JP6459576B2 - Die casting sleeve - Google Patents

Description

  The present invention relates to a die casting sleeve for injecting a molten non-ferrous metal such as an aluminum alloy into a die casting mold.

  In a die casting machine, molten metal (molten metal) is supplied to a sleeve, and the molten metal is injected into a mold cavity communicating with the sleeve by a plunger tip sliding inside the sleeve, and the molten metal is cooled and solidified to produce a die cast product. For this reason, the inner surface of the sleeve may be melted by the molten metal or worn by sliding the plunger tip. When the inner surface of the sleeve is damaged due to melting or abrasion, the molten metal enters between the sleeve and the plunger tip, the sliding resistance of the sleeve increases, and the injection speed decreases, so the product quality decreases. If a large amount of lubricant is used to reduce the sliding resistance between the sleeve and the plunger tip or prevent seizure, impurities such as gas entrainment in the molten metal are likely to occur, resulting in a decrease in product quality. Invite.

In order to reduce melting damage and wear on the inner surface of the sleeve, there has conventionally been proposed a die casting sleeve having a composite structure in which a ceramic inner cylinder is mounted by shrink fitting in a metal outer cylinder of a high-strength low thermal expansion metal. . For example, Japanese Patent Laid-Open No. 7-246449 (Patent Document 1) discloses a die casting sleeve in which a ceramic inner cylinder formed of ceramics such as silicon nitride and sialon is shrink-fitted in a metal outer cylinder of a high-strength, low-thermal-expansion metal. The average thermal expansion coefficient of the high-strength low-thermal-expansion metal from room temperature to 300 ° C. is 1 × 10 ⁻⁶ / ° C. to 5 × 10 ⁻⁶ / ° C., and the average thermal expansion from room temperature to 600 ° C. A die casting sleeve having a coefficient of 5 × 10 ⁻⁶ / ° C. or more is disclosed. Patent Document 1 discloses that a high-strength, low-thermal-expansion metal has such an average coefficient of thermal expansion, so that the shrink-fitting operation can be performed smoothly and easily, and the displacement of the outer and inner cylinders does not occur in the axial direction and the circumferential direction. It describes that a sufficient shrink-fit effect can be secured.

  The sleeve for die casting of Patent Document 1 can be stably injected when the surface temperature of the metal outer cylinder is used in the range from room temperature to 300 ° C. On the other hand, when it is used for die casting of large aluminum alloys, for example, the amount of cooling water becomes insufficient, the injection cycle becomes too fast, and the surface temperature of a part of the metal outer cylinder When the temperature exceeds 300 ° C., the injection becomes difficult to stabilize and there is a risk of causing molding defects. Moreover, depending on the case, there is a possibility of leading to cracking of the ceramic inner cylinder.

Japanese Unexamined Patent Publication No. 7-246449

  Therefore, an object of the present invention is to perform stable injection even when the surface temperature of a part of a metal outer cylinder exceeds 300 ° C. in die casting of a large aluminum alloy. Another object of the present invention is to provide a die casting sleeve capable of suppressing cracking of a ceramic inner cylinder.

  As a result of diligent research in view of the above object, the present inventors have found that in a die casting sleeve in which a ceramic inner cylinder is shrink-fitted in a metal outer cylinder, the metal outer cylinder has a specific composition, and has a room temperature. Fe-Ni-Co-Nb alloy with a small average thermal expansion coefficient from room temperature to 400 ° C and a small difference between the average thermal expansion coefficient from room temperature to 200 ° C and the average thermal expansion coefficient from room temperature to 400 ° C. When configured, in die casting of large aluminum alloys, it has been found that stable injection is possible even when the surface temperature of a part of the metal outer cylinder exceeds 300 ° C. The present invention has been conceived.

  First, the inventors paid attention to the upper and lower temperatures of the metal outer cylinder when injection was performed at a temperature from room temperature to 300 ° C. using a die casting sleeve. Usually, as shown in FIG. 1, the die-casting sleeve is used by injecting molten metal from a supply port provided in the upper part of the sleeve arranged in the horizontal direction. Since the molten metal injected at this time stays in the lower part of the temporary sleeve before injection is performed, the temperature on the lower side of the metal outer cylinder becomes higher than the upper side by repeatedly injecting, so that the upper and lower sides of the metal outer cylinder are A temperature difference occurs. Thus, if a temperature difference arises in the upper and lower sides of a metal outer cylinder, a thermal expansion difference will arise in the upper and lower sides of a metal outer cylinder.

