JP2000351054A - Sleeve for die casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute smooth injection by preventing the fixation of a plunger tip caused by the fusion of molten steel with a portion where the molten metal poured from a pouring hole drops without substantially damaging the heat retaining properties which a double-structure die casting sleeve possesses. SOLUTION: In the sleeve 10 for die casting constituted by metallurgically joining an inner cylinder 12 made of a tool steel having a thermal conductivity higher than that of an outer cylinder 11 with the outer cylinder 11 made of an alloy steel having the thermal conductivity of 10-25 W/(m.K) at 300 deg.C, a notching portion 14 is arranged on the outer cylinder 11 at the portion where the molten metal 31 poured from the pouring hole 13 arranged in the sleeve 10 drops, and the thickness of the outer cylinder 11 in this portion is made thinner than the other portion of the outer cylinder 11 to enhance the heat radiation in this portion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die-casting sleeve which serves both as a pouring receiver and a pressurizing cylinder in an aluminum or magnesium die-casting machine, and more particularly to a so-called heat-insulating alloy on the outer periphery of an inner cylinder made of tool steel. The present invention relates to an improvement of a double-structured die-casting sleeve formed by metallurgically joining steel outer cylinders.

[0002]

2. Description of the Related Art Conventionally, a sleeve for die casting has been
Tool steel such as SKD61 (JIS) is used.
This sleeve for die casting has a thermal conductivity of 29 W / (m
-Since the temperature is relatively high (K) (300 ° C), the molten metal (molten metal) poured into the die-casting sleeve is cooled in a short time, and particularly, the molten metal in a portion in contact with the die-casting sleeve starts to solidify.

[0003] Therefore, when the molten metal is injected from the die-casting sleeve and injected into the mold, there is a problem that poor running of the molten metal and entrainment of the heat insulating chill layer occur.
In particular, in the die casting of a thin-walled molded product with a small pouring amount, there was a tendency that molding defects such as a hot water boundary and a poor hot water run-off occurred frequently.

[0004] In order to solve these problems, a die-casting sleeve having a double structure in which an outer cylinder made of a so-called heat-insulating alloy steel is metallurgically joined to the outer periphery of an inner cylinder made of tool steel. (Japanese Patent Application No. 10-109408)
No., Japanese Patent Application No. Hei 11-73079).

[0005] This double-structured die-casting sleeve is
The inner cylinder made of tool steel has abrasion resistance and heat check (crack) resistance, and the outer cylinder made of heat-insulating alloy steel has heat insulation and thermal shock resistance. It has the advantage of being able to suppress the occurrence of molding defects, such as excellent heat retention of molten metal, poor hot water, poor running around the water, and entrainment of a heat insulating chill layer, and a reduction in the defect rate of die-cast products.

[0006]

However, the double-layered die-casting sleeve has a plunger due to the seizure of the molten metal into the lower part of the pouring port, that is, the portion where the molten metal falls from the pouring port in a relatively short time. The chip may be stuck, causing a malfunction.

According to the present invention, the plunger chip is fixed to the portion where the molten metal poured from the pouring hole falls due to the seizure of the molten metal without substantially impairing the heat retaining property of the double-structured die-casting sleeve. It is an object of the present invention to provide a die-casting sleeve which prevents the injection and enables smooth injection.

[0008]

According to the present invention for achieving the above object, the present invention provides a thermal conductivity of 10 to 25 W / (m · K) (3
(00 ° C.) in a die casting sleeve in which an inner cylinder of tool steel having a higher thermal conductivity than the outer cylinder is metallurgically joined in an outer cylinder made of an alloy steel of (00 ° C.). The thickness of the outer cylinder where the molten metal poured from the gate falls is zero or less than the thickness of the other parts of the outer cylinder.

As described above, by reducing the thickness of the outer cylinder at the portion where the molten metal falls to zero or thinner, the inner cylinder at this portion is less covered by the outer cylinder having a low thermal conductivity, and the amount of heat dissipation increases. I do. Therefore, the seizure of the molten metal which is concentrated on this portion is suppressed.

