JPH0551607A - Manufacturing method of powder forged gear made of Al-Si alloy with homogeneous material - Google Patents

Abstract

(57) [Summary] [Purpose] A with a homogenous material and a dense tooth profile.
A powder forged gear made of 1-Si alloy is manufactured. [Composition] A powder forged gear made of Al-Si alloy is composed of a press-molded body of rapidly solidified Al-Si alloy powder.
Hot forging is performed on a green compact having a theoretical density ratio of ˜85% to form a plate-shaped forged chip material having a theoretical density ratio of 99% or more, which is hot punched from the forged chip material. It is manufactured by cutting out a punched gear material having a tooth profile and subjecting the gear material to heat treatment and chamfering other than the tooth profile.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a rapidly solidified Al-Si alloy powder as a raw material and utilizes hot forging and hot punching to make a tooth profile surface materially uniform and dense. The present invention relates to a method for manufacturing.

[0002]

2. Description of the Related Art Conventionally, for example, a gear of a rotary gear pump is
As illustrated in the schematic plan view of FIG. 2, it comprises a pair of driving gear P and driven gear P ', and among these gears, the driving gear P is, for example, the method described in Japanese Patent Laid-Open No. 2-16988. As shown in the schematic perspective view in FIG. 3, in the cavity of the forging die 1A having the toothed surface 1a on the side surface,
A tablet-shaped green compact T having a theoretical density ratio of 65 to 85%, which is a press-molded body of rapidly solidified Al-Si alloy powder, is charged, and a tooth surface 1b corresponding to the tooth surface of the die is placed therein. It is also known that hot forging is performed by the forging punch 1B to form a tooth profile and densify to a theoretical density ratio of 95% or more.

[0003]

However, in the Al-Si alloy powder forged gear manufactured by the above-mentioned conventional method, during the hot forging process, the material of the outer surface of the green compact forming the tooth profile is changed. Since the flow is extremely small and stagnates at the same time as the formation of the tooth profile, densification of the tooth profile and inter-powder bonding are not performed sufficiently, and the material non-uniformity is significant compared to the center of the gear. is the current situation.

[0004]

Therefore, the present inventors have
From the above viewpoint, the tooth profile surface is dense and sound A
As a result of conducting research to produce a powder forged gear made of 1-Si alloy, firstly, a compact having a theoretical density ratio of 65 to 85%, which is a press-molded body of rapidly solidified Al-Si alloy powder, Hot forging is performed to form a plate-shaped forged chip material having a theoretical density ratio of 99% or more, and then a punched gear material having a tooth profile is cut out from this forged chip material by hot punching. Al-S manufactured by heat-treating and chamfering for dimensioning other than tooth profile
The powder-forged gear made of i-based alloy has 99% or more in theoretical density ratio in both the tooth profile and the central part, and is dense and homogeneous in material,
We obtained the research result that the tooth profile can be practically used as it is.

The present invention has been made based on the above-mentioned research results, and a compact having a theoretical density ratio of 65 to 85%, which is made of a press-molded body of rapidly solidified Al-Si alloy powder, Hot forging is performed to form a plate-shaped forged chip material having a theoretical density ratio of 99% or more, and a punched gear material having a tooth profile is cut out from the above forged chip material by hot punching to obtain the above gear material. By heat treatment and chamfering other than the tooth profile surface, Al-Si which is homogeneous in material quality
The method is characterized by a method for producing a powder-forged gear made of a system alloy.

In carrying out the method of the present invention, the rapidly solidified Al-Si alloy powder is in a weight percentage (hereinafter,% relating to the composition of the component represents weight percentage), Si: 12 to 30%, Fe and Ni. One or two of them: 1-10%,
In addition, if necessary, Cu: 1 to 5%, Mg: 0.3 to 2%, one or two of, and a balance of Al and inevitable impurities, and , A particle size of -30 + 350 mesh formed by gas atomization is desirable.

In this case, the Si component has a function of improving wear resistance, and therefore, if the content of Si component is less than 12%, desired excellent wear resistance cannot be secured,
On the other hand, if the content exceeds 30%, the strength will decrease, so the content was made 12 to 30%.

The Fe and Ni components include Al and S.
It forms an intermetallic compound with i to improve heat resistance, high temperature strength and wear resistance, but its content is 1
If the content is less than 10%, the desired effect cannot be obtained, while if the content exceeds 10%, the toughness decreases, so the content is preferably 1 to 10%.

Further, since the Cu and Mg components have the effect of further improving the strength by the aging effect, they are contained as necessary, but their contents are Cu:
If it is less than 1% and Mg: less than 0.3%, the desired strength-improving effect cannot be obtained, while the content is Cu: 5 respectively.
% And Mg: 2%, the toughness decreases, so the contents are Cu: 1 to 5%,
Mg: 0.3 to 2% is preferable.

Regarding the powder particle size, the particle size is -30 to +3 by gas atomization using an inert gas or air.
When the mesh size is 50 mesh, the primary crystal Si in the powder becomes fine particles of 10 μm or less and is uniformly dispersed in the matrix by the rapid solidification by atomization, and the refinement of Si in the powder causes the forged gear to have high strength. It has excellent wear resistance.

Similarly, if the theoretical density ratio of the green compact is less than 65%, the powder is liable to be damaged during handling. On the other hand, if the value exceeds 85%, gas such as water vapor or air existing inside is likely to occur. Since it becomes difficult to remove, it is preferable to set it to 65 to 85%.