  Here, when a die-casting sleeve having a metal outer cylinder made of a high-strength, low-thermal-expansion metal having a thermal expansion coefficient as indicated by B in FIG. 1 of Patent Document 1, the lower side of the metal outer cylinder is used. When the temperature is 300 ° C. or lower, the coefficient of thermal expansion of the metal outer cylinder is small, so that the difference in thermal expansion between the upper side and the lower side of the metal outer cylinder is small and stable injection can be performed.

  However, since the injection capacity (heat capacity) is large in die casting of a large aluminum alloy, for example, when the amount of cooling water becomes insufficient or the injection cycle becomes too fast, the cooling effect is not sufficient, It has been found that the surface temperature of the lower side of the metal outer cylinder may rise to a temperature above 300 ° C and below 400 ° C. As shown by B in FIG. 1 of Patent Document 1, when the metal outer cylinder is made of a metal whose coefficient of thermal expansion suddenly increases above 300 ° C., the temperature on the lower side of the metal outer cylinder is If the temperature exceeds 300 ° C., the difference in thermal expansion between the upper and lower sides of the metal outer cylinder becomes large, the center axis of the die casting sleeve is curved, and the injection becomes difficult to stabilize.

  The inventors of the present invention have come up with the present invention as a result of intensive investigations on a configuration that can stably perform injection even when the temperature on the lower side of the metal outer cylinder rises to a temperature exceeding 300 and not higher than 400 ° C.

That is, the die casting sleeve of the present invention is a die casting sleeve in which a ceramic inner cylinder is shrink-fitted in a metal outer cylinder,
Fe-Ni-Co-, wherein the metal outer cylinder contains 29-35 wt% Ni, 12-23 wt% Co and 2-5 wt% Nb, and has a Ni / Co ratio of 0.8-2 Composed of Nb alloy,
Average thermal expansion coefficient α _M200 from room temperature to 200 ° C., average thermal expansion coefficient α _M400 from room temperature to 400 ° C., and average thermal expansion coefficient α _M600 from room temperature to 600 ° C.
α _M400 ≦ 7.5 × 10 ⁻⁶ / ℃,
| α _M400 -α _M200 | ≦ 1 × 10 ^-6 / ℃,
α _M600 ≧ 5 × 10 ^-6 / ° C and α _M600 > α _M400
It is characterized by satisfying.

The ceramic inner cylinder has an average thermal expansion coefficient α _C200 from room temperature to 200 ° C., an average thermal expansion coefficient α _C400 from room temperature to 400 ° C., and an average thermal expansion coefficient α _C600 from room temperature to 600 ° C. of 4 × 10. ^It is preferably ⁻⁶ / ° C. or lower.

α _M400 preferably satisfies 4.5 × 10 ⁻⁶ / ° C. ≦ α _M400 ≦ 7.5 × 10 ⁻⁶ / ° C., more preferably 5.0 × 10 ⁻⁶ / ° C. ≦ α _M400 ≦ 6.5 × 10 ⁻⁶ / ° C. preferable.

α _M600 preferably satisfies α _M600 ≧ 7 × 10 ⁻⁶ / ° C.

  The metallic outer cylinder preferably has a tensile strength at 300 ° C. and 400 ° C. of 800 MPa or more.

  The metal outer cylinder is composed of 29 to 35 mass% Ni, 12 to 23 mass% Co, 2 to 5 mass% Nb, 0.4 to 1.5 mass% Al, 1.2 to 3 mass% Ti, 0.1 mass% It preferably consists of the following C, the balance Fe and unavoidable impurities. The metal outer cylinder preferably has a Ni / Co ratio of 1.1 to 2, more preferably a Ni / Co ratio of 1.2 to 2.

  When the outer diameter of the ceramic inner cylinder before shrink fitting is d1 and the inner diameter of the metal outer cylinder before shrink fitting is D2, the shrinkage rate: (d1-D2) / D2 is in the range of 0.001 to 0.003. Is preferably within.

  By using the die casting sleeve of the present invention, even when the surface temperature of a part of the metal outer cylinder exceeds 300 ° C. due to insufficient cooling, stable injection can be performed. Therefore, the occurrence of molding defects can be reduced, and cracking of the ceramic inner cylinder can be suppressed.

