JP2506476B2 - Free cutting brass - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial field of application" The present invention is widely used for hydraulic parts, machine parts, etc.,
The present invention relates to free-cutting brass having excellent machinability, especially perforation property.

"Prior art" Conventionally, free-cutting brass (for example, JIS C3601 to C3605) in which Pb is added to Cu-Zn alloy is widely used as a material for hydraulic parts such as bearings, gears, screws, valves, and machine parts. Has been done.

"Problems to be solved by the invention" Generally, commercially available free-cutting brass (for example, JIS C36
01-C3605), in order to reduce the manufacturing cost of raw materials, many scraps must be used as raw materials in the manufacturing process, and many impurity elements that are easily mixed in the scraps can be directly used as products. It was brought into the ground brass material.

Of the above impurity elements, the upper limit of Fe and Sn content is specified by JIS standards, etc., but other elements are not specified and processed into products using free-cutting brass materials. In particular, when the drilling work is involved, a significant change in the tool life is recognized, and in the current situation that most of the product processing is processed by the parallel simultaneous processing of automatic machines, the tool change time changes significantly. To be like
When the tools are replaced within a certain period of time, the dimensions of the machined part often cannot meet the required specifications of the product, and a large number of man-hours must be devoted to the dimension inspection of the machined part to prevent product defects. Since it becomes unnecessary, it was desired to present a solution to the problem at an early stage.

An object of the present invention is to solve the above problems and to provide a free-cutting brass which has good machinability, particularly piercing property, and can maintain a long tool life.

[Means for Solving the Problem] As a result of earnest research, the present inventors have found that commonly used free-cutting brass contains Fe, and Si and P coexist with Fe as impurities. If Si and P are
It was found that this compound reacts with Fe to form a compound, and that this compound is one of the causes for shortening the life of the tool, and has reached the present invention described below.

That is, according to the present invention, Cu is 56.0 to 63.0 wt% and Pb is 1.8%.
~ 4.5% by weight, 0.01% by weight or more of Fe, the balance Zn and unavoidable impurities, the content of Si and P is 0.001 each
The problem was solved by disclosing a copper alloy prepared to be less than wt%.

"Operation" The operation of the present invention will be described in detail below.

The present invention limits the Cu content to 56.0 to 63.0% by weight, but in this case, the Cu content is specified to be 56.0% by weight or more because the Cu content is the tensile strength of the material. , Stretch,
In addition, 56.0% by weight or more is necessary to maintain an appropriate hardness, and conversely, if the Cu content exceeds 63.0% by weight, the α phase region in the material increases, This is because the hot workability of the material deteriorates rapidly.

On the other hand, from the economical aspect, it is preferable to keep the amount of copper, which is expensive as a raw material, as small as possible.

Also, although the Pb content is limited to 1.8 to 4.5% by weight,
In this case, Pb is an element necessary for improving the machinability of the material, but if the Pb content is less than 0.8% by weight, the machinability cannot be improved sufficiently. On the contrary, when the Pb content exceeds 4.5% by weight, the hardness of the material increases and the elongation of the material decreases, which weakens the deformability of the material when creating the material. This is because it will end up.

Furthermore, in the present invention, the content of Fe is specified to be 0.01% by weight or more, but although Fe is an elemental impurity, it is almost inevitable when the free-cutting brass targeted by the present invention is dissolved and produced. It is something that is brought into the material, and in the production of free-cutting brass, the presence of Fe cannot be avoided, and it is often associated with other elements contained in free-cutting brass. In addition, since a hard compound dispersed phase is formed, the wear of the machining tools is promoted and the changeover time of the machining tools may vary from tool to tool, which prevents the efficiency of the cutting process. Was there.

However, when the Fe content is less than 0.01% by weight, the possibility that a particularly hard compound dispersed phase is formed is extremely small even in the coexistence state with Si and P, and it becomes This is because the wear phenomenon of tools is extremely reduced.

In the production of the free-cutting brass targeted by the present invention, further, when the Fe content is 0.01% by weight or more, the Si and P contents are less than 0.001% by weight, respectively. In this case, the content of Si or P is specified to be less than 0.001% by weight when the content of Si or P exceeds 0.001% by weight. It is used for material processing due to the presence of a hard compound dispersed phase such as FeSi or FeP formed by the reaction of Si or P with Fe that has been mixed in the raw material of free-cutting brass. This is because the wear of the machining tool becomes severe.

"Examples" Examples of the present invention will be described in detail below.

Example 1 In an air melting furnace, 2990 g of electrolytic copper, 1850 g of electrolytic zinc, 150 g of metallic lead, and 10 g of mild steel thin plate were melted as raw materials to obtain a thickness of 30 mm,
A copper alloy ingot having a width of 100 mm, a length of 150 mm and a weight of 5 kg was melted.

