JPWO2018021465A1 - Plunger tip for die casting and die casting shot sleeve - Google Patents

Abstract

A die-casting plunger tip for sliding in the injection sleeve, comprising a cylindrical tip body, a cylindrical tip sleeve mounted on the tip side outer periphery of the tip body to form a sliding surface, and a cylindrical tip sleeve An average thermal expansion coefficient at 20 to 200 ° C. of the tip body, comprising a cylindrical ring externally fitted to the tip body on the end side and a nut screwed to the tip body on the rear end side of the cylindrical ring 10 to 14 x 10 -6 / ° C, average thermal expansion coefficient of 20 to 200 ° C of the cylindrical tip sleeve is 1 to 6 x 10-6 / ° C, and average heat of 20 to 200 ° C of the cylindrical ring The axial length of the cylindrical tip sleeve at 20 ° C. is LB and the axial length of the cylindrical ring at 20 ° C. is LC at an expansion coefficient of 12 to 25 × 10 −6 / ° C. When the formula: 0.05 ≦ LC / LB ≦ 0.90 is satisfied.

Description

  The present invention relates to a die-casting plunger tip that slides in an injection sleeve that becomes a molten metal flow path of a die-casting machine.

  Since the conventional die-casting plunger tip is formed using S45C and SKD 61, the plunger tip thermally expands during the process of injecting the molten metal supplied in the injection sleeve with the tip, and the inner surface of the injection sleeve and the plan The clearance set with the outer peripheral surface of the jar tip becomes narrow, and when it is severe, abnormal friction and scratch may occur between the plunger tip and the injection sleeve. Therefore, there is a problem that the life of the plunger tip and the injection sleeve is shortened.

  Japanese Utility Model No. 3-21814 can cool the tip itself by passing cooling water inside to ease the thermal expansion of the plunger tip and allow the clearance with the injection sleeve to be set as small as possible. A plunger tip is disclosed.

  However, in the plunger tip described in Japanese Utility Model Application Publication No. 3-221814, if the amount of cooling water etc. is increased to suppress the thermal expansion of the tip and the cooling effect is enhanced, the aluminum melt supercooled in the injection sleeve solidifies As a result, the solidified pieces may be mixed into the die-cast product to form a broken chill layer. Since the broken chill layer has poor continuity with the periphery, it becomes a starting point of breakage when a load is applied to the product, and causes, for example, product defects such as chipping during finish machining. On the other hand, if the cooling water amount is reduced and operated so that the broken chill layer is not generated, the cooling effect becomes insufficient, so the expansion of the plunger tip becomes large, and the inner surface of the injection sleeve and the outer peripheral surface of the plunger tip The clearance set in between may become narrow, and the plunger tip may bite into the injection sleeve. Furthermore, in order to prevent the occurrence of galling, if the outer diameter of the tip is set smaller in consideration of the thermal expansion of the tip, the clearance between the injection sleeve and the tip becomes large before the tip is sufficiently thermally expanded. Insertion of the molten metal between the injection sleeves and the like causes a problem of scumming.

JP-A-9-85413 discloses a plunger tip in which the tip body is formed of a low thermal expansion material (average thermal expansion coefficient at 20 to 40 ° C. is 2 to 5 × 10 ^-6 / ° C.). For low thermal expansion materials, C: 0.8 to 1.0%, Si: 0.5 to 1.0%, Mn: 0.2% or less, Ni: 30.0 to 34.0%, Co: 10.0 to 15.0%, the balance is Fe and unavoidable by weight ratio It describes an alloy consisting of impurities.

  However, the above-mentioned alloy (Fe-based alloy containing 30 to 34% of Ni) described as a low thermal expansion material for chips in JP-A-9-85413 generally has a thermal conductivity of 15 to 17 W / m · K. Because of the low temperature, the time required to solidify the molten aluminum at the tip of the injection tip is long compared to the conventional S45C and SKD61. For this reason, there is a problem that cycle time becomes long and productivity falls.

  Japanese Patent Application Laid-Open No. 10-137913 comprises a cylindrical tip body and a cylindrical ring mounted on the outer periphery of the tip body to form a sliding surface for the injection sleeve, and the cylindrical ring can be replaced with the tip body. Discloses a plunger tip configured in With the plunger tip having such a configuration, when the surface of the plunger tip becomes rough due to use and movement becomes poor, the tip body can be left as it is, and only the cylindrical ring on the surface can be replaced, which wastes material. And waste can be prevented, contributing to resource saving, as well as economic advantages. In addition, by making only the cylindrical ring exchangeable in this way, only this ring can be formed of an expensive material excellent in heat resistance and wear resistance, and the cost can be reduced without quality deterioration. It can be planned.

  Japanese Patent Laid-Open No. 10-137913 discloses that the cylindrical ring is fixed to the tip body by bringing the cylindrical ring fitted on the tip body into contact with the stepped portion formed at the front end of the tip body. It is described that a double-nut type nut is screwed from the part, and the cylindrical ring is pressed against the step portion of the tip body and screwed and fixed firmly. Furthermore, in place of the method using the double nut, it is described that it can be fixed by shrink fitting method or screwing method.

  However, in the configuration described in JP-A-10-137913, for example, when a hot die steel is used for the tip body and a cemented carbide or ceramic having a thermal expansion coefficient smaller than that of steel is used for the cylindrical ring, Although it is possible to suppress expansion, a difference in thermal expansion difference between both members due to temperature rise during use causes a gap to be formed in the axial direction of both members. When such a gap is formed, molten metal is inserted at the time of pressurization, and galling occurs. In addition, the ring may be broken due to the radial expansion difference.

  Japanese Patent Application Laid-Open No. 2-46961 is a plunger tip slidably disposed in a cylinder having an inner wall made of a ceramic material and used for pressure injection molding of molten metal, wherein two rings made of the ceramic material And a cylindrical sleeve made of a metal material and having an outer diameter slightly smaller than the outer diameter of the ring, disposed in a weir direction such that the ring is located at both ends of the sleeve, and a tip head The plunger tip held and fixed by the stopper provided on the side and the stopper provided on the plunger rod side is disclosed. With such a configuration, the plunger tip made of a metal material is heated during the die-casting operation and the shaft Even in the case of thermal expansion in the direction, the sleeve made of a metal material also expands in the axial direction in the same manner. Ring and without throat drop N 殆 the clamping force of the sleeve, is described as can be held at a desired value.

  Japanese Patent Application Laid-Open No. 2-46961 describes that the sleeve is formed of the same heat-resistant metal material as the tip head and the tip-side cylinder. That is, since the sleeve, the tip head and the tip side cylinder are made of materials having substantially the same coefficient of thermal expansion, and the ring is made of a material (ceramic) having a coefficient of thermal expansion lower than them. In order not to reduce the clamping force of the ring and the sleeve against the axial expansion of the tip head (and the tip side cylinder), the axial length of the ring relative to the axial length of the sleeve is used. It is necessary to form so as to be as short as possible (see page 1, left lower column, line 1). However, if the axial length of the sliding portion (the ring portion) is shortened as described above, there is a problem that airtightness can not be sufficiently secured even if a material (ceramic) having a low thermal expansion coefficient is used.

  Therefore, the object of the present invention is to minimize the setting of the clearance with the injection sleeve by suppressing the thermal expansion of the plunger tip in the radial direction and to improve the air tightness, and to damage the plunger tip and the injection sleeve due to sliding wear. It is an object of the present invention to provide a die-casting plunger tip and a die-casting shot sleeve using the same, which can reduce the

  In view of the above objects, as a result of intensive studies, the present inventors externally fitted a cylindrical tip sleeve made of a low thermal expansion material to the tip body, and when fixing with a nut, between the cylindrical tip sleeve and the nut Inserting a cylindrical ring made of a material having a larger average thermal expansion coefficient than the tip body, or fixing the cylindrical tip sleeve with a nut member in which the cylindrical ring and a nut are integrally formed. The present inventors have found that it is possible to absorb the difference in thermal expansion between the tip body and the cylindrical tip sleeve that occur in a high temperature state during use, and prevent a gap from being formed in the axial direction of both members.

That is, the first die-casting plunger tip of the present invention is
A die-casting plunger tip that slides in an injection sleeve that becomes a molten metal flow path, comprising:
A tip body having a cylindrical shape and having cooling water circulating means therein, a cylindrical tip sleeve mounted on the tip side outer periphery of the tip body and forming a sliding surface for the injection sleeve, and a rear end side of the cylindrical tip sleeve A cylindrical ring externally fitted to the tip body, and a nut screwed to the tip body on the rear end side of the cylindrical ring,
The chip has an average thermal expansion coefficient α _A of 10 to 14 × 10 ⁻⁶ / ° C. at 20 to 200 ° C.,
Average thermal expansion coefficient α _B of 20 to 200 ° C. of the cylindrical tip sleeve is 1 to 6 × 10 ⁻⁶ / ° C., and average thermal expansion coefficient α _C of 20 to 200 ° C. of the cylindrical ring is 12 to 25 × 10 ^-6 / ° C,
satisfy α _C −α _A 0.50.5 × 10 ⁻⁶ / ° C.,
Let L _{B be} the axial length of the cylindrical tip sleeve at 20 ° C., and L _C be the axial length of the cylindrical ring at 20 ° C.
0.05 ≦ L _C / L _B ≦ 0.90 (1)
It is characterized by satisfying.

  In the first die-casting plunger tip, at 20 ° C. and an operating temperature, the cylindrical tip sleeve preferably has a larger outer diameter than the tip end of the tip body and the cylindrical ring.

