JPS62251411A - Manufacture of valve lifter for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve wearing resistance, by using a sintered alloy, in which double boride particles containing Fe are dispersed in a stainless system combined phase, for the sliding part of a valve lifter, which slides on a cam shaft, and forming a surface hardening processed layer on a part excepting the sliding part. CONSTITUTION:A valve lifter 1 is provided between a cam shaft and intake and exhaust valves sliding on the cam shaft, and the upper surface of the valve lifter 1, sliding with the cam shaft, provides a layer 3 integrally forming a sintered alloy in which hard quality particles, consisting of double boride of one or more kinds of boride forming element such as Mo, W, Cr, Ti, V, Co containing Fe, are uniformly dispersed in a combined phase of martensite system and stainless steel system. After the whole unit of said valve lifter applies surface hardening treatment, a surface hardened layer is removed from the layer 3, and the valve lifter is manufactured by polishing a surface of the layer 3 removing said hardened layer.

Description

[Detailed Description of the Invention] t9. [Objective of the invention] (Industrial application field) This invention relates to valve train parts J#l of internal combustion engines for automobiles.
−f 4dim :t j'1. A /< Jl/
F137jJ -L Ijl + X 4 /7'l
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(Prior art) In recent years, the high performance and maintenance-free design of IL has progressed, and as a result, the friction between the pulp lifter and the camshaft, which is used as a valve mechanism part of an internal combustion engine, has increased.
For some parts, the required sliding characteristics have become even more stringent.

Conventionally, this type of valve lifter has no sliding contact with the camshaft! It has a structure in which 11 parts are integrally formed (for example, Nl5SAN service bulletin IV (Japanese 56th year l)
θ Monthly issue No. 446, p. 31), the materials used for the sliding parts of such valve lifters with the camshaft are those that corrode the surface of machine structural alloy steels such as JISSCM materials and SCr materials. Those that were subjected to charcoal quenching and tempering treatment, or those that integrated a carbide-dispersed iron-based sintered alloy thin plate with the valve lifter body were used.

(The problem that IJIJ is trying to solve) However, with conventional valve lifters, the wear resistance of the valve lifter itself is not satisfactory or the camshaft is aggressive to the mating material. There remained the problem that the

(Purpose of the Invention) This invention was made in view of these conventional problems. We provide a valve lifter for internal combustion engines that has a moving part (crown part) and has excellent wear resistance because the desired parts other than the part that slides with the camshaft (crown part) are surface hardened. It is intended to.

[Structure of the Invention] (First Step to Solve the Problems) The method of manufacturing a valve lifter for four internal combustion engines according to the present invention is such that the sliding part of the valve lifter with the camshaft is joined to martensitic stainless steel. Mo, W, Cr, and Ti containing Fe in the phase.

Kouga grains consisting of complex borides of boride-forming elements such as V and Co, more preferably 1I31 with a grain size of 10 gm or more! Quality particles - more than 9! Preferably 40 in weight ratio
As a sintered alloy having a structure uniformly dispersed by ~58%, the complex boride-based sintered alloy is more preferably integrated with a valve lifter body made of mechanical structural (alloy) steel,
Next, surface hardening treatment, 9! Preferably, after carrying out a surface hardening treatment that combines carburizing treatment or carbonitriding treatment and quenching and tempering treatment, the surface hardening layer of the complex boride-based sintered alloy portion described in +iiij, which forms the sliding part with the camshaft, L. In the more desirable case described above, the soaked iR layer or the carbonitrided layer is removed and the surface is polished so that the surface roughness Rmaxl is more preferably 2 pm or less. By making the sliding part of the sintered alloy a sintered alloy having a structure in which hard grains E made of complex boride are uniformly dispersed as shown in L, the wear resistance J The present invention is characterized in that it attempts to solve the problems listed in item Iij by making full use of the strong bonding strength between the stainless steel binder phase and the complex boride.

This invention will be explained in more detail below.

In the method for manufacturing a valve lifter for an internal combustion engine according to the present invention, the sintered alloy used for the sliding part of the pulp lifter has a structure in which hard particles made of complex boride are uniformly dispersed in a stainless steel binder phase. It is something. In this case, the FIP particles.

Mo containing Fe, W, Cr, T i,
It is formed from a complex boride containing any one of boride-forming elements such as V and Go.

