JP7401907B2 - Spool bush for die casting mold - Google Patents

Description

The present invention relates to a spool bush for a die-casting mold.

For example, a recessed portion coaxial with the inner peripheral surface of a cylindrical bush main body is provided, a cylindrical insert liner is fitted into the recessed portion, and a cooling fluid is provided on the outer peripheral surface of the insert liner. A spool bush for a die casting casting machine has been proposed, which is provided with a cooling groove for flowing water (for example, see Patent Document 1).
According to the spool bush for a die-casting machine described in Patent Document 1, a good cooling effect can be obtained by the cooling fluid, and cracks due to thermal stress are less likely to occur.

Furthermore, the inner circumferential surface of the spool bushing body made of a high-strength, low-thermal-expansion metal material having a predetermined coefficient of thermal expansion in contact with the molten metal has a thickness made of any one of Fe-based alloy, Co-based alloy, Ni-based alloy, and Ti-based alloy. A spool bush for a die-casting machine in which a 2 mm thick coating layer is metal-bonded by HIP method or overlay method has also been proposed (see, for example, Patent Document 2).

According to the spool bush for a die-casting machine described in Patent Document 2, since it has a composite structure of a spool push body and a coating layer, it is more durable than general hot mold steel (JIS: SKD61, etc.). Thermal expansion due to heating of the spool bush main body can be reduced, and the tensile strength at high temperatures can be increased, so that thermal deformation can be reduced.

Japanese Patent Application Publication No. 2003-10953 (pages 1 to 4, Figures 1 to 5) Japanese Patent Application Publication No. 2008-221220 (pages 1 to 8, Figures 1 and 2)

However, in the spool bush for a die-casting machine described in Patent Document 1, the recessed fitting part of the bush main body is open only to the injection sleeve side, so the insert liner fitted in the recessed fitting part is not connected to the plunger tip or the injection sleeve. There is a problem in that when the insert liner is galled by solidified metal, it takes a lot of time and effort to replace the insert liner.
On the other hand, the spool bush for a die-casting machine described in Patent Document 2 requires special equipment and a large cost in order to coat the coating layer. Moreover, if galling occurs in the coating layer itself, not only the coating layer but the entire spool bush including the spool bush main body must be replaced with a new one, which is extremely uneconomical. There was a problem.

The present invention solves the problems explained in the background art, and even if galling occurs on the inner circumferential side of the bushing body due to a plunger chip, etc., only the inner sleeve on the inner circumferential side that has suffered the galling can be easily replaced. An object of the present invention is to provide a spool bush for a die-casting mold that can be used in a die-casting mold, and which can provide a good cooling effect.

In order to solve the above-mentioned problems, the present invention includes separately fitting a pair of sleeves into the inner peripheral surface and outer peripheral surface of the bushing body, and arranging a tapered ring on the end surface (die-casting mold) side of these sleeves. It was created based on the idea.
That is, the spool bush for a die-casting mold of the present invention is a spool bush used for a flow path for press-fitting molten metal into a die-casting mold, and has a cylindrical shape as a whole and has a cooling water flow path formed on the outer peripheral surface. an inner sleeve inserted along the entire length of the inner peripheral surface of the bush main body and having a hollow portion , and a removable inner sleeve that covers the outer peripheral surface of the bush main body and the opening of the cooling water flow path. an outer sleeve, and a tapered ring whose end surface on the side opposite to the die-casting mold side is in surface contact with each end surface of the bush main body, inner sleeve, and outer sleeve on the die-casting mold side and is removably disposed; The tapered ring has a built-in cooling water circulation flow path that has a regular polygonal or circular shape when viewed in the axial direction, and a cooling water circulation path that has a regular polygonal or circular shape when viewed in the axial direction. A tapered hole that is inclined so that the die-casting mold side expands is provided therein, and the slope of the tapered hole is continuous to the inner circumferential surface of the die-casting mold side in the hollow part of the inner sleeve. shall be .