[0010] It is preferable that the thin portion of the outer cylinder is provided within a range of 50 mm or less from below the pouring port toward the mold from an end of the pouring port on the mold side. Also,
The outer cylinder is SUS630, SUS631, or an equivalent thereof, and the inner cylinder is preferably SKD61, SKD8, or an equivalent thereof. Further, the inner cylinder of the SKD61, SKD8, or an equivalent thereof is The inner surface is preferably nitrided after quenching, and the thickness of the inner cylinder is preferably 1 to 6 mm.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic sectional view of a main part of a die casting machine to which a die casting sleeve 10 according to the present invention is applied. Reference numeral 21 denotes a fixed die plate, 22 denotes a movable die plate, 23 denotes a fixed mold, and 24 denotes a movable mold. . Die casting sleeve 1 according to the present invention
Numeral 0 is attached to the fixed die plate 21 and the fixed mold 23 via a bush 25 with a flange attached to the fixed die plate 21 and a mold sleeve 26 attached to the fixed mold 23. In FIG. 1, 2
7 is a plunger, 28 is a plunger chip provided at the tip of the plunger 27, 29 is a cavity corresponding to a molded product obtained by die casting, and 30 is a runner.

FIG. 2 shows the die-casting sleeve 10 of FIG.
Has a so-called double structure composed of an outer cylinder 11 and an inner cylinder 12. The outer cylinder 11 is made of SUS630 or SUS6 having a heat conductivity of 16 to 20 W / (m / K).
31 or their equivalents and thermal conductivity of 12 to 20 W /
(M / K) low thermal conductivity alloy steel (C: 0.1-0.5w)
t%, Si: 3 to 7 wt%, Ni: 5 to 18 wt%, C
r: 0.5 to 8 wt%, with the balance being Fe) or the like and having a thermal conductivity of 10 to 25 W / (m · K) (300 ° C.). The inner cylinder 12 has a heat conductivity of 29 W /
(MK) (300 ° C.) or higher, which is made of tool steel made of SKD61, SKD8 or their equivalent.

A method of manufacturing the die casting sleeve 10 will be described below. (1) As shown in FIG. 3, a solid inner cylinder 12a, which is a material of the inner cylinder 12, is inserted into a solution-treated outer cylinder 11a, which is a material of the outer cylinder 11, and a boundary between the two. Both ends are welded and sealed by electron beam welding or the like as indicated by the symbol W, and then heated to about 1100 ° C. under a high pressure of about 1000 atm by hot isostatic pressing (HIP) to join the two metallurgically. I do.

As shown in FIG. 4, this double structure is formed by combining the outer cylindrical member 11a and the inner cylindrical member 12a with the HIP sealed can 10
0, and HIP may be performed.
1a may be filled as a powder, and this may be sintered and simultaneously diffusion bonded to the inner cylinder 12a. Further, although not shown, the outer cylinder 11a and the inner cylinder 12a are metallurgically joined by brazing. Various methods can be adopted. In FIG. 4, reference numeral 101 denotes a lid, and 102 denotes a vacuum evacuation pipe.

(2) As described above, the outer cylinder 11a and the inner cylinder 12a are metallurgically joined to form a double structure.
Perform annealing of step 2.

(3) Next, machining is performed to the shape shown in FIG. That is, processing of the outer peripheral shape of the outer cylinder 11, processing of the inner peripheral shape to make the inner cylinder 12 have a predetermined thickness and a predetermined inner diameter at the same time, processing of both ends, processing of the pouring port 13, and furthermore, outside The notch 14 is processed to reduce the thickness of the cylinder 12.

The above inner peripheral shape processing is not preferable since the heat retaining property is greatly reduced when the thickness of the inner cylinder 12 exceeds 6 mm. It is preferable that the thickness of the cylinder 12 is not less than 1 mm.

Further, the processing of the above-mentioned cut portion 14 is as follows.
The molten metal 31 (see FIG. 1) poured from the pouring port 13 is dropped to a portion where the molten metal 31 falls (ie, a position below the pouring port 13 in FIG. 2). On the other hand, if the width is too large, the heat retention is lowered and the strength of the sleeve is lowered.
As shown in FIG. 2A, the distance L from the mold side end 13a of the pouring port 13 to the mold side in the longitudinal direction is 5 mm.
It is preferable to set the range to be within 0 mm. In addition, at the time of pouring, as shown in FIG.
The tip of the plunger tip 28 is located at a position substantially corresponding to the opposite end of the die side to close the die side of the die-casting sleeve 10, and the molten metal 31 does not flow rightward in FIG. In consideration of the strength of the sleeve, it is preferable to set the pouring hole 13 to a position substantially corresponding to the end of the pouring port 13 on the side opposite to the mold.

Further, as shown in FIG. 2 (b), the circumferential direction of the cutout portion 14 is a concave portion slightly larger than the pouring port 13 as shown in FIG. As shown in FIG. 2 (c), the ceiling surface is a cylindrical surface along the inner cylinder 12, or further, as shown in FIG.
4 is preferable. Furthermore, the notch 14 is formed so that the thickness of the outer cylinder 11 becomes partially zero and the inner cylinder 12
May be exposed.

