JPS5836042B2 - Dougou Kinno Setsusakusetupuno Ryoushita Dougou Kinsei Hin no Seizouhou - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a method of manufacturing copper alloy sintered parts and forged parts using copper alloy cutting chips and other scraps generated in large quantities mainly from machine factories. .

There are two methods of manufacturing various parts using bronze or brass materials: methods of using powder and forming it by forging or other methods, and methods of manufacturing ingots by plastic processing, cutting, grinding, etc. be.

Of these, most of the powders used for powder compacting of steel alloys are mixtures and alloy powders (atomized powder), which are copper powder (electrolytic powder or atomized powder) mixed with tin powder or zinc powder, etc.
However, the reality is that these powders are expensive to process, approximately twice as expensive as the base metal.

On the other hand, machining of welded materials generates a large amount of chips, but conventionally these powders are recovered as scrap at less than half the cost of bare metal, and then remelted and used for forging and casting materials. It wasn't too much.

The present invention was created as a result of repeated research and experiments in view of the above-mentioned circumstances, and it is based on the fact that copper alloy chips are inexpensive and available in large quantities, and that copper alloys are highly ductile. We focused on the fact that it has a lot of hard materials, good formability, and poor bonding (entanglement) between chips.
Copper alloy chips, which were conventionally treated as scrap, can be used directly as a powder molding material without being remelted and sintered or forged, allowing mass production of various copper alloy products at extremely low cost. It is something.

In other words, according to the present invention, copper, which is an important resource, can be used effectively, and the cost of raw materials can be drastically reduced compared to copper alloy products made using conventional powder metallurgy, resulting in a significant reduction in product costs. Moreover, due to the above-mentioned properties of the copper alloy, peeling on the outer periphery can be extremely reduced, resulting in a product with good dimensions and shape. Since hot forging can be carried out, it is also possible to omit the intermediate sintering step, thereby also reducing the product cost.

However, the basic feature of the present invention is that a compacted powder or shaped body is made from bronze or brass cutting chips, either as they are or crushed into an appropriate size and shape, and this is used in the case of bronze. In the case of brass, sintering is carried out at a temperature of 840 to 1080 DEG C. and a temperature that partially produces a liquid phase, and in the case of brass, a temperature of 900 to 960 DEG C. and a temperature that partially produces a liquid phase.

Further, the second feature of the present invention is that the brass sintered crystal or pre-consolidated powder compact obtained as described above is heated to 850 to 95
It is forged by heating to 0°C and at a temperature that partially produces a liquid phase.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings.The present invention uses cutting chips generated from a machine factory as a raw material for producing copper alloy products, and this is its basic feature.

Here, the cutting chips of the copper alloy used are lathes, drilling machines,
Anything produced from various machine tools such as milling machines or grinding machines may be used.

The chips may be used in the state described in 11 above, but if the chips have a low apparent density, such as in a large shape or in a continuous state, the chips should be of an appropriate size and shape to be filled into the die during molding. It should be crushed or cut into pieces.

The photograph in FIG. 1 shows chips generated from a lathe (single-function machine) as an example of chips used in the method of the present invention.

In addition, if chips are caused by oxidation during dry cutting, work hardening, or oils and fats caused by the use of oil such as cutting oil, heat treatment such as reduction treatment or annealing, or degreasing treatment should be applied to the chips. should be kept.

Although a single type of chips may be used, powders or chips of different metals may be used in combination to improve formability during compaction, sinterability, forging formability, material quality, etc. Of course this is true.

Therefore, the next step of the present invention is a step of obtaining a sintered product using the above-mentioned chips as a raw material, and a step of forging the sintered product or unsintered compacted powder or shaped body obtained in this step. The process involves compacting the chips and then heating and sintering them at a specific temperature in an atmosphere.

1. The latter is a step of hot or warm forging to form the chips into a pellet powder, and a step of sintering or heating the unsintered pellet in an IT atmosphere or air to a specific temperature range; This process consists of forging a heated pillet into a desired shape by hot extrusion, drawing, rolling, die forging, or other methods.

In addition, in the sintering process, sizing,
Coining and resintering steps may be performed, and in the first forging step, depending on the shape and other factors, reheating and forging may be performed after forging, or heat treatment may be performed.

To explain the above steps in detail, the present invention first uses the above-mentioned chips to produce a compacted powder body as a pellet for sintering or forging.

This method uses a die 2 and a punch 3 as shown in FIGS. Then, as shown in FIG. 2, the chips 1 are filled into a die 2 and cold compressed into a desired shape by a punch 3 to form a green compact.

The shape of the compacted powder body 4 should be almost the same as the product shape, but when shaped as a forging pillet,
It is formed into a cylinder, cylinder or other simple shape.

