CN1011000B - Method for mfg. tape reel - Google Patents

Abstract

To make the shape and accuracy excellent by providing a gate part in an extent enclosed by an extension line in an inner tube connecting the center of a tape reel and both ends of fitting place of a clasp of a winding core and the outer periphery of the inner tube, and molding by injecting a resin from the gate part. The extent of a gate part in which the accuracy of a tape reel becomes best is a part 10 enclosed by an extension line in an inner tube connecting the center of the tape reel and both ends 9 of fitting place of a clasp of a winding core 4 and the outer periphery of the inner tube 2. When a caulking boss is in this extent, it is enough to drop the gate at the tip. However, when there is a problem of defective caulking with another side plate due to influence of remaining gate, etc., a projection part 11 is provided in the outer peripheral part of the inner tube 2 and the gate is dropped in this part. If the caulking boss is not available, a recess part 5' is provided on a top plate 5 considering the remaining gate, and the gate is dropped in this part, or a dummy boss 12 is provided, and the gate is dropped at the tip.

Description

Method for mfg. tape reel

The present invention is relevant with the manufacture method and the mould therefor thereof of video tape disc, the manufacture method of concrete relevant tape reel, and this method can make the manufacturing of tape reel that improved gate location and structure and high-precision characteristics are arranged, and the mould of relevant this tape reel.

Brief description is as follows:

Fig. 1 and 2 is planimetric maps, and desirable gate location of the present invention is shown;

Fig. 3 and 4 is the gate location schematic sectional view;

Fig. 5 is a schematic sectional view, a relative side plate is shown is placed on the top board;

Fig. 6 is a planimetric map, and the gate location of the tape reel parts of moulding in the example is shown;

Fig. 7 is a view, and the measurement point in the geometrical precision test of tape reel parts of moulding in the example is shown;

Fig. 8 is the planimetric map with conventional formed in mould tape reel parts;

Fig. 9 is the cut-open view along Fig. 8 A-A ' line;

Figure 10 is a cut-open view, and the mould that gate system manufacturing tape reel is used before adopting is shown;

Figure 11 is a planimetric map, and conventional gate location as an example is shown;

Figure 12 is a planimetric map, and the tape reel parts of another form of the present invention are shown.

1 ... side plate

2 ... cylinder

3 ... stiffening rib

4 ... magnetic-tape core

5 ... top board

5 ' ... groove

6 ... central boss

7 ... the interlocking boss

10 ... the gate location scope that the present invention determines

Along with electronics industry developing rapidly in recent years, family expenses video tape recorder universal considerable.The demand of videotape and parts thereof increases thereupon.Yet the high precision of these parts and high efficiency production are very important.In these parts, especially high precision is arranged with the tape reel part requirement.Because, video tape recorder is to store and played-back image and acoustic signal with tape, and the tape reel parts are direct parts of wound tape in the above, this parts occur any to precision prescribed the most small depart from the distortion and/or the wrinkle that all can cause tape, just may cause pattern distortion, noise, or the like.

Now as an example, introduce being constructed as follows of tape reel parts.As seen from accompanying drawing, especially in Fig. 8 as seen, this planimetric map letter illustrates tape reel parts, Fig. 9 is analysing and observe along Fig. 8 A-A ' line, the tape reel parts comprise 1, one cylinder 2 of a circular side panel be located at plate 1 in the heart, magnetic-tape core 4 is by the periphery of floor 3 around cylinder 2, be provided with an outshot 6 as rotation center at the top of cylinder 2 top plate portion 5, some interlocking boss 7 are arranged around it.Unshowned relative side plate (on it porose for boss embed with) join on these tape reel parts, boss is rabbeted, and just forms a tape reel.The hot runner mould cut-open view that Figure 10 uses for gate system moulding tape reel before adopting.Mould 15 has cast gate 16 and heating member 17.Resin evenly is injected into whole die cavity by cast gate 16, so form tape reel parts.When making this tape reel parts with injection moulding, in order to improve precision, the mould inevitable requirement has high precision, and, determine that cast gate will be located at that to inject resin on what position of mould also be very important.Reason is, if the resin injection is inhomogeneous, and above-mentioned magnetic-tape core 4(and cylinder 2) just can not obtain satisfied cylindricity, the cylindricity of magnetic-tape core requires very high, causes magnetic-tape core and the distortion of other parts because shrink inhomogeneous meeting.Especially especially outstanding in this phenomenon when increasing the forming operation number of times and shorten cool time.Therefore, the selection of gate location is to the far-reaching factor of throughput rate.

For this reason, the inventor is in order to overcome this difficulty, to the gate location of gate system before adopting for the basis, done a series of research, and propose on a position with respect to the respective front ends of rabbeting boss 7, a cast gate (Japanese Utility Model communique 58-42108 number) to be set, as shown in figure 11.But these gate locations have brought following problem.

Any problem does not take place as will make winding the time, cylindricity does not just require to be lower than 30 μ.But, cast gate is arranged on in the interlocking boss 7 shown in Figure 11 one, and in the time of for example on 8, the not cylindricity of the tape reel that manufacturing is come out is the grade of 50-80 μ, sometimes may cause the distortion and/or the fold of tape during winding, cause tape to damage and pattern distortion.Noticed a phenomenon in addition, i.e. broken belt during high speed winding.