According to the spool bush for a die-casting mold, the following effects (1) to (3) can be obtained.
(1) Even if galling occurs on the tip surface of the plunger tip (piston) that pumps the molten metal to the die-casting mold side or on the inner peripheral surface of the inner sleeve due to the solidified material of the molten metal, the taper ring can be removed and After loosening the bolt whose tip had entered the inner sleeve, the galled end face of the inner sleeve is hammered along the axial direction with a copper hammer, for example, to connect it with a new inner sleeve. Replacement work can be done quickly and easily.
(2) Since the outer sleeve is sandwiched between the bush main body and the tapered ring, by removing the tapered ring and the outer sleeve as described above, the cooling formed on the outer peripheral surface of the bush main body can be removed. Maintenance such as inspection and replacement of the water flow path and sealing materials such as O-rings placed before and after (on both sides) of the flow path can be performed quickly and reliably.
(3) It can be easily assembled by fitting the bush main body, outer sleeve, inner sleeve, and taper ring together and bolting them together, so it can be manufactured at a relatively low cost compared to the spool bush of Patent Document 2. It is possible.

The molten metal includes, for example, molten metal of aluminum and its alloy, zinc and its alloy, or magnesium and its alloy.

FIG. 1 is a schematic cross-sectional view showing how the spool bush for die-casting molds of the present invention is used. (A) is a sectional view showing the spool bushing, and (B) is an enlarged view of the dashed-dotted line portion B in (A). (A) and (B) are partial schematic diagrams showing mutually different types of tapered rings included in the spool bush. (A) and (B) are sectional views showing a maintenance procedure for the spool bush.

Below, modes for carrying out the present invention will be described.
FIG. 1 is a schematic cross-sectional view showing how a spool bush for a die-casting mold (hereinafter simply referred to as a spool bush) 1 of the present invention is used, and arrows in the figure indicate the flow of molten metal. For convenience, in FIGS. 1 and 2, the right side is referred to as the distal end side, and the left side is referred to as the proximal end side.
The spool bush 1 is tightly piped between the die-casting mold 30 and the plunger sleeve 35, as shown in FIG. The die-casting mold 30 consists of a fixed mold 31 and a movable mold 32, and between the two is located an upward sprue core 33 that communicates with a cavity (not shown).

On the other hand, the plunger sleeve 35 has an upwardly opened pouring port 36 for injecting molten metal made of aluminum alloy or the like, and a plunger tip (piston) that slides inside the tube of the plunger sleeve 35 toward the distal end and the proximal end. ) 38, and a plunger rod 39 for moving the plunger tip 38 forward and backward.
The distal end surface of the plunger sleeve 35 enters a recessed portion of the spool bushing 1 located at the proximal end surface of the bushing body 2 and the inner sleeve 10, which will be described later.

FIG. 2(A) is a sectional view showing the spool bush 1 according to the present invention. Note that the arrow in FIG. 2(A) indicates the direction in which the molten metal being pumped flows.
As shown in FIG. 2(A), the spool bush 1 includes a bush main body 2 which has a cylindrical shape as a whole and has a plurality (two) of cooling water channels 5 formed in parallel on an outer peripheral surface 4. A cylindrical inner sleeve 10 that is tightly inserted (fitted) into the inner peripheral surface 3 side of the bush main body 2, a cylindrical outer sleeve 13 that covers the outer peripheral surface 4 side of the bush main body 2, and the outer sleeve. 13, the bush main body 2 and the inner sleeve 10 are provided with a tapered ring 14 whose proximal end surface is disposed in surface contact, including concave-convex fitting, on the distal end surface.