  In the first die-casting plunger tip, the cylindrical ring is preferably made of austenitic stainless steel.

The second die-casting plunger tip of the present invention is
A die-casting plunger tip that slides in an injection sleeve that becomes a molten metal flow path, comprising:
A tip body having a cylindrical shape and having cooling water circulating means therein, a cylindrical tip sleeve mounted on the tip side outer periphery of the tip body and forming a sliding surface for the injection sleeve, and a rear end side of the cylindrical tip sleeve It consists of a nut member screwed to the tip body,
The nut member includes a ring portion that abuts on the rear end side of the cylindrical tip sleeve, and a nut portion integrally formed on the rear end side of the ring portion.
The chip has an average thermal expansion coefficient α _A of 10 to 14 × 10 ⁻⁶ / ° C. at 20 to 200 ° C.,
Average thermal expansion coefficient α _B of 20 to 200 ° C. of the cylindrical tip sleeve is 1 to 6 × 10 ⁻⁶ / ° C., and average thermal expansion coefficient α _D of 20 to 200 ° C. of the nut member is 12 to 25 × 10 ^-6 / ° C,
satisfy α _D αα _A ,
Let L _{B be} the axial length of the cylindrical tip sleeve at 20 ° C., and L _D1 be the axial length of the ring portion at 20 ° C.
_{0.05 ≦ L D1 / L B ≦} 0.90 ··· (1 ')
It is characterized by satisfying.

In the second die-casting plunger tip, an average thermal expansion coefficient α _A of 20 to 200 ° C. of the tip body and an average thermal expansion coefficient α _D of 20 to 200 ° C. of the nut member are α _D −α _A ≧ It is preferable to satisfy 0.5 × 10 ⁻⁶ / ° C.

  In the second die-casting plunger tip, the cylindrical tip sleeve preferably has an outer diameter larger than the tip end portion of the tip body and the nut member at a temperature of 20 ° C. and at the time of operation.

In the first or second die-casting plunger tip, when the inside diameter of the injection sleeve at 20 ° C. is D, the formula:
L _B 0.30.3 × D (2)
It is preferable to satisfy

  The cylindrical tip sleeve is preferably made of a high strength and low thermal expansion metal. The high strength and low thermal expansion metal is a Fe-Ni based alloy containing 29 to 45% by mass of Ni, or 29 to 35% by mass of Ni, 12 to 23% by mass of Co, 0.5 to 1.5% by mass of Al and It is preferable that it is a Fe-Ni-Co-Al-Ti based alloy containing 0.8 to 3% by mass of Ti.

The cylindrical tip sleeve comprises a base material made of the Fe-Ni-based alloy or the Fe-Ni-Co-Al-Ti-based alloy, and an iron having a thickness of 0.5 to 5 mm joined to the outer peripheral surface of the base material. It consists of a corrosion resistant layer consisting of a -C-Ni-Cr base alloy
The corrosion resistant layer is preferably made of a Fe-C-Ni-Cr based alloy containing 0.2 to 0.7% by mass of C, 1 to 7% by mass of Cr and 1 to 20% by mass of Ni.

  It is preferable that the surface layer from the surface of the corrosion resistant layer to a depth of 0.5 mm have a C content of 0.2 to 0.7 mass%, a Cr content of 2 to 7 mass%, and a Ni content of 0.1 to 15 mass%.

  The corrosion resistant layer further contains 0.5 to 3% by mass of Mo, 0.3 to 1.5% by mass of V, 2% by mass or less of Co, 0.5% by mass or less of Al, 0.5% by mass or less of Ti, 0.5% by mass or less of Si It is preferable to contain Mn of 1.0% by mass or less, P of 0.04% by mass or less, and S of 0.03% by mass or less.

  The cylindrical tip sleeve preferably comprises a nitrided layer 150 to 500 μm thick from the surface.

  The cylindrical tip sleeve comprises 0.5 to 3.0% by mass of C, 0.1 to 2.7% by mass of Si, 0.1 to 1.0% by mass of Mn, 25 to 40% by mass of Ni, 3 to 7% by mass of Co, and the balance is Fe And it is preferable to consist of low thermal expansion cast iron which has a structure which has 1-10 area% of a graphite while having a composition containing unavoidable impurities.

  The cylindrical tip sleeve is preferably made of one selected from silicon nitride ceramics, sialon ceramics, silicon carbide ceramics and carbonaceous ceramics.

  The cylindrical tip sleeve includes at least two selected from a cylindrical tip sleeve made of the high strength and low thermal expansion metal, a cylindrical tip sleeve made of low thermal expansion cast iron, and a cylindrical tip sleeve made of the ceramic. It may be arranged in a direction.

The third die casting plunger tip of the present invention is
A die-casting plunger tip that slides in an injection sleeve that becomes a molten metal flow path, comprising:
A tip body having a cylindrical shape and having cooling water circulating means therein, a cylindrical tip sleeve mounted on the tip side outer periphery of the tip body and forming a sliding surface for the injection sleeve, and a rear end side of the cylindrical tip sleeve A cylindrical ring externally fitted to the tip body; and fixing means for holding and fixing the cylindrical tip sleeve and the cylindrical ring from both ends in the axial direction,
The cylindrical tip sleeve comprises a base material of high strength and low thermal expansion metal and a corrosion resistant layer of 0.5 to 5 mm in thickness joined to the outer peripheral surface of the base material, and the high strength low thermal expansion metal is Fe-Ni base alloy containing 29 to 45% by mass of Ni, or 29 to 35% by mass of Ni, 12 to 23% by mass of Co, 0.5 to 1.5% by mass of Al and 0.8 to 3% by mass of Ti Fe--C--Ni consisting of an Fe--Ni--Co--Al--Ti based alloy, wherein said corrosion resistant layer contains 0.2-0.7% by mass of C, 1-7% by mass of Cr and 1- 20% by mass of Ni. -Cr base alloy,
The chip has an average thermal expansion coefficient of 10 to 14 × 10 ⁻⁶ / ° C. at 20 to 200 ° C.,
The average thermal expansion coefficient of the base material of the cylindrical tip sleeve at 20 to 200 ° C. is 1 to 6 × 10 ⁻⁶ / ° C., and the average thermal expansion coefficient of the cylindrical ring at 20 to 200 ° C. is 12 to 25 × 10 It is characterized by being ^-6 / ° C.

  In the third die-casting plunger tip, the fixing means may have a front end side fixing portion and a rear end side fixing portion, and the cylindrical ring may be integrally formed with the rear end side fixing portion.

  In the third die-casting plunger tip, the cylindrical tip sleeve preferably has an outer diameter larger than the tip end of the tip body and the cylindrical ring at 20 ° C. and at the operating temperature.

In the third die-casting plunger tip, when the axial length of the cylindrical tip sleeve at 20 ° C. is L _B and the inner diameter of the injection sleeve at 20 ° C. is D, the formula is:
L _B 0.30.3 × D (2)
It is preferable to satisfy

  The die-cast shot sleeve according to the present invention comprises an injection sleeve comprising the first to third die-casting plunger tips and an inner cylinder made of silicon nitride ceramic or sialon ceramic in an outer cylinder made of a low thermal expansion metal. And is characterized by

  Since the setting of the clearance between the plunger tip and the injection sleeve can be minimized to improve the air tightness, defects such as cavities and segregation (broken chill) of the die cast product can be suppressed. By externally fitting a cylindrical tip sleeve made of a low thermal expansion material, thermal expansion of the plunger tip is suppressed, and abnormal friction and scratching between the plunger tip and the injection sleeve can be prevented, and the plunger tip and While the life of the injection sleeve is improved, stable die casting operation becomes possible.

It is a schematic cross section of the 1st plunger tip for die-casts of this invention. It is a fragmentary sectional view showing typically an example of a cylindrical tip sleeve. It is a fragmentary sectional view which expands and shows the outer peripheral surface vicinity of the cylindrical chip sleeve shown to Fig.2 (a). It is a schematic cross section which shows the state which inserted the 1st plunger tip for die-casts of this invention in the injection sleeve. It is a schematic cross section of the 2nd plunger tip for die-casts of this invention.

[1] Die casting plunger tip
(A) First aspect
(1) Configuration FIG. 1 shows a cross-sectional view of the first die-casting plunger tip 1 of the present invention and an enlarged view of a circled portion. The first die-casting plunger tip 1 according to the present invention has a cylindrical main body 2 having cooling water circulating means 7 inside and a tip end side outer periphery of the tip main body 2 and an injection sleeve 8 (see FIG. 3) A cylindrical tip sleeve 3 forming a sliding surface with respect to the cylinder, a cylindrical ring 4 externally fitted to the tip body 2 at the rear end side of the cylindrical tip sleeve 3, and a rear end side of the cylindrical ring 4 It consists of a nut 5 screwed to the tip body 2;
The chip has an average thermal expansion coefficient α _A of 10 to 14 × 10 ⁻⁶ / ° C. at 20 to 200 ° C.,
Average thermal expansion coefficient α _B of 20 to 200 ° C. of the cylindrical tip sleeve is 1 to 6 × 10 ⁻⁶ / ° C., and average thermal expansion coefficient α _C of 20 to 200 ° C. of the cylindrical ring is 12 to 25 × 10 ^-6 / ° C,
satisfy α _C −α _A 0.50.5 × 10 ⁻⁶ / ° C.,
Let L _{B be} the axial length of the cylindrical tip sleeve at 20 ° C., and L _C be the axial length of the cylindrical ring at 20 ° C.
0.05 ≦ L _C / L _B ≦ 0.90 (1)
It is characterized by satisfying.