Therefore, the inventor etc. have carried out further research in order to improve the magnetic-tape core geometrical precision, and the result promptly draws the present invention.

The present invention proposes a kind of method of making tape reel, with the used mould of this method of enforcement, be characterised in that in the process of tape reel parts of injection moulding, these tape reel parts comprise a tape reel side plate, covered cylinder be provided with like this center that makes side plate have one open-ended, a magnetic-tape core centers on the outer rim of covered cylinder, an outshot is set as rotation center on the top board of covered cylinder, several interlocking boss are arranged, have a gate portions be formed on by between two terminations of brake component seat on tape reel center and the magnetic-tape core line and extended line thereof defined, and by (Fig. 1 and 2 oblique line part) in the circumjacent zone of the outer rim of inner cylinder, resin is by this gate portions injection moulding.

Now the used tape reel mould of the manufacture method that the present invention is proposed is with reference to description of drawings.

The gate location scope synoptic diagram that Fig. 1 uses for moulding tape reel of the present invention.

In above-mentioned injection moulding operation, the scope of gate part of the best geometry precision of tape reel can be provided, as shown in Figure 1, be by the oblique line part that connecting line and extended line thereof defined and be equivalent to Fig. 1 by this part 10 of the part 10(in the circumjacent zone of the outer rim of inner cylinder 2 between two terminations 9 of the brake component seat on tape reel center (central boss position) and the magnetic-tape core 4).As for gate location, as an interlocking boss is arranged in this part, just cast gate can be located on the top of this interlocking boss, if but because the problem of cast gate remnants might produce bad interlocking to relative side plate the time, outshot 11 can be set on the outer rim of inner cylinder 2, as shown in Figure 2, cast gate just is arranged on this part.

If do not rabbet boss in this scope, a groove 5 ' to hold cast gate remnants, cast gate just is located in this groove just can be provided with on top board 5 as shown in Figure 3 so, or as shown in Figure 4, an empty boss 12 is set, and cast gate just is located on its top.

The height of empty boss 12 must be lower than central boss 6, preferably flushes or more lower slightly with the top of relative side plate 13, (a place among Fig. 5) as shown in Figure 5, Fig. 5 represents the situation that relative side plate is in place.

As for the number of cast gate, the layout of available single-point cast gate, or, select which kind of arrangement for use with the layout of multi-point sprue actually, be decided by each interlocking boss, top board structure, or otherwise consideration.

The used forming method of tape reel manufacture method of the present invention can adopt hot runner type or cold pouring channel type, and without particular limitation.

The resin material that the present invention is used can be any conventional thermoplastic resin that uses.These resins comprise polyacetal (homopolymerization type or copoly type), polypropylene, tygon, poly terephthalic acid phenylene ester, such as poly terephthalic acid butenylidene ester, and polyamide.By required performance, available any known filler mixes, and desirable especially resin is a polyacetals.

From top narration and below for example as seen, in the injection moulding of tape reel, a cast gate is arranged on the geometrical precision that can improve the tape reel of institute's moulding on the tram according to the present invention.

Example 1

Cast gate is arranged on the respective tops of the interlocking boss shown in 14-1～14-6 among Fig. 6 and comes the moulding tape reel like this.In order to test the relation between gate location and the magnetic-tape core geometrical precision, out-of-roundness and non-cylindricity have been done measurement.Measurement result is listed in table 1.Measurement is carried out on three position b, the c of Fig. 7, d.The measurement of out-of-roundness and non-cylindricity is undertaken by Japanese industrial standard JISBO621.Condition of molding is: 700 kilograms/centimeter of injection pressures; 1 meter/minute of injection rate; The time of an operating process added cold Pu but 5 seconds in 10 seconds for injection.

At this as seen, the numerical value of out-of-roundness or non-cylindricity is the smaller the better.Therefore, obviously the tape reel ratio of precision Comparative Examples of this example be high.

Example 2

The gate location of magnetic-tape core and the relation between the geometrical precision have been done test with perforated tray shown in Figure 12.Measurement result is listed in table 2.Cast gate is located on the top of interlocking boss, and the position is identical with example 1.Cast gate is located at empty boss shown in Figure 6, and (14-7,14-8) (14-9,14-10) magnetic-tape core on has also been done measurement with the top board groove.Measurement is identical with example 1 with condition of molding.

Perforated tray as referred to herein is the dish that has through hole on the tape reel side plate, and the shape in hole without limits.Used tape reel is that those include on the tape reel side plate from the radial rib 19 of iron chains limit shape member 18 stretching, extensions and the tape reel of excircle rib 20 in this example.

In Figure 12, label 21 expression stop tooths.

Claims (3)

1, a kind of method of making tape reel, be used for injection moulding by the tape reel side plate, for the covered cylinder that makes this side plate center have opening to be equipped with, around the magnetic-tape core of this covered cylinder, be located at the tape reel of the tape reel part that constitutes as rotation center outshot and interlocking convex etc. on this covered cylinder top board, it is characterized in that: gate portions be arranged on by between two terminations of the brake component seat on tape reel center and the magnetic-tape core connecting line and extended line thereof defined and by the periphery of inner cylinder round the zone in.

2, such as in the claim 1 the tape reel manufacture method of proposition, it is characterized by on the tape reel side plate has through hole.

3, such as in claim 1 or 2 the tape reel manufacture method of proposition, it is characterized by the tape reel side plate and comprise radial rib and circumferential rib.

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