At the front and rear (both sides) of the pair of front and rear cooling water channels 5 provided along the circumferential direction of the outer circumferential surface 4 of the bush body 2, grooves 6 having a rectangular cross section and a narrow width are individually formed. An O-ring 7 is fitted in each of the grooves 6 over the entire circumference so that the outer circumferential portion of the groove 6 that protrudes outward comes into close contact with the inner circumferential surface of the outer sleeve 13 . The pair of front and rear O-rings 7 seal the cooling water in each of the cooling water channels 5 , and also allow the outer sleeve 13 to be removed .
As shown in FIG. 2(A), a flange 8 having a rectangular cross section is provided at the proximal end of the bush main body 2, which abuts the same proximal end surface of the outer sleeve 13 and has a rectangular cross section. It protrudes (overhangs) along the At least one (for example, four) female threaded holes 21 are formed in the flange 8 and extend through the flange 8 in its axial direction.
Note that a bolt (not shown) screwed into the female screw hole 21 normally has its male screw tip in contact with the proximal end surface of the outer sleeve 13, but when the outer sleeve 13 is removed and the During maintenance of the ring 7, it is removed from the female threaded hole 21 or loosened slightly toward the proximal end.

Furthermore, at least one female threaded hole 22 is formed in the flange 8 of the bush main body 2, passing through the flange 8 in the radial direction. The deepest part of the female screw hole 22 is located inside the inner sleeve 10. That is, a bolt (not shown) screwed into the female threaded hole 22 has its male threaded end inserted into the inner sleeve 10 from the outer circumferential surface thereof, thereby preventing the inner sleeve 10 from being moved inadvertently. are doing. A larger recess 23 for accommodating the bolt head of the bolt is coaxially located on the opening side of the female threaded hole 22.
Further, as shown in FIG. 2(A), the inner sleeve 10 has a hollow portion 11 and a tapered inner circumferential surface 12 therein. A pair (two) of female threaded holes 20 are formed in the proximal end surface of the inner sleeve 10 at symmetrical positions with respect to the central axis. As will be described later, by individually screwing elongated bolts (not shown) into each of the female screw holes 20, it is utilized to facilitate the work when replacing the inner sleeve 10.

The bush main body 2 and the inner sleeve 10 are both made of hot mold steel (e.g., equivalent to JIS: SKD61), which are subjected to necessary cutting processes. As illustrated in FIG. 2(B), these surfaces have a layer of iron nitride (a compound of Fe and N) produced by the penetration and diffusion of N and C elements during the isonite treatment. A nitrogen diffusion layer 41 is formed below the iron nitride thin layer 40 (with a thickness of approximately several μm to several tens of μm).
Further, as shown in FIG. 2(A), a water supply/drainage connection fitting 18 is attached to the outer sleeve 13, which communicates with the end of each of the cooling water channels 5 individually.
Further, the outer sleeve 13 is made of die block steel (e.g., equivalent to JIS: STK41) and subjected to necessary plastic working, and then at least the inner circumferential surface thereof is coated with electroless Ni plating. It is coated with a nickel film layer (not shown) for rust prevention.

In addition, as shown in FIG. 2(A), the tapered ring 14 has a tapered hole 16 that expands on the distal end side along the axial direction, and has a cooling hole in the thick part 15 on the proximal end side. A water circulation channel 17 is built-in. The proximal end side of the tapered ring 14 has a concave concave end surface that receives the convex convex end surfaces of the bush main body 2, the inner sleeve 10, and the outer sleeve 13. There is. The tapered hole 16 has a large diameter at the distal end and a small diameter at the proximal end, and is inclined at about 3 to 6 degrees (for example, 5 degrees) with respect to the imaginary horizontal line (center line). . As shown in the figure, this inclination continues to the inner circumferential surface 12 on the distal end side of the inner sleeve 10.

