JPH01303683A - Manufacture of tape guide and tape cassette using the tape guide - Google Patents

Abstract

PURPOSE:To inexpensively produce the tape guide of high performance by pressing plural knife edges provided at a tool to a metallic cylinder part circumferential face forcibly, forming many channels parallel to a tape traveling direction and forming the protrusion of a section approximately circular shape between the adjoining channels. CONSTITUTION:A partial or complete cylinder to have the cylinder face of a range connecting slidably with a tape at least is formed with rolling the sheet metal of non-magnetic stainless material and so on, plural knife edges provided at a tool are pressed forcibly to the part connecting slidably with the tape at least of a cylinder part and are plastic-deformed, many actually parallel channels extending in the traveling direction of the tape are formed on a cylinder part circumferential face, and many protrusions 7a of which section shape is approximately circular shape are formed between the channels. Since the protrusions 7a have gentle curvature and extend in the traveling direction of the tape, when a contact area with the tape decreases and friction coefficient with the tape practices friction repeatedly, they do not become high. Thus, a tape guide 7 of high performance can be manufactured easily and inexpensively.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to storing a magnetic tape in a pair of upper and lower halves and holding or guiding the position or running path of the tape in the pair of upper and lower halves. The present invention relates to a method of manufacturing a fixed tape guide and a tape cassette equipped with the tape guide.

2. Description of the Related Art Conventionally, as a typical tape cassette of this type, a video cassette of the VH3 system can be mentioned. FIG. 6 shows a conventional tape cassette. In FIG. 6, a magnetic tape (hereinafter simply referred to as tape) 3 is wound around a pair of reels 2 and 2 inside the half 1, and the position or path of the tape 3 is arranged in a pair of cylindrical shapes. It is held or guided by a tape guide 4.4, a guide ball 6, and a guide roller e.

As shown in Figure 6, the tape guide 4 is a seamless metal pipe whose surface is made of stainless steel such as SUS 316 with roller burnishing or super finishing, or made of brass or aluminum. The base is hard chromium plated and the plating layer is finished by grinding, and the metal plate is rolled into a cylindrical shape as shown in Figure 7, and the hard chrome plating is applied to the stainless steel or brass base. The plated layer is then polished and finished by grinding.

Further, the tape guide 4 is made of resin, which is thought to be made by injection molding polyacetal, and what is thought to be made of a stainless steel sheet metal rolled into a cylinder and subjected to barrel polishing.

The tape guide 4 also has a metal or resin base with many minute recesses 4a dotted on the surface as shown in FIG. One in which protrusions 4b are formed in the circumferential direction, one in which protrusions 4C are dotted as shown in FIG. As shown in Figure 9, a groove 4e is provided in the circumferential direction, and as shown in Figure 9E, a number of protrusions 4f in the axial direction are provided in the circumferential direction.

Problems to be Solved by the Invention However, with such a conventional configuration, first, in the case of metal tape guides, hard chrome plating is applied and the plating layer is ground, which has poor friction and wear characteristics against various types of tapes. Although it has the best performance, it has the disadvantage of high processing costs such as plating, and especially when manufacturing by cutting metal pipes, the material cost is the highest.

In addition, stainless steel surfaces finished with roller burnishing or super finishing do not cost as much as plating and grinding, but variations in processing conditions have a large effect on the friction and wear characteristics with the tape. It has the disadvantage of poor friction and wear properties for certain types of tape.

Furthermore, when the surface of a stainless steel base material is subjected to only barrel processing without grinding, the drawbacks of those subjected to roller burnishing or superfinishing are even more pronounced.

Next, tape guides based on resin have a significant cost advantage compared to metal ones, especially when manufactured by injection molding using a common resin such as polyacetal. Even if various surface shape improvements are made, it is not possible to obtain a tape guide with performance equivalent to that of metal because the friction and wear characteristics of the material are significantly different from those of metal, especially hard chrome plating and stainless steel. The reality is that it is not.

The present invention solves these problems, and aims to provide a method for manufacturing a tape guide with high performance comparable to that of a tape guide that is plated and ground, and a tape cassette equipped with the same tape guide. be.