  The cylindrical tip sleeve 3 is mounted so as to abut on the rear end face 6a of the flange portion 6 formed at the tip end portion of the tip body 2, and via the cylindrical ring 4 externally fitted on the rear end side. In a state of being pressed against the rear end face 6a by the nut 5, the screw is firmly fixed. A screw 4 a for screwing the nut 5 is provided at the outer rear end of the chip body 2. With such a configuration, the cylindrical tip sleeve 3 is firmly fixed and held on the tip end side of the tip body 2 without being displaced or falling off. A cooling water circulating means 7 is provided inside the chip body 2, and a screw 4b for screwing and fixing a rod 9 (see FIG. 3) is provided on the rear end side of the chip body 2. As shown in FIG. 3, the rod 9 is provided with a cooling water passage 10 for supplying water to the cooling water circulating means 7 inside the tip body 2.

Attach the cylindrical tip sleeve 3 with a low average thermal expansion coefficient α _{B at} 20 to 200 ° C (α _B : 1 to 6 x 10 ^-6 / ° C) to the tip body 2, and the cylindrical tip sleeve 3 is a sliding surface By forming such a structure, it is possible to suppress the thermal expansion of the plunger tip in the radial direction, and it is possible to minimize the setting of the clearance with the injection sleeve and improve the air tightness. Damage due to sliding wear of the injection sleeve can be reduced.

Furthermore, the average thermal expansion coefficient α _{A of} the chip body 2 at 20 to 200 ° C., the average thermal expansion coefficient α _B of 20 to 200 ° C. of the cylindrical tip sleeve 3 and the average thermal expansion coefficient α of 20 to 200 ° C. of the cylindrical ring 4 the _C, alpha _a is ^{10~14 × 10 -6 / ℃, α} B is 1~6 × 10 ^-6 / ℃, and alpha _C is ^{12~25 × 10 -6 / ℃, α} C -α a ≧ 0.5 × set so as to satisfy the 10 ^-6 / ° C., and the axial length of the cylindrical tip sleeve 3 at 20 ° C. L _B, and the axial length L _C of the cylindrical ring 4 at 20 ° C. ,formula:
0.05 ≦ L _C / L _B ≦ 0.90 (1)
Cylindrical tip sleeve 3 and cylindrical ring 4 such that the axial length L _C of cylindrical ring 4 is in the range of 5 to 90% of the axial length L _B of the cylindrical tip sleeve. Set the axial length of A plan in which the cylindrical tip sleeve 3 does not loosen in the axial direction during operation because the tip body 2, the cylindrical tip sleeve 3 and the cylindrical ring 4 have such an average thermal expansion coefficient and the axial length. A jar tip is obtained.

Here, when the average thermal expansion coefficient α _{C at} 20 to 200 ° C. of the cylindrical ring 4 is the same as the average thermal expansion coefficient α _{A at} 20 to 200 ° C. of the tip body 2 (that is, α _C = α _A ) In order to prevent the cylindrical tip sleeve 3 and the cylindrical ring 4 from loosening with respect to the axial expansion of the tip body 2 in the case, it is necessary to make the length of the cylindrical ring 4 sufficiently large. The axial length of the tip sleeve 3 can not be made sufficiently long. Also, when the average thermal expansion coefficient α _{C at} 20 to 200 ° C. of the cylindrical ring 4 is smaller than the average thermal expansion coefficient α _{A at} 20 to 200 ° C. of the tip body 2 (ie, α _C <α _A ), It becomes difficult to prevent the cylindrical tip sleeve 3 and the cylindrical ring 4 from loosening against axial expansion of the tip body 2.

The average thermal expansion coefficient alpha _A of 20 to 200 ° C. of the chip body 2 is more preferably from 11~13 × 10 ^-6 / ℃, average thermal expansion coefficient of 20 to 200 ° C. of the cylindrical tip sleeve 3 alpha _B is more preferably 1.5 to 3.5 × 10 ⁻⁶ / ° C., and the average thermal expansion coefficient α _C at 20 to 200 ° C. of the cylindrical ring 4 is 17 to 20 × 10 ⁻⁶ / ° C. preferable. The lower limit of the ratio L _C / L _B of the axial length L _C of the cylindrical ring 4 to the axial length L _B of the cylindrical tip sleeve is preferably 0.1, and more preferably 0.2. The upper limit of the ratio L _C / L _B is preferably 0.35 and more preferably 0.5.

  The axial length of the cylindrical tip sleeve 3 and the cylindrical ring 4 is set so that the cylindrical tip sleeve 3 having the smallest average thermal expansion coefficient does not loosen at the operating temperature. That is, when the tip body 2, the cylindrical tip sleeve 3 and the cylindrical ring 4 axially expand, the total amount of expansion of the cylindrical tip sleeve 3 and the cylindrical ring 4 is greater than the amount of expansion of the tip body 2. Set to be large.

  When the plunger tip 1 of the present invention is used for die casting of a product made of aluminum alloy or the like, the injection sleeve 8 is in direct contact with the molten aluminum alloy on the tip surface of the tip body 2 or in direct contact with the molten aluminum alloy. The temperature of the entire plunger tip rises due to heat transfer from the inner circumferential surface of the cylindrical tip sleeve 3 to the cylindrical tip sleeve 3, but since the cooling water circulating means 7 is provided inside the tip body 2, the cylinder of the tip body 2 The temperature of the portion facing the cylindrical tip sleeve 3 and the cylindrical ring 4 is estimated to be about room temperature to 90 ° C., and the temperature of the cylindrical tip sleeve 3 and the cylindrical ring 4 in direct contact with this is estimated to be about 100 to 200 ° C. Be done.

In the plunger tip 1 of the present invention to prevent galling between the injection sleeve 8, it is set to be smaller than the thermal expansion coefficient alpha _A of the thermal expansion coefficient of the cylindrical tip sleeve 3 alpha _B tip body 2, further The thermal expansion coefficient α _C of the cylindrical ring 4 disposed in the axial direction with respect to the cylindrical tip sleeve 3 is set larger than the thermal expansion coefficient α _A of the tip body 2. That is, the axial length L _C of the cylindrical ring 4 is shorter than the axial length L _{B of the} cylindrical tip sleeve 3 by forming the cylindrical ring 4 with a material having a larger thermal expansion coefficient. Even when the die body is used for die casting, the axial elongation of the portion of the chip body 2 facing the cylindrical tip sleeve 3 and the cylindrical ring, the elongation of the cylindrical tip sleeve 3 and the elongation of the cylindrical ring 4 Thus, the cylindrical tip sleeve 3 is strongly pressed against the flange portion 6 of the tip body 2 and firmly fixed.

Furthermore, the axial length L _B of the cylindrical tip sleeve 3 at 20 ° C. is given by the formula: where the inner diameter of the injection sleeve at 20 ° C. is D:
L _B 0.30.3 × D (2)
It is preferable to satisfy Since the outer peripheral surface of the cylindrical tip sleeve 3 forms a sliding surface for the inner peripheral surface of the injection sleeve 8, the injection by the L _B that satisfies the condition is carried out smoothly and stably. L _B is more preferably 0.4 × D or more, still more preferably 0.5 × D or more, and most preferably 0.6 × D or more. On the other hand, it is preferable that L _B ≦ 1.0 × D, since the sliding resistance increases if L _B becomes too long. L _B is more preferably 0.9 × D or less, most preferably 0.8 × D or less.

The cylindrical tip sleeve 3 forms a sliding surface with respect to the inner peripheral surface of the injection sleeve 8, so the tip portion 2a of the tip body 2 and the cylinder can be used at both room temperature (20 ° C.) and operating temperature. It is preferable to be configured to have an outer diameter larger than the ring 4. That is, when the tip body outer diameter at room temperature (20 ° C.) is D _A , the cylindrical tip sleeve outer diameter is D _B , and the cylindrical ring outer diameter is D _C ,
D _B > D _A , and
D _B > D _C
The filled, and D _A tip body distal end outside diameter at the temperature when the operation when ', the cylindrical tip sleeve outer diameter D _B' were, a cylindrical ring outer diameter and D _C ',
D _B '≧ D _A ', and
D _B '> D _C '
Meet. Specifically, it is preferable that D _B -D _A = 0.01 to 1.2 mm and D _B -D _C = 0.5 to 10 mm.

A clearance is set to exist radially at 20 ° C. between the inner peripheral surface of the cylindrical tip sleeve 3 and the tip body 2. The radial clearance between the inner peripheral surface of the cylindrical tip sleeve 3 and the tip body 2 is represented by the formula: [fitting diameter x (average thermal expansion coefficient of tip body α _A- average thermal expansion coefficient α of the cylindrical tip sleeve _It is preferable that it is the quantity represented by _B ) x 20-100 mm]. For example, when the fitting diameter is 100 mm, the radial clearance is preferably 0.02 to 0.10 mm.

  The present invention is preferably applied to a die-casting plunger tip having an outer diameter of 30 mm to 400 mm, and more preferably one having an outer diameter of 50 mm to 300 mm. The present invention is preferably applied to a die-casting plunger tip having a total length of 50 mm to 600 mm, and more preferably one having a total length of 60 mm to 500 mm.

  The average thermal expansion coefficient (corresponding to the average linear expansion coefficient or the average linear expansion coefficient) of the tip body 2, the cylindrical tip sleeve 3 and the cylindrical ring 4 is JIS Z 2285-2003 “a method of measuring the linear expansion coefficient of a metal material” Measure based on When the cylindrical tip sleeve 3 is a ceramic, the average thermal expansion coefficient is measured based on JIS R 1618-2002 “measurement of thermal expansion by thermal mechanical analysis of fine ceramics”. A differential expansion thermal mechanical analyzer is used as a measurement device of the average thermal expansion coefficient.