Due to the slope continuous with the inner circumferential surface 12, the inner diameter d1 of the hollow portion 11 of the inner sleeve 10 is smaller than the inner diameter d2 at the minimum position of the tapered hole 16 passing through the tapered ring 14. As a result, the inner circumferential surface of the hollow portion 11 of the inner sleeve 10 is the part most affected by contact with molten metal, which will be described later.
Furthermore, a set of water supply/drainage connection fittings 19 are communicated with the lower end side of the cooling water circulation passage 17 in the front-rear direction in FIG. 2(A).
Note that the taper ring 14 is also made by cutting the same hot die steel as described above, and then its surface is coated with the iron nitride (compound) layer 40 and the nitrogen diffusion layer 41 by isonite treatment or the like. has been done.

FIG. 3(A) is a partial schematic perspective view of the upper half of the tapered ring 14 as seen along its axial direction.
As shown in FIG. 3(A), the cooling water circulation flow path 17 has a trapezoidal shape in the upper half, and a substantially regular octagonal shape in the entire tapered ring 14, and has a trapezoidal shape at the bottom side. There is no horizontal side, and a pair of water supply/drainage connection fittings 19 are individually connected to the lower end sides of a pair of left and right symmetrical inclined sides that communicate with both ends of the virtual horizontal side.
In order to obtain the cooling water circulation flow path 17 having a substantially regular octagonal shape as a whole, the inside of the taper hole 16 must be drawn from the outer peripheral surface of the ring-shaped steel material, which is the material of the taper ring 14, when viewed in the axial direction. After drilling seven linear holes that enter tangentially to the circumferential surface at intervals of 45 degrees and making them communicate with each other midway, the outer circumferential end of each of the linear holes is closed off with a faucet 17z. There is.

FIG. 3(B) is a transparent partial schematic view along the axial direction of the taper ring 14 which incorporates a cooling water circulation flow path 17r of a different form from the above.
As shown in FIG. 3(B), the cooling water circulation flow path 17r has a semicircular shape along the tapered hole 16 in the upper half, and has a substantially circular shape in the entire tapered ring 14. The pair of water supply/drainage connection fittings 19 are individually connected to a pair of ends that are close to each other on the bottom side.
In order to provide the circular cooling water circulation passage 17r inside the taper ring 14, for example, an aluminum alloy or a magnesium alloy having a shape similar to the entire outer shape of the cooling water circulation passage 17r is prepared in advance. An arc-shaped core (not shown) is manufactured using a metal brazing material having a relatively low melting point. Next, a steel coating is applied to the entire surface of the core by thermal spraying or the like, and then the core with the coating is set in a mold (not shown) dedicated to the taper ring 14, and then An example of this method is to simultaneously pour a molten metal of cast steel of the same type and simultaneously dewax the metal brazing material.

Below, the usage method and maintenance procedure of the spool bush 1 will be explained.
As indicated by the arrow in FIG. 1, the molten metal is pushed by the plunger tip 38 and passes through the hollow portion 11 of the inner sleeve 10 of the spool bushing 1 from inside the plunger sleeve 35, and then flows to the fixed side. The material is fed under pressure into the cavity through a sprue core 33 between the mold 31 and the movable mold 32. During repeated die-casting operations, the plunger tip 38 may inadvertently become axially runout, or a portion of the molten metal may inadvertently solidify on the inner wall surface of the hollow portion 11 of the inner sleeve 10. , the solidified metal may collide with or rub against the inner circumferential surface of the hollow portion 11 of the inner sleeve 10.

The inner sleeve 10, which has been continuously subjected to the axial runout of the plunger tip 38 and the collision of solidified metal, has abrasion resistance including galling resistance and heat resistance due to the iron nitride layer 40 coated on its surface. , corrosion resistance, and high fatigue strength, it is possible to effectively counter local deformation (hereinafter referred to as galling) of the inner circumferential surface of the hollow portion 11 (hereinafter referred to as effect (4)). ).
However, over a long period of time, the inner peripheral surface of the hollow portion 11 of the inner sleeve 10, which has been continuously subjected to the axial vibration of the plunger tip 38 and the collision of the solidified metal, undergoes thermal deformation due to thermal stress, etc. As a result of the loss of the required smoothness, for example, sliding (advancing and retracting) operations of the plunger tip 38 may become impossible, and the die casting operation may be stopped.

