JP5552664B1 - Copper alloy casting manufacturing method and briquette used in the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper alloy casting production method capable of producing a high quality copper alloy casting with good workability and low cost by using cutting scraps.
In the process of melting a molten metal, a briquette 3 including an alloy component 2 having a melting point lower than that of copper is contained in the cutting scrap 1 of the copper alloy and is compressed and solidified is submerged in the molten metal 5 and melted. It is characterized by that.
[Selection] Figure 1

Description

  The present invention relates to a method for producing a copper alloy casting, a briquette used in the method, and a copper alloy casting.

  In conventional castings such as brass, lead is added in order to improve machinability and hot water flow, and there is a problem in that lead dissolves when it is put on water and adversely affects the human body and the environment. Therefore, zinc, aluminum, bismuth, or the like is added instead of adding lead (see, for example, Patent Document 1).

In small and medium-sized foundries, ingots that have been pre-adjusted to a predetermined mix are purchased and are rarely melted or cast. Copper alloy scrap (press residue, piping materials, etc.) is used as return material for gates and weirs. , Mixing cutting scraps (also called Dalai powder or Zaray powder) generated when the surface of the casting is cut with a lathe, and lacking components (pure metal, etc.) (adjusting the composition by melting before casting) ). For example, in the case of a brass (Cu—Zn) cast product, to melt 500 kg, about 100 kg of return material, about 200 kg of cutting waste (net brass excluding oil), about 200 kg of brass-based scrap, About 20 kg of pure zinc and about 1 kg of pure aluminum scrap are used. Melting is basically carried out in the order from the one with the highest melting point to the furnace. Below, the casting procedure of a copper alloy casting is shown.
(1) Remaining heat in the furnace (2) Melting return material + scrap (3) Melting cutting waste (4) Removing floating oxides (5) Inputting alloy components such as zinc, aluminum, bismuth (6) Up to casting temperature Temperature rise (7) Degassing, removal (8) Component confirmation (9) Hot water, casting

  FIG. 7 shows the step (3) of melting the cutting waste in the furnace among the above steps. In the figure, 1 is cutting waste, 4 is a crucible, 5 is molten metal, 6 is a heavy oil burner, and 7 is a dust collector. Respectively. When the cutting waste 1 is melted, the heating of the furnace is stopped and the dust collector 7 is stopped. However, the cutting oil adhering to the cutting waste 1 is pyrolyzed or burned to generate smoke and flame. The workability was extremely poor and dangerous. Moreover, since the cutting waste 1 floats on the surface of the molten metal 5 because of its low specific gravity, and the cutting waste 1 is close to normal temperature, the molten metal surface 5a is solidified into a shelf shape, and the portion floating in the shelf shape. To the bottom of the crucible 4 having a high temperature with an iron rod, and the molten metal 5 must be melted while stirring. This operation is dangerous and time-consuming. Further, the cutting waste 1 has problems such as poor heat conductivity and time to be melted, and a large surface area, so that the metal component is consumed due to oxidation before being completely melted. Further, as described above, as the molten metal 5 is stirred with an iron rod or the like, the oxide is caught in the molten metal 5 and cannot be removed even in a subsequent removal process, which causes casting defects. For this reason, most suppliers that cast brass-based materials did not remelt the scraps of brass-based materials themselves and sold them to recyclers at a low price.

  In addition, in the step (4) of adding alloy components such as zinc, aluminum, and bismuth, these components have a melting point lower than that of copper and are easily oxidized, so that the dissolved zinc reacts with oxygen in the molten metal. In addition, there is a risk of rapid sublimation (vaporization), and the molten metal may scatter around the environment, and the added zinc, etc. will be lost by about 10% due to oxidation, etc., so it is necessary to add more zinc etc. in anticipation of that amount And the use of flux to reduce and remove oxides has increased costs.

Japanese Patent No. 3335002

  In view of the above-described circumstances, the present invention uses a cutting scrap to produce a high-quality copper alloy casting with good workability and low cost, a briquette used in this method, and lead The object is to provide a low-cost and high-quality copper alloy casting that does not cause harm.