Means for Solving the Problems In order to solve these problems, the method for manufacturing a tape guide of the present invention involves rolling a non-magnetic stainless steel sheet metal and forming a part of the tape guide having at least a cylindrical surface in a range that comes into sliding contact with the tape. Alternatively, a complete cylinder is created, and a plurality of cutting edges provided on a tool are forcibly pressed against at least the portion of the cylindrical portion that makes sliding contact with the tape, thereby plastically deforming the cylindrical portion to form a substance extending in the running direction of the tape on the outer peripheral surface of the cylindrical portion. It is characterized by forming a large number of parallel grooves, and forming a large number of protrusions having a substantially arcuate cross-section in the drawing of the grooves.

In order to reduce the cost of tape guides, which are relatively expensive among the components of VHS tape cassettes, the inventor has developed tape guides made of various materials, shapes, and finishing methods as described above from commercially available cassette and component manufacturers. As a result of friction tests with various tapes obtained in the form of sample products and own prototypes with different base films and magnetic coatings, it was found that at present it is difficult to obtain a tape guide made of resin that is comparable to a tape guide made of metal. We reached a conclusion and attempted to manufacture a stainless steel sheet metal tape guide at a low cost comparable to resin ones using a processing method mainly based on press processing and barrel polishing, which have high productivity and low processing costs. Ta.

However, since such tape guides have the above-mentioned drawbacks, we have investigated various surface shapes that can compensate for these drawbacks. It is clear that the example shown in FIG. 9 mentioned above is intended for a tape guide made of resin, but the inventors also studied the shapes of these tape guides, produced prototypes, and conducted experiments.

As a result, it is not easy to accurately make the shape and dimensions of the recesses in products with many minute recesses as shown in Figure 8, and only incomplete prototypes are obtained, and the test results are also poor. I could not get good results because the tape was easily scratched.

Next, the shape shown in FIG. 9 is not easy to prototype or actually produce if it is made of metal, and the shape shown in FIG.

In the case of shapes with sharp edges around the protrusions such as B, D, and E, the shape of these protrusions may change when the tape cassette with these tape guides is left in a high-temperature environment for a long time. It has been found that the magnetic head is transferred to the tape that is in contact with the magnetic head, which prevents close contact between the magnetic head and the tape.

In addition, if the shape has a surface that stands up against the running direction of the tape, as shown in B and E in Figures 8 and 9, dust etc. that has been swept up in that area may fall off irregularly and cause the tape to Concerns remain about a phenomenon that is difficult to confirm through experiments, such as adhesion to the tape and obstructing contact between the tape and the magnetic head.

Furthermore, through these experiments, it was confirmed that when protrusions or recesses are provided on the surface of the tape guide to reduce the contact area with the tape, the coefficient of friction with the tape tends to decrease.

Based on the above experimental results and considerations, the inventors have created a surface shape that satisfies the following conditions: it can be processed using simple methods such as press processing, it is difficult for dust to accumulate, and it is difficult for protrusions to be transferred to the tape. As a result of the selection and comparative evaluation, the shape, dimensions, and processing method described above were determined to be optimal.

Effect With this configuration, the protrusions provided on the surface of the tape guide have a gentle curvature without sharp edges, and the protrusions extend in the running direction of the tape, reducing the contact area with the tape. The coefficient of friction with the tape does not increase even after repeated friction, and there is no risk of dust etc. accumulating and falling off.
Moreover, such a shape can be easily and inexpensively and highly accurately formed by methods such as pressing or rolling.

Embodiment FIG. 1 is a perspective view of a tape guide of a tape cassette according to an embodiment of the present invention, and the tape guide 7 is provided with a large number of protrusions 7a in the running direction of the tape.

FIG. 2 is an enlarged sectional view of the protrusion 7a, and the protrusion 7a has a substantially arcuate cross-sectional shape. Two adjacent protrusions 7a, ? A groove 7b is provided between the grooves a. This groove 7b is formed by pressing a large number of straight cutting edges 8a provided on the tool 8 against the tape guide 7, as shown in FIG. The cross-sectional shape of is naturally formed as a result of the groove 7b being formed by the cutting edge 8a, and is formed freely without being forced by direct pressure or the like from a tool.

As a result, the protrusions of the protrusions 7a that come into contact with the tape do not have sharp edges, and even if there are minute chips or scratches on the cutting edge 8a of the tool 8, those shapes are transferred to the parts that come into contact with the tape. Moreover, even if the tool 8 is pressed against the tape guide 7 after barrel polishing to form the protrusion 7a, the part of the protrusion 7a that contacts the tape will not be in contact with the tool 8, so the surface of the tape guide 7 will not be damaged. There is a high degree of freedom in the order of process organization without compromising the quality of the process.

