JPH0994648A - Plunger tip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plunger tip which can produce a good cast product without cast defect by facilitating the sliding between the plunger tip and a plunger sleeve without using lubricator. SOLUTION: In the plunger tip, a columnar plunger tip core metal 3 forming the outer peripheral part with two steps is arranged at the center part. A cylindrical sliding part 2 composed of a composite (c/c composite) of carbon fibers and carbon matrix is fitted on a short diameter columnar part of this plunger tip core metal 3. Then, the end part of this sliding part 2 together with a long diameter columnar end part of the plunger tip core metal 3 are interposed with the cap part of mushroom-like head 4, and the stem part of the head 4 is screwed with the tip part of the plunger tip core metal 3. Further, a plunger rod 5 is screwed with the rear end part of the tip core metal 3 so as to advance/retreat the plunger tip constituted in such a way in the plunger sleeve.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plunger tip in a molten metal injection part of a die casting machine, and more particularly to a plunger tip suitable for high pressure casting.

[0002]

2. Description of the Related Art FIG. 5 is a sectional view showing a conventional plunger tip inserted in a cylindrical plunger sleeve in a molten metal injection part of a die casting machine. As shown in FIG. 5, the cylindrical plunger tip 42 inserted into the plunger sleeve 41 has an opening at its rear end, and a cooling space 42a is provided therein. Further, a front end portion of a plunger rod 45 for advancing and retracting the plunger tip 42 in the plunger sleeve 41 is screwed into an open rear end portion of the plunger tip 42. Inside the plunger rod 45, there is a through hole 45a which becomes a flow path for cooling water in the longitudinal direction thereof.
Is provided, and a cooling pipe 49 having an outer diameter smaller than its diameter is arranged in the through hole. Further, an O-ring 48 for preventing the cooling water from leaking is provided at the fitting portion between the plunger tip 42 and the plunger rod 45.

In the molten metal injection section thus constructed, the plunger tip 42 inserted into the plunger sleeve 41 is driven by a driving device (not shown) provided at the rear end of the plunger rod 45. , Sliding in the plunger sleeve 41 via the plunger rod 45, and is pushed deeply. As a result, pressure is applied to the molten metal injected into the plunger sleeve 41. Then, the molten metal to which this pressure is applied flows into the mold, and a dense and highly accurate cast product is manufactured.

Normally, the plunger sleeve and the conventional plunger tip 42, plunger rod 45, etc. are manufactured from SKD61 etc., but the plunger tip 42 which comes into contact with the molten metal at the time of casting thermally expands, Seizure may occur between the inner peripheral surface of the jar sleeve 41 and the outer peripheral surface of the plunger tip 42. Therefore, the plunger tip 42 is cooled as follows to prevent seizure.

First, the through hole 4 of the plunger rod 45.
Cooling water is caused to flow in the direction of the arrow in the cooling pipe 49 arranged in 5a. Then, this cooling water is supplied into the cooling space 42a provided inside the plunger tip 42. Then, the cooling water supplied into the space 42a passes through the through hole 45a of the plunger rod 45.
Through the drainage port (not shown) provided at the rear end portion of the plunger rod 45 through the gap between the inner surface of the water cooling pipe 49 and the outer peripheral surface of the water cooling pipe 49. In this way, by circulating the cooling water inside the plunger tip 42 and cooling the plunger tip 42, thermal expansion of the plunger tip 42 is suppressed, and the plunger sleeve 41 and the plunger tip 42 are separated from each other. Prevents seizure.

Further, in this way, the plunger tip 42
By cooling, the appropriate clearance can be maintained between the inner peripheral surface of the plunger sleeve 41 and the outer peripheral surface of the plunger tip 42. Further, since a graphite-based lubricant or the like is applied to the sliding surface of the plunger tip 42 that comes into contact with the inner peripheral surface of the plunger sleeve 41 by spraying or the like, the plunger tip 41 inside the plunger sleeve 41 during casting. 42 can be easily slid.

