JPS62189130A - Tape reel made of plastic - Google Patents

Abstract

PURPOSE:To improve quality, accuracy and productivity, by a method wherein a position of a valve gate is set at the center in the direction of the diameter of a drum part of a reel and the outside of a driving shaft hole. CONSTITUTION:A boss 6 part of a spring support to be provided on the central part of the upper part of the outside of an end in an axial direction of a drum part 2 of a reel is positioned at a gate G. As for injection molding of the drum part 2, a hot runner system of a valve gate method is adopted, a recessed curved surface 17a is provided on the tip of an action valve pin 17 of a hot runner mold, and traces of the gate is finished smooth by forming the summit 6a of the tip of the boss 6 of the spring support into a state of a protruded curved surface. As molten resin is cast through the drum part 2 of the reel, the same is streamed uniformly as a whole without having a deflection in a cavity. Then as the gate G is arranged on the outside of a driving shaft hole of the drum part 2 of the reel, a cooling circuit 20 can be passed through a core block 19 for molding of the driving shaft hole, cooling is performed efficiently and uniformly, a molding cycle can be made into a high speed and internal strain can be reduced also.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plastic tape reel built into a tape cartridge.

[Conventional technology]

FIG. 3 illustrates a conventional tape cartridge with a built-in tape reel, and the tape reel 1 is composed of a reel body 2 with a lower flange and an upper flange 3 integrally connected thereto. The lower flange-equipped reel body 2 is formed into a double cylindrical shape having a drive shaft hole 4 with an open bottom, and is formed in such a manner that the upper end of the drive shaft hole 4 is closed with an upper end wall 5. A spring receiving boss 6 is integrally protruded from the center of the upper surface side, a plurality of welding pins 7 are integrally protruded around the spring receiving boss 6, and a lower flange 8 is integrally protruded from the outer periphery of the lower end of the reel body 2. It is integrally formed into a shape.

On the other hand, the upper flange 3 has the spring receiving boss 6 at its center.
and a center hole 9 for receiving the welding bottle 7 and a coupling hole 1.
It is formed into a flat plate shape with 0. In this way, the center portion of the upper flange 3 is overlapped with the upper surface of the upper end wall 5 of the reel body 2.

After inserting the spring receiving boss 6 and welding bottle 7 into the number holes 9 and 10, the end of the welding bottle 7 protruding from the hole 10 is heated and crushed to integrate the upper flange 3 into the reel body 2. It will be caulked and welded.

Then, this tape reel 1 is rotatably incorporated into the main body case 11 of the tape cartridge, but at this time, the spring receiving boss 6 is pressed down by the reel press plate spring 12 attached to the inner surface of the main body case 11. The tape reel 1 is regulated so that it does not unnecessarily wobble in the thrust direction within the main body case 11.

By the way, when injection molding the reel body 2 having the above shape from a plastic material, care is taken to ensure that no deformation or internal distortion remains in the reel body 2, which is a molded product.

In addition, it is necessary to pay attention to the position of the gate (G) for resin injection in order to avoid spoiling the appearance, but generally, as shown in Figure 4, the gate (G) is set at the welding bottle 7. , or at the center of the inner surface of the upper end wall 5 of the drive shaft hole 4.

[Problems that the invention attempts to solve] However, according to the former gate arrangement described above.

Since the welding bottle 7 is crushed by welding, it has the advantage that there is no need to remove the gate after molding, but on the other hand, since the welding pin 7, which is the gate part, is located off-center from the center of the reel body 2, the material does not form in the cavity. This tends to cause molding defects.

On the other hand, according to the latter gate arrangement, since the gate part is located inside the drive shaft hole 4, there is no need to perform special removal treatment for gate marks, and the gate G is located inside the reel body part 4.
Since it is located at the center in the radial direction of the whole, it has the advantage that the material flows uniformly throughout the cavity without being biased toward the cavity. However, when the gate part is placed in the drive shaft hole 4 which has a double blind alley shape.

This makes it difficult to lower the temperature of the core block in which the drive shaft hole 4 is molded, resulting in a disadvantage that the molding cycle increases significantly.

Furthermore, since it is difficult to uniformly cool the core block, there is a disadvantage that internal distortion tends to remain in the reel body 2 due to the difference in shrinkage of the materials.

This invention was made in order to solve the above-mentioned conventional problems, and the first objective is to improve molding accuracy and reduce internal distortion by devising a single gate arrangement, and to enable high-cycle molding. purpose.

A second object of the present invention is to simplify the gate processing work and ensure a good spring receiving function by devising the gate processing method.

(Means for Solving the Problems) In order to achieve the above first and second objects, the present invention takes the following measures.That is, in order to achieve the first object, the present invention takes the following measures. , the spring receiving boss 6 provided at the center of the outer surface of one axial end of the reel body 2 is positioned at the game 1-G.

