JPH0556564B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a method of manufacturing a permanent magnet erasing head used primarily for erasing audio tapes.

2. Description of the Related Art In general, methods for erasing magnetic recording media such as magnetic tapes include current erasing methods, methods using permanent magnets, and methods using a combination of these methods.

A conventional permanent magnet erasing head will be explained with reference to the accompanying drawings. FIG. 4 shows the structure of a permanent magnet erasing head, and FIGS. 5a and 5b show the erasing principle. As shown in FIG. 4, the core part 2, which was processed in a separate process as shown in FIG. 6, was assembled to the erase head lever body 1 by gluing and solidifying it in a fixed position. As shown in Fig. 6, the core part 2 is processed through a separate and complicated process, and as shown in Fig. 6, after pasting the permanent magnet 3 and the non-magnetic material 4, it is cut into squares using a diamond cutter. cut,
A core with the specified dimensions shown in figure b is made, and one end is rounded to form a tape sliding surface as shown in figure c.
The complex process was completed by polishing it into a shape. Furthermore, the tape sliding surface of the permanent magnet part 3 of the core component 2 has an alternating pattern of N→S→N in the tape running direction as shown in FIG. 5a, and the magnetic field strength gradually decreases as shown in FIG. 5b. The principle is to perform a gradually decreasing alternating type of magnetization, guiding the data recorded and magnetized on the tape to the point where the magnetic field strength becomes zero, and erasing it.

Problems to be Solved by the Invention However, in the conventional manufacturing method, it is necessary to finish the permanent magnet material into the core part 2 through complicated processing steps, and to fix it to the erase head lever main body 1 by a pasting method using an adhesive. However, the specifications were unreasonable and wasteful in terms of cost, including quality assurance such as overflow of adhesive and the position and angle of the attached core component 2.

SUMMARY OF THE INVENTION The present invention aims to provide a method of manufacturing a permanent magnet type erase head which solves the above-mentioned drawbacks of the conventional example and makes it possible to reduce costs and improve quality.

Means for Solving the Problems In order to solve the above problems, the present invention uses an anisotropic resin magnet as a permanent magnet, and adjusts the tape sliding surface to the shape, size and surface roughness of the final finished product, and The bottom of the tape sliding surface is formed into a convex shape,
This permanent magnet is held at a fixed position in a mold, and a resin material is injected into the mold to mold the erase head lever body, and at the same time, the permanent magnet is insert-molded.

Function: With this method, the permanent magnet is insert-molded in the fixed position of the erase head lever body, which not only eliminates the need for a bonding process using adhesive and improves quality, but also allows the permanent magnet to be made of resin. By using magnets, complex shapes can be easily formed and manufacturing costs can be significantly reduced.

Embodiment Hereinafter, an embodiment of the present invention will be described in FIGS. 1 and 2.
This will be explained using the drawings and FIG. FIG. 1 shows a method of manufacturing a permanent magnet erase head using an insert molding method, FIG. 2 shows a completed product, and FIG. 3 shows a resin magnet. FIG. 1A shows a plan view, and FIG. 1B shows a front view, showing a permanent magnet 5 set in a lower die 6 of a molding die. In this state, the permanent magnet 5 is fixed in a fixed position by the lower die 6 of the molding die provided to match the shape of the permanent magnet 5, and the movable holding rod 8 provided on the upper die 7 of the molding die is attached to the permanent magnet 5. Clamp by pressing. When the permanent magnet 5 can be held in the mold, a resin material is injected into the cavity 10 forming the erase head lever main body 9 through the injection port 11 and insert molding is performed. After the molding is completed, the movable holding rod 8 is pulled out from the product and the product is taken out. As shown in FIG. 2, the product taken out is a product in which permanent magnets 5 are insert-molded, and the top surface, which is the tape sliding surface, is rounded. FIG. 3 shows a permanent magnet 5 used in the insert molding, with one end surface being rounded surface 1.
2, and the front is molded to have a convex portion 13 on the bottom side surface, the rounded surface 12 is used as a tape sliding surface, and the convex portion 13 is used to prevent the permanent magnet 5 from coming off after insert molding.

Further, as the permanent magnet 5, an anisotropic resin magnet is used, which is constituted by mixing 87 to 91% by weight of magnetic powder such as strontium-based ferrite and a thermoplastic resin such as polyamide, polyacetal, polypropylene, or polyethylene.

Effects of the Invention In the present invention, a permanent magnet is molded into an R-shape in advance and is insert-molded into the erase head lever main body, so unlike the conventional example, the permanent magnet is processed through a complicated process and then bonded to the erase head lever main body. Not only does the assembly process become unnecessary, but the precision of the dimensional variation of the permanent magnets can be improved because the molding method uses resin magnets, and the positional relationship between the permanent magnets is molded in a fixed position because of the insert method. As such, it has the feature of eliminating the need for inspection of pasting positions, angles, etc., making it a major contribution to improving quality and reducing direct costs by approximately 40%.

[Brief explanation of the drawing]

1, 2, and 3 show embodiments of the present invention, and FIG. 1 shows a cross-sectional view of a method of manufacturing a permanent magnet erasing head using an insert molding method. 2 is a front sectional view, FIG. 2 is a perspective view of a finished product molded by insert molding, FIG. 3 is a perspective view of a permanent magnet molded with resin magnet, and FIG.
5 and 6 show a conventional example, FIG. 4 is an exploded perspective view showing the structure of a permanent magnet erase head, and FIG.
The figure shows the erasing principle {Figure a shows an alternating magnetic field,
b indicates a gradually decreasing magnetic field. ), Fig. 6 shows the manufacturing process of the core part, and Fig. 6 shows the process of laminating a permanent magnet and a non-magnetic material and cutting it into grid shapes, and b
1 is a perspective view showing a core that has been cut, and c is a perspective view that shows a core that has been completed after R polishing of the tape sliding surface. 5... Permanent magnet, 6... Molding mold lower mold, 7...
Upper mold of mold, 8...Movable holding rod, 9...Erasing head lever body, 12...R processed surface, 13...
Convex part.

Claims (1)

[Scope of Claims] 1. A permanent magnet having one end rounded and a convex portion on the bottom side thereof is prepared, and a permanent magnet is placed in a mold for forming the lever portion of the erasing head so as to match the convex portion. In addition to providing a magnet holding section, the permanent magnet is held in place via a movable holding rod, and the resin material constituting the main body of the erase head lever section is injected into the mold.
A method for manufacturing a permanent magnet erase head, which comprises removing the holding rod after molding and insert-molding a permanent magnet into the erase head lever main body. 2 Using an anisotropic resin magnet composed of 87 to 91% magnetic powder and 9 to 13% resin by weight, the R shape of the tape sliding surface is adjusted to the shape, dimensions, and surface roughness of the final finished product. A method of manufacturing a permanent magnet type erase head according to claim 1, using a permanent magnet type erase head that is molded.