In addition to the conventional plunger tip shown in FIG. 5, there is the following plunger tip. 6 and 7
FIG. 7 is a cross-sectional view showing another conventional plunger tip. As shown in FIG. 6, the rear end of the head 54 is inserted into one end of the cylindrical sliding portion 52, and the tip of the plunger rod 55 is inserted into the other end. Inside the sliding portion 52, the tip end portion of the plunger rod 55 is screwed into the rear end portion of the head 54, and both ends of the sliding portion 52 are held by the head 54 and the plunger rod 55, respectively. Has been done. The sliding portion 52 is made of ceramics having a low coefficient of thermal expansion, and does not expand much even when it comes into contact with molten metal. Further, similar to the cooling method of the plunger tip 42 shown in FIG.
Cooling water is caused to flow through the cooling pipe 59 arranged inside the plunger rod 55, and the cooling water is supplied to the cooling space 54a of the head 54. As a result, the head 54
To prevent thermal expansion of the head 54 due to contact with the molten metal.

The sliding portion 62 of the plunger tip shown in FIG. 7 is also cylindrical like the sliding portion 52 shown in FIG. 6, and the plunger rod 65 is provided at the inner rear end portion of the sliding portion 62. The rear end of the head 63 is screwed into the front end of the. In addition, like the head 54 shown in FIG. 6, the head 63 has a space 6 for water cooling of the head 63 via a cooling pipe 69 arranged inside the plunger rod 65.
Cooling water is supplied to 3a, and thermal expansion of the head 63 is suppressed.

Lubricant is applied to the outer peripheral surfaces of the sliding portions 52 and 62 of these plunger tips inserted into the plunger sleeve so that they can slide easily during casting. ing.

[0010]

However, like the plunger tip described above, when a lubricant is applied to the outer peripheral surface of the plunger tip for casting, the lubricant comes into direct contact with the molten metal. There is a case where a lubricant is mixed in with and a defect occurs inside the cast product.

The present invention has been made in view of the above problems, and facilitates sliding between the plunger tip and the plunger sleeve without using a lubricant,
An object of the present invention is to provide a plunger tip capable of producing a good casting product without casting defects.

[0012]

SUMMARY OF THE INVENTION A plunger tip according to the present invention is a plunger tip which is inserted into a plunger sleeve of a die casting machine and applies pressure to a molten metal, the sliding tip being in contact with the inner surface of the plunger sleeve. A composite material of carbon fibers and a carbon matrix is arranged in the moving part. Further, it is preferable that a head having a heat retaining property is provided at the tip end portion that comes into contact with the molten metal.

[0013]

In the present invention, the sliding portion of the plunger tip that comes into contact with the inner peripheral surface of the plunger sleeve is made of carbon fiber and a carbon matrix (hereinafter referred to as "c /
Since it is made of c composite), the frictional resistance between the outer peripheral surface of the plunger tip and the inner peripheral surface of the plunger sleeve can be reduced. Therefore, since it is not necessary to apply the lubricant to the outer peripheral surface of the plunger tip, the lubricant is not mixed in the molten metal to cause a defect in the cast product.

Further, a material having a heat retaining property for the head at the tip end where the plunger tip comes into contact with the molten metal, for example, T
By producing from an alloy such as i-6Al-4V, it is possible to suppress a decrease in the temperature of the molten metal and manufacture a good cast product.

[0015]

Embodiments of the present invention will be specifically described below with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing a plunger tip inserted in a cylindrical plunger sleeve 1. As shown in FIG. 1, the plunger tip is provided with a cylindrical plunger tip core metal 3 having a peripheral portion formed in two steps at the center.
C / c on the short diameter cylinder of the plunger tip core metal 3.
A cylindrical sliding portion 2 made of a composite is fitted. The mushroom-shaped head 4 is sandwiched between the end portion of the sliding portion 2 and the long diameter cylindrical end portion of the plunger tip core metal 3 by the umbrella portion thereof, and the handle portion of the head 4 is the plunger tip portion. It is screwed to the tip of the core metal 3.