(2) Chip body The chip body 2 is excellent in heat resistance and wear resistance, and as described above, a material having an average thermal expansion coefficient α _A of 20 to 200 ° C. satisfying 10 to 14 × 10 ⁻⁶ / ° C. It consists of The chip body 2 is preferably made of, for example, an alloy tool steel such as SKD 61 (the average thermal expansion coefficient at 20 ° C. to 200 ° C. is 13 × 10 ⁻⁶ / ° C.). The chip body is preferably made of a material having a tensile strength of 1200 MPa or more. The chip body is cylindrical, and the temperature of the tip part at the time of operation can be suppressed to about 200 ° C, and the temperature of the mating surface with the cylindrical tip sleeve can be suppressed to about 90 ° C. It has cooling water circulation means 7 for flowing.

  The tip end face of the tip body 2 preferably has a truncated cone portion 2b with a height of 3 to 20 mm at its central portion, as shown in FIG. That is, it is preferable that the peripheral portion 2c of the tip end surface be formed lower than the central portion. The diameter of the upper base of the truncated cone portion 2b is preferably smaller by 2 to 10 mm than the outer diameter of the tip body 2, and more preferably smaller by 5 to 10 mm. The diameter of the lower base of the truncated cone portion 2b is preferably 1 to 9 mm smaller than the outer diameter of the tip body 2, and more preferably 4 to 9 mm smaller. Thus, by having the truncated cone portion 2b at the center of the tip surface of the tip body 2, the molten metal in contact with the peripheral portion 2c solidifies in the initial stage, and the metal between the injection sleeve and the plunger tip Prevent molten metal from entering and prevent the occurrence of galling.

(3) Cylindrical tip sleeve The cylindrical tip sleeve uses a low thermal expansion material having an average thermal expansion coefficient α _B of 1 to 6 × 10 ⁻⁶ / ° C. at 20 to 200 ° C. By using such a low thermal expansion material, the clearance between the injection sleeve and the plunger tip can be maintained at an appropriate interval even during operation, and the occurrence of galling can be prevented. As the low thermal expansion material, (a) low thermal expansion metal or (b) ceramic is preferable. By forming the cylindrical tip sleeve from a low thermal expansion material, the injection sleeve / plunger tip clearance in die-casting can be kept stable in the range of 0.01 to 0.10 mm without causing the problem of galling.

(a) Low Thermal Expansion Metal As the low thermal expansion metal, the average thermal expansion coefficient of (a-1) 20 to 200 ° C. is 1 to 5 × 10 ⁻⁶ / ° C., and the tension at a temperature of 20 ° C. to 500 ° C. High strength low thermal expansion metal having a strength of 590 MPa or more, or (a-2) average thermal expansion coefficient at 20 to 200 ° C. of 1 to 6 × 10 ⁻⁶ / ° C., temperature of 20 ° C. to 500 ° C. It is preferable to use a low thermal expansion cast iron having a tensile strength of at least 300 MPa.

(a-1) High strength low thermal expansion metal
(composition)
The high strength and low thermal expansion metal material is preferably a Fe-Ni based alloy containing 29 to 45% by mass of Ni. In particular, the high strength and low thermal expansion metal material is Fe-Ni-Co containing 29 to 35% by mass of Ni, 12 to 23% by mass of Co, 0.5 to 1.5% by mass of Al and 0.8 to 3% by mass of Ti. It is preferable to be a -Al-Ti base alloy. By using such a material, the strength of the cylindrical tip sleeve can be enhanced. More preferably, it is a Fe-Ni-Co-Al-Ti based alloy containing 30 to 35% by mass of Ni, 12 to 17% by mass of Co, 0.5 to 1.5% by mass of Al and 1.5 to 3% by mass of Ti. is there. Al and Ti are precipitation strengthening elements and contribute to the improvement of the strength (e.g. tensile strength). Besides Al and Ti, Nb can be used as a precipitation strengthening element. Nb may be contained in combination with the contents of Al and Ti. As for Nb, 2-5 mass% is preferable. Materials constituting such a cylindrical tip sleeve include 29 to 35% by mass Ni, 12 to 23% by mass Co, 0.5 to 1.5% by mass Al, 0.8 to 3% by mass Ti, the balance Fe and unavoidable impurities It is more preferably composed of 30 to 35% by mass of Ni, 12 to 17% by mass of Co, 0.5 to 1.5% by mass of Al and 1.5 to 3% by mass of Ti, the balance of Fe and unavoidable impurities.

(Corrosion resistant layer)
The cylindrical tip sleeve 3 is more preferably, as shown in FIG. 2A, a base material 31 made of a high strength and low thermal expansion metal material, an outer peripheral surface of the base material 31 (and its tip end if necessary. It is preferable to comprise the corrosion resistant layer 32 joined to the surface). The formation of the corrosion resistant layer 32 is preferably by bonding in such a manner that the material of the base material 31 and the material of the corrosion resistant layer 32 mutually diffuse, that is, metallurgical bonding. The thickness of the corrosion resistant layer 32 is preferably 0.5 to 5 mm, more preferably 2 to 3 mm. If it is less than 0.5 mm, sufficient corrosion resistance may not be obtained. Further, as described later, since the corrosion resistant layer 32 is made of a material having an average thermal expansion coefficient larger than that of the base material 31, if it exceeds 5 mm, the average thermal expansion coefficient of the entire cylindrical tip sleeve 3 is increased, and the injection sleeve The clearance between the and the plunger tip can not be maintained properly. The corrosion resistant layer 32 is preferably formed on the outer peripheral surface of the cylindrical tip sleeve 3, but is preferably also formed on the axial end face of the cylindrical tip sleeve 3.

  The corrosion resistant layer 32 is an Fe-C-Ni-Cr based alloy containing 0.2 to 0.7% by mass of C, 1 to 7% by mass of Cr, 1 to 20% by mass of Ni, the balance substantially Fe and unavoidable impurities. It is preferable to consist of This alloy is high in wear resistance because carbides are finely dispersed, and is excellent in erosion resistance because carbides dispersed in the alloy are less likely to react with non-ferrous molten metals. The Fe-C-Ni-Cr base alloy further contains 0.5 to 3% by mass of Mo, 0.3 to 1.5% by mass of V, 2% by mass or less of Co, 0.5% by mass or less of Al, 0.5% by mass or less of Ti, You may contain 0.5 mass% or less Si, 1.0 mass% or less Mn, 0.04 mass% or less P, and 0.03 mass% or less S. The Fe-C-Ni-Cr base alloy may most preferably contain 0.1 to 4 wt% W. In addition, since the metal component of the base material 31 is diffused in the corrosion resistant layer 32 as described later, the metal composition is not uniform in the thickness direction. Therefore, the metal composition of the corrosion resistant layer 32 mentioned here is an average composition of the entire corrosion resistant layer 32.

  That is, since the corrosion resistant layer 32 is bonded by a method in which the material of the base material 31 and the material of the corrosion resistant layer 32 mutually diffuse, the corrosion resistant layer 32 is formed near the bonding portion between the base material 31 and the corrosion resistant layer 32. The metal component of the matrix 31 is diffused more, and the metal component of the corrosion resistant layer 32 is diffused more to the matrix 31. On the other hand, the surface of the corrosion resistant layer 32 most distant from the joint (surface layer described later In the case of part), the degree of diffusion from the base material 31 is the lowest.

  In the surface layer portion 32s of the corrosion resistant layer 32, that is, a portion from the surface of the corrosion resistant layer 32 to a depth of 0.5 mm (see FIG. 2B), 0.2 to 0.7 mass% of C, 2 to 7 mass% of Cr and It is preferable to contain 0.1 to 15% by mass of Ni. That is, the surface layer portion 32s is preferably made of an Fe--C--Ni--Cr based alloy containing 0.2 to 0.7% by mass of C, 2 to 7% by mass of Cr and 0.1 to 15% by mass of Ni. When the C content, the Cr content, and the Ni content of the surface layer portion 32s are in the above ranges, the corrosion resistance and the wear resistance of the surface of the corrosion resistant layer 32 become more excellent.

  When the C content in the surface layer portion 32s is less than 0.2 mass%, the corrosion resistance is reduced, and the life of the cylindrical tip sleeve is shortened due to premature dissolution, and when it exceeds 0.7 mass%, the toughness is reduced to cause cracking or peeling. It will be easier. When the Cr content of the surface layer portion 32s is less than 2% by mass, the corrosion resistance is reduced, and the life of the cylindrical tip sleeve is shortened due to early melting, and when it exceeds 7% by mass, the toughness is reduced to cause cracking or peeling. It will be easier. When the Ni content in the surface layer portion 32s is less than 0.1% by mass, the thermal shock resistance is reduced to easily cause heat cracks, and when it exceeds 15% by mass, the early corrosion and abrasion resistance decrease due to the corrosion resistance lowering. Early wear tends to occur, the life of the cylindrical tip sleeve is shortened, and the machinability is also reduced, leading to an increase in manufacturing cost. Preferred ranges of the C content, the Cr content, and the Ni content of the surface layer portion 32s are 0.3 to 0.5 mass%, 3 to 5 mass%, and 1 to 12 mass%, respectively.