When the die casting described above is stopped, the die casting mold 30 is removed from the plunger sleeve 35 and the spool bush 1, and then removed from the spool bush 1 as shown in FIG. 4(A). After removing the taper ring 14, the bolt screwed into the female screw hole 22 of the flange 8 of the bush main body 2 is loosened.
As a result, the distal end surface of the inner sleeve 10, which had been inserted into the inner circumferential surface 3 side of the bush main body 2, is exposed to the outside. Note that, in the inner sleeve 10, the proximal end surface in which the pair of female screw holes 20 are formed is already exposed to the outside.
In this state, as shown by the solid arrow in FIG. 4(B), the front end surface of the inner sleeve 10 is hammered with light pressure P along the axial direction using, for example, a copper hammer (not shown). do.

As a result, as shown in FIG. 4(B), the proximal end side of the inner sleeve 10 can be sequentially pulled out from the proximal end surface of the bush main body 2 to the outside.
Alternatively, as shown by the dashed arrow in FIG. 4(B), relatively long and slender bolts 20b are individually screwed into a pair of female threaded holes 20 formed in the proximal end surface of the inner sleeve 10. The pair of bolts 20b may be pulled toward the proximal end along the axial direction.
If for some reason it is difficult for the inner sleeve 10 to come out of the inner circumferential surface 3 of the bushing body 2 when driving with the pressure P, the operation of pulling the pair of bolts 20b may be used in combination.

Furthermore, by inserting a new inner sleeve 10 into the inner circumferential surface 3 of the bush main body 2 by performing the reverse operation described above, the replacement work with a new inner sleeve 10 can be easily and quickly completed.
In addition, when the tapered ring 14 is removed, the outer sleeve 13 is removed from the bush main body 2, and a pair of cooling water passages 5 exposed to the outside and a pair of O-rings 7 located before and after the outer sleeve 13 are removed. You may check. In this case, depending on the degree of deterioration of the O-ring 7, it is desirable to replace it with a new O-ring 7.

According to the spool bush 1, the tip surface of the plunger tip 38 that pumps molten metal such as aluminum alloy to the die-casting mold 30 side, and the inner circumferential surface of the hollow portion 11 of the inner sleeve 10 by the solidified material of the molten metal. Even if galling occurs, remove the taper ring 14 and loosen the bolt whose tip has entered the inner sleeve 10 toward the bushing body 2, and then remove the tip surface of the inner sleeve 10 where the galling occurred. By simply driving the inner sleeve 10 along the axial direction with a copper hammer or the like, replacement with a new inner sleeve 10 can be performed easily and in a short time.
Further, the outer sleeve 13 can be attached to the cooling water passage 5 formed on the outer circumferential surface 4 of the bush main body 2 or before and after the cooling water passage 5 by simply removing the taper ring 14 as described above. Maintenance work such as inspection and replacement of the arranged O-ring 7 can be performed quickly and reliably.

Furthermore, it can be easily assembled by fitting or bolting the bush body 2, outer sleeve 13, inner sleeve 10, and taper ring 14 together, so it can be manufactured at a lower cost than conventional spool bushes. obtain.
In addition, the iron nitride layer 40, which has wear resistance including galling resistance, heat resistance, corrosion resistance, and high fatigue strength, is formed on the surfaces of the bush main body 2, inner sleeve 10, and tapered ring 14. is formed, the durability of the sprue bushing 1 is enhanced (effect (4)).
Therefore, it is easily understood that the above-mentioned effects (1) to (4) can be obtained according to the sprue bush 1.

