JPS6053377B2 - Method for manufacturing guide drum for magnetic tape scanning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a magnetic tape guide drum with good surface condition and excellent wear resistance using a Si-Si alloy.

Generally, the guide drum of a magnetic tape scanning device is made of a cast N or A1 alloy.

If necessary, the surface is treated with ceramic coating, alumite coating, or various types of plating to reduce the coefficient of friction and prevent scratches on the tape or static electricity from forming on the contact surface. ing. However, this type of surface treatment is not sufficient in terms of wear resistance and sliding friction coefficient, and
There is a problem that requires troublesome post-processing such as polishing and lapping. Therefore, it has drawbacks such as difficulty in achieving dimensional accuracy, and the number of man-hours required for finishing, making it unsuitable for mass production. SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a magnetic tape guide drum that provides a high-quality playback screen for a long period of time.

The present invention involves rapidly solidifying a molten N-Si alloy, forging the obtained ingot into a drum shape, dividing the eutectic silicon by the forging, and then machining the magnetic tape on the outer periphery of the drum. The object of the present invention is to form parallel, substantially continuous processed lines with a surface roughness of 1 to 6 μm along the direction of magnetic tape travel in the guide path.

A magnetic tape scanning device in a magnetic head type magnetic recording/reproducing device of a VTR has the following configurations (1) to (4).

(1) A cylindrical stationary drum is included, and a magnetic tape is inserted along the smooth surface of a guide path formed on the outer periphery of the drum. (2) a rotating magnetic head device including at least one magnetic head slightly protruding from the circumference of the drum in a radial direction and provided at a position where it can make full contact with the magnetic tape; (3) by supporting the magnetic head device and the guide drum concentrically and forming a small gap between the lower end of the magnetic head device and the upper end of the guide drum;
(4) means for supporting the support means to rotate independently of the guide drum; and (4) means for driving the support means.

An example is shown in FIGS. 1 and 2.

A rotary disk 3 is inserted between a cylindrical stationary upper drum 1 and a stationary lower drum 2 with a clearance (gap) 4 maintained therebetween. The rotary disk 3 and the drums 1 and 2 are coaxially fixed by a shaft 5, and the upper drum 1 and lower drum 2 are connected by a connector 6 and a bolt 6'. The rotary disk 3 is fixed to the shaft 5, and can be rotated by a ball bearing 11 and a rotating sliding part.On the other hand, the drums 1 and 2 are mounted on a base plate 18, as shown in FIG. The rotary disk 3 is fixed with bolts 10 and an auxiliary base plate 17.The rotary disk 3 is composed of one or more magnetic heads 7, and the magnetic head 7 is connected to the tape guides 8 of the drums 1 and 2 and the rotary disk 3. 0.05~0.37m in the radial direction of
Extruded within the range of. A diagonal or spiral tape guide 8 is cut into the drums 1 and 2 to properly guide the magnetic tape. As shown in FIGS. 1 and 2, the lower drum 2 is integrated with a sleeve 9, and a bush 13 is attached to the sleeve 9 for grounding purposes. The pulley 14 is fixed to the shaft foot 5 with bolts 16, and is driven by a belt 15 to rotate the pulley 14, thereby rotating the shaft 5 and the rotary disk 3. Another type of magnetic head type recording/reproducing device has an upper drum 20 that rotates and a lower drum 21 that is stationary, as shown in FIG.

Therefore, this type does not require a rotary disk 3 as shown in FIG. In this type, a pair of magnetic heads 22 that protrude slightly from the tape guide are combined with the drum 20, and the upper drum 20 is fixed to the shaft 5. This upper drum 20 has a rotating sliding part 12 and a ball bearing 1.
1 and is rotatable by means similar to those shown in FIGS. 1 and 2. The present invention provides an apparatus as described above, in which at least one of the upper drum 1, the lower drum 2, and the rotary disk 3 in FIGS. 1 and 2, and at least one of the upper drum 20 and the lower drum 21 in FIG. It is manufactured by the method described above.

