JPH04132864A - Heat resistant machine element for engine - Google Patents

Abstract

PURPOSE:To improve durability and reliability of the machine-element of an engine by fusing a heat resisting steel on the surface of a first layer to form a second layer after capsule powder produced by covering the surface of heat resisting steel powder with ductile metallic powder is fused on the surface of the heat resisting machine element by ultrasonic waves. CONSTITUTION:A recessed part 9 is formed in the surrounding part of a cylinder head under surface 4 surrounded with suction and discharge valves 2 and 3 and a hot plug mounting hole 6, capsule powder 12 prepared such that heat resisting steel powder 10 serving as a core is covered with ductile metallic powder 11 is charged therein, and an uniform capsule powder layer is formed on the inner surface of the recessed part 9. The capsule powder 12 is fused to each other by using an ultrasonic fusing machine 13 to form a first layer 14 on the surface of the recessed part 9. Padding welding of a heat resisting steel is applied to the surface of the first layer 14 with high density energy to form a second layer 16 in a given thickness. Thermal shrinkage of the first layer 14 is transmitted to the ductile metal of the second layer 16, and since a thermal crack is effectively prevented from occurring through absorption of the ductile metal, a cylinder head 1 which is internally increased in roughness and ductility and durable to a thermal crack is provided.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to metal mechanical elements of engines such as cylinder heads and pistons, and particularly to engines in which a heat-resistant metal is fused to the heat-receiving surface of the metal mechanical elements. Concerning heat-resistant mechanical elements.

[Prior Art] Mechanical elements of engines that are directly exposed to combustion gas energy and heated to high temperatures include cylinder heads and pistons. There is a need to improve the strength of the combustion surface, especially the thermal cracks that occur on the combustion surface. Thermal cracks occur intensively in parts with a small cross-section due to thermal stress, that is, in parts with thin wall thickness.1 For example, thermal cracks in a cylinder head occur in the intake/exhaust boat a as shown in Figure 6. ,
Thermal cracks in the piston tend to occur in the partition wall C between b and the partition walls e and f between the intake/exhaust bolts a and b, respectively, and the hot plug mounting hole or fuel injection nozzle mounting hole 6, as shown in Figure 7. It tends to occur in the area that borders the upper part of the cavity.

Therefore, the applicant investigated methods of casting cylinder heads and pistons with alloys, reinforcing the combustion surfaces of mechanical elements with FRM, and remelting methods of partially remelting using high-density energy beams.

Alloy casting method...Although alloy casting is effective in improving the heat resistance of machine elements, it deteriorates castability, making it difficult to obtain sound castings, and deteriorates the mechanical properties of castings. It is not suitable for mass production because it is difficult to adjust the alloy concentration in the base material, and it is difficult to eliminate variations in strength and ensure a constant strength.

FRM reinforcing method: The material itself is expensive in this technology, so reinforcing members made of FRM are bonded to the partition walls.

Considering that it must be melted and installed, the cost becomes quite high.

Remelting method: The combustion surfaces of cylinder heads and pistons are remelted using high energy density lasers, TIG, or electron beams. Although this method has the advantage of refining the metal structure only in specific parts and extending the crack life, the S crack life due to the refinement of the metal weave is lower than that without remelting. This is approximately twice as high as the actual output power, which is insufficient to meet the high output requirements that will be required in the future.

As described above, the above method has its advantages and disadvantages, and there is room for improvement as a technology that can satisfy mass production.

For this reason, heat-resistant alloys (stainless steel, NIMONIC80
A, INCONEL or Co, Ni.

alloys such as MO, W, etc.) on the heat-receiving surface of metal mechanical elements.
Technology of fusion welding and cladding with high energy density beams such as G, MIG, and PTA (Japanese Patent Laid-Open No. 61-9132
3, Japanese Patent Application Laid-open No. 60-70136, etc.), we found a new finding that heat shrinkage cracking occurs in heat-resistant metals due to the difference in heat shrinkage rate between metal machine elements and heat-resistant metals. I found a problem.

Therefore, as a result of intensive research, the present applicant found that by forming a ductile metal layer on the heat receiving surface of a metal machine element by ultrasonic bonding, and then fusion welding a heat-resistant metal layer on the surface of the ductile metal layer, the heat-resistant metal layer and the metal It was discovered that the heat shrinkage stress that occurs between the heat-resistant mechanical elements and the manufactured mechanical elements is absorbed by the ductile metal layer, and shrinkage cracking of the heat-resistant metal layer due to heat shrinkage is prevented. (Patent Application No. 1-284115))
.

[Problems to be Solved by the Invention] However, in view of the recent trends toward higher engine output and increased mechanical loads, it is desirable to further improve the bondability between the heat-resistant metal layer and the ductile metal layer to reduce heat shrinkage stress by reducing the heat shrinkage stress to the ductile metal layer. It is necessary to ensure that the stress is transmitted to the ductile metal so that the ductile metal effectively absorbs the heat shrinkage stress.