It is sectional drawing which shows an example of the sleeve for die-casting of this invention. It is a graph which shows temperature T and the average thermal expansion coefficient from room temperature to temperature T regarding the metals B to E constituting the metal outer cylinder and the ceramics A constituting the ceramic inner cylinder. It is sectional drawing which shows another example of the sleeve for die-casting of this invention. FIG. 4 is an exploded sectional view showing a metal outer cylinder and a ceramic inner cylinder constituting the die casting sleeve of FIG. 3. FIG. 4 is an exploded cross-sectional view showing the die casting sleeve of FIG. 3.

The die-casting sleeve of the present invention is formed by shrink fitting a ceramic inner cylinder in a metal outer cylinder, the metal outer cylinder being 29 to 35 mass% Ni, 12 to 23 mass% Co, and 2 An average thermal expansion coefficient α from room temperature to 200 ° C. of the metal outer cylinder, which is composed of an Fe—Ni—Co—Nb alloy containing ˜5 mass% Nb and having a Ni / Co ratio of 0.8˜2. _M200 , average thermal expansion coefficient α _M400 from room temperature to 400 ° C., and average thermal expansion coefficient α _M600 from room temperature to 600 ° C., α _M400 ≦ 7.5 × 10 ⁻⁶ / ° C., | α _M400 −α _M200 | ≦ 1 It is characterized by satisfying × 10 ⁻⁶ / ° C., α _M600 ≧ 5 × 10 ⁻⁶ / ° C., and α _M600 > α _M400 .

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings, but the present invention is of course not limited thereto. The description regarding each embodiment is applicable also to other embodiment unless there is particular notice.

(1) First embodiment
(a) Overall Configuration FIG. 1 shows a first embodiment of a die casting sleeve according to the present invention. In FIG. 1, a straight line AA indicates the central axis of the sleeve 1. The die casting sleeve includes a metal outer cylinder 11 and a ceramic inner cylinder 12 mounted in the metal outer cylinder 11 by shrink fitting.

  A front end ring member 2 for fixing to a die casting machine is attached to a front end portion of the metal outer cylinder 11, and a rear end ring member 3 is fixed to a rear end surface of the metal outer cylinder 11 by a bolt 31. A flange-like convex part 11c is formed at a position adjacent to the tip part on the outer peripheral surface of the metal outer cylinder 11, and the tip ring member 2 is fixed to the hook-like convex part 11c by bolts 51, 51, Deviation from the tip of the outer cylinder 11 is prevented.

  The metal outer cylinder 11 has an opening near the rear end surface, and the ceramic inner cylinder 12 has an opening at a position aligned with the opening of the metal outer cylinder 11. Both openings that communicate with each other constitute a molten metal supply port 7. The dimensions of the metal outer cylinder 11 can be, for example, an inner diameter of 90 to 180 mm, an outer diameter of 150 to 300 mm, and an overall length in the axial direction of 600 to 1300 mm.

(b) Average thermal expansion coefficient Since the metal outer cylinder 11 has α _M400 ≦ 7.5 × 10 ⁻⁶ / ° C. and has a relationship of | α _M400 −α _M200 | ≦ 1 × 10 ⁻⁶ / ° C., the metal Even if the temperature of the outer cylinder becomes 400 ° C., the metal outer cylinder does not loosen with respect to the ceramic inner cylinder. Even if the cooling is insufficient and the temperature on the lower side of the metal outer cylinder exceeds 300 ° C. and reaches 400 ° C. or lower, the difference in thermal expansion between the lower side and the upper side of the metal outer cylinder is small. The bending of the central axis of the sleeve is suppressed. For this reason, even if it is die-casting of a large sized aluminum alloy, injection can be performed stably and generation | occurrence | production of a molding defect can be reduced. Further, since α _M600 ≧ 5 × 10 ⁻⁶ / ° C. and α _M600 > α _M400 , the metal outer case is used at a heating temperature of 550 to 600 ° C. during shrink fitting between the metal outer cylinder and the ceramic inner cylinder. Since the difference in thermal expansion coefficient between the cylinder and the ceramic inner cylinder is large, the shrink-fitting operation can be performed smoothly and easily.