The analytical values of the molten ingot are 60.6% by weight for Cu and 3.
03 wt%, Fe 0.19 wt%, unavoidable impurities and Zn are the balance, Si, which is an unavoidable impurity, is less than 0.001 wt%, and P is also less than 0.001 wt%. there were.

For the ingot melted as above, the entire surface is 2m on the hard side
After chamfering each m, it was hot-rolled at 750 ° C. to obtain a hot-rolled sheet having a thickness of 13 mm. After heating this hot-rolled sheet in a nitrogen gas atmosphere at 450 ° C for 1 hour to anneal the hot-rolled sheet, both surfaces of the hot-rolled sheet were chamfered by 1 mm each, and a test material with a thickness of 11 mm And

In the present invention, as a means for evaluating the piercing property of the test material, the diameter defined by the Japan Tool Industry Association Standard TAS-1103,
We decided to use an unused straight shank drill with 1.0 mm, total length 100 mm, groove length 40 mm.First, in order to measure the initial cutting resistance value of the unused straight shank drill, after attaching this straight shank drill to the NC drilling machine, 2300 revolutions per minute with this straight shank drill and 1
While performing a rotary drilling work with a drilling speed of 0.68 mm per rotation, while making one test hole with a depth of 5 mm in the above test material, the thrust value at the time of drilling the test material AST-BL type instrument manufactured by Kiki Co., Ltd. ", and the depth of the test material is 1 to 4 mm in order to exclude the unstable part of the measured value.
The average value of the thrust values obtained when the holes were drilled was determined, and this average value was used as the initial cutting resistance value of the unused straight shank drill. Then, after mounting the straight shank drill whose initial cutting resistance value of the unused straight shank drill was measured on the NC drilling machine, while giving the straight shank drill 1500 revolutions per minute and a drilling speed of 1.58 mm per revolution. , Depth to the test material
After drilling 5 mm holes, measuring the initial resistance value of the straight shank drill after drilling 500 holes in the same way as measuring the initial cutting resistance value of the unused straight shank drill. The numerical difference between the measured cutting resistance value and the initial cutting resistance value was 0.00 Kg. About the straight shank drill that measured the initial resistance value of the straight shank drill after performing the 500 holes, further 500 holes were drilled for the same test material, and a total of 1000 holes were drilled. The numerical difference between the initial resistance value of the straight shank drill measured later and the initial cutting resistance value was 0.03 Kg. In addition, in the same way as the above-mentioned drilling test, 1000 holes were stacked, and the total
The numerical difference between the cutting resistance value of the straight shank drill measured after making 2000 holes and the initial cutting resistance value is 0.
It was 26 kg.

In each case, the drilling was performed without using cutting oil, and the generated chips were removed by blowing air.

"Example 2" 2900 g of electrolytic copper, 1895 g of electrolytic zinc, 200 g of metallic lead, and 5 g of mild steel thin plate were melted as raw materials in an air melting furnace, and the analysis value of the ingot was 58.0% by weight of Cu and Pb. 4.01% by weight, Fe
0.09% by weight, the balance of unavoidable impurities and Zn, and 0.00% of Si, which is an unavoidable impurity.
The cutting resistance value and the initial cutting resistance of the straight shank drill when the same drilling test as in Example 1 was performed except that the P content was less than 1% by weight and the P content was also less than 0.001% by weight. The numerical differences from the values were 0.01 kg after 500 perforations, 0.03 kg after 1000 perforations, and 0.14 kg after 2000 perforations, respectively.

[Example 3] In an air melting furnace, 3100 g of electrolytic copper, 1795 g of electrolytic zinc, 100 g of metallic lead, and 5 g of mild steel sheet were melted as raw materials, and the analysis value of the ingot was 62.0 wt% Cu and Pb. 2.03% by weight, Fe
0.11% by weight, the balance of unavoidable impurities and Zn, and the unavoidable impurities of Si is 0.00
The cutting resistance value and the initial cutting resistance of the straight shank drill when the same drilling test as in Example 1 was performed except that the P content was less than 1% by weight and the P content was also less than 0.001% by weight. The numerical differences from the values were 0.00 kg after 500 perforations, 0.04 kg after 1000 perforations, and 0.30 kg after 2000 perforations, respectively.

[Example 4] 3000 g of electrolytic copper, 1848 g of electrolytic zinc, 150 g of metallic lead, and 2.5 g of mild steel sheet were melted as raw materials in an air melting furnace, and the analysis value of the ingot was 60.2 wt% Cu. 3.10 wt% Pb, Fe
0.03% by weight, unavoidable impurities and Zn
Is the balance, and Si, which is an unavoidable impurity, is 0.
The cutting resistance value of the straight shank drill and the initial cutting resistance when the same drilling test as in Example 1 was performed except that the treatment was performed so as to be less than 001% by weight and P was also less than 0.001% by weight. The numerical differences from the values were 0.02 Kg after 500 perforations, 0.03 Kg after 1000 perforations, and 0.20 Kg after 2000 perforations, respectively.