Further, in order to move the plunger tip constructed as described above forward and backward in the plunger sleeve, the tip end portion of the plunger rod 5 is screwed to the rear end portion of the tip core metal 3. Plunger sleeve 1
Is made of steel, titanium alloy, ceramics, or the like.

In the molten metal injection part of the casting machine constructed as described above, first, the molten metal is injected into the plunger sleeve 1.
Injected inside. Then, the plunger tip slides in the plunger sleeve 1 via the plunger rod 5 by a drive device (not shown) provided at the rear end portion of the plunger rod 5, and is deeply pushed.
As a result, pressure is applied to the molten metal, and the molten metal flows into the mold to produce a dense and highly accurate cast product.

In this embodiment, the sliding portion 2 where the plunger tip contacts the inner peripheral surface of the plunger sleeve 1 is c /
Since it is made of c-composite, the sliding portion 2 exerts a solid lubricating action, and casting can be performed without applying a conventionally used lubricant to the plunger tip. For this reason, the lubricant is not mixed with the molten metal, so that a good cast product can be manufactured.

Further, the head 4 is made of a material having a high heat retaining property such as Ti-6Al-4V or ceramics, so that even if the molten metal has a high specific heat, the temperature drop can be suppressed and good casting can be performed. Goods can be manufactured.

Next, as a second embodiment, a plunger chip whose tip core bar has a head function will be described. FIG. 2 is a sectional view showing the plunger tip according to the present embodiment. As shown in FIG. 2, a head portion 13a larger in diameter than the body portion of the tip core bar 13 is formed at the tip of the cylindrical plunger tip core bar 13. The head portion 13a is in contact with the end portion of the sliding portion 2 which is externally fitted to the chip core bar 13 from the rear end portion thereof. Then, the nuts 16 and 17 are fitted to the rear end portion of the chip core bar 13, and the head portion 13a and the nuts 16 and 17
The sliding portion 2 is fixed to the outer peripheral portion of the cored bar 13. Also,
Similar to the plunger tip shown in FIG. 1, tip core metal 1
A plunger rod 5 is screwed onto the rear end portion of 3.

As with the first embodiment described above, the plunger tip thus constructed can be inserted into the plunger sleeve and operated to produce a good cast product.

Next, as a third embodiment, a plunger tip having a cooling space formed in the tip core of the plunger tip according to the first embodiment will be described. FIG. 3 is a sectional view showing the plunger tip according to the present embodiment. In addition to the sliding portion 2 and the head 4 which compose the plunger tip according to the first embodiment described above, in the plunger tip according to the present embodiment, as shown in FIG. A space 23a for cooling is formed. Further, a through hole 25a is provided in the longitudinal direction inside the plunger rod 25, and a cooling pipe 29 having an outer diameter smaller than its diameter is provided in the through hole 25a.
Is arranged. Further, the tip end portion of the plunger rod 25 is screwed to the rear end portion of the tip core metal 23, and cooling water leaks to the fitting portion between the tip core metal 23 and the plunger rod 25. O to prevent that
A ring 28 is provided.

The sliding portion 2 of the plunger tip shown in FIG.
Is made from a low friction coefficient c / c composite, so even if a slight thermal expansion occurs due to contact with molten metal, the sliding function does not deteriorate extremely, When expanded, there is a risk of cracking in the sliding portion 2 due to the difference in thermal expansion coefficient between the chip core metal 3 and the sliding portion 2. Therefore, it is preferable to provide a clearance between the sliding portion 2 and the core metal 3. On the other hand, like the chip core bar 23 shown in FIG. 3, a cooling space 23a is provided therein,
If cooling water is circulated in this space 23a to cool the cored bar 23, it is not necessary to provide such a clearance.