A preferred composition of the N-Si alloy is 8 to 15% by weight of Si-
0.5-4% by weight of CU-0.05-1. Mg in weight %
The remainder is an alloy consisting essentially of N. This alloy is rapidly solidified from a molten metal to finely crystallize Si crystals. The faster the cooling rate, the better, but desirably 3
Continuous casting is preferably performed at a cooling rate of 0 to 60° C./Sec or higher. The Si crystal (eutectic Si) in the form of an ingot is acicular or flaky, and in this state is not suitable for use as a magnetic tape guide drum. If the eutectic Si remains in the form of needles or flakes, it is impossible to form a substantially continuous machining line. Also, when forming machined lines and running the tape, S
The crystal grains are stripped off, creating depressions on the outer circumferential surface of the guide drum, and abrasion particles are mixed into the depressions, causing flickering on the screen and damage to the magnetic tape. This ingot is warm forged at a working degree of 30% or more in a temperature range of 200°C to below the melting point, and then shaped again in the above temperature range, or Processing degree is 30% within the temperature range
Due to the above external force during molding, the S1 crystal (eutectic Si) is mechanically finely divided and uniformly dispersed. In this case, if the temperature after processing is above the recrystallization temperature and below the melting point, the Si crystals separated by external force will be spheroidized. The average particle diameter of the divided spheroidal Si crystals is 1.7 μm or less. It is desirable that the forging process divides the eutectic Si into particles having an average grain size of 5 μm or less. This facilitates forming a substantially continuous machining line. Molded products made by warm forging are subjected to T4 treatment (450-52
0°C x 1h → quenching 1 week or more), T6 treatment (4
50~520'C x 1h → Rapid cooling → Artificial aging; For example, 15
It is desirable to perform heat treatment such as 0 to 200'CX8)1-air cooling) or T5 treatment (quenching immediately after warm forming → artificial aging). The molded product made as described above is finished by machining, and the magnetic tape guide path on the outer periphery of the drum has a surface roughness of 1 to 6 μm along the tape traveling direction.
Parallel, almost continuous processing lines are formed.

In the present invention, the ingot is forged and the eutectic S1 is finely divided before being machined, so that the machining lines can be formed to be substantially continuous.

As a result, the burr friction coefficient can be kept small. Then, it is applied to the magnetic tape guide drums shown in FIGS. 1, 2, and 3. AC-i and AC-? shown in Example Table 1 After melting the composition, a full friction test piece and an actual magnetic tape guide drum were manufactured by a casting method.

On the other hand, after melting the N-Si alloy with the composition shown in Table 1,
A billet was prepared by continuous casting at a cooling rate of 0 to 60°C/Sec, and subjected to 40 to 90% plastic working at 450°C. After that, various heat treatments such as 450℃~520℃×1
Those subjected to solution treatment of h and left for more than one week, and 1
Aging treatment was performed at 70° C. → gradual cooling. In addition, a heat treatment was performed in which the material was rapidly cooled immediately after warm forging. Si after plastic working
The crystal size is 1.6 μm to 2.8 μm. From the above sample, a sliding friction test piece 30 and an actual magnetic tape guide drum were fabricated by machining. FIG. 4 shows a method of measuring the slippery friction coefficient, in which a VTR magnetic tape (CrO2 tape) 31 is set on a load 32 and a spring gauge 33. The angle θ of the magnetic tape at this time
is 90. The magnetic tape 31 is pulled by a force Fw for determining the flattening friction coefficient and a spring gauge 33, and a flattening friction force F-1 is obtained. However, the load in this case is within the range of 10 to 100 y. From the test results conducted using such equipment and conditions, the sliding friction coefficient μ can be determined using the following formula. FIG. 5 shows the measurement results obtained using the above formula.

Curve A is the slip friction coefficient of the N-S1 alloy, and is 0.
The value is 3 or less. Normally, when a VTR is recording and playing under normal operating conditions, this N-Si alloy has a low friction coefficient of 0.24 to 0.25, making it suitable for use as a guide drum.

