JPS6336964A - Piston - Google Patents

Abstract

PURPOSE:To form a piston having welded strength with carrier ring by casting a ring carrier having the prescribed penetrating holes as arranging a heat insulating member at heat inlet side in a mold for piston. CONSTITUTION:In the top land part 4 of piston 1, the ring carrier 5 arranging the heat insulting layer 8 at the heat inlet side is integrately cast, and in the circumferential ring groove 6, a piston ring 50 is fitted. And, in this ring carrier 5, the penetrating hole 9 is arranged toward vertical direction. At the time of casting, the heat insulating layer 8 is set as fitting to the carrier casting in the mold 20, and by pouring molten metal in a runner 22a, the oxide film between the carrier and the heat insulating material is broken and remelted, to exhaust as foreign material to a riser 22b from the penetrating hole 9. In this way, the oxide film is not remained in the internal part and the piston having high welded strength with the carrier 5 is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a piston to which a ring carrier can be bonded with sufficient welding strength.

[Prior Art] As a conventional proposal for integrally bonding a ring carrier to a piston, there is a piston ring/insert bonding method described in JP-A-56-144F356.

In this proposal, a ring carrier is set in a split mold, and after a measured amount of molten aluminum is poured into the mold, a predetermined pressure is applied inside the mold.

[Problems to be Solved by the Invention] However, the above proposal still has the problem that it is difficult to remove the oxide film on the surface of the ring carrier that has been subjected to aluminization treatment (Alphine treatment) because there is no flow in the molten metal. The inability to remove the oxide film is undesirable because it causes poor welding and reduces welding strength.

This is because even when the oxide film is melted, it floats on the molten aluminum layer on the ring carrier side inside this oxide film and separates it from the poured molten metal. This occurs because the floating oxide film is broken and cannot be moved and discharged to the outside.

In addition, since the ring carrier is simply placed on the supporting part of the mold, when pouring metal by tilting the mold like in general casting, the ring carrier is placed in the specified position. There is a risk that it will not be incorporated into the industry.

[Means for Solving the Problems] The present invention aims to solve the above problems, and the present invention supports a ring carrier whose heat input side is covered with a heat insulating member in a mold, and also supports a ring carrier whose heat input side is covered with a heat insulating member. A piston is formed by forming a molten metal channel that penetrates vertically on the support side of the piston.

[Function] When molten metal is poured into the mold, the molten metal quickly raises the temperature of the ring carrier. The molten metal channel formed vertically through the support side of the mold improves the flow of the molten metal on the support side.

Therefore, the oxide film of the ring carrier and the heat insulating layer is destroyed by the flow of the molten metal, and foreign matter such as this oxide film is carried to the mold's push channel. As a result, defective welding of the ring carrier will not occur, and a high-quality piston can be formed. Further, in the molded piston, the heat input side of the ring carrier, that is, the cavity side of the piston is covered with a heat insulating member, so that heat transfer to the ring groove of the ring carrier can be prevented. This prevents abnormal wear of the piston ring fitted into the ring groove.

[Embodiment] A preferred embodiment of the piston of the present invention will be described below with reference to the accompanying drawings.

First, the structure of the piston of this invention will be explained.

Reference numeral 1 shown in FIG. 1 is a piston formed by pouring molten aluminum or its alloy into a mold and solidifying it. A cavity 3 is formed in the top 2 of the piston 1 by being recessed in the axial direction. The top land portion 4 of the piston 1 is integrally provided with a link ring 1 flia 5 made of a high nickel metal material such as Niresist cast iron, and the outer circumferential side portion 5a of the ring carrier 5 is provided on the outer circumferential side portion of the piston 1. It forms the same cylindrical surface as 1a. , 6 is a ring groove formed along the circumferential direction of the ring carrier 5, and the piston ring 50 is fitted into this ring groove 6.

Incidentally, as shown in FIGS. 2 and 3, the ring carrier 5 is provided with a through hole 9 extending in the vertical direction in a radial portion on the support side of the mold. This through hole 9 forms a molten metal channel through which molten metal, which is the material for forming the piston 1, passes in the vertical direction when the ring carrier 5 is cast.

A plurality of through holes 9 are provided at intervals in the circumferential direction of the ring carrier 5 as necessary.

4 to 6 show other opening directions of the through hole 9.

FIG. 4 shows an example in which the through hole 9 is formed to be inclined downward from the support side position of the mold, and FIGS. 5 and 6 show the through hole 9.
An example is shown in which the groove is inclined in a direction intersecting the circumferential direction when viewed from above.

By forming the through holes 9 in this manner, the flow of the molten metal can be further improved, and the temperature of the ring carrier 5 can be quickly raised to near the temperature of the molten metal.

Further, 7 is an oil gear for cooling the piston 1 and reducing heat conduction to the ring carrier 5.

A heat insulating layer 8 is provided within the piston 1 to prevent heat from being conducted from the cavity 3 to the ring groove 6 of the ring carrier 5. The heat insulating layer 8 is formed by forming a collar part 8b that is seated on the upper surface 5b of the ring carrier 5 at one end of a cylindrical part 8a that is fitted to the inner circumferential surface 5a of the ring carrier 5. The radial length of the flange portion 8b is formed so as not to close the through hole 9. As the material for forming the heat insulating layer 8, ceramic fiber such as alumina fiber, which can form an air layer inside, is used.

By forming the piston 1 in this way, the high-temperature heat from the cavity 3 is prevented from being transmitted by the heat insulating layer 8, so that this heat is taken away by the cooling oil of the oil gear gallery 7. Therefore, abnormal wear of the piston ring 50 due to temperature rise is prevented.

