JPS63203742A - Aluminum alloy for dat drum - Google Patents

Abstract

PURPOSE:To develop an Al alloy having superior wear resistance, friction characteristic, machinability, and forgeability and suitable for drum for digital audio tape recorder, by incorporating specific amounts of Si, Cu, Mg, or further at least one element among Sn, Pb, and Bi to Al. CONSTITUTION:An Al alloy which has a composition containing, by weight, 14-25% Si, 0.5-5.0% Cu, and 0.3-3.0% Mg of further containing one or more kinds among 0.2-2.0% Sn, 0.2-2.0% Pb, and 0.2-2.0% Bi is refined and then cooled rapidly at >=10<2> deg.C/sec cooling rate so as to be formed into an Al-alloy powder in which the average grain size of Si grains and the average distance among Si grains are regulated to 0.3-3.5mum and <=10mum, respectively. This powder is subjected to heating and vacuum degassing and then to hot pressing so as to be formed into a drum. In this way, the lightweight drum for digital audio tape recorder excellent in wear resistance, machinability and forgeability and reduced in friction coefficient can be obtained.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an aluminum alloy having high rI4 wear and friction properties and excellent machinability and forgeability for use in drums of DAT (digital audio tape recorders). .

[Prior Art] In a DAT, a magnetic tape rotates and runs around a drum to perform recording and reproduction. Therefore, the drum material is required to have the following properties.

(a) Non-magnetic: Since the magnetic tape comes into contact with it, it must be non-magnetic.

(b) Conductivity: Conductivity is necessary to prevent charging.

(C) Lightweight: Because it rotates at high speed, it must be lightweight.

(d) Abrasion resistance: If the drum is worn out, accurate recording and reproduction cannot be performed, so abrasion resistance is necessary. In particular, DAT uses metal tape or vapor-deposited tape, so a high degree of abrasion resistance is required.

(e) The coefficient of friction is small and stable: If the coefficient of friction with the tape is large, the tension applied to the tape becomes large, making accurate recording and reproduction impossible. Therefore, the coefficient of friction must be small and stable. Particularly in the case of DAT, metal tape or vapor-deposited tape is used, and these tapes have a higher friction coefficient than iron oxide tape, and the friction coefficient tends to increase with running time, so the drum material is Advanced friction properties are required.

Cf) Machinability: In order to finish the drum with high precision, it must have good machinability and low finished surface roughness.

((J) 111 Formability: It may be formed by cold forging, and in that case, forgeability is required.

Conventionally, in order to meet these various demands, various aluminum alloys (221B, 4032, A 390, etc.) have been tested for application.

[Problems to be Solved by the Invention] Among the conventional materials described above, there is no material that satisfies all of the above-mentioned characteristics. Especially wear resistance, stability of friction coefficient, and machinability.
There is no material that satisfies all these properties at the same time. That is, in the case of 2218 alloy, the machinability is good, but the wear resistance is poor and the coefficient of friction is also somewhat large. 40 with approximately 12% Si added
In the case of 32 alloy, the wear resistance is considerably improved, and the coefficient of friction,
Although the machinability is good, it is still not sufficient as a DAT material. In the case of A390 alloy containing approximately 17% Sl, the wear resistance is good, but the coarse Si particles cause chipping and wear of the cutting tool, and the roughness of the finished surface becomes rough. In addition, the friction coefficient is large and unstable.

The present invention provides a material suitable for a DAT drum that satisfies the above-mentioned characteristics.

[Means for solving the problems] The present invention uses Si: 14 to 25% and Cu: 0.5% based on Shigenobu standards.
~5.0%, Mg: 0.3~3.0%, or further 3n: 0.2~2.0%, Pb: 0.2~
2.0% and [Si: 0.2 to 2.0%, and the remaining unavoidable impurities and Al, the average particle size of Si particles is 0.3 to 3.5 μm1 DA characterized by an average interparticle distance of 10 μm or less
This is an aluminum alloy for T drums.