"Comparative Example 1" In an air melting furnace, 2988 g of electrolytic copper, 1850 g of electrolytic zinc, 150 g of metallic lead, 10 g of mild steel thin plate, 1.6 g of Cu master alloy containing 15% Si were used as raw materials, and an ingot was analyzed. The content of Cu is 60.2% by weight, Pb is 2.80% by weight, Fe is 0.16% by weight, Si is 0.002% by weight, and inevitable impurities and Zn are the balance and are inevitable impurities. The numerical difference between the cutting resistance value of the straight shank drill and the initial cutting resistance value when the same drilling test as in Example 1 was performed except that P was treated to be less than 0.001% by weight, respectively. ,
0.25 kg after 500 holes, 0.34 kg after 1000 holes, 200
After 0 perforations was 0.46 Kg.

"Comparative Example 2" In an air melting furnace, 2957 g of electrolytic copper, 1850 g of electrolytic zinc, 150 g of metallic lead, 10 g of mild steel sheet, 33.3 g of Cu master alloy containing 15% Si were used as raw materials, and an ingot was analyzed. The content of Cu is 60.0% by weight, Pb is 2.50% by weight, Fe is 0.14% by weight, Si is 0.072% by weight, and unavoidable impurities and Zn are the rest, and are inevitable impurities. The difference between the cutting resistance value of the straight shank drill and the initial cutting resistance value when the same drilling test as in Example 1 was performed, except that P was treated to be less than 0.001% by weight, respectively. ,
0.54 kg after 500 holes, 0.60 kg after 1000 holes, 200
After 0 holes were 0.84 kg.

"Comparative Example 3" In an air melting furnace, 2988 g of electrolytic copper, 1850 g of electrolytic zinc, 150 g of metallic lead, 10 g of mild steel thin plate, 1.7 g of Cu master alloy containing 15% P were melted as raw materials, and an ingot was analyzed. The content of Cu is 60.4% by weight, Pb is 1.91% by weight, Fe is 0.12% by weight, P is 0.003% by weight, and inevitable impurities and Zn are the balance, and are inevitable impurities. The difference between the cutting resistance value of the straight shank drill and the initial cutting resistance value when the same drilling test as in Example 1 was performed, except that Si was treated to be less than 0.001% by weight, respectively. ,
0.19 kg after 500 holes, 0.60 kg after 1000 holes, 200
It was 0.98 Kg after 0 perforations.

“Comparative Example 4” In an air melting furnace, 2983 g of electrolytic copper, 1850 g of electrolytic zinc, 150 g of metallic lead, 10 g of mild steel sheet, 6.7 g of Cu master alloy containing 15% P were melted as raw materials, and an analysis of the ingot was performed. The values are 60.5% by weight of Cu, 2.34% by weight of Pb, 0.10% by weight of Fe and 0.013% by weight of P, and inevitable impurities and Zn are the balance, and are inevitable impurities. The difference between the cutting resistance value of the straight shank drill and the initial cutting resistance value when the same drilling test as in Example 1 was performed, except that Si was treated to be less than 0.001% by weight, respectively. ,
0.21 Kg after 500 perforations, 0.40 Kg after 200 perforations, 200
After 0 holes were 1.02 kg.

[Comparative Example 5] In an air melting furnace, 2957 g of electrolytic copper, 1850 g of electrolytic zinc, 150 g of metallic lead, 10 g of mild steel thin plate, 33.3 g of Cu master alloy containing 15% P were melted as raw materials, and analysis of ingot The content of Cu is 60.5% by weight, Pb is 2.37% by weight, Fe is 0.19% by weight, P is 0.073% by weight, and inevitable impurities and Zn are the balance, and are inevitable impurities. The difference between the cutting resistance value of the straight shank drill and the initial cutting resistance value when the same drilling test as in Example 1 was performed, except that Si was treated to be less than 0.001% by weight, respectively. ,
0.54 kg after 500 holes, 0.72 kg after 1000 holes, 200
After 0 perforations were 1.18 Kg.

As described above, in the case of the present invention, the cutting resistance in the drilling test of the straight shank drill, which has a great relation to the wear of the tool, is remarkably improved as compared with the comparative example.

Incidentally, already disclosed in the examples and comparative examples, each composition of the present invention alloy and comparative alloy, as a result of the perforation test for the alloy of each composition, 500, 1000, 2000 of The cutting resistance value of the straight shank drill for each repeated drilling process is shown in Table 1.

"Effects of the Invention" In the case of the present invention, as is clear from the examples,
Since it has been possible to easily provide free-cutting brass having a low cutting resistance value and excellent machinability, especially piercing property, there is a great contribution to the industry.

Claims (1)

(57) [Claims] 1. A Cu content of 56.0-63.0% by weight, Pb content of 1.8-4.5% by weight, Fe content of 0.01% by weight or more, the balance being Zn and inevitable impurities, and Si and P contents of 0.001 respectively. Free-cutting brass characterized by less than wt%.