  In order to achieve the above object, a method for producing a copper alloy casting according to the first aspect of the present invention includes, in the process of melting a molten metal, the cutting waste of the copper alloy includes an alloy component having a melting point lower than that of copper and is compressed. The solidified briquette is melted by being submerged in a molten metal. Examples of the alloy component having a lower melting point than copper include zinc, bismuth, and aluminum. In addition, melting means mixing and melting the materials so as to achieve the target composition, keeping them at an appropriate temperature, and removing necessary gases and non-metallic inclusions in the molten metal to produce a sound casting. Accordingly, it means adding a crystal grain refining material or the like and performing a uniform dispersion treatment.

  The briquette according to a second aspect of the present invention is characterized in that a copper alloy cutting waste includes an alloy component having a melting point lower than that of copper and is compressed and solidified. Examples of the alloy component having a lower melting point than copper include zinc, bismuth, and aluminum. These alloy components are preferably included in the center of the briquette.

The copper alloy casting according to the present invention is a lead-free copper alloy casting containing zinc, bismuth and aluminum, and at least part of zinc, bismuth and aluminum is contained in a briquette made of copper alloy cutting waste. It is characterized by being added by submerging it in a molten metal and melting it. The content of bismuth is preferably 0.4 to 0.8 wt%, but is not limited to this range. The aluminum content is preferably 0.3 to 0.7 wt%, but is not limited to this range. Lead-free means that lead is not particularly added, and may contain lead at the level of impurities.

  According to the first aspect of the present invention, there is provided a method for producing a copper alloy casting, comprising: in a process of melting a molten metal, a briquette obtained by compressing and solidifying a copper alloy cutting scrap containing an alloy component having a melting point lower than that of copper. By submerging and melting, most of the oil contained in the cutting waste is removed in advance, so there is less gas generation due to thermal decomposition of the oil, and the surface area is smaller and the density is lower than the state of the cutting waste. Since it is high, heat conduction is good, and it is melted without touching air at the bottom of the furnace where the temperature is higher than that of the molten metal, so that it can be dissolved in a short time and oxidation can be significantly reduced. In addition, alloy components such as zinc, which has a melting point lower than that of copper, are included in the briquette of cutting waste. Therefore, the oil remaining in the cutting waste previously melted is thermally decomposed in the molten metal to remove copper. In addition to contributing to the acid, it gradually melts in the molten metal whose temperature is somewhat lowered by the latent heat of melting of the cutting waste. It is possible to prevent the oxidation of zinc due to oxygen in the molten metal and the scattering of the molten metal due to the rapid sublimation of the generated zinc oxide, which frequently occur when such as is directly added to the molten metal consisting only of copper. As described above, according to the method of the present invention, workability when melting molten metal is greatly improved, cutting scraps can be used, and loss due to oxidation of alloy elements having a melting point lower than that of copper is small. Since the amount of flux used can be remarkably reduced by suppressing the oxidation, the cost can be reduced. Moreover, since the generation of casting defects due to oxide entrainment can be reduced, the quality of the casting can be improved.

  The briquette according to the second aspect of the present invention includes an alloy component having a melting point lower than that of copper in the cutting scrap of the copper alloy, and is compressed and solidified. Therefore, most of the oil contained in the cutting scrap is removed in advance. Gas generation due to thermal decomposition is small, and the surface area is small and the density is high compared to the state of cutting chips, so heat conduction is good, and this is exposed to air at the furnace bottom where the temperature is higher than the molten metal surface. By melting without oxidization, it can be dissolved in a short time and oxidation can be remarkably reduced. In addition, alloy components such as zinc, which has a melting point lower than that of copper, are included in the briquette of cutting waste. Therefore, the oil remaining in the cutting waste previously melted is thermally decomposed in the molten metal to remove copper. In addition to contributing to the acid, it gradually melts in the molten metal whose temperature is somewhat lowered by the latent heat of melting of the cutting waste. It is possible to prevent the oxidation of zinc due to oxygen in the molten metal and the scattering of the molten metal due to the rapid sublimation of the generated zinc oxide, which frequently occur when such as is directly added to the molten metal consisting only of copper.