In order to achieve the second object, the present invention adopts a hot runner system during injection molding of the reel body 2,
In particular, a valve gate type real runner system is adopted. Then, a concave curved surface 17a is provided at the tip of the operating valve pin 17 of the hot runner mold, and the tip top portion 6a of the spring receiving boss 6 is formed into a convex curved shape using this concave curved surface 17a, so that the gate mark is smoothed.

Here, when forming the top end 6a of the spring receiving boss 6 into a convex curved shape, it is preferable to form it in a terrace shape as shown in FIG. It is optional.

[Effect]

In this case, during injection molding of the reel body 2, the molten resin is injected from the radial center position of the entire reel body 2, so that the resin is uniformly flowed throughout the cavity without drifting. Further, since the gate G is disposed outside the drive shaft hole 4 of the reel body 2, it becomes possible to pass the cooling circuit 20 through the core block I9 for forming the drive shaft hole.

Cooling is performed efficiently and uniformly, making it possible to speed up the molding cycle and reduce internal strain.

The top end 6a of the spring receiving boss 6 is formed into a convex curved surface with the concave curved surface 17a of the tip of the operating valve pin 17 of the hot runner mold, and the gate marks are smoothed, so that the gate processing work can be eliminated. , press the reel 1
2 will be accepted and supported in a stable manner.

〔Example〕

Two embodiments of the present invention will be described below with reference to FIGS. 1 and 2. The overall structure of the target plastic tape reel is almost the same as the conventional one described above, so the same reference numerals will be given and the explanation will be omitted, and only the points that are different from the conventional reel body will be explained. .

FIG. 1 shows the structure of a hot runner mold for a lower flange-equipped reel body 2 that is injection molded using a valve gate type real runner system, in which 13 is a fixed mold, 14 is a movable mold, and 15 is a movable mold. cavity,] 6 is a preheating bush, 1
7 is an operating valve pin that moves up and down within the preheating valve nozzle 16 between positions A and B, and has a concave curved surface 17a at its tip.
18 is a heat insulating ring, and G is a valve gate, which are set at a position corresponding to the top end 6a of the spring receiving boss 6 at the center of the upper surface of the upper end wall 5 of the reel body 2, which is a molded product. Note that 21 indicates a hot runner. and,
On the side of the movable mold 14, a cooling circuit 20 is incorporated in a core block 19 for forming the drive shaft of the reel body 2.

Thus, the two-actuating valve pin 17 is raised to the A position, and molten resin is injected into the cavity 15 through the valve gate G. After injection, the operating valve pin 17 is lowered to the B position. Then, since the valve gate G is at the center position in the radial direction of the reel body 2, the molten resin is uniformly flowed into the cavity 15, forming the reel body 2 with the lower flange having the spring receiving boss 6 and the welding bottle 7. At the same time, the concave curved surface 17a of the two-actuation valve pin 17 forms the top end 6a of the spring receiving boss 6 into a terraced convex curved surface to smooth the gate mark. When the molded product is taken out, it is cooled and solidified, and at this time, the inner surface of the dead-end reel body 2 is uniformly cooled and solidified in a short time by the cooling circuit 20 in the core block 19.

〔Effect of the invention〕

As explained above, according to the present invention, the reel body 2
The top end 6a of the spring receiving boss 6 is molded with the end of the operating valve pin 17 of a hot runner mold of the valve gate type. In other words, since the valve gate G is positioned at the radial center of the reel body 2 and outside the drive shaft hole 4, the quality and precision of injection molding can be improved, and productivity can be significantly improved. . Moreover, the tip top portion 6a of the spring receiving boss 6 is the concave curved surface 17 of the tip of the operating valve pin 17.
A is formed into a convex curved shape to smooth out the traces, so there is no need for gate treatment after molding.

Nevertheless, the top end portion 6a of the spring receiving boss 6 has the advantage of stably receiving and supporting the reel presser plate spring 12.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing the configuration of a molding die directly used for carrying out the present invention, and FIG. 2 is a sectional view showing a spring receiving boss. FIG. 3 is a sectional view of a tape cartridge incorporating a conventional tape reel, and FIG. 4 is a sectional view of a reel body with a lower flange of the tape reel. 1...Tape reel. 2...Reel body. 3...Top flange. 4... Drive shaft hole. 5...Top end wall. 6...Spring receiver boss. 6a...Tip apex. 8...Lower flange. 17... Operating valve pin. 17a...Concave curved surface. G......Gate.

Claims (1)

[Claims] (1) The tip apex 6a of the spring receiving boss 6 protruding from the center of the outer surface of one axial end of the reel body 2 has a concave curved surface 17a at the tip of the operating valve pin 17 of the valve gate type hot runner mold. A plastic tape reel characterized by being formed into.