(Nitrided layer)
The cylindrical tip sleeve preferably has a nitrided layer with a thickness of 150 to 500 μm on its surface. The nitride layer improves the wear resistance and erosion resistance of the tip sleeve 3 surface. The corrosion resistant layer made of a Fe-C-Ni-Cr base alloy contains Cr, which has a strong affinity for nitrogen, so it facilitates the diffusion of nitrogen into the alloy and forms a nitrided layer containing a large amount of nitride. It's easy to do. The reaction with the molten metal hardly occurs due to the iron nitride formed on the outermost surface by nitriding. From the above reasons, non-ferrous metals can be obtained by adopting a structure having a covering layer made of a Fe-C-Ni-Cr base alloy excellent in corrosion resistance and a nitrided layer formed on the outermost surface portion in contact with nonferrous molten metal. It is possible to suppress the erosion caused by the reaction with the molten metal. In addition, even if a part of the nitrided layer disappears during use, the erosion resistance of the coating layer of the Fe-C-Ni-Cr base alloy is less likely to cause erosion due to penetration of the molten metal, and the erosion is It is possible to suppress rapid progress. The nitrided layer can be formed on the surface of the corrosion resistant layer by nitriding such as sulfidation nitriding, salt bath soft nitriding, gas nitriding, gas soft nitriding, plasma nitriding and the like. Among them, sulfurized nitriding is preferable because it contains S and thus the lubricity is improved and the sliding resistance with the injection sleeve is reduced.

(a-2) Low Thermal Expansion Cast Iron As low thermal expansion cast iron, the average thermal expansion coefficient at 20 to 200 ° C. is 1 to 6 × 10 ⁻⁶ / ° C., 0.5 to 3.0 mass% C, 0.1 to 2.7 mass% Si, having a composition containing 0.1 to 1.0% by mass of Mn, 25 to 40% by mass of Ni, 3 to 7% by mass of Co, the balance containing Fe and unavoidable impurities, and having 1 to 10% by area of graphite Preferably it is a low thermal expansion cast iron having a texture. Since the low thermal expansion cast iron has the above composition, it has low thermal expansion, and since it has graphite, the graphite functions as a lubricant to reduce the sliding resistance with the inner surface of the injection sleeve, and the injection sleeve and plunger tip It can prevent the occurrence of galling.

(composition)
Low thermal expansion cast iron: 0.5 to 3.0% by mass C, 0.1 to 2.7% by mass Si, 0.1 to 1.0% by mass Mn, 25 to 40% by mass Ni, 3 to 7% by mass Co, balance Fe and unavoidable Contain the organic impurities. The low thermal expansion cast iron may further contain 0.01 to 0.1% by mass of Mg as an optional element.

(i) C: 0.5 to 3.0% by mass
C dissolves in the matrix and crystallizes as graphite. The content of C needs to be 0.5% by mass or more for graphitic crystallization, but when it exceeds 3.0% by mass, the mechanical properties of the tip sleeve are deteriorated. The lower limit of the content of C is preferably 0.75% by mass. The upper limit of the content of C is preferably 2.2% by mass.

(ii) Si: 0.1 to 2.7 mass%
Si is an element necessary for crystallizing graphite, and it is necessary to contain 0.1% by mass or more, but if it exceeds 2.7% by mass, the mechanical properties of the tip sleeve will be deteriorated. The lower limit of the content of Si is preferably 0.2% by mass. The upper limit of the content of Si is preferably 2.4% by mass.

(iii) Mn: 0.1 to 1.0% by mass
Mn needs to be 0.1% by mass or more because it has a deoxidizing action of the molten metal, but if it exceeds 1.0% by mass, the mechanical properties of the tip sleeve deteriorate. The lower limit of the content of Mn is preferably 0.2% by mass. The upper limit of the content of Mn is preferably 0.6% by mass, and more preferably 0.4% by mass.

(iv) Ni: 25 to 40% by mass
Ni is effective to make the base a heat-resistant, corrosion-resistant, austenite-based structure and to make it have a low thermal expansion. Ni is also effective as an auxiliary element for graphitization. When Ni is less than 25% by mass or Ni is more than 40% by mass, an average thermal expansion coefficient of 20 to 200 ° C. can not be obtained at 1 to 6 × 10 ⁻⁶ / ° C. The lower limit of the content of Ni is preferably 30% by mass, and the upper limit of the content of Ni is preferably 36%.

(v) Co: 3 to 7% by mass
Co, like Ni, is also effective for achieving low thermal expansion. If Co is less than 3% by mass, or more than 7% by mass, an average thermal expansion coefficient of 20 to 200 ° C. of 1 to 6 × 10 ⁻⁶ / ° C. can not be obtained. The lower limit of the content of Co is preferably 4.5% by mass, and the upper limit of the content of Co is preferably 5.5% by mass.

(vi) Mg: 0 to 0.1% by mass
Mg preferably contains Mg in order to spheroidize graphite in the structure of low thermal expansion cast iron to improve mechanical strength. When Mg exceeds 0.1% by mass, the upper limit is preferably 0.1% by mass to inhibit graphitization. 0.01 mass% is preferable and, as for the minimum of content of Mg, 0.02 mass% is more preferable. The upper limit of the content of Mg is more preferably 0.06% by mass.

(vii) Other Elements The balance of the tip sleeve composition consists essentially of Fe and unavoidable impurities. Among the unavoidable impurities, P and S cause deterioration of mechanical properties, so it is preferable to reduce them as much as possible. Specifically, the content of P is preferably 0.05% by mass or less, and the content of S is preferably 0.05% by mass or less. Further, Cr, Mo, V, W and Nb are carbide-forming elements, and in order to inhibit graphitization, each of 0.1 mass% or less is preferable.

(Organization)
The low thermal expansion cast iron preferably has 1 to 10% by area of graphite, with the balance being austenite phase.

(i) Graphite: 1 to 10 area%
If the amount of the graphite is less than 1%, the lubricating action of the graphite is not sufficient, so that the occurrence of galling between the injection sleeve and the plunger tip can not be prevented. On the other hand, when the area ratio of graphite exceeds 10 area%, the mechanical properties of the tip sleeve deteriorate. The lower limit of graphite is preferably 3 area%. The upper limit of graphite is preferably 7 area%. The form of graphite in low expansion cast iron may be flake graphite or spherical graphite, but spherical graphite is preferable from the viewpoint of securing the mechanical strength of the tip sleeve.

(ii) Other structures In the low thermal expansion cast iron, the balance other than graphite is preferably in the austenite phase. The austenite phase is effective to obtain low thermal expansion. In the remaining portion, 5 to 20 area% of pearlite phase may be present.

(Characteristic)
The average thermal expansion coefficient of low thermal expansion cast iron at 20 to 200 ° C. is 1 to 6 × 10 ⁻⁶ / ° C., preferably 1 to 5 × 10 ⁻⁶ / ° C., 1 to 4 × 10 ⁻⁶ / ° C. It is more preferable that the temperature is ° C. The tensile strength of the low thermal expansion cast iron is preferably 300 MPa or more, and the elongation is preferably 8 to 35%.

(b) Ceramics As the ceramics, ceramics having an average thermal expansion coefficient of 20 to 200 ° C. of 1 to 6 × 10 ⁻⁶ / ° C., specifically silicon nitride ceramics, sialon ceramics, silicon carbide ceramics, carbon Ceramics composed of one or more selected from high quality ceramics are preferable. Among them, silicon nitride ceramics or sialon ceramics having an average thermal expansion coefficient of 20 to 200 ° C. of 1.5 to 3 × 10 ⁻⁶ / ° C. are more preferable. Since these ceramics have a small deformation, the sealing performance is increased, and therefore, the insertion of molten metal is prevented and the occurrence of galling is prevented. Furthermore, these ceramics are excellent in corrosion resistance and wear resistance to non-ferrous metal melt such as aluminum alloy, and can reduce the erosion and wear of the inner surface of the injection sleeve.

(c) Other Configurations The cylindrical tip sleeve may be made of low thermal expansion metal (high strength low thermal expansion metal or low thermal expansion cast iron) or ceramic alone, but cylindrical tips made of these different materials The sleeves may be arranged in two or more axial directions. As a preferred example, high strength low thermal expansion metal / low thermal expansion cast iron / ceramics, high strength low thermal expansion metal / low thermal expansion cast iron, high strength low thermal expansion metal / ceramics, low thermal expansion cast iron / from the tip side of the tip body Although the composition of ceramics etc. is mentioned, the composition containing a high strength and low thermal expansion metal is preferred. Also, a plurality of high strength and low thermal expansion metals, a plurality of low thermal expansion cast irons, or a plurality of ceramics may be included. It is preferable that the cylindrical tip sleeves be in contact without any gap.

  When the cylindrical tip sleeve is made of low thermal expansion metal (high strength low thermal expansion metal and / or low thermal expansion cast iron) and ceramics, the tip side of the tip body is made of low thermal expansion metal to prevent breakage of the ceramic. Preferably, a cylindrical tip sleeve is arranged. In particular, it is preferable to dispose the cylindrical tip sleeve made of ceramics on the most rear end side, that is, the side in contact with the cylindrical ring.

  In the case of arranging a plurality of cylindrical tip sleeves, it is preferable to arrange materials in order from the material with the smaller thermal expansion coefficient to the material with the larger thermal expansion, from the front end side to the rear end side of the chip body. By arranging in this manner, the thermal expansion difference between the adjacent cylindrical tip sleeves can be reduced, and a step hardly occurs even during operation. The axial length of the two or more cylindrical tip sleeves is not particularly limited, and may be any length.

