periphery of the cylindrical member, and the cylindrical member from the inner periphery to a predetermined temperature After the induction heating, the cylindrical member is cast by pouring into a casting mold.

  Also in the induction heating apparatus for casting the cylindrical member of the present invention, the induction heating coil has a coil pitch at both ends smaller than the central pitch, and an axial coil length longer than the length of the cylindrical member. It is desirable that both end portions of the coil are disposed in the cylindrical member so as to project a predetermined length in the axial direction from both ends of the cylindrical member disposed in the casting mold.

  Since the casting method and the induction heating apparatus for casting the cylindrical member of the present invention can cast by casting the cylindrical member from the inner periphery by inserting an induction heating coil in the inner peripheral position of the cylindrical member to be cast. Compared to the case of induction heating from the outside of the mold of the known invention, the distance between the heating coil and the cylindrical member is reduced, and the heating is uniformly performed with a small electric power, and a plurality of large castings casting a plurality of cylindrical members are also cast. The cylindrical member can be heated easily and quickly uniformly at the same time, and the cast product and the cylindrical member can be cast with good fusion properties. As a result, the heating time is shortened as compared with the conventional heating by a burner or an external induction heating method, so that mass production is possible and the cost can be reduced.

  Hereinafter, the present invention will be specifically described for casting in which four cylindrical members according to an embodiment shown in the drawings are cast. FIG. 1 is a cross-sectional view of a state in which a cylindrical member induction heating device is placed in a mold in casting a cylindrical member according to an embodiment of the present invention, FIG. 2 is a front view of the induction heating device of the present invention, and FIG. It is detail sectional drawing which shows the relationship between this induction heating coil and a cylindrical member.

  As shown in a cross section in FIG. 1, a casting mold 10 for casting the casting 1 is composed of a gate mold 11, a lower casting mold 12, a body casting mold 13, and a lid core 14 that forms an internal shape of the casting. Shaped with sand. A space that forms the shape of the cast product 1 is formed in the body mold 13 together with the lid core 14, and four cylindrical members 2 are arranged at a predetermined pitch interval and are predetermined by the hollow core 15 of the hollow cylinder. Positioned and mounted in position. The lid core 14 is provided with a through hole 14a having a diameter substantially the same as the inner diameter of the hollow core 15 at a position concentric with the arranged cylindrical members, and a lower diameter enlarged portion 14b and a bag hole of the lower mold 12 are provided. The hollow core 15 is held by 12a. The induction heating coil 21 is inserted through the through hole 14 a and the inner periphery of the hollow core 15. The cylindrical member 2 is made of cast iron, and an aluminum alloy is poured into the casting mold 10 through the gate 11a of the gate mold and the plurality of runners 12b of the lower mold 12, and the cylindrical member 2 is cast by casting.

As shown in FIG. 3, the induction heating coil 21 is a multi-turn cylindrical coil having an outer diameter with which a predetermined interval can be obtained between the inner periphery of the cylindrical member via the hollow core 15, and the coil pitch t _{2 at} both ends. Is smaller than the central pitch t ₁ . The coil length l of the induction heating coil 21 is longer than the length L of the cylindrical member 2 so that both ends of the coil protrude from the both ends of the cylindrical member 2 placed on the casting mold 10 by a predetermined length in the axial direction. Arranged. The induction heating coil 21 is supported by a support rod 22 and connected to a bus bar 23, and a high frequency current is applied from the induction power supply 20. As shown in FIG. 2, the four induction heating coils 21 are arranged with their centers coincident with the arrangement pitch interval P of the four cylindrical members.

  The induction power source 20 is driven to move up and down by a driving means (not shown), and is moved between a standby position above the mold 10 and an inner peripheral position of the cylindrical member 2 indicated by a solid line, as indicated by a chain line in FIG. As this driving means, a widely used driving method in which the induction power source 20 is slid on the rail and driven by air pressure, hydraulic pressure, screw or the like can be applied. Details are omitted.

  Hereinafter, the operation of the induction heating apparatus in the casting of the cast product having the above configuration will be described. First, the cylindrical member 21 is positioned and mounted at a predetermined position of the mold 10 by the hollow core 15. Then, the induction power source 20 is raised to the standby position of the chain line in FIG. 1, the induction coil 21 is positioned at the center of the cylindrical member, and the mold 10 is placed thereunder, and then the induction power source 20 is driven by driving means (not shown). When lowered, the induction coil 21 passes through the through hole 14a of the lid core 14 and falls to a predetermined position where the inner periphery of the cylindrical member 2 is heated.

  In this state, electric power is applied from the induction power source 20 to the induction heating coil 21 to heat the cylindrical member 2 to a predetermined temperature, and then the induction heating coil 21 is raised to the standby position. In this state, the molten aluminum alloy is poured from the gate 11a by gravity or pressurization while the cylindrical member 2 is heated to a predetermined temperature. In this way, since the cylindrical member 2 is in contact with the molten aluminum alloy in the state of being heated at the time of casting, the fusion between the cylindrical member and the cast product is increased, and highly reliable cast-off casting is performed.