Since the copper alloy casting according to the present invention does not contain lead, damage caused by lead can be prevented. By containing bismuth instead of lead, free machinability equivalent to that containing lead can be obtained. Furthermore, containing aluminum together with bismuth has the effect of further improving the hot water flow and improving the casting surface. In addition, when adding zinc, bismuth, and aluminum, at least a part of the zinc is included in a briquette made of copper alloy cutting waste, and this is submerged and melted in the molten metal. Oxidation can be prevented, and high-quality copper alloy castings can be provided at low cost.

It is sectional drawing which shows how to make a briquette. It is a photograph which shows the external appearance of a briquette. It is sectional drawing which shows a mode that a briquette is immersed in a molten metal and it is made to melt. It is a photograph of the tensile test piece of the copper alloy casting created by the method of this invention, and the copper alloy casting created by the conventional method. It is a photograph of the hardness measurement test piece of the copper alloy casting produced by the method of this invention, and the copper alloy casting produced by the conventional method. (A) is a photograph of cutting waste when the copper alloy casting according to the present invention is cut with a lathe, and (b) is a comparative example, and a copper alloy casting containing no lead and bismuth according to a conventional method is cut with a lathe. It is a photograph of the cutting waste at the time. It is sectional drawing which shows a mode when melting the conventional cutting waste.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the method for producing a copper alloy casting according to the present invention, in the process of melting a molten metal, a briquette including an alloy component having a melting point lower than that of copper is included in the cutting scrap of the copper alloy and submerged in the molten metal. It is characterized by melting.
FIG. 1 shows how to make briquettes, in which a cylindrical cylinder is filled with cutting scraps 1 of a copper alloy casting, and an alloy component 2 having a melting point lower than that of copper so as to be located at the center of the cutting scraps 1. For example, zinc, bismuth, aluminum or the like is added. Thereafter, pressure is applied by a hydraulic piston to form a briquette 3 having a shape as shown in FIG. The applied pressure is a pressure exceeding the proof stress of the copper alloy (100 to 200 N / mm ² , depending on the material). Thus, by compressing and solidifying the cutting waste 1 into the briquette 3, the oil contained in the cutting waste 1 and water derived from the water-soluble cutting oil are squeezed out, and the surface area is larger than that of the cutting waste. Since the density is small and the density is high, the thermal conductivity is good, and it is easy to melt.

  As shown in FIG. 3, the briquette 3 manufactured in this way is submerged in the molten metal 5 in the crucible 4 using a phospholyzer 8 and melted without contact with air. As a result, the portion of the cutting waste 1 around the briquette 3 is melted quickly without being oxidized, and oil and water derived from the water-soluble cutting oil are squeezed out to some extent, so that smoke and flame are generated at the time of charging. Can be prevented. Further, the alloy component 2 such as zinc contained in the central portion of the briquette 3 contributes to deoxidation of copper by thermally decomposing the oil remaining in the cutting waste 1 previously melted in the molten metal, and the cutting waste. Since the melt is gradually melted in the molten metal 5 whose temperature is somewhat lowered by the latent heat of melting 1, oxidation of zinc by oxygen in the molten metal, which has frequently occurred when zinc or the like is added directly to the molten metal And the scattering of the molten metal 5 by the rapid sublimation of the produced | generated zinc oxide can be prevented.

An example of actually producing a brass casting by the method of the present invention will be described below. The furnace (crucible) was heated and 150 kg of return material such as a sprue and weir made of brass and 150 kg of brass scrap were put into the furnace and melted. A briquette prepared in advance was submerged in the molten metal using a phosphorizer and melted. Briquette is made of brass casting, 200kg of cutting waste, including zinc 22kg, aluminum 0.7-0.8kg, bismuth 4-5kg, 40 pieces so that one briquette is about 5kg. Then, the product that was compressed and solidified was used.
Processes other than the above were the same as in the conventional manufacturing method, and the floating oxide was removed, degassed and degassed as appropriate, and after confirming the components, the hot water was poured into a mold and cast. Table 1 shows the result of analyzing the components of the cast product.

