JPH10113756A - Sleeve for magnesium die casting cylinder and manufacture thereof and magnesium die casting cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lengthen the durable term of an Mg die casting cylinder. SOLUTION: A steel-made cylindrical body 21 is incorporated into an SS 41-made HIP tube 31, and an SS41-made core rod 33 is inserted into the center of the cylinder hole. Co base powder (grain diameter <=450μm) in a 'TRIBALLOY(R)' is filled into the gap between the core rod 33 and the steel- made cylindrical body 21, and after closely sealing and evacuating, pressure- sintering is executed at 1190 deg.C and 1200atm for 180min in an HIP apparatus. Then, the HIP tube 31 is shaven off from the sintered product obtd. in such a way and the core 33 is shaven off and further, a coating layer 23 is finished so as to match to the outer diameter of a piston. In such a way, the sleeve 20 is obtd. and the obtd. sleeve 20 is shrinkage-fit into the main body 11 of the die casting cylinder 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sleeve for an Mg die casting cylinder.

[0002]

2. Description of the Related Art Conventionally, as a Mg die-casting cylinder, there has been used a cylinder formed by nitriding the inner surface of a steel cylinder or a cylinder using hot tool steel. Further, a steel cylinder in which a ceramic coating is applied to the inner surface by using a CVD deposition method has been proposed (Japanese Patent Laid-Open No. 57-47).
566).

[0003]

However, the temperature of 640 to 650 ° C., which is the temperature of molten Mg, is a region in which the structure changes near the transformation point of steel and causes abrasion resistance and heat resistance due to nitriding treatment and hot tool steel. However, the improvement of the properties is not enough, and even in the case of ceramic coating, there is a problem of peeling of the coating layer, and it has not been a sufficient measure.

[0004] For this reason, the conventional Mg die-casting cylinder still does not have sufficient erosion resistance to the Mg alloy.
There is a problem that the service life is short. Therefore, the present invention
An object of the present invention is to extend the service life of a Mg die-cast cylinder.

[0005]

Means for Solving the Problems, Embodiments of the Invention, and Effects of the Invention According to the sleeve for a Mg die-cast cylinder of the present invention, as described in claim 1, the inner surface of the steel cylinder is formed by C
It is characterized by being coated by a metal diffusion bonding with a surface layer made of either an o-based alloy or an Fe-based alloy.

More specifically, as set forth in claim 2, the surface layer comprises at least 45% by weight of Co, 8 to
25 wt% Cr, 20-42 wt% Mo, and
The alloy contains 5 to 12% by weight of Si and 0.5% by weight or less of Ni, and the microstructure of the alloy is mainly a Raves phase of a hard phase of 10% by volume or more and a relatively soft matrix phase of 90% by volume or less. And the microstructure of the alloy comprises at least 10% by volume of an alloy comprising a Rave's phase. That is, it is characterized in that the inner surface of the steel cylinder is covered with a so-called tribaloy (trade name; the same applies hereinafter). Here, even tribaloys are particularly limited to those based on Co. This is because Ni-based tribaloys are eroded by Mg. Also,
4. The method according to claim 3, wherein the surface layer comprises 3 to 6% by weight.
Cr, 10 to 20% by weight of 2Mo + W, and 1.0 to
4% by weight of V, 0.8 to 3% by weight of C,
It is possible to reduce the cost by using 2% or less of Co and 0.5% by weight of Ni, with the balance being unavoidable impurities and Fe, and using an Fe-based alloy.

Further, as set forth in claim 4, the surface layer is formed of a cermet obtained by dispersing ceramics in one of a Co-based alloy and an Fe-based alloy. Further, as described in claim 5, the surface layer has a hardness of HRC40 or more. By setting the hardness to HRC 40 or more, sufficient wear resistance against sliding of the piston during die casting is exhibited.

According to the Mg die-casting cylinder sleeve of the present invention, the surface layer containing either a Co-based alloy or an Fe-based alloy formed by metal diffusion bonding exhibits high corrosion resistance to Mg, Also, it shows high abrasion resistance and can greatly improve the life of the sleeve as compared with conventional products. In addition, because of metal diffusion bonding, there is no problem such as separation due to thermal shock.