There are various forms of complex borides, such as MxNyBz (M and N are metals), but especially Mo.
2FeB2 type, WFeB type and W7FeBP
It is more preferable that the mold is mainly made of complex boride because the transverse rupture strength and hardness become stably high.
2FeB type 2.

For complex borides of W Fe B type or W2FeB2 type, Mo and W are mutual and Fe is Cr.

Partial substitution with Ni and Co also gives good results.Fe and MO are used as boride-forming elements.

The reason for selecting W, Cr, Ti, V, Co, etc. will be described.

Fe is characterized by the fact that this Fe-containing complex boride exhibits higher hardness and toughness, and by adding appropriate amounts of Cr and Ni, the binder phase is made of martensitic stainless steel and exhibits excellent corrosion resistance. Since complex borides are industrially easily obtainable and inexpensive, the sintered alloy used for the sliding part of the valve lifter according to the present invention has the following properties: 1. It is more preferable to include as much as possible within the range.

Mo and W are elements of the Via group in the periodic table.

All of them form highly hard complex borides, especially the above-mentioned Mo
2Fen2 type, W Fe B type and W, FeB2
This is an element necessary to form a type of complex boride. Furthermore, Mo and W have a remarkable effect on the transverse rupture strength, wear resistance, and corrosion resistance of the binder phase.

Cr a) It is a 5-year old compound that forms a definite complex boride.

In particular, when Cr is added to hard particles, the corrosion resistance of the hard particles can be significantly improved. Further, Cr is an element that is strongly desired to be added in order to combine with Fe in the binder phase and improve the corrosion resistance of the binder phase based on stainless steel.

Ti is an element of group 1lla in the periodic table, and ■ is an element of group Va in the periodic table, both of which are the aforementioned MO2FeB2 type and W.
MO of complex borides of F e B type and W2FeB2 type
Alternatively, it is substituted with W, and is alloyed in the binder phase, which not only increases the hardness but also has the effect of preventing coarsening of crystal grains during liquid phase sintering. Zr and Hf belong to the same 1ira group, and Nb belongs to the same Va group as ■.

Ta and the like can also be expected to have the same effects as Ti and V, respectively.

CO is an element that forms a stable complex boride, and when added to hard particles, it has the effect of improving wear resistance. In particular, as mentioned above, this Co is Mo2FeB2 type,
The effect is wJ'A when Fe is substituted with the -- part of W Fe B type and W2FeB2 type complex borides.

・Addition of B which combines with the above-mentioned Gensu to form a complex boride: As for 11, if this B addition 11Y is too small, 1 For example, if it is less than 3 ton 1%, hard particles - is too small, for example, the weight ratio of ;I, 11 of hard particles t is less than 40%, resulting in insufficient wear resistance and L
Note B: When the amount added is too large 1 For example, if it exceeds 4.8%, the proportion of the binder phase is insufficient, and the proportion of hard particles exceeds 5°8% by weight, resulting in a decrease in transverse rupture strength. Not only will the impact value be lowered, but it will also increase the amount of wear on the camshaft, which is the mating material, so adding B should be
It is particularly preferable that the proportion of hard particles be 4.8% by weight, and it is particularly preferable that the proportion of hard particles be 40 to 58% by weight, and it is especially preferable that the proportion of hard particles be within the above range. When I did.

Since it has a good balance between wear resistance, conformability, transverse rupture strength, and impact value, it is the most preferable characteristic for the sliding part of the valve lifter camshaft.

On the other hand, if the particle size of the hard particles made of complex boride is too large, for example, in a state exceeding lOILmt-, the complex boride will aggregate, resulting in an unrestricted distribution and increasing variations in hardness. As a result, not only mechanical properties such as transverse rupture strength and impact value but also abrasion resistance deteriorate, so that the particle size of the hard particles made of complex boride is particularly preferably 10 mm or less.

One of the characteristics of the sintered alloy forming the sliding part of the valve lifter according to the present invention is that the bonding phase is made of stainless steel. This stainless steel matrix has a strong bond with the hard phase, complex boride, and not only has high corrosion resistance, but also has the great advantage of being extremely inexpensive compared to Co-based or N12Jli bonded phases. .

Furthermore, among stainless steels, martensitic stainless steels have particularly excellent properties as a sliding member as a binder phase. This is because when the binder phase is austenitic or ferritic stainless steel, the adhesiveness of the binder phase increases, and as a result, the amount of wear on the interfering material and itself increases. This is because the martensitic stainless steel binder phase has low adhesion and exhibits excellent conformability. In addition, Ni to the bonding phase
If the content is too much and becomes austenitic, the adhesion will increase as mentioned above, which is undesirable. The larger the amount, the better the corrosion resistance of the binder phase, which is preferable.