In addition, a tensile test piece and a hardness measurement test piece were respectively produced from the casting by the method of the present invention and the casting by the conventional method, and the tensile strength, elongation and hardness were measured. The measurement results are shown in Table 2. FIG. 4 is a photograph of each tensile test piece (No. 4 test piece defined in JIS), and FIG. 5 is a photograph of each hardness measurement test piece.

  As is apparent from Table 2, it can be seen that the tensile strength and the elongation according to the present invention are greatly improved as compared with the conventional method. This is clear from the fact that the test piece of the casting according to the present invention is stretched and narrowed in the photograph of FIG. . There was no difference in hardness between the present invention and the conventional method. However, as shown in FIG. 5, the conventional method had defects 9 due to oxide entrainment reaching the surface. Such defects were not observed in the present invention.

  FIG. 6 (a) is a photograph of cutting waste when a lead-free copper alloy casting containing bismuth and aluminum according to the present invention is cut with a lathe, and FIG. 6 (b) is a lead / bismuth obtained by a conventional method as a comparative example. It is the photograph of the cutting waste when the copper alloy casting which does not contain is cut with a lathe. As is apparent from this photograph, the cutting waste of the comparative example curls in a spiral shape and is long, whereas the cutting waste of the present invention is short, and it is understood that the cutting performance is good.

Next, when aluminum is poured into the molten copper alloy as it is, and when the aluminum is included in the briquette of cutting scraps, this is submerged and melted in the molten metal. The following experiment verified how the amount of molten aluminum changes.
First, 0.85 kg of aluminum was put into a 460 kg molten metal as it was and melted. Next, 0.982 kg of aluminum contained in 40 kg of cutting scrap briquette was submerged in the melt and melted. Before injecting aluminum, after injecting aluminum as it is, and after injecting aluminum contained in a briquette of cutting scraps, each of the ingots is made by drawing in molten metal little by little. The amount of aluminum contained in was analyzed. The analysis results are shown in Table 3.

As shown in Table 3, the yield was about 60% when aluminum was introduced as it was, while the yield was greatly improved to about 95% when aluminum was included in the briquette of cutting waste. did. As is clear from this result, aluminum that is easily oxidized can be melted with good yield by including aluminum in the briquette of cutting waste and melting it.
Although aluminum is described here, the same can be said for other components such as zinc and bismuth.

  As described above, the cutting waste is compressed and solidified into briquettes, submerged in the molten metal and melted, so that gas and flames at the time of charging can be prevented and oxidation can be prevented quickly. Was able to be dissolved. In addition, for low melting point additive elements such as zinc, there is little loss due to oxidation during melting, whereas in the conventional melting method, it was necessary to add 10 to 70% of the target content and melt In the method of the present invention, it was confirmed that an increase of about 2.5 to 5% is sufficient. Since the generation of gas and oxides can be suppressed, the amount of flux used is significantly reduced. Furthermore, according to the conventional method, the rate of occurrence of casting defects such as cracks due to oxide entrainment was about 25%, whereas according to the method of the present invention, the occurrence of casting defects such as cracks due to oxide entrainment occurred. The rate could be reduced to almost 0%. In addition, by adding bismuth instead of adding lead, it is possible to obtain good hot water flow and free-cutting properties while preventing lead from melting and adversely affecting the human body. Furthermore, the addition of aluminum has the effect of further improving the hot water flow and improving the casting surface.

  The present invention is not limited to the embodiments described above. The alloy component to be included in the briquette of cutting waste may be only one of zinc, bismuth, and aluminum, or may be plural. Further, alloy components other than zinc, bismuth and aluminum may be included in the briquette. The present invention can be applied to any copper alloy, and can be used not only for brass but also for bronze, white copper, and the like. The copper alloy casting of the present invention can be applied to all castings including copperware and Buddhist tools.

DESCRIPTION OF SYMBOLS 1 Cutting waste 2 Alloy component whose melting point is lower than copper 3 Briquette 4 Crucible 5 Molten metal

Claims (2)

  In the process of melting a molten metal, a briquette containing an alloy component whose melting point is lower than that of copper is included in the cutting scrap of the copper alloy and is melted by submerging in the molten metal. Production method.   A briquette characterized in that an alloy component having a melting point lower than that of copper is included in the cutting scrap of the copper alloy and is solidified by compression.