(4) Cylindrical ring The cylindrical ring is made of a material having an average thermal expansion coefficient α _C of 12 to 25 × 10 ⁻⁶ / ° C. That is, it is formed of a material whose average thermal expansion coefficient is equal to or higher than the average thermal expansion coefficient of the chip body and higher than the average thermal expansion coefficient of the cylindrical tip sleeve. In particular, the cylindrical ring is preferably made of a material having an average thermal expansion coefficient of 17 to 20 × 10 ⁻⁶ / ° C. at 20 to 200 ° C., and a material having a Young's modulus of 180 to 210 GPa and a tensile strength of 450 to 550 MPa. It is preferred to use Specifically, austenitic stainless steels such as SUS304 and SUS316, aluminum alloys, copper alloys and the like can be exemplified. Among them, austenitic stainless steels such as SUS304 and SUS316 are particularly preferable. By forming the cylindrical ring from a material having such characteristics, it is possible to prevent the formation of a gap due to the axial expansion difference between the tip body and the cylindrical tip sleeve.

(5) Nut The nut 5 is a material having an average thermal expansion coefficient equal to or less than the average thermal expansion coefficient of the tip body 2 and preferably made of a material having a tensile strength and a Young's modulus equivalent to the tip body 2. Specifically, an alloy tool steel such as SKD 61 or a metal material equivalent to the cylindrical tip sleeve 3, for example, an Fe-Ni-Co-Al-Ti based alloy is preferable.

(B) Second Embodiment A second die-casting plunger tip 101 of the present invention is shown in FIG. The second die-casting plunger tip 101 according to the present invention has a cylindrical shape, a tip body 102 having cooling water circulating means 107 inside, and a tip end side outer periphery of the tip body 102 mounted on a tip and sliding against an injection sleeve (not shown). A cylindrical tip sleeve 103 forming a dynamic surface, and a nut member 112 screwed to the tip body 102 on the rear end side of the cylindrical tip sleeve 103, the nut member 112 comprising the cylindrical tip It comprises a ring portion 112a that abuts on the rear end side of the sleeve 103, and a nut portion 112b integrally formed on the rear end side of the ring portion 112a,
The average thermal expansion coefficient α _A of the chip body at 20 to 200 ° C. is 10 to 14 × 10 ⁻⁶ / ° C.,
An average thermal expansion coefficient α _B of 20 to 200 ° C. of the cylindrical tip sleeve is 1 to 6 × 10 ⁻⁶ / ° C., and an average thermal expansion coefficient α _D of 20 to 200 ° C. of the nut member is 12 to 25 × 10 ^-6 / ° C,
satisfy α _D αα _A ,
Let L _{B be} the axial length of the cylindrical tip sleeve at 20 ° C., and L _D1 be the axial length of the ring portion at 20 ° C.
_{0.05 ≦ L D1 / L B ≦} 0.90 ··· (1 ')
Meet.

  The second die-casting plunger tip 101 is a first die-casting plunger tip 1 except that a nut member 112 in which the cylindrical ring 3 and the nut 5 are integrally formed is used instead of the cylindrical ring 3 and the nut 5. It is configured in the same way. Therefore, the nut member 112 will be described in detail below, and the description other than the nut member 112 will be omitted.

  As shown in FIG. 4, the nut member 112 has a ring portion 112 a and a nut portion 112 b integrally formed on the rear end side of the ring portion 112 a, and the ring portion 112 a is the cylindrical tip sleeve 103. In the state of being in contact with the rear end side of the screw, the screw is firmly fixed to the chip body 102 by the nut portion 112 b. A screw is provided on the inner periphery of the nut portion 112 b, and is screwed with a screw provided on the outer rear end of the tip body 102.

Average thermal expansion coefficient alpha _D of 20 to 200 ° C. of the nut member 112 is 12~25 × 10 ^-6 / ℃, average thermal expansion coefficient of 20 to 200 ° C. of the chip body 102 α _A (10~14 × 10 ^-6 / ° C. or higher, that is, α _C αα _A is satisfied. Furthermore, when the axial length of the cylindrical tip sleeve 103 at 20 ° C. is L _B , the axial length L _D1 of the ring portion 112 a at 20 ° C. is: 0.05 ≦ L _D1 / L _B Set to satisfy ≦ 0.90. A plunger tip in which the cylindrical tip sleeve 103 does not loosen in the axial direction during operation when the average thermal expansion coefficient α _{D at} 20 to 200 ° C. and the axial length L _{D1 of the} ring portion 112 a satisfy such conditions Is obtained.

The average thermal expansion coefficient α _D at 20 to 200 ° C. of the nut member 112 is more preferably 17 to 20 × 10 ⁻⁶ / ° C. Here, when the average thermal expansion coefficient α _{D at} 20 to 200 ° C. of the nut member 112 is approximately the same as the average thermal expansion coefficient α _{A at} 20 to 200 ° C. of the tip body 102, the axial direction of the tip body 102 during operation against inflation, in order to be cylindrical tip sleeve 103 is not loosened, it is preferable to large setting the axial length L _D1 of the ring portion 112a of the nut member 112. Therefore, the lower limit of the ratio L _D1 / L _B of the axial length L _D1 of the ring portion 112 a to the axial length L _B of the cylindrical tip sleeve 103 is preferably 0.15, more preferably 0.25. preferable. The upper limit of the ratio L _D1 / L _B is preferably 0.35, and more preferably 0.5.

The nut member is made of a material having an average thermal expansion coefficient α _C of 12 to 25 × 10 ⁻⁶ / ° C. That is, it is formed of a material whose average thermal expansion coefficient is equal to or higher than the average thermal expansion coefficient of the chip body and higher than the average thermal expansion coefficient of the cylindrical tip sleeve. In particular, the nut member is preferably made of a material having an average thermal expansion coefficient of 17 to 20 × 10 ⁻⁶ / ° C. at 20 to 200 ° C., and a material having a Young's modulus of 180 to 210 GPa and a tensile strength of 450 to 550 MPa. It is preferred to use. Specific examples thereof include alloy tool steels such as SKD61, austenitic stainless steels such as SUS304 and SUS316, aluminum alloys, copper alloys and the like.

(C) Third Embodiment The third die-casting plunger tip of the present invention has a cylindrical tip-shaped tip body having cooling water circulating means inside, and a sliding surface for the injection sleeve mounted on the tip outer periphery of the tip body. A cylindrical tip sleeve for forming a cylindrical tip sleeve, a cylindrical ring externally fitted to the tip body on the rear end side of the cylindrical tip sleeve, and the cylindrical tip sleeve and the cylindrical ring from both ends in the axial direction The cylindrical tip sleeve is joined to the outer peripheral surface of the base material 31 and the base material 31 made of high strength and low thermal expansion metal as shown in FIG. 2 (a). The high strength low thermal expansion metal is composed of a corrosion resistant layer 32 having a thickness of 0.5 to 5 mm, and the Fe-Ni base alloy containing 29 to 45% by mass of Ni, or 29 to 35% by mass of Ni, 12 to 23 Fe-Ni-Co-Al containing wt% Co, 0.5 to 1.5 wt% Al and 0.8 to 3 wt% Ti The corrosion resistant layer is made of a Fe-C-Ni-Cr based alloy containing 0.2 to 0.7% by mass of C, 1 to 7% by mass of Cr and 1 to 20% by mass of Ni. The average thermal expansion coefficient of the chip body at 20 to 200 ° C. is 10 to 14 × 10 ⁻⁶ / ° C., and the average thermal expansion coefficient of the base material of the cylindrical tip sleeve at 20 to 200 ° C. is 1 to 6 × 10 ⁻⁶ C./.degree. C. and an average thermal expansion coefficient of 20 to 200.degree. C. of the cylindrical ring is 12 to 25.times.10.sup.- ⁶ / .degree.

  The third die-casting plunger tip has fixing means for holding and fixing the cylindrical tip sleeve and the cylindrical ring from both ends in the axial direction. The fixing means has a front end side fixing portion and a rear end side fixing portion. For example, in the case of the first die-casting plunger tip 1 shown in FIG. 1, the front end portion 2a corresponds to the front end side fixing portion, and a nut Although 5 corresponds to the rear end side fixing portion, the fixing means is not limited to this. For example, instead of screwing and fixing a screw provided on the inner periphery of the nut 5 and a screw provided on the outer rear end of the tip body 2, a ring not provided with a screw of the same shape as the nut 5 The rear end side fixing portion may be formed by fixing the L-shaped member to the outer rear end portion of the tip body 2 with a rod screw.

  In the third die-casting plunger tip, the cylindrical ring may be integrally formed with the rear end side fixing portion. As such an embodiment, for example, although the second die-casting plunger tip 101 shown in FIG. 4 can be mentioned, it is not limited to this.

  In the third die-casting plunger tip of the present invention, the cylindrical tip sleeve 3 made of the high-strength low-thermal-expansion metal described in the first die-casting plunger tip 1 is used. The cylindrical tip sleeve 3 is joined to the outer peripheral surface of the base material 31 and the base material 31 made of an Fe-Ni base alloy or a Fe-Ni-Co-Al-Ti base alloy, as shown in FIG. And a corrosion resistant layer 32 made of an Fe--C--Ni--Cr base alloy having a thickness of 0.5 to 5 mm. With regard to the Fe-Ni-based alloy and the Fe-Ni-Co-Al-Ti-based alloy constituting the base material 31, and the Fe-C-Ni-Cr-based alloy constituting the corrosion resistant layer 32, the first die casting The same one as the plunger tip 1 can be used. Furthermore, as shown in FIG. 2B, the cylindrical tip sleeve 3 may have a nitrided layer 32s having a thickness of 150 to 500 μm on its surface. That is, the configuration of the high strength and low thermal expansion metal material described in the first die casting plunger tip 1 can be used.