Furthermore, it is particularly preferable that the hardness of the bonding alloy forming the sliding part is HRA 80 or higher. This is because if the hardness is less than HRA 80, local scuffing will occur, and this will progress and cause self-scruffing. This is because the amount of wear on both the mating materials increases significantly. On the other hand, if the hardness becomes too large, for example exceeding HRA86, the amount of wear of the camshaft, which is a compensating material, will increase, so it is particularly preferable to set the hardness to HRA86 as the L limit.

Furthermore, if the transverse rupture strength of the sintered alloy forming the sliding part is less than 175 kgf/mm', pitting tends to occur and the amount of wear tends to increase. It is particularly preferable that the transverse rupture force is 175 kgf/mm2 or more, and this transverse rupture force is 175 kgf/mm2 or more.
When the value is less than f/mm', pitting and wear tend to increase. What to do when the surface pressure on the moving parts is high?
J:A.

Furthermore, if the roughness of the surface of the sliding part in contact with the camshaft is too large, the amount of wear on the camshaft, which is the phase f material, will increase, so the surface roughness should be Rmax l.
, 24 m or less is particularly preferable.

In order to integrate the above-mentioned sintered alloy in which hard particles made of complex boride are uniformly dispersed in the martensitic stainless steel binder phase with the valve lifter body, this sintered alloy is formed into a thin plate and is used in the valve lifter body. It is preferable that the valve lifter is integrated with the main body, and the valve lifter main body that is integrated with the sintered metal thin plate is made of cold forged moatable steel 1.
For example, it is particularly preferable to use (alloy) n4 for mechanical structures.

This is because the R method for manufacturing the raw material for the valve lifter body is a method of cold forging to form the rough material.
This is because, in addition to being the most suitable in terms of material yield and production speed, a certain degree of hardness is required for the portion of the valve lifter body that comes into contact with the sintered alloy thin plate. In other words, if the hardness of the part of the valve lifter main body that contacts the sintered alloy thin plate is low, local buckling will occur at the part that contacts the sintered alloy thin plate during use, and this will cause cracks in the sintered alloy thin plate. Furthermore, due to repeated stress, buckling progresses and the shape exceeds the allowable shape for a valve liter, causing problems in valve operation. Therefore, the hardness of the portion of the valve lifter main body in contact with the sintered alloy thin plate that is necessary to prevent such buckling is determined by the surface pressure applied to the valve lifter, the thickness of the sintered alloy thin plate, and the hardness. Although it varies depending on transverse rupture force, etc., if the valve lifter body is made of machine structural (alloy) steel, cold forging is possible, and at the same time,
By heat treatment after carburizing or carbonitriding, which will be described later, it is possible to stably obtain hardness that does not pose problems in practical use.

In addition, if the thickness of the boride-based sintered alloy thin plate, which is preferably made into a thin plate in order to be integrated with the valve lifter main body, is too thin, for example, if it is less than 0.2 mm, then the sintered alloy If the surface pressure applied to the thin plate is too high, the amount of wear on the camshaft will increase due to elastic deformation of the valve lifter body, or fine cracks will occur in the sintered alloy thin plate during use, which is undesirable.On the other hand, if the plate is too thick, 1 For example, if the thickness exceeds 0.8 mm, the cost will increase and there will be no particular effect in terms of wear resistance, so it is particularly preferable to set the thickness to 0.2 to 0.8 mm.

The boride-based sintered alloy thin plate and the 7-help lifter body can be integrated by the following method.

That is, a molded body of a boride-based sintered alloy thin plate is fitted around a valve lifter with a button λh4+f='Hb, +fii
;'+! , heating at a temperature lower than the melting point of the valve lifter body to liquid-phase sinter the formed body of the boride-based sintered alloy thin plate and at the same time unite it with the valve lifter body. The temperature during this liquid phase sintering varies depending on the composition of the boride-based sintered alloy thin plate, but is generally 1150 to 1350°C.

By the way, this type of valve lifter is required to have a certain degree of wear resistance not only on the part that slides on the camshaft, but also on the outer circumferential surface of the valve lifter body and the sliding surface on the internal plunger. If the mechanical structural (alloy) steel is used as it is, it may cause increased wear or adhesion, so it is necessary to perform surface hardening treatment to improve wear resistance.