The ceramic inner cylinder 12 is preferably low in thermal expansion, for example, an average thermal expansion coefficient α _C200 from room temperature to 200 ° C., an average thermal expansion coefficient α _C400 from room temperature to 400 ° C., and an average from room temperature to 600 ° C. The thermal expansion coefficient α _C600 is more preferably 4 × 10 ⁻⁶ / ° C. or less, and most preferably 1 × 10 ⁻⁶ / ° C. to 4 × 10 ⁻⁶ / ° C. In order to reduce deformation due to heat of the molten metal, the ceramic inner cylinder 12 preferably has a relationship of | α _C400 −α _C200 | ≦ 1 × 10 ⁻⁶ / ° C.

  For the metal outer cylinder 11, for example, metals C and D shown in FIG. 2 can be used. For example, A shown in FIG. 2 can be used for the ceramic inner cylinder 12.

If α _M400 is too large, the effect of shrink fitting will be reduced. Therefore, in order to attach the metal outer cylinder to the low thermal expansion ceramic inner cylinder without loosening, the metal outer cylinder is α _M400 ≦ 7.5 × 10 ⁻⁶ / ℃ To satisfy. α _M400 ≦ 6.5 × 10 ⁻⁶ / ° C. is preferable. By bringing | α _M400 −α _M200 | of the metal outer cylinder close to | α _C400 −α _C200 | of the ceramic inner cylinder, the metal outer cylinder and the ceramic inner cylinder can be firmly attached. For that purpose, the metal outer cylinder is made to satisfy | α _M400 −α _M200 | ≦ 1 × 10 ⁻⁶ / ° C. More preferably, the metal outer cylinder looks at | α _M400 −α _M200 | ≦ 0.5 × 10 ⁻⁶ / ° C. Further, the metal outer cylinder preferably satisfies 4.5 × 10 ⁻⁶ / ° C. ≦ α _M400, and more preferably satisfies 5.0 × 10 ⁻⁶ / ° C. ≦ α _M400 . The metal outer cylinder preferably satisfies α _M600 ≧ 7 × 10 ⁻⁶ / ° C., and more preferably satisfies α _M600 ≧ 8 × 10 ⁻⁶ / ° C.

  The average thermal expansion coefficient (corresponding to the average linear expansion coefficient or the average linear expansion coefficient) of the metal outer cylinder is measured based on JIS Z 2285-2003 “Measuring method of linear expansion coefficient of metal material”. The average coefficient of thermal expansion of the ceramic inner cylinder is measured based on JIS R 1618-2002 “Measurement of thermal expansion by thermomechanical analysis of fine ceramics”. A differential expansion thermomechanical analyzer is used as a measurement device for the average thermal expansion coefficient. You may measure at room temperature, for example at 25 degreeC.

(c) Composition The metal outer cylinder of the die casting sleeve is α _M400 ≦ 7.5 × 10 ⁻⁶ / ° C., | α _M400 −α _M200 | ≦ 1 × 10 ⁻⁶ / ° C., α _M600 ≧ 5 × 10 ⁻⁶ / ° C. In order to satisfy α _M600 > α _M400 , the metal outer tube contains 29 to 35% by mass of Ni, 12 to 23% by mass of Co and 2 to 5% by mass of Nb, and 0.8 to 2 Ni. It is composed of an Fe—Ni—Co—Nb alloy having a / Co ratio. By using such a material, the strength of the metal outer cylinder can be increased. By setting the Ni content to 29-35 mass%, the Co content to 12-23 mass%, and the Ni / Co ratio to 0.8-2, the effect of shifting the inflection point of the average thermal expansion coefficient to the high temperature side is achieved. Demonstrated. The Nb content is preferably 3 to 4% by mass. Nb is a precipitation strengthening element and contributes to the improvement of strength (for example, tensile strength). In addition to Nb, Al and Ti can be used as precipitation strengthening elements. In combination with the Nb content, at least one element selected from Al and Ti may be contained. The material constituting such a metal outer cylinder is 29 to 35 mass% Ni, 12 to 23 mass% Co, 2 to 5 mass% Nb, 0.4 to 1.5 mass% Al, 1.2 to 3 mass% Ti, 0.1% by mass or less of C, the balance Fe, and inevitable impurities are preferable. The Al content is more preferably 0.5 to 1.5% by mass.