The method for manufacturing the sleeve for an Mg die-cast cylinder according to the present invention comprises the steps of:
A powder containing either an o-based alloy or an Fe-based alloy is filled into the inner surface of a steel cylinder and sintered under pressure under hot isostatic pressure to form a center hole. In this case, more specifically, as described in claim 7, the powder comprises at least 45% by weight of Co, 8 to 25% by weight of Cr, 20 to 20% by weight.
A hard phase containing 10% by volume or more and 90% by volume containing 42% by weight of Mo and 1.5 to 12% by weight of Si and containing 0.5% by weight or less of Ni and having a microstructure of mainly an Rave's phase. % Of a relatively soft matrix phase, and wherein the alloy has a microstructure of at least 10% by volume of a Rave's phase. In addition, as described in claim 8, the powder comprises 3 to 6% by weight of Cr, 10 to 30% by weight of 2Mo + W, and 1.0% by weight.
-4% by weight V, 0.8-3% by weight C,
12% or less of Co and 0.5% by weight or less of Ni, the balance being unavoidable impurities and Fe, and HRC4
It is an alloy powder having a hardness of 0 or more.

[0010] According to a ninth aspect of the present invention, the powder is a cermet powder obtained by dispersing ceramics in one of a Co-based alloy and an Fe-based alloy. According to these manufacturing methods, cermet, tribaloy or high-speed steel in which ceramics are dispersed in either a Co-based alloy or an Fe-based alloy on the inner surface of a steel cylinder is subjected to hot isostatic pressing (HIP). Metal diffusion bonding at
(g) The tribaloy layer and the high-speed steel layer do not peel off during use in die casting.

In this case, the hot isostatic press sintering is preferably performed with a steel mandrel inserted in the center of the alloy powder. By doing so, the center hole can be easily formed. An Mg die-cast cylinder in which the cylinder sleeve manufactured by the method of the present invention is integrated with a plunger sliding surface of a steel body by an appropriate method such as mechanical fixing of pins, keys, screws, shrink fitting, welding, or the like. Has excellent erosion resistance and can have a sufficiently long service life.

The Co group described in claims 1, 4, 6, and 9
As the alloy, for example, Stellite 1, Stellite 6,
Stellite 12 or the like can be used. Claims
The Fe-based alloys referred to as 1, 4, 6, and 9 are, for example, molybdenum
It is possible to use stainless steel, tungsten high-speed steel, etc.
Wear. Further, as the ceramics according to claims 4 and 9
Means Al as well as carbides such as VC, TiC and WC._Two
O_Three, Zr_TwoO_Three, Cr _TwoO_Three, TiO_TwoOxides such as
BN, Si_ThreeN_FourSuch as nitride, TiB_Two, ZrB _TwoEtc.
Various ceramics such as borides can be used.

It is desirable that the surface layer of the Co-based alloy according to any one of the first, second, fourth, and fifth aspects has Ni of 0.5% by weight or less and Ni + Fe of 3% by weight or less. . Further, it is desirable that the surface layer of the Fe-based alloy described in each of the first, fourth, and fifth aspects contains Ni at 0.5% by weight or less.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a preferred embodiment of the sleeve for a Mg die-casting cylinder and a method of manufacturing the same according to the present invention will be described. [Embodiment 1] As shown in FIG. 1, a Mg die-cast cylinder 10 of the embodiment has a main body 11 and a sleeve 2 made of a composite material.
0 is attached by shrink fit. The sleeve 20 has a tribaloy coating layer 23 on the inner surface of a steel cylinder 21.

The compositions of the steel cylinder 21 and the coating layer 23 are as follows.

[0016]

[Table 1]

As the steel cylinder 21 having the above composition, a forged product or a cast product is used. As shown in FIG. 2, the steel tubular body 21 is housed in an HIP pipe 31 made of SS41, and a mandrel 33 made of SS41 is inserted into the center of the tubular hole.
A tribaloy powder (manufactured by Gas Atomize, particle size ≦ 425 μm) is filled between the mandrel 33 and the steel cylinder 21, and after being sealed and degassed, subjected to pressure sintering at 1190 ° C. and 1200 atm for 180 minutes in a HIP apparatus. Then, the HIP tube 31 and the mandrel 33 are scraped from the sintered product thus obtained, and the coating layer 23 is finished according to the outer diameter of the piston. In the example, the sleeve 20 was adjusted to have an inner diameter of 80 mm and an outer diameter of 110 mm. In addition, the thickness of the coating layer 23 is 5 m.
m. Thus, the sleeve 20 is obtained. When the surface hardness of the coating layer 23 of the sleeve 20 thus obtained was measured, the hardness was Hv847 (HRC63).