There are various R methods for this surface hardening treatment, but gas carburizing or carbonitriding is the most preferred in consideration of the required characteristics of the valve lifter as well as efficiency and stability in actual production.

This is because gas nitriding requires an extremely long treatment time to leave a certain degree of hardened layer depth even after polishing after heat treatment, which will be described later. In carburizing and carbonitriding, there are problems with pollution, and because the valve lifter has a complicated shape, it not only takes 7 hours to completely remove the adhered salt bath, but also only a small portion of the salt bath is removed. However, this is not very preferable because the salt bath components may remain and corrode the valve lifter.

In addition, hydraulic valve lifters not only receive high hydraulic pressure from the inside, but also are required to be lighter (thinner) than other machines, so after surface hardening, quenching and tempering are applied to increase strength. It is particularly desirable to increase the hardness as much as possible, and the quenching and tempering conditions may be those for structural steel (H steel) that guarantees normal hardenability.

After this quenching and tempering treatment, finishing polishing is performed to correct the damage caused by the surface hardening treatment and heat treatment. The finishing polishing allowance is usually 0.15 to 0.2 mm for the sliding part with the camshaft (lifter crown surface), and about 0.2 to 0.4 mm in diameter for the lifter outer peripheral surface.

Here, for a valve lifter in which the carburized or carbonitrided layer depth of the sintered alloy part of the sliding part with the camshaft is 0.3 mm, the surface of the sintered alloy part is polished by 0.15 mm to remove heat treatment distortion. When we conducted a durability test on a vehicle with one that was polished to 0.5 mm and one that had the carburized or carbonitrided parts redundantly removed, we found that, contrary to our initial expectations, it was polished by 0.5 mm ωF. Carburizing or soaking) Rf effect? It was found that the amount of wear was much smaller when the J part was completely removed. As a result of various investigations into the reasons for this, we found that carbon or nitrogen diffuses into a binder phase similar to stainless steel during carburizing or N)R'M, resulting in excessive precipitation of carbides or nitrides, resulting in the formation of complex borides. The proportion of the binder phase that binds the parts decreases, resulting in a lower bonding force, and when that part is subjected to sliding under high surface pressure, hard particles are more likely to fall off, accelerating wear. 'Ml! Flt.

From the above, in order to prevent a decrease in wear resistance of the sliding part of the valve lifter with the camshaft due to surface hardening treatment 1, for example, carburizing or carbonitriding treatment, the surface of the sliding part with the camshaft must be Hardened layers, such as carburized or carbonitrided layers, must be removed by grinding.

If the thickness of the carburized or carbonitrided layer on the sliding part of the valve lifter with the camshaft is within the machining allowance after heat treatment, it will inevitably be removed during machining. This is advantageous because there is no need to remove the abrasive material, which saves time and resources. However, if the carburized or carbonitrided layer on the sliding part of the valve lifter mentioned in 1iii. ! The carburized or carbonitrided layer on the outer peripheral surface of the valve lifter body, which requires high U properties, becomes thinner, and the carbonitrided layer may be removed during preparation for casting straightening after heat treatment. , resulting in insufficient wear resistance.

Therefore, the inventors investigated the material of the cam of the valve lifter,
As a result of various tests conducted while changing the carburizing or carbonitriding treatment conditions, the thickness of the carburized or carbonitrided layer before cutting of the boride-based sintered alloy part was 0.05 to 0.
If it is within the range of 15 mm, there is no need to polish or remove the sliding part of the valve lifter with the camshaft more than necessary, and other parts where wear resistance is required, such as the outer periphery of the valve lifter. It was found that a carburized or carbonitrided layer remained even after finishing, and the wear resistance satisfied the 1-minute performance requirement.

This is the friction with the camshaft! There is a difference in the rate of formation of the immersion R or carbonitrided layer between the boride-based sintered alloy that forms part of the valve lifter and the machine structural (alloy) steel that forms the valve lifter body. For (alloy),
Steel forms an immersion 1R or carbonitrided layer that is about 4 to 20 times thicker, so on the outer periphery of the valve lifter, the finish 1 after heat treatment; 1 - Processing allowance is about 0.2 to 0.4 mm in diameter) 1 minute thick! J LLI * S1,11+Table S+! , breath f
J A-&v%h()l2norr:l f1. %
S4- )h 慴*,ru.