  By forming the metal outer cylinder from an Fe—Ni—Co—Nb alloy and performing heat treatment, the metal outer cylinder becomes high in strength. Examples of the heat treatment include a combination of a solution treatment (900 to 1000 ° C.) and an aging treatment (580 to 750 ° C.) performed subsequently. For example, the tensile strength at 300 ° C. and 400 ° C. of the metal outer cylinder is preferably 800 MPa or more, and more preferably 900 MPa or more. By having such high temperature strength, the ceramic inner cylinder 12 can be sufficiently protected against internal stress when the molten metal injected into the sleeve 1 is injected. The metal outer cylinder 11 preferably has an elongation of 15% or more (particularly 20% or more) at room temperature, a thermal conductivity of 20 W / m · K or less, and a Young's modulus of 130 GPa or more.

  As the ceramic constituting the ceramic inner cylinder, a silicon nitride sintered body such as silicon nitride or sialon excellent in melting resistance, wear resistance, heat resistance, molten metal heat retention and seizure resistance is preferable. The structure of the silicon nitride sintered body is composed of silicon nitride particles or sialon particles and a grain boundary phase containing a rare earth element.

(d) Shrinkage ratio In order to firmly shrink-fit the metal outer cylinder and the ceramic inner cylinder, it is preferable that the shrinkage ratio ≧ 1/1000. Further, in order to suppress cracking of the ceramic inner cylinder, it is preferable that the shrinkage-fitting ratio ≦ 3/1000. The shrinkage rate is the shrinkage rate = (d1−D2) / D2, where d1 is the outer diameter of the ceramic inner tube before shrink fitting and D2 is the inner diameter of the metal outer tube before shrink fitting. The value represented.

(2) Second Embodiment A sleeve 1 shown in FIGS. 3 to 5 is a die casting sleeve in which a ceramic inner cylinder 12 is shrink-fitted in a metal outer cylinder 11. The sleeve 1 corresponds to a sleeve (referred to as a regenerated sleeve) in which a sleeve similar to that shown in FIG. 1 is used in die casting and the worn ceramic inner cylinder is replaced. The method for reclaiming a die casting sleeve according to the present invention includes a step of flaring a used ceramic inner tube from the metal outer tube, and a new ceramic product in the metal outer tube after the tempering step. A shrink fitting process for shrink fitting the inner cylinder, a diameter expanding layer forming process for forming a diameter expanding layer on the outer peripheral surface of the metal outer cylinder before or after the shrink fitting process, and the new inside the metal outer cylinder. A diameter expansion layer processing step of processing the diameter expansion layer into a cylindrical outer shape after the ceramic inner cylinder is shrink-fitted and attached. Before forming the expanded diameter layer, a grinding process is performed in which the outer periphery of the metal outer cylinder is ground. FIG. 4 shows the relationship when the metal outer cylinder 11 is shrink-fitted into the new ceramic inner cylinder 12 before the diameter expansion layer forming step. FIG. 5 shows the relationship when the front end ring member 2 and the rear end ring member 3 are provided on the sleeve after the diameter expansion layer processing step.

  Even if the outer diameter of the metal outer cylinder is reduced by the grinding step, since the enlarged diameter layer is formed and the cylindrical outer shape is processed, the size of the metal outer cylinder does not match the size of the holding member of the die casting machine. Playback can be repeated until The metal outer cylinder that is repeatedly used has a long life, and is preferable from the viewpoint of cost reduction and resource and environmental protection. Even if the reproduction is repeated, the sleeve can be made free from looseness when mounted on the die casting machine.

  As shown in FIG. 4, the metal outer cylinder 11 is provided with two annular holding surfaces 11e and 11f between the flange-shaped convex portion 11c and the opening portion 11d on the outer peripheral surface. Since the annular holding surfaces 11e and 11f are processed into a cylindrical outer shape every time they are regenerated, it is preferable to have a larger outer diameter than other portions of the outer peripheral surface of the metal outer cylinder 11. Specifically, it is preferable that the annular holding surfaces 11e and 11f be higher by about 0.5 to 6 mm than other portions of the outer peripheral surface of the metal outer cylinder 11. In this embodiment, the number of the annular holding surfaces 11e and 11f is 2, but it is of course not limited, and may be one or three or more. However, it is preferable to fix the sleeve 1 to the die casting machine by the two annular holding surfaces 11e and 11f because it is most stable. The processing of the annular holding surfaces 11e and 11f into a cylindrical outer shape can be performed by cutting, grinding, or polishing.