Since the cutting edge 8a of the tool 8 is straight, manufacturing requires high-cost machining such as electrical discharge machining, as is the case with the tools necessary to obtain the shape shown in FIGS. 8 and 9B. If the cutting edge 8a of the cutting edge 8a is worn out, correction processing is also easy. Moreover, since only the substantially sharp cutting edge 8a of the tool 8 presses against the tape guide 7, the pressing force can be extremely small compared to the case where the entire shape is forcibly created.

The tool 8 may be pressed vertically against the tape guide 7 (in this case, a flat plate before being rolled into a cylinder) using a press.
Alternatively, a so-called rolling method may be used in which a cutting edge 8a is formed on the circumferential surface of a roller and the cutting edge 8a is rotated and pressed against the movement of the plate material of the tape guide 7. In this case, the tool 8 can be manufactured using a lathe, making its manufacture and modification even easier.

The tip of the cutting edge 8a of the tool 8 may be provided with a small radius or a flat portion as a general method to extend tool life.

The tape guide 7 is in the form of a flat plate or rolled into a cylinder by pressing, and then finished by barrel polishing to a surface roughness of 0.1 to 0.8 μm (peak-to-peak). Since the tape partially contacts the tape guide 7, the tape does not easily stick to the tape guide 7 even if the roughness is 0.2 μm or less.

From the viewpoint of manufacturing the tool, it is desirable that the interval between the protrusions 7a is 0.1 mm or more, and from the viewpoint of effectiveness on the tape, the interval is 2 m.
Desirably 111 or less.

The height h of the protrusion in Fig. 2 is 0 from the viewpoint of ease of processing.
．． 2 or less is desirable, and from the point of view of the effect on the tape, it is 0.
．． 0.005 μm or more is desirable.

If the tool 8 is a roller, the cutting edge 8a may be spiral,
Therefore, even if the protrusion 7a is slightly inclined with respect to the running direction of the tape, the effect is maintained.

Since the tape guide 7 does not need to undergo processing involving rotation such as grinding, it does not need to be a closed (complete) cylinder;
As shown in the figure, it may have a semi-cylindrical or U-shaped cross-section, limiting the use of material to only the portion that contacts the tape.

When the distance between adjacent protrusions 7a is wide, or when the groove 7b is shallow, some flat portions may appear at the tops of the protrusions 7a.

Unless the cutting edge 8a of the tool 8 is significantly worn out, the height h and shape of the protrusion 7a formed on the surface of the tape guide 70 are determined almost solely by the force with which the tool 8 is pressed, so the height should be adjusted even when mass production is performed. The shape of the pod is stable.

Effects of the Invention As described above, according to the present invention, tape guides with high performance and stable quality can be produced at low cost with high productivity, and by using this, inexpensive tape cassettes can be supplied. It will be done.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a tape guide of a tape cassette according to an embodiment of the present invention, FIG. 2 is a partial sectional view thereof, and FIG.
FIG. 4 is a perspective view showing a tape guide of a tape cassette according to another embodiment of the present invention, and FIG. 5 is a tape to which the tape guide of the tape cassette of the present invention is applied. FIG. 6 is a plan view showing the main parts inside the cassette, and FIG. 9 is a diagram showing the shape of a conventionally used tape guide. 7...Tape guide, 7a...Protrusion,
h...Protrusion height of the protrusion, 7b...Groove,
8...Tools. Name of agent: Patent attorney Toshio Nakao and 1 other person7~
Tape Guide An-11 Frame Evaporation Figure 1 Figure 2 C Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (4)

[Claims] (1) A plurality of cutting edges provided on a tool are forcibly pressed against the outer circumferential surface of the cylindrical portion of a metal tape guide to plastically deform the outer circumferential surface of the cylindrical portion, and a large number of grooves substantially parallel to the tape running direction are formed on the outer circumferential surface of the cylindrical portion. 1. A method for manufacturing a tape guide, characterized in that a protrusion having a substantially arcuate cross section is formed between adjacent grooves. (2) The manufacturing method according to claim 1, wherein the outer circumferential surface in sliding contact with the tape has a large number of grooves substantially parallel to the tape running direction, and protrusions having a substantially arcuate cross section are formed between the adjacent grooves. A tape cassette with a metal tape guide obtained by the method. (3) The tape cassette according to claim 2, wherein the surface of the tape guide is finished by barrel polishing. (4) The tape cassette according to claim 2, wherein the tape guide has a substantially semi-cylindrical shape.