(4) Next, the die-casting sleeve 10 is quenched and further subjected to a nitriding treatment. By this quenching and nitriding, the hardness of the inner peripheral surface of the inner cylinder 12 becomes about HV1000, and when this is SUS630, the outer cylinder 11 is age hardened by the above nitriding treatment to obtain a hardness of about HV400. be able to.

(5) Finally, the die-casting sleeve 10
Honing is applied to the inner peripheral surface of the die to complete the die-casting sleeve 10.

The operation of the die-casting sleeve 10 manufactured as described above will be described. As shown in FIG.
The molten metal 31 is poured from the pouring port 13 using the ladle 32. The poured molten metal 31 falls on the inner surface of the inner cylinder 12 at a position below the pouring port 13. Molten melt 31
Flows on the lower inner surface of the inner cylinder 12 and is stored in the lower part in the die-casting sleeve 10. After pouring a predetermined amount of the molten metal 31, the plunger 27 and the plunger tip 28 are advanced, and the molten metal 31 in the die-casting sleeve 10 is filled into the cavities 29 of the molds 23 and 24 through the runner 30.

By the way, at the time of the above-mentioned pouring, the inner surface of the inner cylinder 12 at a position below the pouring port 13 into which the hot molten metal 31 to be newly poured falls one after another is heated most strongly and becomes high temperature. The outer cylinder 11 is provided with the molten metal 3 in the die-casting sleeve 10.
In order to keep the temperature of the heat sink 1 high, the heat dissipation is weakened if the thickness is large because the heat insulating alloy steel is used as described above.
Since the cut-out portion 14 is provided to reduce the thickness, heat radiation in this portion is promoted, and the local rise of the temperature of the falling portion of the molten metal 31 is prevented. Therefore, the seizure of the molten metal on this portion, which has conventionally been a problem, is eliminated, and the plunger tip 28 can be moved smoothly.

The provision of the cutouts 14 partially reduces the strength of the die-casting sleeve 10, but the amount of the molten metal 31 poured into the die-casting sleeve 10 must satisfy the entire volume of the die-casting sleeve 10. In other words, since the plunger tip 28 is only a part, when the plunger tip 28 is advanced and injected, the molten metal 31
Is applied after the plunger tip 28 has passed through the cutout 14, and the reduction in strength due to the cutout 14 does not cause a problem.

[0025]

As described above, according to the present invention, the molten metal is poured into the portion where the molten metal poured from the pouring port falls, without substantially impairing the heat retaining property of the double-structured die-casting sleeve. This prevents the plunger tip from sticking due to image sticking, thereby enabling an effect of enabling smooth injection.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a main part of a die casting machine to which a die casting sleeve according to the present invention is applied.

FIG. 2 is a view showing an embodiment of a die casting sleeve according to the present invention, wherein (a) is a longitudinal sectional view and (b) is (a).
(C) and (d) are cross-sectional views taken along line AA of FIG.
FIG. 13 is a cross-sectional view showing different modified examples corresponding to FIG.

FIG. 3 is a view showing a state during the production of the die casting sleeve according to the present invention.

FIG. 4 is a diagram showing another example of a state during the production of the die casting sleeve according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Die-casting sleeve 11 Outer tube 11a Outer tube material 12 Inner tube 12a Inner tube material 13 Pouring port 13a Mold side end of pouring port 14 Notch (thin portion) 21 Fixed die plate 22 Moving die plate 23 Fixed die 24 Moving mold 27 Plunger 28 Plunger tip 29 Runner 30 Cavity 31 Molten metal

Claims (5)

[Claims] 1. A thermal conductivity of 10 to 25 W / (m · K)
A die casting sleeve in which a tool steel inner cylinder having a higher thermal conductivity than the outer cylinder is metallurgically joined to an outer cylinder made of (300 ° C.) alloy steel, which is provided on the die casting sleeve. A die casting sleeve, wherein the thickness of an outer cylinder at a portion where a molten metal poured from a pouring port falls is zero or less than the thickness of other portions of the outer cylinder. 2. A thin-walled portion of the outer cylinder is provided over a range of 50 mm or less from below a pouring port to a die side from a die-side end of the pouring port. 2. The die-casting sleeve according to 1. 3. The SUS 630, SUS 63,
1 or an equivalent thereof, wherein the inner cylinder is SKD6
The die-casting sleeve according to claim 1 or 2, wherein the sleeve is a SKD8 or an equivalent thereof. 4. The die casting sleeve according to claim 3, wherein the inner surface of the inner cylinder is nitrided after quenching. 5. The die-casting sleeve according to claim 1, wherein the inner cylinder has a thickness of 1 to 6 mm.