The sleeve 20 thus obtained was shrink-fitted in the main body 11 of the die-cast cylinder 10, and a die-cast product was actually manufactured using a molten Mg alloy. As a result, the sleeve 20 exhibited sufficient wear resistance and corrosion resistance. No abnormalities were found even after checking after using 400,000 shots. [Example 2] In Example 1, the steel cylinder 2 of the sleeve 20 was used.
Although the coating layer 23 of tribaloy was provided on the inner surface of No. 1, in Example 2, a coating layer of a cermet based on a Co-based alloy was formed instead. The composition of the steel cylinder 21 and the coating layer 23 is as follows.

[0019]

[Table 2]

The cermet is provided as a powder. Cermet powder is melted in a conventional induction furnace and produced by gas atomization and has a particle size of 365 μm. Then, as in Example 1, the steel cylinder 21 and the mandrel 33 made of SS41 are inserted into the HIP can 31 made of SS41, and the cermet powder is filled between the mandrel 33 and the steel cylinder 21. After sealing and degassing, it is applied to a HIP device at 1140 ° C. and 1200 atm.
Sinter under pressure for 80 minutes. Then, the HIP tube 31 and the mandrel 33 are scraped from the sintered product thus obtained, and the coating layer 23 is finished according to the outer diameter of the piston. Also in this embodiment, the inner diameter is 80 mm and the outer diameter is 110 m.
m sleeve 20 was adjusted. Note that the thickness of the coating layer 23 is 5 mm. Thus, the sleeve 20 is obtained. When the surface hardness of the coating layer 23 of the sleeve 20 thus obtained was measured, the hardness was Hv599 (HRC51).

The sleeve 20 thus obtained was shrink-fitted into the main body 11 of the die-cast cylinder 10, and a die-cast product was actually manufactured using a molten Mg alloy. As a result, the sleeve 20 exhibited sufficient wear resistance and corrosion resistance. No abnormality was found at all even after use after 200,000 uses.

Incidentally, when comparing the case of the tribaloy coating of Example 1 with the case of the Co-based cermet coating of Example 2, the abrasion resistance is finally one half that of the Co-based cermet. Was. [Embodiment 3] In Embodiment 1, the steel cylinder 2 of the sleeve 20 is used.
Although the tribaloy coating layer 23 was provided on the inner surface of No. 1, in Example 3, a coating layer based on an Fe-based alloy was formed instead. The composition of the steel cylinder 21 and the coating layer 23 is as follows.

[0023]

[Table 3]

The Fe-based alloy powder is melted by a conventional induction furnace and manufactured by gas spraying, and has a particle size of 365 μm. Then, similarly to the first embodiment, the steel cylinder 21 and the mandrel 33 made of SS41 are inserted into the HIP can 31 made of SS41, and the Fe-based alloy powder is put between the mandrel 33 and the steel cylinder 21. After filling and sealing and deaeration, the mixture
Pressure sintering at 1200 ° C. and 1200 atm for 180 minutes. And
The HIP tube 31 was scraped off from the sintered product thus obtained,
Further, the mandrel 33 is scraped off, and the covering layer 23 is finished according to the outer diameter of the piston. Also in this embodiment, the inner diameter 8
The sleeve 20 was adjusted to 0 mm and the outer diameter 110 mm. Note that the thickness of the coating layer 23 is 5 mm. Thus, the sleeve 20 is obtained. When the surface hardness of the coating layer 23 of the sleeve 20 thus obtained was measured, the hardness was Hv48.
4 (HRC48).

The sleeve 20 thus obtained was shrink-fitted into the body 11 of the die-casting cylinder 10, and a die-cast product was actually manufactured using a molten Mg alloy. As a result, sufficient wear resistance and corrosion resistance were obtained. No abnormality was found at all even after use after 200,000 uses.