Curve D is the slip coefficient of friction when a ceramic coating is applied to the surface, and it can be seen that the present N-Si alloy is much superior to the ceramic coating. We also tested a rod with hard chrome plating, and found that the coefficient of friction was greater than that of a ceramic rod. Curve B is AC-?Curve C is AC-? This is the coefficient of friction when the surface of the material is mechanically finished to a roughness of 3 to 4 μm. AC-i and AC-? The slip friction coefficient is 0.27-0.31 even under a load of 30-40y.
6 to 0.27, indicating that the present N-Sj alloy is superior. If the sliding friction coefficient is large, it tends to cause flickering on the screen, and it has been confirmed that the sliding friction coefficient measured in this way reproduces the sliding friction of the actual magnetic tape guide drum. confirmed. According to experiments, the coefficient of friction of the magnetic tape guide drum is 0.
．． 3 or less, preferably 0.28 J:). It should be below. In addition, in order to obtain a slip friction coefficient of 0.3 or less, the surface roughness is 1 to 6 μm, preferably 2 to 5 μm.
It should be m. Figures 6a to 6c are N-Si alloys, AC-Hiroshi and AC-? The cross section of the surface of a magnetic tape guide drum made of wood was photographed using a microscope at 40C@, and all of these were machined to a surface roughness of 3 to 4 μm.

Fig. 6a shows the present N-Si alloy, Fig. 6b shows AC-?, and Fig. 6c shows AC-? It is a material. Book A1-S made of forged products
I-based alloys are small Si crystals, but AC made of forged products
One, AC-? The material is large Si crystal, and cavities are also visible. Also, when looking at the surface condition, -Si alloys only have unevenness due to machined lines, but AC-Hiro and AC-? The material shows marks where relatively large S1 crystals were removed, or unevenness caused by casting cavities. A raised area was observed at the edge of the depression created when the Si crystal was removed, and it was confirmed that this was the cause of tape damage. FIGS. 7a to 7c are the results of observing the tape guide surface of the magnetic tape guide drum using an electron microscope, and the magnification is 200 h.

FIG. 7a shows the N-Si alloy of the present invention, FIG. 7b shows AC Kazuhiro, and FIG. 7c shows AC-? This is the surface condition of the material, and all of these have been machined to a roughness of 3 to 4 μml! It is. As can be seen from this figure, this N-Si
The surface of the alloy has a machined line that is almost continuous in the direction of movement of the magnetic tape and is smooth*2. However, AC Kazuhiro and AC-Yuzai have depressions on the surface, especially AC-? The wood has large dents. This depression is a plan view of the unevenness shown in FIG. 6, and is a trace or a cavity where relatively large Si crystals were removed during machining. These depressions can also cause damage to the magnetic tape. Another important feature of the invention is that it has good abrasion resistance.

Figures 8a to 8c show the results of wear tests conducted continuously at 600 to 700F1r using an actual magnetic tape guide drum.

The magnetic tape used in this test was the same as that used in the slippery friction test. Figure 8a shows the N of the present invention.
-Si-based alloy, Figure 8b is AC-, Figure 8c is AC-
? These are the test results for manufactured drums, and the amount of wear is shown by the decrease in roughness. For comparison, Figures 8a to 8c
The roughness before the test is shown on the left side of the figure, but these curves are recorded by the roughness meter, and the actual surface is shown in Figures 7a to 7a.
It should be noted that there is a depression as shown in Figure 7c. The wear amount of the N-Si drum of the present invention is 0.
．． 5 μm, but AC Kazuhiro and AC-B drums have a diameter of 0.
7 to 0.9 μm, and it can be seen that the N-Si drum of the present invention can maintain a desired surface condition even after long-term use, and has excellent wear resistance. Furthermore, as shown in Table 1, the inventors conducted the above tests on drums with different N-Si alloy compositions, Si crystal sizes, and heat treatments, and found that when the Si crystals were larger than 5 μm, It was found that it was difficult to bring the tape guide surface into a desired surface state by machining, and that the size of the Sj crystals should be 5 μm or less. Processing conditions T4: 500'C x 1hr → rapid cooling - left at room temperature for over 1 week T5: 470°C warm forming → rapid cooling → 170'C x 8ll
r Aging treatment T6: 500℃×1hr → Rapid cooling → 1700℃
Cx811r aging treatment Ascast: Also as cast,
If the amount of Sj is less than 8% by weight, the amount of wear on the drum will increase, and if it is more than 15% by weight, a large amount of primary Si crystals that cannot be divided and dispersed by plastic working will crystallize.
C-I and AC-? Like wood, dents can form during machining and can damage the magnetic tape.