[2] Die-cast shot sleeve As shown in FIG. 3, by inserting the die-casting plunger tip 1 of the present invention into the injection sleeve 8, the clearance setting between the plunger tip 1 and the injection sleeve 8 is minimized and air tightness is achieved. An improved die cast shot sleeve is obtained. By using this die-cast shot sleeve, defects such as cavities can be reduced mainly in die-cast products. The same effect can be obtained by using the second die-casting plunger tip or the third die-casting plunger tip instead of the first die-casting plunger tip.

In particular, silicon nitride ceramics or sialon ceramics (20 ° C. to 300 ° C.) are contained in the outer cylinder 8 a made of low thermal expansion metal (average thermal expansion coefficient from 20 ° C. to 300 ° C .: 1 to 6 × 10 ^-6 / ° C.) Setting the clearance between the plunger tip 1 and the inner cylinder 8b of the injection sleeve 8 by using the injection sleeve 8 having the inner cylinder 8b consisting of 1.5 to 3 × 10 ^-6 / ° C. Thus, a die-cast shot sleeve can be obtained which is further minimized to improve air tightness.

  The present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

Example 1
The tip body 2, the cylindrical tip sleeve 3, the cylindrical ring 4 and the nut 5 were prepared as follows, and the first die-casting plunger tip 1 of the present invention shown in FIG. 1 was produced.

(a) Chip Body The chip body 2 was manufactured using SKD 61 (average thermal expansion coefficient at 20 to 200 ° C .: 13 × 10 ⁻⁶ / ° C.). The surface of the tip portion was nitrided to form a 0.2 mm thick nitrided layer in order to improve the resistance to melt of aluminum. The surface hardness after nitriding was HRC 45. The outer diameter of the tip portion of the tip body 2 is 125.00 mm, the outer diameter of the portion to which the cylindrical tip sleeve 3 and the cylindrical ring 4 are fitted is 95.00 mm, the total length 180 mm, and the axial thickness of the flange portion 6 is the peripheral edge The thickness of the tip central portion was 15 mm, and the thickness of the tip central portion was 15 mm. Inside the chip body 2, a space having an inner diameter of 75 mm and a length of 100 mm was provided as a cooling water circulating means 7. In the tip portion, a truncated cone 2b having an axial height of 10 mm and a taper angle of 45 ° was provided, and the diameter of the lower base of the truncated cone 2b was 115 mm. Further, at the rear end portion, in order to tighten the nut 5 at the time of assembling the plunger tip, screw processing with an axial length of 38 mm and an M90 pitch 2 was performed.

(b) Cylindrical tip sleeve
32.6% by weight of Ni, 14.9% by weight of Co, 0.8% by weight of Al, 2.3% by weight of Ti, 0.04% by weight of C, the balance of Fe and unavoidable impurities, and having an average tensile strength of 1200 MPa and 20 to 200 ° C. After SKD61 is welded to the outer peripheral surface and inner end face of a cylindrical base material made of high strength and low thermal expansion metal with a thermal expansion coefficient of 3.2 × 10 ^-6 / ° C to a thickness of 1.5 mm, and then SKD61 After welding to a thickness of 1.5 mm and aging at 600 ° C. for 10 hours, the surface of the cladding layer is worked out by about 0.5 mm to have an outer diameter of 125.225 mm, an inner diameter of 95.07 mm and a length A 130 mm cylindrical tip sleeve was obtained. After collecting a sample for composition analysis from the obtained cylindrical tip sleeve, a cylindrical tip sleeve having a shape shown in FIG. 1 with an outer diameter of 125.225 mm, an inner diameter of 95.07 mm and a length of 95 mm was obtained.

  The composition in the range of 0.5 mm in depth from the outer surface of the cylindrical tip sleeve was obtained by lathe cutting the sample for composition analysis of the collected cylindrical tip sleeve to the depth of 0.5 mm from the outer surface. It analyzed using. Similarly, the composition within a depth of 2 mm from the outer surface was analyzed using chips obtained by lathe cutting the sample for composition analysis to a depth of 2 mm from the outer surface. C and S use a carbon-sulfur analyzer (EMIA-320V2) manufactured by Horiba, Ltd. and analyze the other metal components using a high-frequency inductively coupled plasma emission spectrometer (ICPS-8100) manufactured by Shimadzu Corporation. Did.

  The composition in the range of 0.5 mm in depth from the outer surface is C: 0.29%, Si: 0.20%, Mn: 0.59%, Ni: 1.53%, Cr: 3.05%, Mo: 1.25%, V: 0.73%, Co It was 1.9%, Al: 0.05%, Ti: 0.13%, P: 0.001%, S: 0.001%, Fe: balance.

  C: 0.34%, Si: 0.35%, Mn: 0.52%, Ni: 7.78%, Cr: 2.8%, Mo: 1.12%, V: 0.64%, the composition in the range of depth 2 mm from the outer surface Co: 3.83%, Al: 0.18%, Ti: 0.42%, P: 0.002%, S: 0.001%, Fe: Remainder.

(c) Cylindrical ring The cylindrical ring was produced using SUS304 (average thermal expansion coefficient at 20 to 200 ° C .: 18 × 10 ⁻⁶ / ° C.). The resulting cylindrical ring had an outer diameter of 124.4 mm, an inner diameter of 95.07 mm and a length of 25 mm.

(d) Assembly to plunger tip and injection sleeve
The nut 5 was made using SKD61. The dimensions were an outer diameter of 124 mm and a length of 35 mm, and an internal thread was processed with an M90 pitch 2 and a length of 35 mm. Furthermore, in order to be able to axially clamp the cylindrical tip sleeve and the cylindrical ring, the outer diameter portion is provided with a pair of flat surfaces (a distance of 110 mm between the flat surfaces) parallel to each other.

As shown in FIG. 3, the cylindrical tip sleeve 3 and the cylindrical ring 4 are sequentially mounted on the tip body 2 and screwed with the nut 5 to fix the cylindrical tip sleeve 3 and the cylindrical ring 4, and a plunger The chip 1 was assembled. The plunger tip 1 was inserted into an injection sleeve 8 to form a die-cast shot sleeve 11 and assembled into a die-cast machine. The injection sleeve 8 is a low thermal expansion metal (average from 20 ° C. to 300 ° C.) consisting of 32.5% by weight of Ni, 15.0% by weight of Co, 0.8% by weight of Al, 2.2% by weight of Ti, the balance Fe and unavoidable impurities. Thermal expansion coefficient: 3.6 × 10 ⁻⁶ / ° C., average thermal expansion coefficient from 20 ° C. to 600 ° C .: 9.5 × 10 ⁻⁶ / ° C.) Outer cylinder 8 a, Si ₃ N ₄ : 87 mass%, Y ₂ Sialon inner cylinder 8b (average thermal expansion coefficient of 20 to 200 ° C .: 2) obtained by sintering raw material powder having a composition of O ₃ : 6% by mass, Al ₂ O ₃ : 4% by mass and AlN: 3% by mass The one obtained by shrink-fitting and integration of (× 10 ⁻⁶ / ° C.) was used. Its internal diameter was 125.30 mm.

  Using this combination of injection sleeve and plunger tip (die-cast shot sleeve), 5000 shots of aluminum product (ADC 12, product weight about 15 to 17 kg) were cast using a die-casting machine with a clamping force of 1000 tons, resulting in injection Insertion of the molten metal into the minute gap between the inner surface of the sleeve and the plunger tip and the occurrence of galling on the inner surface of the injection sleeve are not observed, and the prior art plunger tip integrally formed of SKD 61 is used. In comparison, good results were obtained.

Example 2
Low thermal expansion cast iron (composition C: 0.98 mass%, Si: 0.35 mass%, Mn: 0.29 mass%, Ni: 32.5 mass%, Co: 5.22 mass%, Mg: 0.048 mass%, P: 0.013 mass) %, S: 0.006% by mass, the balance Fe and unavoidable impurities), and the first die-casting plunger tip is produced to constitute a die-cast shot sleeve in the same manner as in Example 1 to construct a die-cast machine I assembled it. The coefficient of thermal expansion of the cylindrical tip sleeve and the area ratio of graphite were measured using the test piece collected from the end of the low thermal expansion cast iron. The area ratio of graphite was measured by image analysis after mirror-polishing a test piece. As a result, the average thermal expansion coefficient at 20 to 200 ° C. was 2.1 × 10 ⁻⁶ / ° C., and the area ratio of graphite was 5 area%.

  As a result of injection molding of the aluminum melt using this die casting machine, the same results as in Example 1 were obtained.

Example 3
A first die-casting plunger tip is produced in the same manner as in Example 1 except that the cylindrical tip sleeve is produced with sialon (average thermal expansion coefficient of 20 to 200 ° C .: 2 × 10 ^-6 / ° C). A die cast shot sleeve was constructed and a die cast machine was assembled.

  As a result of injection molding of the aluminum melt using this die casting machine, the same results as in Example 1 were obtained.

Example 4
Instead of using the cylindrical ring 4 and the nut 5, a second die-casting plunger tip 101 shown in FIG. 4 is used in the same manner as in Example 1 except that a nut member 112 as shown in FIG. 4 is used. A die-casting shot sleeve was fabricated and assembled into a die-casting machine. The nut member 112 had a shape in which the cylindrical ring 4 and the nut 5 used in Example 1 were integrated, and was manufactured using the SKD 61.

  As a result of injection molding of the aluminum melt using this die casting machine, the same results as in Example 1 were obtained.