The embodiments herein are not exhaustive disclosures.
For example, the cooling water flow path 5 provided on the outer circumferential surface 4 of the bush main body 2 may be one or three or more in parallel.
Further, the surface contact portion between the distal end surface of the bush main body 2, the inner sleeve 10, and the outer sleeve 13 and the proximal end surface of the tapered ring 14 has a substantially right-angled shape as seen in FIG. 2(A). The concave portion and the convex portion may be fitted into each other.

Furthermore, at least one female threaded hole (not shown) is further cut along the axial direction across the thick portion 15 of the tapered ring 14 and the distal end side of the outer sleeve 13, Inadvertent detachment of the tapered ring 14 may be prevented by allowing the tip of the male screw of the bolt to be screwed into the female screw hole to enter the outer ring 13.
In addition, the cooling water circulation channels 17, 17r built into the taper ring 14 may have a configuration in which two or more are provided in parallel along the front and back of the axial direction.

According to the present invention, even if galling occurs on the inner circumferential side of the bushing body due to a plunger chip, etc., the inner sleeve on the inner circumferential side having the galling can be easily replaced, and a good cooling effect can be obtained. We can reliably provide spool bushes for molds.

1 Spool bush (spool bush for die-casting mold)
2 Bush body 3 Inner peripheral surface 4 Outer peripheral surface 5 Cooling water flow path
6 Groove
7 O-ring
8 Flange 10 Inner sleeve 11 Hollow part
12 Inner peripheral surface
13 Outer sleeve 14 Tapered ring 16 Tapered hole 17, 17r Circulation channel 21, 22 Female screw hole 30 Die-casting mold 40 Thin layer of iron nitride d1, d2 Inner diameter

Claims (6)

A spool bush used in a flow path for pressurizing molten metal into a die-casting mold,
A bushing body that has a cylindrical shape as a whole and has a cooling water flow path formed on its outer peripheral surface;
an inner sleeve inserted along the entire length of the inner peripheral surface of the bush main body and having a hollow part ;
a removable outer sleeve that covers the outer peripheral surface of the bush main body and the opening of the cooling water flow path;
A taper ring is provided on each end surface of the bush main body, inner sleeve, and outer sleeve on the die-casting mold side , and the end surface on the side opposite to the die-casting mold side is in surface contact with and is removably disposed ,
Inside the taper ring, there is a built-in cooling water circulation channel that has a regular polygonal or circular shape when viewed in the axial direction.
A tapered hole that is inclined so that the die-casting mold side expands along the axial direction is provided in the center side of the tapered ring, and the slope of the tapered hole is such that the die-casting mold in the hollow part of the inner sleeve Continuous to the inner peripheral surface of the side ,
Spool bush for die casting molds. Recessed grooves are individually formed on both front and rear sides of the cooling water flow path along the circumferential direction of the outer peripheral surface of the bushing body, and within each recessed groove, an outer peripheral portion protruding to the outside of the recessed groove. an O-ring that tightly contacts the inner circumferential surface of the outer sleeve is fitted over the entire circumference ;
The spool bush for a die-casting mold according to claim 1. The inner diameter of the hollow portion of the inner sleeve is smaller than the minimum inner diameter of the tapered hole passing through the tapered ring.
The spool bush for a die-casting mold according to claim 1 or 2. The end surface of the tapered ring on the side opposite to the die-casting mold side is configured to receive a convex end surface of the bush main body, the inner sleeve, and the end surface of the outer sleeve on the die-casting mold side. It has a concave conical shape ,
A spool bush for a die-casting mold according to any one of claims 1 to 3. A flange that abuts an end surface of the outer sleeve on the side opposite to the die -casting mold side is protruded along the radial direction at an end portion of the bushing body opposite to the die- casting mold side.
A spool bush for a die-casting mold according to any one of claims 1 to 4. The flange of the bush main body has a female threaded hole into which a bolt into which a male threaded tip abuts is inserted, on at least one of the end surface of the outer sleeve opposite to the die-casting mold side and the outer surface of the inner sleeve. is formed,
The spool bush for a die-casting mold according to claim 5.

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