Figure 10 is an actual photograph of a compacted powder compact (pillet for forging) formed using brass-based cutting chips as a raw material, and Figure 11 is an actual photograph of a compacted compact formed using bronze-based cutting chips. be.

In the present invention, the powder compact 4 obtained in the above step is then sintered, but the sintering heating temperature must be within a specific range in this step.

That is, the temperature varies depending on the material and composition of the cutting chips used, but when used as a raw material for bronze-based cutting chips, that is, when it generally contains 5 to 15 parts of Sn, the temperature is 840.
~1080℃ range, in the case of brass, that is, generally Zn
If the temperature is 30 to 45 degrees Celsius, the temperature should be in the range of 900 to 960°C.

These temperatures are generally 50°C or more higher than the sintering heating temperature used in powder metallurgy, and a feature of the present invention is that sintering is performed at high temperatures and within a specific temperature range. be.

In other words, when sintering bronze with conventional powder, the common method is to melt tin, which has a low melting point, and perform liquid phase sintering, and the sintering heating temperature is 7.
This is carried out in the range of 50 to 820°C, but according to the inventor's study, when cutting chips are used as raw materials, solid phase sintering occurs in this temperature range, and the sintering rate is lower than that of powder. There is little condensation and the strength does not increase.

Therefore, in the present invention, sintering is performed within a temperature range in which a partial liquid phase is generated. Sintering is carried out at 900-960°C in a brass system, that is, with a Zn content of 30-45.

As a result, alloying between chips can be accurately achieved, and sintered crystals having the same strength as when using powder can be obtained.

Regarding brass, when a low melting point metal such as lead is added to the mother powder made of yellow lead, the sintering temperature naturally decreases as in general alloying.

The heating atmosphere in the sintering process should be a reducing atmosphere such as hydrogen, and the heating time, preheating, and cooling conditions should be appropriately set depending on the material and the state of the chips.

FIG. 12 shows an example of a product obtained by sintering the powder compact shown in FIG. 11 in the above heating temperature range.

As described above, after this step, sizing, coining, and resintering may be performed to obtain the final product in order to correct the process precision and homogenize the material as necessary.

The above is the basic aspect of the present invention, but the present invention is not limited to such a method. In particular, when the raw material is brass-based chips, a compacted powder body as a pellet is made and this is sintered in the above temperature range. As mentioned above, it also includes a mode in which the product is manufactured by hot or warm forging after 1 or 11 hot or warm forging without sintering.

However, when performing such hot forging, 1
First, the powder compact 4 is preheated, and the heating temperature at this time needs to be particularly within the range of 850 to 950°C.

This is one special feature of the present invention.

That is, when hot forging normally ingot material, 700-85
Although this is done in the range of about 0°C, the inventors have investigated that it is possible to perform the heating accurately when the raw material is cutting chips at this temperature.The heating temperature is higher than usual, In particular, it is preferable to set the heating temperature in the range of 850 to 950° C. This allows a partially molten state to be formed, which facilitates alloying, thereby eliminating residual pores.

Although it is preferable to perform the above-mentioned heating in an atmosphere, forging is possible even in the atmosphere, and the heating time is extremely short compared to heating for sintering. Although it depends on the shape, approximately 5 to 20 minutes is sufficient, and under these conditions, the powder compact (pillet for forging) can be heated almost uniformly, and forging by direct extrusion, drawing, rolling, and die forging is possible. becomes.

Next, we move on to the process of forging the preheated compact, but since copper alloy has the property of easily causing plastic deformation, it is necessary to use a material with higher density and strength. It is advantageous to increase the amount of plastic deformation.

That is, for example, when forging a copper alloy gear according to the present invention, first a step is taken to obtain a cylindrical forged body from a cylindrical pillar by a method similar to backward extrusion, and then this cylindrical forged body is It is preferable to use a step of forging the gear into a desired shape.

This increases the amount of plastic deformation, promotes the compression and alloying of chips, and makes it possible to achieve a state that is almost close to true density, except for some residual pores on the skin surface.

The specific die forging process is described in Figures 4 to 6.
In the steps shown in FIGS. 4 to 6, the heated billet 4 is placed on the lower mold 5 configured into the desired shape, and the upper mold 8 and the inner punch 7 are By lowering the pellet 4 to compress and plastically deform it, a forged body 6 having a desired shape as shown in FIG. 6 is obtained.

In this case, it is possible to adopt a closed method, but in order to increase the amount of plastic deformation and reduce residual pores, it is advantageous to use a method that exposes holes and increases the forging flow.

However, if the product shape is relatively simple and high strength is not required, it is possible to make a forged product using this process alone, but if the product has a complex shape or is made of a stronger material, Alternatively, the shape of the mold may be changed as shown in FIGS. 7 to 9, and the heating and forging steps may be repeated again to produce the final product.