Desirably, it is about 1% by heel weight near the N-Sj eutectic component. Furthermore, Mg combines with Si to form an intermetallic compound,
It acts to strengthen the precipitation of the base. However, when Mg is added in an amount of 0.05% by weight or less, the effect is small, and when added in an amount of 1.0% by weight or more, the toughness and impact value tend to decrease, resulting in poor warm castability. The content should desirably be 0.3 to 0.6% by weight. In addition, Cu is dissolved in the N base and Cu2
In addition to forming Al and strengthening through heat treatment,
Improve machinability or wear resistance. However, Cu
If it is less than 0.5% by weight, the heat treatment effect is small, and 3% by weight.
If it exceeds 4% by weight, the improvement in mechanical properties will be saturated, so from an economical point of view it should be 4% by weight or less, and preferably 1% by weight.
It is preferable to add up to 3% by weight. Others Fe, Cr, Ni, Zr
, Ti, etc. may be present in the alloy, but their total amount should be less than 5% by weight. As described in detail above, by manufacturing a magnetic tape guide drum by the method of the present invention, the surface condition and wear resistance of the drum are improved compared to conventional ceramic coatings, AC-coatings, AC-coatings, and AC-coatings.
? It has excellent characteristics not found in other products such as the above.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the external appearance of the magnetic tape scanning device, FIG. 2 is a sectional view thereof, and FIG. 3 is a sectional view of the magnetic tape scanning device having a different structure from FIGS. 1 and 2. Figure 4 is a schematic diagram of the test device for the helical friction coefficient, Figure 5 is a graph showing the results of the helical friction coefficient test, Figure 6 is a micrograph showing the metal structure of the cross section of the surface of the magnetic tape guide drum, and Figure 7 is The figure is a scanning electron micrograph showing the macroscopic metal structure of the tape guide surface of the magnetic tape guide drum, and Figure 8 shows the results of measuring the surface condition of the magnetic tape guide drum before and after use using an aging meter. There is a graph. 1... Stationary upper drum, 2... Stationary lower drum, 3... Rotating disk, 4... Gap, 5...
...Shaft, 6...Connector, 6''...
...Bolt, 7...Magnetic head, 8...
・Tape guide, 9...Sleeve, 10...
Bolt, 11...Ball bearing, 12...
... Excitation coil, 13 ... Bush, 14.
...Pulley, 15 ...Magnetic tape, 20
・・・・Rotating drum, 21・・・Stationary drum, 2
2...Magnetic head, 30...Test piece, 3
1...magnetic tape, 32...weight, 33...
...It's all about springs.

Claims (1)

[Scope of Claims] 1. In a magnetic tape scanning device that includes a circular stationary drum and a rotating drum and slides and guides a magnetic tape along a guide path formed on the outer periphery of these drums, at least one of the drums is 1. A method for manufacturing a guide drum for a magnetic tape scanning device, the method comprising manufacturing a guide drum by a process. (1) a step of rapidly cooling and solidifying a molten aluminum-silicon alloy to produce an ingot; (2) a step of forging the ingot, dividing the eutectic silicon and producing a drum-shaped molded product; (3) By machining, the outer periphery of the molded product has a surface roughness of 1 to 6 along the traveling direction of the magnetic tape.
A step of forming parallel, substantially continuous processing lines of μm. 2. The method of manufacturing a guide drum for a magnetic tape scanning device according to claim 1, characterized in that the forging step divides the eutectic silicon of the ingot into particles having an average grain size of 5 μm or less. 3. In a magnetic tape scanning device that includes a circular stationary drum and a rotating drum and slides and guides a magnetic tape along a guide path formed on the outer periphery of these drums, at least one of the drums is manufactured by the following process. A method for manufacturing a guide drum for a magnetic tape scanning device, characterized in that: (1) a step of rapidly cooling and solidifying a molten aluminum-silicon alloy to produce an ingot; (2) a step of forging the ingot, dividing the eutectic silicon, and producing a drum-shaped molded product; (3) a step of subjecting the molded product to heat treatment including solution treatment and subsequent aging treatment; and (4) machining to create a surface roughness of 1. Forming parallel, substantially continuous working lines of ~6 μm. 4. The method for manufacturing a guide drum for a magnetic tape scanning device according to claim 3, characterized in that the forging step divides the eutectic silicon of the ingot into particles having an average grain size of 5 μm or less.