Claims (22)

A die-casting plunger tip that slides in an injection sleeve that becomes a molten metal flow path, comprising:
A tip body having a cylindrical shape and having cooling water circulating means therein, a cylindrical tip sleeve mounted on the tip side outer periphery of the tip body and forming a sliding surface for the injection sleeve, and a rear end side of the cylindrical tip sleeve A cylindrical ring externally fitted to the tip body, and a nut screwed to the tip body on the rear end side of the cylindrical ring,
The chip has an average thermal expansion coefficient α _A of 10 to 14 × 10 ⁻⁶ / ° C. at 20 to 200 ° C.,
Average thermal expansion coefficient α _B of 20 to 200 ° C. of the cylindrical tip sleeve is 1 to 6 × 10 ⁻⁶ / ° C., and average thermal expansion coefficient α _C of 20 to 200 ° C. of the cylindrical ring is 12 to 25 × 10 ^-6 / ° C,
satisfy α _C −α _A 0.50.5 × 10 ⁻⁶ / ° C.,
Let L _{B be} the axial length of the cylindrical tip sleeve at 20 ° C., and L _C be the axial length of the cylindrical ring at 20 ° C.
0.05 ≦ L _C / L _B ≦ 0.90 (1)
Plunger tip for die casting characterized by satisfying. In the die-casting plunger tip according to claim 1,
A die-casting plunger tip characterized in that the cylindrical tip sleeve has an outer diameter larger than that of the tip body tip and the cylindrical ring at 20 ° C. and an operating temperature.   The plunger tip for die-casting according to claim 1 or 2, wherein the cylindrical ring is made of austenitic stainless steel. A die-casting plunger tip that slides in an injection sleeve that becomes a molten metal flow path, comprising:
A tip body having a cylindrical shape and having cooling water circulating means therein, a cylindrical tip sleeve mounted on the tip side outer periphery of the tip body and forming a sliding surface for the injection sleeve, and a rear end side of the cylindrical tip sleeve It consists of a nut member screwed to the tip body,
The nut member includes a ring portion that abuts on the rear end side of the cylindrical tip sleeve, and a nut portion integrally formed on the rear end side of the ring portion.
The chip has an average thermal expansion coefficient α _A of 10 to 14 × 10 ⁻⁶ / ° C. at 20 to 200 ° C.,
Average thermal expansion coefficient α _B of 20 to 200 ° C. of the cylindrical tip sleeve is 1 to 6 × 10 ⁻⁶ / ° C., and average thermal expansion coefficient α _D of 20 to 200 ° C. of the nut member is 12 to 25 × 10 ^-6 / ° C,
satisfy α _D αα _A ,
Let L _{B be} the axial length of the cylindrical tip sleeve at 20 ° C., and L _D1 be the axial length of the ring portion at 20 ° C.
_{0.05 ≦ L D1 / L B ≦} 0.90 ··· (1 ')
Plunger tip for die casting characterized by satisfying. In the die-casting plunger tip according to claim 4,
An average thermal expansion coefficient α _A of 20 to 200 ° C. of the chip body and an average thermal expansion coefficient α _D of 20 to 200 ° C. of the nut member satisfy α _D −α _A 0.50.5 × 10 ⁻⁶ / ° C. Plunger tip for die casting characterized by In the die-casting plunger tip according to claim 4 or 5,
A die-casting plunger tip characterized in that the cylindrical tip sleeve has an outer diameter larger than the tip end of the tip body and the nut member at a temperature of 20 ° C. and at the time of operation. In the die-casting plunger tip according to any one of claims 1 to 6,
Assuming that the inner diameter of the injection sleeve at 20 ° C. is D, the formula:
L _B 0.30.3 × D (2)
Plunger tip for die casting characterized by satisfying.   The plunger tip for die-casting according to any one of claims 1 to 7, wherein the cylindrical tip sleeve is made of a high strength and low thermal expansion metal.   9. The die-casting plunger tip according to claim 8, wherein the high strength and low thermal expansion metal is a Fe-Ni based alloy containing 29 to 45% by mass of Ni.   The plunger tip for die casting according to claim 8, wherein the high strength low thermal expansion metal comprises 29 to 35% by mass Ni, 12 to 23% by mass Co, 0.5 to 1.5% by mass Al and 0.8 to 3% by mass A plunger tip for die casting, characterized in that it is an Fe-Ni-Co-Al-Ti base alloy containing Ti. The plunger tip for die casting according to claim 9 or 10, wherein the cylindrical tip sleeve is a base material composed of the Fe-Ni-based alloy or the Fe-Ni-Co-Al-Ti-based alloy, and the base material. And a corrosion-resistant layer of a 0.5-5 mm thick Fe-C-Ni-Cr base alloy joined to the outer peripheral surface of the
The said corrosion resistant layer is made of a Fe-C-Ni-Cr based alloy containing 0.2 to 0.7% by mass of C, 1 to 7% by mass of Cr and 1 to 20% by mass of Ni. Jar tip. In the die-casting plunger tip according to claim 11,
The surface layer from the surface of the corrosion resistant layer to a depth of 0.5 mm has a C content of 0.2 to 0.7 mass%, a Cr content of 2 to 7 mass%, and a Ni content of 0.1 to 15 mass%. Die casting plunger tip. In the die-casting plunger tip according to claim 12,
The corrosion resistant layer further comprises 0.5 to 3% by mass of Mo, 0.3 to 1.5% by mass of V, 2% by mass or less of Co, 0.5% by mass or less of Al, 0.5% by mass or less of Ti, 0.5% by mass or less of Si A die-casting plunger tip characterized by containing 1.0 mass% or less of Mn, 0.04 mass% or less of P, and 0.03 mass% or less of S. In the die-casting plunger tip according to any one of claims 8 to 13,
The said cylindrical tip sleeve has a 150-500 micrometers-thick nitrided layer from the surface, The plunger tip for die-casts characterized by the above-mentioned.   The plunger tip for die casting according to any one of claims 1 to 7, wherein the cylindrical tip sleeve comprises 0.5 to 3.0% by mass of C, 0.1 to 2.7% by mass of Si, 0.1 to 1.0% by mass of Mn, 25 It is characterized by being composed of low thermal expansion cast iron having a composition containing 40 to 40% by mass of Ni, 3 to 7% by mass of Co, the balance containing Fe and unavoidable impurities, and having a structure having 1 to 10% by area of graphite. Plunger tip for die casting.   The plunger tip for die casting according to any one of claims 1 to 7, wherein the cylindrical tip sleeve is made of one selected from silicon nitride ceramics, sialon ceramics, silicon carbide ceramics and carbonaceous ceramics. Plunger tip for die casting characterized by In the die-casting plunger tip according to any one of claims 1 to 7,
A cylindrical tip sleeve comprising the high strength low thermal expansion metal according to any of claims 8 to 14, a cylindrical tip sleeve comprising low thermal expansion cast iron according to claim 15, and the cylindrical tip sleeve according to any of claims 8 to 14, A plunger tip for die casting characterized in that two or more types selected from cylindrical tip sleeves made of the ceramic described in 16 are disposed in the axial direction. A die-casting plunger tip that slides in an injection sleeve that becomes a molten metal flow path, comprising:
A tip body having a cylindrical shape and having cooling water circulating means therein, a cylindrical tip sleeve mounted on the tip side outer periphery of the tip body and forming a sliding surface for the injection sleeve, and a rear end side of the cylindrical tip sleeve It has a cylindrical ring externally fitted to the tip body, and fixing means for holding and fixing the cylindrical tip sleeve and the cylindrical ring from both ends in the axial direction,
The cylindrical tip sleeve comprises a base material of high strength and low thermal expansion metal, and a corrosion resistant layer of 0.5 to 5 mm in thickness joined to the outer peripheral surface of the base material,
The high-strength low-thermal-expansible metal is an Fe-Ni-based alloy containing 29 to 45% by mass of Ni, or 29 to 35% by mass of Ni, 12 to 23% by mass of Co, 0.5 to 1.5% by mass of Al and 0.8 It consists of an Fe-Ni-Co-Al-Ti base alloy containing ~ 3 mass% Ti,
The corrosion resistant layer comprises a Fe-C-Ni-Cr based alloy containing 0.2 to 0.7% by mass of C, 1 to 7% by mass of Cr and 1 to 20% by mass of Ni,
The chip has an average thermal expansion coefficient of 10 to 14 × 10 ⁻⁶ / ° C. at 20 to 200 ° C.,
The average thermal expansion coefficient of the base material of the cylindrical tip sleeve at 20 to 200 ° C. is 1 to 6 × 10 ⁻⁶ / ° C., and the average thermal expansion coefficient of the cylindrical ring at 20 to 200 ° C. is 12 to 25 × 10 Plunger tip for die casting characterized by ^-6 / ° C. In the die-casting plunger tip according to claim 18,
The die tip for a plunger tip for die-casting, wherein the fixing means has a front end side fixing portion and a rear end side fixing portion, and the cylindrical ring is integrally formed with the rear end side fixing portion. In the die-casting plunger tip according to claim 18 or 19,
A die-casting plunger tip characterized in that the cylindrical tip sleeve has an outer diameter larger than that of the tip body tip and the cylindrical ring at 20 ° C. and an operating temperature. In the die-casting plunger tip according to any one of claims 18 to 20,
Let L _{B be} the axial length of the cylindrical tip sleeve at 20 ° C., and D be the inside diameter of the injection sleeve at 20 ° C.
L _B 0.30.3 × D (2)
Plunger tip for die casting characterized by satisfying.   A plunger tip for die casting according to any one of claims 1 to 21, and an injection sleeve comprising an inner cylinder made of silicon nitride ceramic or sialon ceramic in an outer cylinder made of a low thermal expansion metal. Die cast shot sleeve characterized by

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