However, if the thickness of the carburized or carbonitrided layer before JuJi of the sintered alloy part is too small, for example 0.
If the thickness is less than 0.5 mm, the thickness of the carburized or carbonitrided layer in areas where wear resistance is required, such as the outer periphery of the valve lifter, is too thin, and the carburized or carbonitrided layer is sometimes removed. This is not preferable because it results in insufficient wear resistance.

On the other hand, if the thickness of the carburized or carbonitrided layer before the sintered alloy part is too thick, for example 0.15 m.
If it exceeds m, it is not preferable because it only increases the amount of grinding of the sintered alloy part during finishing and does not have a particularly favorable effect on the wear resistance of other parts.

The carburizing or carbonitriding treatment conditions may be those generally used for machine structural (alloy) steel, but the treatment temperature may be changed from the viewpoint of shortening the treatment time.
900-930℃ for carburizing, 850-88℃ for carbonitriding
About 0°C is more preferable.

('Example) Embodiments of the present invention will now be described.

First, the ni and do parts of the valve lifter body 2 of the valve lifter 1 shown in the attached diagram are made of JIS alloy steel for mechanical structure.
30M415 material is made into raw materials and cold forged separately to create the pre-rough material.Next, each processed material is cut into an approximate shape by cutting, and then the parts of the valve lifter body 2 are made. A molded body of boride-based sintered alloy thin plate 3 is set on the side crown surface.

This molded body of the boride-based sintered alloy thin plate 3 is made of Fe-Cr produced by water or gas atomization as a poron source.
- Using B-based alloy powder, this powder and Fe, Mo, W, C
Metal powders of R, Ti, V, Co, and Ni, or alloy powders containing these two, and carbon powder are adjusted and mixed to have the chemical composition shown in Table 1, and these mixed powders are milled in a vibrating ball mill. After wet pulverization in an organic solvent using a hat, drying and granulation are performed, and a pressing force of 1500 to 2000 kg is applied.
f/cm2 to obtain a compact density ratio of 45 to 50% as shown in Table 1, and further molded at 1100% in vacuum.
After pre-firing with 'O', the thickness was made to 0.8 mm using a cutting knife.

Next, a pre-sintered body of a boride-based sintered alloy thin plate 3 which has been pre-sintered and cut as described in E is set on the crown surface of one part side of the valve lifter main body 2, and is heated in a vacuum furnace. By liquid-phase sintering the formed body of the boride-based sintered alloy thin plate 3 at the sintering temperature shown in Table 1 and at the same time metallurgically bonding it to the L side crown surface of the valve lifter main body 2, In addition, for boride with the specifications shown in ljl,,L! The liquid-phase sintered strip 1 of the molded body of the boride-based sintered alloy plate 3 has a temperature of 1150 to 3500C, depending on its chemical composition, etc. Heating for 15 to 90 minutes is particularly preferred. That is, the sintering temperature is 1150°
At temperatures below C, sintering does not proceed for 1 minute, resulting in a sintered body with many pores, and 1350°C? : If it exceeds this, the crystal grains will become coarser, resulting in a low transverse rupture strength. Moreover, if the sintering time is less than 15 minutes, the metallurgical bond between the boride-based sintered alloy f, b plate 3 and the valve lifter body 2 will not last for 1 minute,
This is due to the fact that even after 90 minutes, no strong bulge was observed.

In this way, a valve lifter incorporating a thin boride-based sintered alloy sheet 3 having the specifications shown in Table 2 was installed on the side of the main body 2, and
9J cutting after cold forging ■ After combining the two-shaped IE valve lifter and the do part side of the main body 2 and joining the boundary part by welding, +If to remove the unevenness after welding and the welding/r casting. Cutting is performed to make a carburized or carbonitrided surface roughening material.

Next, the assembled material is subjected to carburizing or carbonitriding treatment. In this case, the carburizing or carbonitriding treatment conditions are: gas carburizing or gas iR nitriding, the carburizing temperature is 930°C, the U carbonitriding temperature is 880'C, and the treatment time is changed to As shown in Table 2, the thickness of the carburized or carbonitrided layer of the sintered alloy (thin plate 3) is 0.
03mm, 0.07mm, 0.10mm, 0.13mm
, 0.15 mm, and 0.30 mm.

Next, 850-880℃ after immersion 1 or carbonitriding treatment.
Tempering treatment is performed by oil cooling and quenching, and then air cooling from 150 to 200°C.