  As shown in FIG. 5, diameter-enlarged layers 8 and 8 are formed on the annular holding surfaces 11e and 11f of the metal outer cylinder 11, respectively. The roundness of the outer peripheral surface of the metal outer cylinder 11 changes due to the tempering of the old ceramic inner cylinder 12 and the shrink-fit of the new ceramic inner cylinder 12, but it should be processed by providing expanded layers 8 and 8 With this, the roundness of the outer peripheral surface can be restored. The diameter-expanding layers 8 and 8 are preferably a plating layer, a sprayed layer, or a build-up weld layer from the viewpoint of film formation speed, but of course are not limited. The formed enlarged diameter layers 8 and 8 are ground into a cylindrical outer shape. When the diameter expansion layers 8 and 8 are hard metal plating layers, the plating layer is preferably formed on the outer peripheral surface of the metal outer cylinder after shrink fitting a new ceramic inner cylinder. When the diameter expansion layer is a sprayed layer or a build-up weld layer, it is preferable to form the sprayed layer or the build-up weld layer on the outer peripheral surface of the metal outer tube before shrink fitting a new ceramic inner tube. .

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Example 1
30% Ni, 20% Co, 4% Nb, 0.5% Al, 1.5% Ti, 0.05% C, the balance Fe and unavoidable impurities with high strength and low thermal expansion Metal outer cylinder 11 (outer diameter 300 mm, inner diameter 180 mm, length 1000 mm) made of metal C (see Table 1), 87 mass% Si ₃ N ₄ , 6 mass% Y ₂ O ₃ , A ceramic inner cylinder 12 (outer diameter 180 mm, inner diameter 130 mm, length 1000 mm) made of sialon formed by blending and sintering 4% by mass of Al ₂ O ₃ and 3% by mass of AlN Then, shrink fitting with a shrinkage rate of 0.001, shrinking and bolting the front end ring member 2 made of hot tool steel to the front end portion 11a of the metal outer cylinder 11, and further attaching the rear end ring member 3 with bolts, A sleeve 1 having the structure shown in FIG. 1 was constructed.

The average thermal expansion coefficients from room temperature to a predetermined temperature T of the metal C constituting the metal outer cylinder 11 and the sialon constituting the ceramic inner cylinder 12 are shown in C and A of FIG. Table 2 shows the average thermal expansion coefficient α _{M200 of} metal C from room temperature to 200 ° C., the average thermal expansion coefficient α _M400 from room temperature to 400 ° C., and the average thermal expansion coefficient α _M600 from room temperature to 600 ° C. The average thermal expansion coefficient α _C200 of ceramics A from room temperature to 200 ° C is 2.0 × 10 ^-6 / ° C, the average thermal expansion coefficient α _C400 from room temperature to 400 ° C is 2.4 × 10 ^-6 / ° C, and from room temperature to 600 ° C The average coefficient of thermal expansion α _C600 was 2.9 × 10 ⁻⁶ / ° C. Table 3 shows the tensile strength of metal C at 300 ° C, 350 ° C and 400 ° C, and the Young's modulus at room temperature.

注：各金属の単位は質量％であり、各金属はさらにFe（残部）及び不可避的不純物を含む。

Note: The unit of each metal is% by mass, and each metal further contains Fe (remainder) and inevitable impurities.

注：平均熱膨張係数の単位は［／℃］

Note: Unit of average thermal expansion coefficient is [/ ° C]

  The manufactured sleeve 1 was attached to an injection device of a horizontal die casting machine having a clamping force of 350 tons and used for die casting of an aluminum alloy (automobile parts: molding weight 16 kg). Although it was continuously used until the temperature of the lower side of the metal outer cylinder 11 measured with the radiation thermometer reached 350 to 400 ° C., injection could be performed stably. Specifically, there was no unevenness in the injection speed of the plunger tip, and there was no molding of a water fistula or nest. Moreover, no cracks occurred in the ceramic inner cylinder.

Example 2
A sleeve 1 was produced in the same manner as in Example 1 except that the metal outer cylinder 11 was produced from metal D having the composition shown in Table 1. The average thermal expansion coefficient of metal D from room temperature to a predetermined temperature T is shown in FIG. 2D, and α _M200 , α _M400 and α _M600 are shown in Table 2. Table 3 shows the tensile strength at 300 ° C, 350 ° C and 400 ° C, and the Young's modulus at room temperature.