[Means for Solving the Problems] In order to solve the above problems, the present invention forms a first layer by ultrasonically welding capsule powder, which is made by coating the surface of heat-resistant steel powder with ductile metal powder, onto the surface of a heat-resistant mechanical element. After that, heat-resistant steel was fusion welded to the surface of the first layer to form a second layer.

[Function] When capsule powder is ultrasonically welded to the surface of a mechanical element that requires heat resistance, the ductile metal powder on the surface of the capsule powder is effectively melted, and the heat-resistant steel is metallographically bonded to the surface of the mechanical element. A uniformly diffused first layer is formed. After ultrasonic melting, when heat-resistant steel is fusion welded to the surface of the first layer and the second layer is laminated, the ductile metal on the surface of the first layer melts and exposes the 5!8 #4. The heat-resistant steel of the second layer and the heat-resistant steel of the first layer become compatible, and good fusion welding is performed.

Therefore, the heat shrinkage stress of the second layer is
Reliably transmitted to heat-resistant steel diffused in IIm,
Heat shrinkage stress becomes absorbed by the ductile metal of the first layer. For this reason, it is hot compared to the conventional one! The occurrence of cracks is prevented.

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

(Embodiment 1) As shown in FIG. 3, the cylinder head 1 has an intake boat 2.
and an exhaust port 3 are respectively formed. These intake boats 2 and exhaust ports 3 are formed to open in a cylinder head lower surface 4 corresponding to a cylinder bore (both not shown) of the engine. The intake boat 2 and the exhaust port 3 are connected between the intake boat 2 and the exhaust port 3.
As a result of forming the partition wall 5, the partition wall 5 is formed. The cylinder head has a hot plug mounting hole 6 opened in the lower surface 4 of the cylinder head at a position close to the partition wall 5.
is formed, and as a result of forming the hot plug mounting hole 6, the intake boat 2. Bulkhead 7 between hot plug mounting holes 6
is formed and the exhaust boat 3. A partition wall 8 is now formed between the hot plug mounting holes 6.

Now, in order to improve the strength of the partition walls 5, 7.8 against thermal stress, the present invention is shown in FIGS. 1, 2, and 2 (a), (b), (c), and (d). As such, the partition wall 5
, 7.8, that is, the lower surface 4 of the cylinder head surrounded by the intake/exhaust valves 2, 3 and the hot plug mounting hole 6.
A recess 9 of a predetermined depth is formed in the surrounding area. Then, capsule powder formed by coating heat-resistant steel powder as a core with ductile metal powder is introduced, and a layer of capsule powder is formed on the inner surface of the recess 9 with a thickness of -. The heat-resistant steel powder and the ductile metal powder constituting the capsule powder are both pulverized using a fine powder pulverizer. Heat-resistant steel powder (Ni, Cr, M
alloy steel with O, Co, and W) has a grain size of 20 to 500 μm.
ductile metal powder (Cu, Cu-based alloy, Aj
, Aj-based alloys) are ground to a particle size of approximately 1710 particles of heat-resistant steel powder. After this, ductile metal powder is added to the heat-resistant steel powder,
For example, by mixing about 30% by weight, the third
As shown in the figure, ductile metal powder 11 is attached to the surface of heat-resistant steel powder 10 to form capsule powder 12.

After that, the ductile metal powder 11 is fixed to the heat-resistant steel powder 10 using a stirrer. As the stirrer, one having rotary blades in the housing and configured to centrifugally transfer the capsule powder 12 along the inner surface of the housing is used.

That is, the capsule powder 12 is mixed with a stirrer at 1,000~
By centrifugally rolling in the range of 7000 rpm, moderate frictional heat is generated at the joint surface of the heat-resistant steel powder 10 and the ductile metal powder 11, and at the same time, the ductile metal powder 11 is transferred to the surface of the heat-resistant steel powder 10 by impact force. The heat-resistant steel powder 10 and the ductile metal powder 11 are fixed to each other by this frictional heat and impact force, and a capsule powder 12 in a perfect form as a fusion welding material is obtained. However, if the material of the cylinder head 1 is aluminum or aluminum alloy, the ductile metal powder 11 is
If the capsule powder 12 is made of J or AJ alloy, and the material of the cylinder head 1 is cast iron, the ductile metal powder 1
A capsule powder 12 in which 1 is Cu or a Cu-based alloy is used. Next, as shown in FIG. 2(B), capsule powder 12 is fused to this layer using ultrasonic fusion welding 1113 such as a magnetostrictive vibrator, and as shown in FIG. A first layer 14 is formed on the surface. Note that the ultrasonic fusion welding unit 1i13 may be provided with a simultaneous supply device 15 for the capsule powder 12 to form a layer in the recess 9 immediately before ultrasonic welding. , capsule powder 12
The heat-resistant steel powder 10 of 100 mL serves as the core material, and the finer the particle size, the easier it is to join. become. In other words, the first layer 14 is formed in which the heat-resistant steel is uniformly diffused in structure.

Next, heat-resistant steel (Ni.