In FIGS. 7 to 9, 6' is the rough material obtained in the above process, and the rough material 6' is placed in a lower mold 9 formed into a desired final shape (for example, a gear), and then placed in an upper mold 10. Then, the inner bunch 11 is lowered to compress and plastically deform the rough material 6', and the forged product 12 as shown in FIG.
This is what you take out.

Note that the forging method of the present invention is not limited to die forging as described above, and various forging methods such as extrusion, drawing, and rolling can be used.

1.Of course, the shape of the product is not limited to those with a particular tooth weight, but can also include cylindrical bodies, cup-shaped bodies, columnar bodies,
It can be a plate-shaped body, etc.

Next, specific examples of the present invention will be shown.

Example 1 (I) A sintered product was manufactured according to the present invention using bronze chips.

(II) The chips are cutting chips (Cu-1
o%Sn-5%Pb) was pulverized to a size in the range of 10 to 45 mesh.

The intended manufacturing shapes are a cylindrical body with an outer diameter of 39φ and a height of 27 m, and a ring-shaped body with an outer diameter of 46φ, an inner diameter of 32φ and a height of 10 mm.

During manufacturing, the die is filled with cutting chips as shown in Figure 2, and the die and punch are coated with zinc stearate in advance to obtain a density of about 7.8f/cIIL3, about 6Ton/cIrL2. Pressure was applied.

Next, the obtained compacted powder body was heated and sintered at a temperature of 870°C for 1 hour in a hydrogen atmosphere flow in an electric furnace with a bushing set.
Before and after sintering and heating, the product was preheated and cooled for 30 minutes each in the same furnace.

The obtained product is as shown in FIG.

ω However, the inventors obtained products by using the same materials as above and changing the sintering heating temperature conditions to 840°C and 760°C, and from each product, JSPM with a surface area of 7 crrL2 was obtained.
A standard Sarel tensile test piece was prepared on 2-64, and a tensile strength test was conducted.

The results are shown in FIG. 13.

As is clear from FIG. 13, when the heating temperature range of the present invention is used, a strength of K9/9 is obtained.

In other words, SKM type 11 (Cu-10%Sn
According to this standard, the density is 6.8f/crrL3
tensile strength 10k9/III2 or more, density 7.2f/c
In the case of rrL3, the tensile strength is 1 5 k97 mm2 or more.

However, when the above-mentioned bronze cutting powder is sintered as a raw material, the sintering temperature is 87%, as is clear from Fig. 13.
It can be seen that at 0°C, the strength is comparable to that of powdered products.

Note that the mechanical strength is inferior to those of the above standards at temperatures below 840°C, but because it contains lead, it is a substitute for products used in powder metallurgy as porous materials such as bearings. It is quite possible.

Here, the reason why the strength deteriorated at 840 degrees Celsius is due to the inclusion of lead, which helps improve the formability of the cutting chips, and the shape of the chips, which are used as raw materials for powder metallurgy. This is much larger than the particle size of the powder, so the contact area between chips is smaller than that between powder particles, and the effect is that the sintered part is reduced overall.

However, the cutting chips generated from bronze-based materials have low ductility and are brittle, so they are relatively easy to crush.
It is possible to create a finer shape than in the case of this example, and it is also possible to generate a liquid phase and sinter it by mixing tin or other metal powder or chips with bronze chips. Because of this, it is relatively easy to improve the strength, and sufficient strength can be obtained by heating and sintering at 840° C. or higher.

Even taking these steps into consideration, it is clear that it is more advantageous to use the cutting powder of the present invention as a raw material than to use the bronze powder used in conventional powder metallurgy.

Example 2 (1) A forged product was manufactured using cutting chips of a high-strength brass material as a raw material.

(II) High-strength brass-based cutting chips (composition of Cu-34%Zn-2%AI 3%Mn-other impurities) generated in a lathe (see Figure 1) were used as chips. .

The product and its shape are boss outer diameter 58φ, gear outer diameter 72.5
φ, height 12 mm, number of teeth 27, pitch circle diameter 67 mtx.
It is a gear with a cam angle of 30 degrees and a tooth thickness of 4.5 million millimeters.

The forging process for final product 1 was a hot forging double-strike forming method.

As for the pellet, the one having the shape of Example 1 was compacted in exactly the same process as in the same Example, and the density at that time was 6.6.
-6.7fl-/cIrL3.

Preheating was carried out in the atmosphere at 870°C for 10 minutes, and then the heated cylindrical pellet was forged for the first time using the backward extrusion method as shown in Figures 4 to 6. A plate-shaped primary forged body was obtained.

The forging force at this time was 6 to 7 Ton A1rL2, and a 150 Ton 7-rection press was used as the press.