  First, the uniformity of the temperature distribution of the cylindrical member by induction heating was measured using one cylindrical member. In the experiment, a cylindrical member having an outer diameter D1 = 91 mmφ, an inner diameter D2 = 82.5 mmφ, and a length L = 121 mm shown in FIG. 3 was used. The outer diameter of the coil is d = 52.5 mmφ so that a gap of 15 mm is formed between the inner diameter of the cylindrical member, and both ends of the coil length L = 175 mm are evenly projected from both ends of the length l of the cylindrical member. Arranged. The coil pitch was set to 1 / 3.5 of the coil gap at the center at both ends.

  The experiment was performed for the case where the hollow core was not inserted and the case where the hollow core 15 having an inner diameter D3 = 67.5 mmφ in which a cast sand layer having a thickness of about 7.5 mm was formed on the inner diameter of the cylindrical member was inserted. The heating temperature was measured for five ABCEF lengths of the cylindrical member outer diameter portion. The results are shown in Table 1.

  From the experimental results of Table 1, although the heating efficiency is lower than when there is no hollow core due to the insertion of the hollow core, the outer peripheral temperature of the cylindrical member is slightly higher than when there is no hollow core due to the insertion of the hollow core. Uniformity is obtained. However, in any case, the specification of 450 ° C. to 500 ° C. could be satisfied.

  Based on the above experimental results, a hollow core was used for a cast product in which four cylindrical members were arranged at intervals of a pitch P = 96.7 mm, and the four cylindrical members were simultaneously heated using the apparatus of FIG. The experimental results are shown in Table 2.

  As shown in Table 2, the result was that the specifications of 450 ° C. to 500 ° C. were satisfied for all the cylindrical members, and a heating efficiency of 21% was obtained. The cast product cast by this heating was sufficiently fused with the cylindrical member.

  As described above, in the casting method and the induction heating apparatus of the embodiment of the present invention, the induction heating coil is inserted inside the cylindrical member attached to the casting mold, and the cylindrical member is heated from the inner periphery and heated. Cast. Thereby, even when many cylindrical members were cast, it was possible to heat them quickly and uniformly, and a cast product having a high degree of fusion between the cylindrical member and the cast product was obtained.

  As described above, according to the casting method and induction heating apparatus for casting a cylindrical member of the present invention, even in casting for casting a large number of cylindrical members, a large number of cylindrical members can be heated at the same time. Since casting can be carried out quickly immediately afterwards, it is possible to mass-produce cast products with a high degree of fusion between the cylindrical member and the cast product, thereby reducing the casting cost and contributing to industrial development.

It is a figure which shows the structure of the induction heating apparatus in the casting which casts the cylindrical member of this invention embodiment. It is a front view of the induction heating apparatus of the cylindrical member of this invention embodiment. It is detail sectional drawing which shows the relationship between the induction heating coil of this invention embodiment, and a cylindrical member.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Casting product, 2 Cylindrical member, 10 Casting mold, 11 Lower mold, 12 Lower mold, 13 Body mold, 14 Cover core, 15 Hollow core, 20 Induction power supply, 21 Induction heating coil, 22 Support bar, 23 Busbar

Claims (5)

A cylindrical member is attached to a predetermined position of the casting mold, an induction heating coil is inserted into the inner periphery of the cylindrical member, the cylindrical member is induction-heated from the inner periphery to a predetermined temperature, and then poured into the casting mold. A casting method for casting a featured cylindrical member. The hollow cylindrical member having a predetermined thickness is inserted into the inner periphery of the cylindrical member, positioned in a casting mold, and the cylindrical member is induction-heated from the inner periphery with the core interposed therebetween. A casting method in which the cylindrical member according to 1 is cast. In the induction heating coil, the coil pitch at both ends is smaller than the pitch at the center, the coil length in the axial direction is longer than the length of the cylindrical member, and both ends of the coil are respectively disposed on the casting mold. 3. A casting method for casting a cylindrical member according to claim 1 or 2, wherein the casting member is disposed in the cylindrical member so as to protrude in the axial direction by a predetermined length. In casting in which one or more cylindrical members are cast, one or more induction heating coils for heating the inner periphery of the cylindrical member disposed at the center position of each cylindrical member, and the one or more inductions An induction heating coil moving means for inserting / extracting the heating coil at a predetermined position on the inner periphery of the cylindrical member, the cylindrical member being induction heated from the inner periphery to a predetermined temperature, and then poured into a casting mold. Induction heating device for casting a cylindrical member to be cast. In the induction heating coil, the coil pitch at both ends is smaller than the center pitch, the axial coil length is longer than the length of the cylindrical member, and both ends of the coil are disposed in the casting mold, respectively. 5. The induction heating apparatus for casting a cylindrical member according to claim 4, wherein the cylindrical heating member is disposed in the cylindrical member so as to protrude in the axial direction by a predetermined length.

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