The reasons for adding each component in the above composition are as follows.

Si: Improves wear resistance. This wear resistance is exhibited when the Si particle diameter is appropriately large, as will be described later.

Furthermore, Si also has the effect of lowering the coefficient of friction. If the Si content is less than 14%, wear resistance is insufficient. On the other hand, if 5iffl exceeds 25%, the 81 particles tend to become large, which increases the coefficient of friction and also makes it unstable (the coefficient of friction increases with running time). Furthermore, cold forgeability becomes poor.

Cu: Cu coexists with MCI to impart age hardenability and improve hardness and wear resistance. If it is less than the lower limit, this effect will not be sufficient, and if it exceeds the upper limit, workability and ductility will decrease.

Mg: Coexists with Cu to impart age hardenability and improve hardness and wear resistance. If it is less than the lower limit, this effect will not be sufficient, and if it exceeds the upper limit, workability and ductility will decrease.

3n, Pb, B i : Improves machinability (chip disposal properties) and makes it suitable for precision machining. If it is less than the lower limit, the effect will not be sufficient, and if it exceeds the upper limit, forgeability and ductility will decrease.

The limitations on the average particle diameter of Si particles and the distance between particles are as follows.

Average particle size of Si particles: If it is less than 0.3 μm, wear resistance is poor. If it exceeds 3.5 μm, the friction coefficient becomes large, and the friction coefficient increases with running time.

If the average interparticle distance of Si particles exceeds 10 μm, the surface roughness after cutting will become rough and uneven, and the coefficient of friction with the tape will increase.

The aluminum alloy material according to the present invention can be manufactured according to various manufacturing methods in order to provide the above-specified average particle size and average interparticle distance of Si particles in the above-mentioned alloy composition, but generally, the following methods can be used: It is desirable to make WA using the following method.

That is, first, an aluminum alloy having the invention alloy composition is melted, and then the obtained molten metal is rapidly solidified.

The cooling rate at this time is set to 102° C./S or more in order to make the average particle size of the Si particles fine. Generally, the cooling rate is 1
If 02~b is used, an appropriate average particle size and average interparticle distance of 81 particles will be obtained. It is also possible to use a powder manufacturing method in which the cooling rate exceeds 104°C/S, such as a single roll method, twin roll method, or splat cooling method, but in this case, the average particle size of the Si particles becomes too small. , in any powder molding process, such as vacuum degassing process, hot press process, extrusion process or HIP process, or heat treatment process, heat to 350 to 550'C to grow Si particles to an average size of 0.3 μm or more. It is necessary.

1 q of powder thus obtained is molded into an aluminum alloy material for a drum. Specifically, (a) precompression - container filling - heating vacuum degassing - extrusion, (b) precompression - container filling - heating vacuum degassing - hot press, (C) precompression - container filling - heating vacuum degassing - hot press. Container removal - extrusion, (d) Pre-compression - container filling - heating vacuum degassing -
Molding is performed through steps such as HIP (high temperature isostatic pressing) and (e) precompression-heating-extrusion. More specifically, in step (a), the aluminum alloy powder is pre-compressed to about 60-90% of its true density, then sealed in a predetermined container and heated at 300-550°C, preferably 350-550°C.
Heat to 20°C, evacuate, and degas. If the heating temperature during degassing is less than 300° C., degassing will be insufficient, causing problems such as blistering in the final product and remaining defects due to gas. When the heating temperature exceeds 550℃, Si
This should be avoided as it will cause the particles to grow and become coarse. Furthermore, if the temperature exceeds 520° C., Si particles tend to grow and become coarse, so care must be taken not to make the heating time too long.

Next, the pre-pressure inspection product (billet) that has been subjected to degassing treatment is
Extrusion is carried out by heating to a temperature of 00 to 520°C. If the extrusion temperature exceeds 520°C, the Si particles tend to become coarse, and if it exceeds 550°C, extrusion cracks tend to occur, so it is better to avoid this.