Thereafter, the valve lifter main body 2 was manufactured by grinding in the order of outer diameter → crown surface → inner diameter. As shown in Table 2, the polishing allowance in this case is 0.15 mm for the crown surface (8 degrees of sliding with the camshaft).
(However, excluding N006), the diameter of the outer circumference and inner circumference was required to be 0.3 mm. In addition, for those with a carburized or immersed nitrided layer of 0.3 mm on the crown surface, in addition to final polishing of 0, 15 mm (No, l l), final polishing of 0, 40 mm (No, 6), carburizing or carbonitriding. A prototype was also produced in which all of the layers were removed.

The valve lifter main body 2, which has been assembled in this way, and the separately manufactured outer plunger 4, inner plunger 5. Stopper 6, return spring 7, pole 8
．． A 9° pole spring retainer 10 was assembled to form a hydraulic valve lifter 1, which was assembled into an actual engine and subjected to durability evaluation under the conditions shown in Table 3. This result is the fourth
Table 3: Valve Lifter Abrasion Evaluation Conditions As is clear from Tables 1, 2 and 4, in this example, valve lifters No. 1 to 6 had the following conditions:
Hard? No. 7 pulp lifter with a small proportion of particles, No. 8 pulp lifter with a large proportion of hard particles,
No. 9 has a large particle size of hard particles, No. 9 has a bulb litter, and No. has a large surface roughness on the crown surface.

No. 10 pulp lifter, No. 1 pulp lifter with a carbonitrided layer remaining on the surface of the crown surface, No. 1 pulp lifter, No. 1 pulp lifter where the bonding phase is ferritic stainless steel, No. 13 pulp lifter and the bonding phase is austenitic stainless steel. Compared to the No. 14 pulp lifter, the valve lifter has significantly less camshaft friction (Lt, H), and has excellent wear resistance and resistance to matching materials. It was confirmed that it has less aggressive characteristics. In addition, as in pulp lifter No. 12, where the layer depth is too small in the immersion before finishing, the sliding part between the lifter main body 2 and the outer plunger 4 may be damaged. ! There was no problem with the JL becoming larger.

The results of the wear resistance evaluation under the conditions shown in 3'N are shown in the fifth section.
Shown in the table.

Table 5 Comparison of wear amount by each pulp lifter of the present invention and the conventional example As shown in Table 5, the pulp lifter of the present invention (No.

It can be seen that the wear and tear of 1.1 has decreased.

Incidentally, in the following embodiments, a valve lifter for a gasoline engine has been described.

The valve lifter manufactured according to the present invention can of course be applied to valve lifters for other engine specifications.

L15i! ! 1. As explained above, according to method A of the valve lifter for an internal combustion engine according to the present invention, the sliding part with the camshaft is made of martensitic stainless steel. Mo, W containing Fe in the phase.

As a sintered alloy in which boride-forming elements such as Cr, Ti, V, Co, etc. - hard particles made of the complex boride of the insert 1 - are evenly dispersed, the complex boride-based sintered alloy and the valve lifter are used. After integrating the main body and subjecting it to a surface hardening treatment, the surface hardening layer of the complex boride sintered alloy part that forms the sliding part with the camshaft is removed and the surface is polished. (- Eliminate the adverse effects of the surface hardening layer formed on the surface of the boride-based sintered alloy, and make full use of the excellent wear resistance and conformability unique to the boride-based sintered alloy. This means i + J function, which means that the two mouth molecules have excellent wear resistance. Since the outer diameter parts other than the sliding part (crown part) with the camshaft are surface hardened, we are able to provide a valve lifter for internal combustion engines that has excellent wear resistance in this part. has excellent effects.

[Brief explanation of drawings]

The drawing is an explanatory cross-sectional view of a valve lifter for an internal combustion engine manufactured in an embodiment of the present invention. 1...Valve lifter, 2...Valve lifter body, 3...Boride-based sintered alloy (thin plate).

Claims (1)

[Claims] (1) The sliding part with the camshaft is made of martensitic stainless steel with Fe containing Fe in the binder phase, W, Cr, etc.
Integrating the complex boride-based sintered alloy and the valve lifter body into a sintered alloy in which hard particles made of one or more complex borides of boride-forming elements such as Ti, V, and Co are uniformly dispersed; A method for producing a valve lifter for an internal combustion engine, which comprises performing a surface hardening treatment, then removing the surface hardening layer of the complex boride sintered alloy portion that forms the sliding part with the camshaft, and polishing the surface. .