Similarly, the hot forging is preferably performed at a predetermined temperature in the range of 300 ° C. or higher, preferably the recrystallization temperature of the powder or higher, and the liquidus formation temperature or lower, whereby sufficient densification is achieved. It becomes possible to manufacture a forged gear having a theoretical density ratio of 95% or more.

Further, it is preferable that the hot punching process is carried out at the same temperature as the hot forging process temperature, which is higher or lower than the above temperature range.
This is because it is difficult to form a tooth profile surface with high dimensional accuracy due to deformation or the like.

Next, the method of the present invention will be specifically described with reference to examples. As raw material powders, Al-Si alloy powders A to F each having the composition shown in Table 1 and a particle size of -30 + 350 mesh by rapid solidification by air atomization were used, and 1% of zinc stearate was added to each of them. And then mixed at a predetermined pressure within the range of 3 to 5 ton / cm ² and the tablet has a theoretical density ratio shown in Table 2 and a press-formed product having a diameter of 100 mm and a height of 16 mm. After forming a green compact and performing roasting at a temperature of 350 ° C. for 2 hours in a nitrogen atmosphere, the green compact T is treated as shown in the schematic process diagram of FIG.
It is charged into the cavity of the forging die 2A, hot forged by the forging punch 2B at the same temperature as shown in Table 2, and the theoretical density ratio shown in Table 2 (the theoretical density ratio of the driving gear Same as the above), a plate-shaped forged chip material W having a diameter of 105 mm is formed, and this forged chip material W is subsequently charged into a step portion formed at the upper end portion following the tooth profile surface of the punching die 3A. Similarly, at the temperature shown in Table 2, the punching gear material is cut out by hot punching with a punching punch 3B having a toothed surface on the outer surface, and finally the gear material is cut into the atmosphere at a temperature of 170 ° C. The method of the present invention 1 to
6 was carried out, and in all cases, the tip diameter: 85 mm × the root diameter: 70 mm
× Thickness: A drive gear P having a dimension of 12 mm was manufactured.

[0015]

[Table 1]

[0016]

[Table 2]

For the purpose of comparison, the hot forging process and the hot stamping process shown in FIG. 1 are not performed, and instead, the tooth profile 1 is formed in the cavity as shown in FIG.
Conventional methods 1 to 6 were carried out under the same conditions except that hot forging was performed using the forging die 1A having the a formed thereon and the forging punch 1B having the toothed surface 1b on the outer peripheral surface to manufacture the drive gear.

Then, the theoretical density ratio of each of the various drive gears obtained as a result was measured, and the hardness (Rockwell hardness B scale) of 10 points on the tooth profile was also measured. The values, minimum value and average value are shown in Tables 2 and 3.

[0019]

[Table 3]

[0020]

As is apparent from the results shown in Tables 2 and 3, the drive gears manufactured by the methods 1 to 6 of the present invention all have a theoretical density ratio of 99% or more and have a hardness on the tooth profile. Has a very small variation and a relatively high hardness, which means that the tooth profile is dense and uniform, and a sound tooth surface is formed, while the conventional methods 1 to 6 are used. All of the drive gears have large variations in hardness on the tooth profile and relatively low hardness.As a result, it is shown that many holes are present in the tooth profile. This unhealthy tooth profile surface must be removed.

As mentioned above, according to the method of the present invention,
It is possible to form a tooth profile surface that is homogenous and dense and has high dimensional accuracy in the as-punched state without substantially requiring machining of the tooth profile surface. Al-Si that can be used practically on tooth profile
It is possible to manufacture a powder forged gear made of a system alloy.

[Brief description of drawings]

FIG. 1 is a schematic process diagram showing an embodiment of the method of the present invention.

FIG. 2 is a schematic plan view showing gears of a rotary gear pump.

FIG. 3 is a schematic perspective view showing a conventional method.

[Explanation of symbols]

 1A, 2A Forging die 1B, 2B Forging punch 3A Punching die 3B Punching punch T Compact powder W Forged chip material P Drive gear

Claims (5)

[Claims] 1. A green compact having a theoretical density ratio of 65 to 85% made of a press-molded body of rapidly solidified Al-Si alloy powder is subjected to hot forging to obtain a theoretical density ratio of 99% or more. Forming a plate-shaped forged chip material having, cutting out a punched gear material having a tooth profile from the above forged chip material by hot punching, and subjecting the gear material to heat treatment and chamfering other than the tooth profile Method for producing a powder forged gear made of Al-Si based alloy which is homogeneous in nature. 2. The rapidly solidified Al-Si alloy powder is, by weight%, Si: 12 to 30%, one or two of Fe and Ni: 1 to 10%,
The method for producing a powder forged gear made of a materially homogeneous Al-Si alloy as set forth in claim 1, characterized in that it has a composition containing Al and unavoidable impurities. 3. The rapidly solidified Al-Si alloy powder is, by weight%, Si: 12 to 30%, one or two of Fe and Ni: 1 to 10%,
And further containing 1: 1 of Cu: 1 to 5% and Mg: 0.3 to 2%.
The method for producing a powder forged gear made of a material-homogeneous Al-Si alloy according to claim 1, characterized in that the material has a composition containing one or two kinds and the balance is Al and inevitable impurities. 4. The rapidly solidified Al-Si alloy powder is formed by gas atomization and has a particle size of -30 + 350 mesh.
Alternatively, the method for producing a powder forged gear made of Al-Si alloy which is homogeneous in terms of material as described in 3 above. 5. The hot forging and hot punching are
The material-homogeneous Al-Si alloy powder forging according to claim 1, which is performed at a predetermined temperature in the range of 300 ° C or higher or the recrystallization temperature of the powder or higher and the liquid phase formation temperature or lower. Gear manufacturing method.