JPH09111376A - Leadless free cutting copper alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a leadless free cutting Cu alloy maintaining machinability without containing Pb harmful to the human body by adding metal Ca to a Cu-Zn-Sn alloy. SOLUTION: Metal Ca is added to a Cu-Zn-Sn alloy by about >=0.10% Chips generated by machining the alloy are made fine and the objective leadless free cutting Cu alloy maintaining machinability without losing characteristics peculiar to a conventional metal for contact with water or using Pb harmful to the human body is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a free-cutting copper alloy suitable for cutting, which is mainly used as a metal for water contact such as cocks, valves and joint materials of water supply and distribution facilities. The present invention relates to a lead-free free-cutting copper alloy that maintains free-cutting properties without using lead, which has been used as a component.

[0002]

2. Description of the Related Art Free-cutting copper alloys, which have been used as materials for piping materials in water distribution facilities, have been manufactured with 80-90% Cu and 20% Cu.
~ 10% Sn, Zn, Pb as the main material, Ni, Fe, Sb, Al, Si,
JI in which P and the like are compounded and added according to their respective compounding ratios
SBC 1-3 types C and 6-7 types C are mainly used. Especially for water supply related valves and joints, JI
SBC type 6 bronze casting is used.

[0003]

However, since the free-cutting copper alloy is mainly composed of lead (Pb), which is harmful to the human body, it is exposed to water for a long time as a device related to drinking water, so Elution into water is unavoidable.

In particular, free-cutting copper alloys used as materials for equipment related to water distribution facilities must avoid elution of lead components as much as possible in view of water quality standards.

However, JIS specified by the Water Works Association
Pb, which is said to be easily eluted even in BC6 bronze castings
It contains about 5% of
The reality of Pb elution has to be tolerated.

The problem to be solved by the present invention is to use lead (Pb) itself, which has been used as a basic component of free-cutting property and has been considered harmful to the human body in response to the above situations. In other words, the present invention aims to provide a copper alloy that maintains free-cutting properties.

[0007]

According to the present invention, by adding metallic Ca to a Cu-Zn-Sn type alloy, a calcium content that gives free-cutting property to a basic alloy instead of Pb is contained in the alloy. Has succeeded in achieving its purpose.

[0008]

EXAMPLES Examples of the present invention will be described below according to experiments conducted by the applicants.

First, electrolytic copper, brass (C4641), pure Sn, pure Ca
Using as a raw material, an alloy whose main component other than lead corresponds to Japanese Industrial Standard BC6 was prepared according to each sample ratio in Table 1.

The alloy was melted by using a Tammann furnace, deoxidizing the Cu-P alloy, casting it in a sand mold, and analyzing its composition. The chemical composition of the alloy sample and the chemical composition based on the analysis result are shown in "Table 1". The amount of dissolution was about 800 g per sample, and Cu-P alloy was used for deoxidation.

[Table 1]

Optical microstructure observation, Vickers hardness test, and X-ray diffraction test were carried out for each of these samples for the cast state and the annealed state. Further, the machinability was examined for the cutting powder cut by a lathe.

FIG. 1 shows an optical microscope structure of the alloy of sample No. 3 in a cast state. The added Ca most easily binds to P,
As shown by the arrow in Fig. 1, the compound (CaP
Or it is observed as Ca ₃ P ₂ ).

Ca is also Cu, Zn, Sn and the like. Since the compound phase has a tendency to form a compound, the compound phase was examined by X-ray diffraction, but the diffraction peaks of CaP and Ca ₃ P ₂ could not be confirmed, and a diffraction peak believed to be CuCa was observed.

As a result of investigating the relationship between the Vickers hardness of each sample in the cast state and the Ca content, it is observed that the hardness slightly increases as the Ca content increases.

FIG. 2 is a SEM photograph of chips when a cutting test was performed on each alloy in a cast state by a lathe. The cutting conditions were a cutting speed of 1.4 m / s, a cutting depth of 0.2 mm, a tool feed of 0.09 mm / rev, and a cemented carbide tool bit was used for the tool.

FIG. 2a shows an alloy of sample No. 1 in which Ca is not added as a sample for comparison with the present invention. The chips are continuous and have a long spiral shape.

FIG. 2b shows the alloy of sample No. 2, in which the chips have a short spiral shape or spiral spiral shape due to the addition of 0.1Ca.

2c shows the alloy of sample No. 3, in which the Ca content was further increased by the addition of 0.3 Ca, and the chips had a spiral shape or a small shape.

2D shows the chips of the Japanese Industrial Standard BC6 alloy, which are slightly finer in the BC6 alloy than the chips of the alloy of Sample No. 3 with 0.3 Ca added. However, the alloy of Sample No. 2 containing 0.1Ca was found to be sufficient as a chip that is easy to process.

From these experiments, it was confirmed that by adding Ca to lead-free bronze, an effect of finely turning chips by turning can be obtained, and a free-cutting alloy can be obtained without adding lead that is harmful to the human body. I was able to get it.

[0021]

EFFECTS OF THE INVENTION The free-cutting copper alloy according to the present invention does not lose the characteristics of the conventional metal for contacting water, and does not use lead (Pb) itself which has been used as being harmful to the human body. It was possible to obtain a copper alloy that maintains free-cutting properties, and it has a great effect on material utilization.

[Brief description of the drawings]

FIG. 1 is an optical microscope structure photograph of a cast alloy sample No. 3.

2A is an alloy of sample No. 1, which is a SEM photograph of chips of a Ca-free alloy as a comparative sample to the present invention, FIG. 2B is an alloy of Sample No. 2, and FIG. 2C is a sample No. SEM photograph of each chip of alloy No. 3 and FIG. 2D are SEM photographs of chips of Japanese Industrial Standard BC6 alloy.

Claims (1)

[Claims] 1. A lead-free free-cutting copper alloy obtained by adding metallic Ca to a Cu-Zn-Sn alloy.