The circulation of the cooling water in the space 23a is performed as follows. That is, in the cooling pipe 29 arranged in the through hole 25a of the plunger rod 25, the cooling water is caused to flow in the arrow direction. Then, this cooling water is supplied into the cooling space 23a provided inside the chip core metal 23. And space 2
The cooling water supplied to the inside of 3a is the plunger rod 25.
Through the gap between the inner surface of the through hole 25a and the outer peripheral surface of the cooling pipe 29, and is discharged to the outside from a drain port (not shown) provided at the rear end of the plunger rod 25. In this way, the cooling water is circulated inside the chip core bar 23,
By cooling the chip core bar 23, thermal expansion of the chip core bar 23 can be suppressed, and the sliding portion 2
Can exert a solid lubrication function.

Next, as a fourth embodiment, a plunger chip in which a space for cooling is formed in the chip core of the plunger chip according to the second embodiment will be described. FIG. 4 is a sectional view showing the plunger tip according to the present embodiment. Similar to the above-described third embodiment, a space 33a for cooling is formed in the chip core metal 33, and cooling water is made to flow inside and outside the cooling pipe 29 arranged inside the plunger rod 25. . As a result, the chip core metal 33
Can be suppressed from thermally expanding, and the sliding portion 2 can exhibit a solid lubricating function.

Next, the result of manufacturing a cast product by using the plunger tip according to the third embodiment will be described. In this example, using the plunger tip according to the third example, a high-pressure cast product made of AC4CH alloy was manufactured by a vertical casting machine. As a comparative example, S
A graphite lubricant was applied to the outer peripheral surface of a plunger tip made of KD61, and the alloy material was used to manufacture a high-pressure cast product. As a result, the cast product manufactured in this example was able to reduce the blistering defect after the heat treatment by about 60% as compared with the cast product of the comparative example.

[0027]

As described above, according to the present invention,
Since the composite material of carbon fiber and carbon matrix is placed in the sliding part of the plunger tip that comes into contact with the inner peripheral surface of the plunger sleeve, this sliding part exhibits the function of solid lubricating action, and during casting, The plunger tip can be easily slid without applying a lubricant to the plunger tip.

Further, by providing a head having a heat retaining property at the tip of the plunger tip that comes into contact with the molten metal, it is possible to suppress the temperature drop of the molten metal and to manufacture a good cast product.

[Brief description of drawings]

FIG. 1 is a sectional view showing a plunger tip according to an embodiment of the present invention inserted in a plunger sleeve.

FIG. 2 is a sectional view showing a plunger tip according to an embodiment of the present invention.

FIG. 3 is a sectional view showing a plunger tip according to an embodiment of the present invention.

FIG. 4 is a sectional view showing a plunger tip according to an embodiment of the present invention.

FIG. 5 is a sectional view showing a conventional plunger tip inserted into a plunger sleeve.

FIG. 6 is a sectional view showing a conventional plunger tip.

FIG. 7 is a cross-sectional view showing a conventional plunger tip.

[Explanation of symbols]

 1, 41; Plunger sleeve 2, 52, 62; Sliding part 3, 13, 23, 33; Plunger tip core metal 4, 54, 63; Head 5, 25, 45, 55, 65; Plunger rod 13a Head portion 16, 17; nut 23a, 33a, 42a, 54a, 63a; space 25a, 45a; through hole 28, 48; O-ring 29, 49, 59, 69; water cooling pipe 42; plunger tip

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshio Suzuki 54-3 Hishie, Higashiosaka City, Osaka Prefecture

Claims (2)

[Claims] 1. A plunger tip, which is inserted into a plunger sleeve of a die casting machine and applies pressure to molten metal, has a composite material of carbon fiber and carbon matrix in a sliding portion which comes into contact with an inner surface of the plunger sleeve. Plunger tip characterized by being arranged. 2. A head having a heat retaining property is provided at a tip end portion which comes into contact with the molten metal.
Plunger tip described in.