When the tribaloy coating of Example 1 was compared with the Fe-based alloy coating of Example 3, the final wear resistance was 40% of that of the Co-based cermet. .

[Brief description of the drawings]

FIG. 1 is a front view showing a cross section of a main part of an Mg die casting cylinder of an embodiment.

FIG. 2 is an explanatory diagram related to a method for manufacturing a sleeve for an Mg die-cast cylinder according to an embodiment.

[Explanation of symbols]

10 Mg die casting cylinder, 11 body
20 ... sleeve, 21 ... steel cylinder, 23 ...
Coating layer, 31 ... HIP tube, 33 ... mandrel.

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI C22C 29/06 C22C 1/05 D // C22C 1/05 B22F 3/14 M

Claims (10)

[Claims] An inner surface of a steel cylinder is made of a Co-based alloy, Fe
A sleeve for a Mg die-cast cylinder, which is coated with a surface layer made of any one of base alloys by metal diffusion bonding. 2. The Mg die-cast cylinder sleeve according to claim 1, wherein said surface layer comprises at least 45% by weight of Co, 8 to 25% by weight of Cr, and 20 to 42% by weight.
Mo, and 1.5 to 12% by weight of Si, 0.5% by weight or less of Ni, and the microstructure of the alloy is mainly a Rave's phase having a hard phase of 10% by volume or more and 90% by volume or less. A sleeve for a Mg die-cast cylinder, characterized in that it is composed of a relatively soft matrix phase and that the microstructure of the alloy is composed of an alloy composed of at least 10% by volume of a Rave's phase. 3. The Mg die-cast cylinder sleeve according to claim 1, wherein the surface layer has a C content of 3 to 6% by weight.
r, containing 10-30% by weight of 2Mo + W, and 1.0-4% by weight of V, containing 0.8-3% by weight of C, 12%
A Mg die-cast cylinder sleeve characterized in that the following Co and Ni are contained in an amount of 0.5% by weight or less, and the balance is composed of an alloy consisting of unavoidable impurities and Fe. 4. The Mg die-cast cylinder sleeve according to claim 1, wherein the surface layer is made of a Co-based alloy, Fe
A sleeve for a Mg die-cast cylinder, comprising a cermet obtained by dispersing ceramics in one of base alloys. 5. The Mg die-cast cylinder sleeve according to claim 1, wherein said surface layer is made of HR.
A sleeve for a Mg die-cast cylinder having a hardness of C40 or more. 6. A center hole is formed by filling a powder made of one of a Co-based alloy and an Fe alloy into an inner surface of a steel cylinder and sintering it under hot isostatic pressure. Of producing a sleeve for a Mg die-cast cylinder. 7. The method according to claim 6, wherein the powder comprises at least 45% by weight of Co, 8 to 25% by weight of Cr, and 20 to 4% by weight.
The alloy contains 2% by weight of Mo and 1.5 to 12% by weight of Si, contains 0.5% by weight or less of Ni, and has a microstructure of the alloy mainly composed of a hard phase of 10% by volume or more and a 90% by volume Raves phase. % Of a relatively soft matrix phase and a microstructure of the alloy is a powder of an alloy comprising at least 10% by volume of a Rave's phase. 8. The method according to claim 6, wherein the powder comprises 3 to 6% by weight of Cr, 10 to 30% by weight of 2Mo + W, and 1.
0 to 4% by weight of V, 0.8 to 3% by weight of C, up to 12% of Co and up to 0.5% by weight of Ni,
A method for producing a sleeve for an Mg die-cast cylinder, wherein the balance is an alloy powder comprising unavoidable impurities and Fe. 9. The method of manufacturing a sleeve for a Mg die-cast cylinder according to claim 6, wherein the powder is a cermet powder obtained by dispersing ceramics in one of a Co-based alloy and an Fe-based alloy. Of producing a sleeve for a Mg die-cast cylinder. 10. A cylinder sleeve manufactured by the manufacturing method according to claim 6, wherein the cylinder sleeve is mechanically fixed to a plunger sliding surface of a steel body by pins, keys, screws, or the like.
Mg integrated by an appropriate method such as shrink fit or welding
Die casting cylinder.