  The sleeve 1 was continuously used by die casting in the same manner as in Example 1 until the temperature on the lower side of the metal outer cylinder reached 350 to 400 ° C. There was no molding defect of the nest. Moreover, no cracks occurred in the ceramic inner cylinder.

Example 3
A sleeve 1 was produced in the same manner as in Example 2 except that the shrink-fit rate was changed to 0.002. This sleeve 1 was continuously used by die-casting aluminum alloy until the lower temperature of the metal outer cylinder reached 350-400 ° C, but injection could be performed stably, forming hot water lines and nests. No defects occurred. Moreover, no cracks occurred in the ceramic inner cylinder.

Comparative Example 1
A sleeve 1 was produced in the same manner as in Example 1 except that the metal outer cylinder 11 was made of metal B having the composition shown in Table 1. The average thermal expansion coefficient of metal B from room temperature to a predetermined temperature T is shown in FIG. 2B, and α _M200 , α _M400 and α _M600 are shown in Table 2. Table 3 shows the tensile strength at 300 ° C, 350 ° C and 400 ° C, and the Young's modulus at room temperature.

  The sleeve 1 was continuously used by die casting as in Example 1 until the temperature on the lower side of the metal outer cylinder reached 200 ° C., but injection could be performed stably. However, when it was used until the temperature on the lower side of the metal outer cylinder reached 350 to 400 ° C., the injection sometimes became unstable. Specifically, unevenness in the injection speed of the plunger tip may cause water wrinkles and nests in the product.

Comparative Example 2
A sleeve 1 was produced in the same manner as in Example 1 except that the metal outer cylinder 11 was produced from metal E having the composition shown in Table 1. The average coefficient of thermal expansion of the metal E from room temperature to a predetermined temperature T is shown in E of FIG. 2, and α _M200 , α _M400 and α _M600 are shown in Table 2. Table 3 shows the tensile strength at 300 ° C, 350 ° C and 400 ° C, and the Young's modulus at room temperature.

  This sleeve 1 was continuously used by die casting until the temperature on the lower side of the metal outer cylinder reached 350 to 400 ° C., but injection could be performed, and there was no formation of hot water lines or nests. . However, the metal outer cylinder of Comparative Example 2 has a large coefficient of thermal expansion. There is a risk that the outer cylinder will be loosened and the ceramic inner cylinder will break.

Example 4
After the sleeve 1 of Example 1 was used for die casting, the rear end ring member 3 was first removed from the metal outer cylinder 11 in order to regenerate the sleeve 1 with the ceramic inner cylinder 12 consumed (step S1). Only the tip ring member 2 was heated to a temperature of 450 ° C. to burn off the tip ring member 2 from the metal outer cylinder 11 (step S2). Further, the sleeve 1 is heated to a temperature of 700 ° C. to burn out the ceramic inner cylinder 12 from the metal outer cylinder 11 (step S3), and immediately at the same temperature, a new ceramic inner cylinder 12 is attached to the metal outer cylinder 11. It was shrink-fitted (Step S4). Both end portions of the ceramic inner cylinder 12 were ground to match the surface of the metal outer cylinder.

The two annular holding surfaces 11e and 11f of the metal outer cylinder 11 on which the new ceramic inner cylinder 12 was shrink-fitted were ground into a cylindrical outer shape (step S5). The cylindrical outer shape of the metal outer cylinder was such that the roundness measured at a plurality of locations in the axial direction was 10 μm. Thereafter, except for the two annular holding surfaces 11e and 11f, masking is performed, and a Cr plating layer 8 having a thickness of 60 μm and a current density of 60 A / dm ² is applied to the cylindrical grinding surfaces using a 60 ° C. Sargent bath. Was formed (step S6). The composition of the Cr plating layer 8 was 0.4 mass% oxygen, 0.05 mass% hydrogen and the balance Cr.

  Thereafter, the tip ring member 2 was heated to a temperature of 450 ° C. and shrink-fitted onto the tip portion 11a of the metal outer cylinder 11 (step S7). The front end surface of the shrink-fitted front end ring member 2 was cut into a predetermined size (step S8), and then the front end ring member 2 was screwed to the hook-shaped convex portion 11c (step S9).