The second layer 16 is formed on the surface of the first layer 14 to a predetermined thickness by overlay welding (alloys such as Cr, Mo, Co, W, etc.) using high-density energy. The filling of this second layer 16 is TIG
, MIG, PT that melts heat-resistant steel powder while injecting it.
In this case, since the ductile metal on the surface of the first layer 14 melts first, the heat-resistant steel of the first layer 14 and the heat-resistant steel of the second layer 16 are used. Next, the second layer 16, which is built up by machining, is finished by fusion welding and the cylinder head 1 is completed.

Therefore, the thermal contraction of the first layer 14 is transferred to the ductile metal of the second layer 16, and thermal cracking is effectively prevented by the absorption of the ductile metal. Therefore, the cylinder head 1 is provided which has high internal toughness, high ductility, and is resistant to thermal cracking.

Next, the case of a piston for a diesel engine will be explained. This type of piston has a cavity 7 as shown in FIG.
48 The hanging tube h around the periphery is thin and thermal cracks are likely to occur there. Therefore, the upper surface of the peripheral side portion is recessed in a stepped manner to form the first layer 14 and the second layer 16. As a result, similar to the cylinder head 1 described above, it is possible to form a lip that is highly tough and ductile and resistant to thermal cracking, resulting in a highly durable piston 19.
can be provided. In the case where the cylinder head 1° piston 19 is made of cast iron, the ductile metal prevents the precipitation of a brittle structure (chill layer (FesC)) and improves reliability against cladding.

(Example 2) First, as shown in FIG. 4(A), a copper alloy powder such as Everdur (95, OCu, 1.O7Mn) was placed in the recess 9.
, 3.48Si, Zn1Tr, 5niTr.

AjiTr) is selected and this copper alloy powder 17 is pre-coated on the surface of the recess 9 to a uniform thickness.

Next, as shown in FIG. 4(b), the copper alloy powder 17 is fused using ultrasonic fusion welding 6113 such as a magnetostrictive vibrator, and as shown in FIG. 4(c), the recess 9 is welded. 0 to form a ductile metal layer 18 on the surface, then on the surface of the ductile metal layer 18,
The first layer 14 is ultrasonically fused using the capsule powder 12, and the second layer 16 is laminated by fusion welding heat-resistant steel on the surface of the second layer 16 using high-density energy.

When the ductile metal layer 18 is formed below the first layer 14 in this way, the ductile metal layer 18
8 and the first layer 14 become more compatible with each other, and the stress caused by the difference in thermal expansion becomes more relaxed.

(Example 3) In the same manner as in Example 2, the cylinder head 1 was placed in the recess.
If the material is aluminum or aluminum alloy casting, select a copper alloy powder such as Everdur and pre-coat the surface of the recess 9 with this copper alloy powder 17 to a uniform thickness.Next, as shown in FIG. As shown in FIG. 4(B), the steel alloy powder 17 is fusion welded using an ultrasonic fusion welding machine 13 such as a magnetostrictive vibrator, and a ductile metal layer is formed on the surface of the recess 9 as shown in FIG. 4(B). 9 then ductile metal Fi forming 18
i! 18, using the capsule powder 12 described above, the first
The layer 14 is ultrasonically welded, the heat-resistant steel powder 10 is ultrasonically welded to the surface of the second layer 16 to form the second layer 16, and a heat-resistant metal is further welded to the surface of the second layer using a high-density energy beam. A third layer (not shown) is formed by melting and overlaying. Third
The layer is formed using TIG, MIG, or PTA in the same manner as in Example 2. In other words, in this third embodiment, the stress caused by the difference in thermal expansion is more finely relaxed.

[Effects of the Invention] As is clear from the above explanation, the present invention exhibits the following excellent effects.

The heat shrinkage stress of the second layer can be reliably absorbed by the first layer,
The durability and reliability of the engine's mechanical elements can be improved.

[Brief explanation of the drawing]

FIG. 1 is a detailed sectional view of the main part of the cylinder head according to the present invention, FIG. 2 is a diagram showing the formation process of the first layer and the second layer, and FIG.
The figure is a schematic cross-sectional view of the capsule powder, Figure 4 is a diagram for explaining another example, Figure 5 is a plan view showing the recess formed in the cylinder head, and Figure 6 is a diagram showing thermal cracks occurring in the cylinder head. The schematic diagram shown, FIG. 7, is a schematic diagram showing a thermal crack in a piston. In the figure, 1 is a cylinder head, 10 is a heat-resistant steel powder, 11 is a ductile metal powder, 12 is a capsule powder, 14 is a first layer, 1
6 is the second layer.

Claims (1)

[Claims] 1. A first layer is formed by ultrasonic fusion welding of capsule powder in which the surface of heat-resistant steel powder is coated with ductile metal powder on the surface of a heat-resistant mechanical element, and a first layer is formed by fusion welding heat-resistant steel onto the surface of the first layer. A heat-resistant mechanical element for an engine characterized by forming two layers.