In addition, in method (b), the aluminum alloy material is produced by hot pressing instead of extrusion, in method (C), the container is cut and removed after hot pressing, and in method (d), H' I is produced instead of extrusion. An aluminum alloy material is obtained by P treatment, and (e) is a method in which after preliminary compression, the material is degassed by heating in a gas atmosphere, a vacuum, or a gas such as N 2 or Ar, and then extruded.

[Example] Alloys No. 1 to No. 0.13 in Table 1 were melted to create rapidly solidified powders. Here, only No. 12 is single roll method (
It was made into a ribbon at a cooling rate of 105 to 106° C./S) and pulverized. Others are gas atomized (cooling rate 102
~104°C/S) and classified to a particle size of 297μ or less.

Table 1 The samples were pre-compressed to 70 to 75% of their true density, sealed in an Al container, and vacuum degassed while heating. The heating temperature is No.
In the case of 12, the temperature was set at 300°C to prevent the growth of Si particles, and in the case of NO,13, the temperature was set at 53°C to prevent the growth of Si particles.
It was set to 0'C. The other heating temperatures were -500°C.

The thus encapsulated billet was heated to 350° C. and extruded at an extrusion ratio of 14 to obtain a rod with an outer diameter of 40 mm.

Alloys No. 14 to No. 16 have an outer diameter of 1 after melting.
A 50 mm ingot was prepared and extruded under the same conditions as above.

495°C on the extrusion rod of No. 1~N0.16
Heat treatment was performed for 2 hours → water cooling → 175° C. for 10 hours. The average particle diameter of Si particles, average interparticle distance, and Vickers hardness of this material were measured. A cutting test was also conducted using a diamond cutting tool to evaluate the machinability (bit wear and chipping, cutting processability, and average finished surface roughness). Furthermore, the amount of wear on the drum when the metal tape was run for 1500 hours, and the friction coefficient when the metal tape was slid (measured at the 5th, 500th, and 100th sliding) were evaluated.

The above evaluation results are shown in Table 2.

Table 2 Inventive alloys No. 1 to No. 9 have Si particle diameters and interparticle distances within specified ranges, have excellent wear resistance, have low and stable friction coefficients, and have good machinability. be. On the other hand, N 2 O.10 has a small amount of Si, so the amount of wear is large, and N 0.11 has a large amount of Si and a large Si particle diameter, so the friction coefficient tends to increase. N O, 12 is Si
Because the particle size is small, the amount of wear is large, and No. 13 is Si
Because the particle size is large, the coefficient of friction is large and tends to increase.

When N is 0.14, the amount of wear is large because the amount of Si is small.

No. 15 has a large Si particle diameter and a large interparticle distance, so the friction coefficient is large and shows an increasing tendency. Moreover, the machinability is also poor. No. 16 has a large amount of wear due to a small amount of Si.

[Effects of the Invention] The alloy of the present invention has high wear resistance, friction properties, and excellent machinability, and is a suitable material for DAT drums.

Claims (2)

[Claims] (1) Si: 14~25%, Cu: 0.5~ by weight
5.0%, Mg: 0.3 to 3.0%, remaining unavoidable impurities and Al, and the average particle size of Si particles is 0.
．． An aluminum alloy for DAT drums, characterized in that the average interparticle distance is 3 to 3.5 μm and 10 μm or less. (2) Si: 14~25%, Cu: 0.5~ by weight
5.0%, Mg: 0.3 to 3.0%, and further Sn
:0.2-2.0%, Pb:0.2-2.0% and B
1: An alloy containing one or more of 0.2 to 2.0%, remaining unavoidable impurities, and Al, the average grain size of Si particles is 0.3 to 3.5 μm, and the average interparticle distance is 10μ
An aluminum alloy for DAT drums, which is characterized by having a diameter of less than m.