  The inner surface of the ceramic inner tube 12 and the inner surface of the tip ring member 2 that were shrink-fitted into the metal outer tube 11 were ground to the same surface (step S10). Since the roundness of the outer peripheral surface of the metal outer cylinder 11 in which the new ceramic inner cylinder 12 is shrink-fitted is slightly changed, the outer shape of the plating layer 8 becomes a cylinder (that is, the outer shape is before step S1). ) And averaged 10 μm (step S11). The plated layer had a roundness of 10 μm measured at a plurality of locations in the axial direction. Finally, the rear end ring member 3 was fixed to the rear end surface 11b of the metal outer cylinder 11 with the bolts 31 (step S12).

  As a result of using the regenerated sleeve 1 in an injection device of a horizontal die casting machine with a clamping force of 350 tons and using it for die casting of large aluminum alloys that require high dimensional accuracy, stable injection can be performed. There were no molding defects in the nest. Moreover, no cracks occurred in the ceramic inner cylinder.

1 ... Die-casting sleeve
11 ... Metal outer cylinder
11a ・ ・ ・ Tip
11b ・ ・ ・ Rear end face
11c ...
11d ・ ・ ・ Opening
11e, 11f ... annular holding surface
12 ... Ceramic inner cylinder
12a ... Opening
2 ... Tip ring member
3 ... Rear end ring member
31, 51 ... Bolt
7 ... Molten metal supply port
8 ... Diameter layer
30 ・ ・ ・ Die-casting machine holding member

Claims (7)

A die casting sleeve in which a ceramic inner cylinder is shrink-fitted in a metal outer cylinder,
Fe-Ni-Co-, wherein the metal outer cylinder contains 29-35 wt% Ni, 12-23 wt% Co and 2-5 wt% Nb, and has a Ni / Co ratio of 0.8-2 Composed of Nb alloy,
Average thermal expansion coefficient α _M200 from room temperature to 200 ° C., average thermal expansion coefficient α _M400 from room temperature to 400 ° C., and average thermal expansion coefficient α _M600 from room temperature to 600 ° C.
α _M400 ≦ 7.5 × 10 ⁻⁶ / ℃,
| α _M400 -α _M200 | ≦ 1 × 10 ^-6 / ℃,
α _M600 ≧ 5 × 10 ^-6 / ° C and α _M600 > α _M400
Meet the,
The ceramic inner cylinder has an average thermal expansion coefficient α _C200 from room temperature to 200 ° C., an average thermal expansion coefficient α _C400 from room temperature to 400 ° C. , and an average thermal expansion coefficient α _C600 from room temperature to 600 ° C. of 4 × 10. ^-6 / ° C or less, a die-casting sleeve. 2. The die-casting sleeve according to claim 1 , wherein α _M400 satisfies 4.5 × 10 ⁻⁶ / ° C. ≦ α _M400 ≦ 7.5 × 10 ⁻⁶ / ° C. 3. 3. The die casting sleeve according to claim 1, wherein α _M400 satisfies 5.0 × 10 ⁻⁶ / ° C. ≦ α _M400 ≦ 6.5 × 10 ⁻⁶ / ° C. 3. In die casting sleeve according to any one of claims 1 to 3 for die casting sleeve alpha _M600 is to satisfy the ^{_{α M600 ≧ 7 × 10 -6 /}} ℃. The die-casting sleeve according to any one of claims 1 to 4 , wherein the tensile strength at 300 ° C and 400 ° C of the metal outer cylinder is 800 MPa or more. The die-casting sleeve according to any one of claims 1 to 5 , wherein the metal outer cylinder is 29 to 35 mass% Ni, 12 to 23 mass% Co, 2 to 5 mass% Nb, 0.4 to 1.5. It is composed of Al by mass%, Ti by 1.2 to 3 mass%, C by 0.1 mass% or less, the balance Fe and inevitable impurities, and the metallic outer cylinder has a Ni / Co ratio of 1.1 to 2. Die casting sleeve. In die casting sleeve according to any one of claims 1 to 6, when the outer diameter before shrink fitting of the ceramic inner cylinder and d1, and the shrink-fitting front of the inner diameter of the metallic outer sleeve and D2, baked Fitting rate: (d1−D2) / D2 is in the range of 0.001 to 0.003.

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