The primary forged body had an outer diameter of 57φ, an inner diameter of 48φ, and a height of 23 m.

Next, the bottom and top edges were removed to form a cylindrical rough material (outer diameter 57φ, inner diameter 48φ, height 21mm) as shown in Figure 15.
This material was heated to 870 DEG C. for 10 minutes in the air in the same manner as the primary forging, and secondary forging was performed at a forging pressure of 6 to 7 T/am2 using the molds shown in FIGS. 7 to 9.

In addition, the punch, upper die, and lower die are thoroughly coated with graphite as a lubricant for both the primary and secondary parts, and the die is pre-lubricated with a lubricant of 150 to 250 lubricant before forging.
heated to ℃.

What was obtained by secondary forging is as shown in Fig. 16,
Unnecessary particles generated around the inner diameter and teeth were removed from this product to obtain a final product.

Figure 17 shows this final product. ml In order to examine the mechanical properties of the above-mentioned product, a certain amount of ingot material was used for the primary forging, and it was forged into the same size and shape using the same process as the present invention, and the radial crushing strength and hardness tests were conducted. I did it.

The results are shown in Table 1 when compared with this example.

Note that the radial crushing strength test is a test in which a cylindrical sample is radially crushed using a universal testing machine and the load at which it breaks is measured.

As is clear from Table 1, it can be seen that according to the present invention, almost the same strength can be obtained as compared to a forged product made of ingot material.

The cross-sectional microstructure of the forged product obtained according to the present invention is shown in FIG. 18 (center portion) and FIG. 19 (surface portion).

As is clear from this, according to the method of the present invention, there are almost no residual pores, and sufficient compression and alloying are achieved.
It can be seen that this primary forging state of No. 11 can exhibit sufficient material performance, but if secondary forging is performed using this primary forging as crude material, the material stability and strength can be improved. Therefore, it is clear that a material suitable for forging ingots can be obtained.

In order to obtain such high strength, it is important to keep the heating temperature within the range of the present invention and increase the amount of plastic deformation to improve the pressure bond between chips.

As described above, according to the present invention, copper alloy cutting chips, which were conventionally treated as scrap, are effectively utilized,
This invention is industrially very effective because it has the characteristic of being able to obtain fortune-telling sandals and other products of different materials and shapes at extremely low costs.

[Brief explanation of drawings]

Fig. 1 is a photograph substituted for a drawing showing an example of copper alloy cutting powder, which is the raw material used in the method of the present invention. Figs. 2 and 3 show the step-by-step process of compacting the cutting powder to obtain a green compact. 4 to 6 are cross-sectional explanatory views showing step-by-step the process of forging a pellet obtained by solid powder forming to obtain a forged body, and FIGS. 7 to 9 are sectional views shown in FIG. 6. The crude material obtained in
A cross-sectional explanatory diagram showing step by step the next forging process. Figure 10 is a photograph of a billet formed using brass cutting chips as raw material in the steps shown in Figures 2 and 3. Figure 11 is a photograph of a billet formed using brass cutting chips as raw material in the steps shown in Figures 2 and 3. Figure 12 is a photograph of the sample molded in the process shown in Figures 2 and 3 using cutting chips.
Figure 13 is a graph showing the tensile test results of bronze cutting chips heated and sintered at 780°C, 840°C, and 870°C, respectively.
Photograph of the forged body obtained by forging the pillet shown in the figure, No. 15
The figure is a photograph of a sample obtained by machining the sample obtained in Fig. 14 into a cylindrical rough material, and Fig. 16 is a photograph of a forged body obtained by hot forging the sample in Fig. 15 (C type 2). Figure 17 is a photograph partially showing the final product obtained by processing the forged body in Figure 16, Figures 18 to 15 are photographs showing the microscopic ridges at the center of the cross section of the sample. (X400) and FIG. 19 is a photograph (×100) showing the microstructure on the surface side.

Claims (1)

[Scope of Claims] 1. A powder molded body is made from bronze or brass cutting chips crushed into l1 or an appropriate size shape, and the powder molded body is made of 840 mm in the case of bronze. ~1080℃
A method for producing a copper alloy product using cutting chips of a copper alloy, characterized in that, in the case of brass, sintering is performed within a heating temperature range of 900 to 960° C. and at a temperature that partially generates a liquid phase. 2. A powder compact is made using brass cutting powder (Part 11) or a blowing powder crushed into an appropriate size shape as a raw material, and this is sintered at a heating temperature of 900 to 960°C and at a temperature that partially generates a liquid phase. or unsintered 1850-950℃
A method for producing copper alloy products using copper alloy cutting chips, which is characterized by heating and forging to a temperature range that partially generates a liquid phase.