Next, a specific example of molding the piston of the present invention will be described based on the accompanying drawings.

First, a ring carrier casting is formed.

In forming the ring carrier casting, a mold 12 is used as shown in FIG. This mold 12 is an upper mold 12
a and a lower mold 12b, and when stacked, an annular cavity 13 forming the outer shape of the ring carrier 5 is formed in the mold 12. Further, in this state, a ring-shaped cavity 13b whose diameter is expanded in the radial direction is formed on each of the overlapping surfaces of the cavity 13.

14a is a pouring path, and 14b is a lagoon path.

When molten Niresist is poured into the pouring path 148 of the mold 12 and solidified, a ring carrier casting 5B as shown in FIG. 3 is obtained. This obtained link 1? A through hole 9 having the shape described in FIGS. 2 to 6 is provided in the rear casting 5B. After this processing, the ring carrier casting 5B in which the through hole 9 has been formed is immersed in an Alfin treatment bath 15 shown in FIG. 8 to form an aluminum coating layer on the surface.

Next, the ring carrier casting 5B after the Alfin treatment is set in a piston mold 20 shown in FIG. The piston mold 20 is arranged such that a lower mold 20C, a mother mold 20b, and an upper mold 20a are stacked vertically in this order, and a cavity 21 for forming a piston is formed inside these molds.

Cavities 21a are formed in the mating surfaces of the upper die 20a and the mother die 20b to sandwich and support the collar portion 11 of the ring carrier casting 5B.

Now, the cavity 21a of the mold 20 for such a piston
A ring carrier casting 5B is set in the ring carrier casting 5B, and then a heat insulating layer 8 which has been subjected to Alfin treatment in the same manner as the ring carrier casting 5B is fitted to the ring carrier casting 5B. Here, the radial strength of the brim 8b of the heat insulating layer 8 is set to a length that does not block the through hole 9, or a hole, notch, etc. is formed so that the through hole 9 is not blocked. It is formed like this. In this process, the upper mold 20a is placed on the mother mold 20b,
Molten metal is poured into the pouring path 22a. Inflow is Oshigata Road 2
The molten metal is poured until it rises to 2b, and the molten metal pouring speed and pouring time at this time are set appropriately. Note that a release layer such as a ceramic coating is formed on the surface of the mold 12, 20 that forms the cavity.

According to the above casting method, the molten metal poured into the piston mold 20 quickly circulates within the mold 20, breaks the aluminum oxide film of the heat insulating layer 8 and the ring carrier casting 5B, and the molten metal is oxidized. Remelt the aluminum coating layer inside the membrane. Foreign matter such as an oxide film dissolved here is carried on the tip of the flow of molten metal and passes through the through hole 9 into the push lagoon path 22b.
be carried to. For this reason, there is no place to stagnate in the face of drought,
Ring carrier casting product 5 to ensure removal of foreign matter
The temperature of B is quickly raised to the welding temperature or higher. The blown part of the piston casting formed by casting the ring carrier casting 5B is then machined into a predetermined shape, and the ring groove 6 of the piston ring 50 is formed as shown in FIG. .

9 to 12 show an example in which a molten metal channel is formed in the piston mold 20 instead of the through hole 9.

FIG. 9 shows a horizontal cross section of the mold 20.

As illustrated, the upper mold 20a and the mother mold 20b of the mold 20
The cavity 21a of the mating surface is recessed in the radial direction leaving a part in the circumferential direction, and the recessed part is the 10th
As shown in the figure, the collar 11 of the ring carrier casting 5B
It is designed to surround the area vertically. That is, this depressed portion becomes a molten metal channel 9a. The remaining portion of the cavity 21a in the circumferential direction becomes a portion that supports the flange portion 11 on both sides, as shown in FIG. Figure 11 is the 9th
An example is shown in which a ring carrier casting 5B without a flange portion 11 is fixed and formed at an appropriate position in the mold 20 described in the figure.

Incidentally, in forming the through holes, it is also possible to set ceramic-coated pins in the mold and perform molding at the same time as casting.

[Effects of the Invention] As is clear from the above explanation, according to the piston of the present invention, it is possible to form a piston in which a ring carrier is welded to the piston without oxides inside, and the welding strength of the ring carrier is improved. It is possible to demonstrate the excellent effect of being able to provide high-quality pistons with improved performance.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing a preferred embodiment of the piston of the present invention, FIGS. 2 to 6 are schematic views showing through holes as molten metal passages, and FIG. 7 is a ring carrier casting formed. FIG. 8 is a diagram showing the Alfin treatment process, FIGS. 9 to 12 show an example in which a molten metal channel is formed in a piston mold, and FIG. X-ray cross-sectional view,
FIG. 12 is a sectional view taken along the line xn-xII in FIG. 9, and FIG. 13 is a schematic sectional view showing a specific example of molding and covering the piston. In the figure, 1 is a piston, 5 is a ring carrier, 8 is a heat insulating layer, 9 is a through hole serving as a molten metal passage, and 20 is a mold for the piston.

Claims (3)

[Claims] (1) A piston characterized in that a ring carrier whose heat input side is covered with a heat insulating member is supported in a mold, and a molten metal passage is formed vertically through the supporting side of the ring carrier. (2) The piston according to claim 1, wherein the molten metal passage is formed on the mold supporting side of the ring carrier. (3) The piston according to claim 1, wherein the molten metal passage is formed along an inner wall of a mold in which the ring carrier is supported.