JPS60240424A - Manufacture of tape reel - Google Patents

Abstract

PURPOSE:To eliminate the surfacial sway of tape reels and improve cylindricality and assure the high cycle manufacture of tape reels by providing cooling grooves to be provided on a stationary cavity core on a gate side at a location close to a cavity as far as processing is possible. CONSTITUTION:In a tape reel mold composed of a stationary core 2 and a stationary cavity core 1 and their corresponding movable core 4 and cavity core 3, a cooling groove 24 to be provided inside the stationary cavity core is installed close to a cavity 5 and also with a projection surface. As a result, a temperature differential of the stationary cavity core 1 and the movable cavity core 3 when molded is retained in the range of 0-10 deg.C. Thus the surfacial sway of tape reels is eliminated and the cylindricality of tape reel core is improved. In addition, the molding cycle (injection + cooling time) can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to improvements in tape-reel molding methods. More specifically, in a tape reel mold having a fixed cavity core provided with a gate and a movable cavity core, a method of molding a tape reel with high precision by improving the cooling efficiency of the fixed cavity core. Regarding.

[Prior Art] As is well known, a tape reel molding mold includes a fixed core and a fixed cavity core provided with a gate, and a movable movable core and a movable cavity core. Molten tape reel molding resin is injected into the cavity formed by joining the movable core to the fixed core through a gate provided on the fixed core, and is then introduced into the cavity. The filled resin is cooled and solidified, the mold is opened, and a tape and reel molded product is taken out. However, in conventional tape and reel molding molds, when the molding cycle is shortened, the fixed side cavity temperature rises, causing problems such as surface runout of the tape and reel molded parts and cylindricity of the tape winding core to rapidly increase. .

In order to improve these problems, we conducted a thorough study and found that in conventional molds, the position of the cooling water channel is inappropriate based on the constraints of the mold structure, so the cooling efficiency of the cavity in the fixed side cavity core on the gate side has been improved. It was found that the temperature difference between the stationary side cavity and the movable side cavity became large, and the surface runout of the reel molded part and the cylindricity of the tape winding core deteriorated.

Based on this knowledge, we conducted a study and found that by increasing the cooling efficiency of the stationary side cavity core and using a mold that can cool it uniformly, it is possible to reduce the temperature difference during molding between the stationary side cavity and the movable side cavity. The inventors have invented a tape reel molding method that can improve the surface runout and cylindricity of the tape reel and enable high-cycle manufacturing of tape reels.

Hereinafter, the present invention will be explained using the drawings.

FIG. 1 is a schematic cross-sectional view showing an example of a conventional hot runner type tape reel molding die. In FIG. is a stationary cavity core, which is assembled by attaching the stationary core 2 to the stationary cavity core 1. Reference numeral 3 designates a movable cavity core that can be moved toward and away from this, and 4 designates a movable core, which is assembled by attaching the movable core 4 to the movable cavity core 3. 5 is a cavity formed when these cores are joined. A nozzle of a molding machine (not shown) is connected to the nozzle contact surface 6 of the mold, and the molten resin is injected into the mold through the nozzle, passed through the runner 7, heated by the hot tip 8, and then released from the gate 9. Fill the caviar. The birch-ing surface 10 is a contact surface between the stationary mold and the movable mold. The fixed side mold includes the above-mentioned fixed side cavity core l and fixed side core 2, as well as a fixed side mounting plate 11,
Manifold block 12, fixed side spacer block 13, fixed side receiving plate 14. It is composed of a fixed side template 15 and the like. On the other hand, the moving side mold has a moving side mold plate 16 and a moving side receiving plate 17.
, upper ejector plate 18. It is composed of a lower ejector plate 19, a moving side spacer block 2o, a moving side mounting plate 21, etc. The hatched parts are cooling grooves, 22 is for gate or hot chip cooling, 24
26 is a cooling groove for cooling the cavity of the stationary cavity core, 26 is a cooling groove for cooling the tape reel side plate of the moving cavity core, and 28 is a cooling groove for cooling the cylindrical core of the tape reel. 23 is a cooling water inlet/outlet path to the cooling groove 22, 25 is a cooling water inlet/outlet path to the cooling groove 24, 27 is a cooling water inlet/outlet path to the cooling groove 26, 29
is a cooling water inlet/outlet passage to the cooling groove 28. FIG. 2 is a plan view of essential parts showing the positional relationship between the cooling groove 24 and the cavity 5 in the A-^ cross section of the stationary cavity core portion l shown in FIG. 31 is the outer peripheral end of the cavity of the reel side plate;
2 is the outer end of the fixed side cavity core, 33 is the outer peripheral end of the fixed side core, 2.5-1 is the cooling water inlet/outlet passage 25
25-2 indicates the entrance to the cooling groove 24, and 25-2 indicates the exit from the cooling groove 24. In the conventional mold shown in Figs. 1 and 2, it is not possible to make the cooling groove 24 for cooling the cavity on the gate side closer to the cavity 5, so the cooling efficiency of the molded product is poor and the molding is difficult to cool the cavity on the moving side and the fixed side. The temperature difference between 5℃ and 1
It is large at 5 degrees Celsius. Furthermore, if the molding cycle is shortened, the temperature of the stationary side cavity increases, causing problems such as surface runout of the molded product and cylindricity of the tape core.

[Problems to be Solved by the Invention] The object of the present invention is to solve the problem in a molding die consisting of a fixed cavity core and a movable cavity core joined to the fixed cavity core. By placing the cooling groove in the core as close to the cavity as possible during machining, the stationary cavity core is sufficiently cooled, and the temperature difference between the moving and stationary cavity cores is reduced. The object of the present invention is to reduce the surface run-out of a tape reel of a VTR used in a VTR, improve the cylindricity of a tape winding core, and shorten the molding cycle (injection + cooling time).

[Means for solving the problem] That is, the present invention consists of a fixed core and a fixed cavity core on the gate side, and a movable core and a movable cavity core opposing these, which are provided in the fixed cavity core. Using a tape reel mold in which the cooling groove is provided close to the cavity and its projected surface overlaps the cavity of the reel side plate, the temperature difference during molding between the fixed cavity core and the movable cavity core is reduced. This relates to a tape-reel molding method characterized by injection molding a resin while maintaining the temperature within a range of 0 to 10°C.According to the present invention, by sufficiently cooling the stationary side cavity, The difference in cavity temperature between the moving side and the stationary side is reduced, the surface runout of the tape reel and the cylindricity of the tape core are improved, and the molding cycle (injection and cooling time) can be shortened.

[Example] Next, the present invention will be explained with reference to FIG. 3 showing a preferred embodiment thereof. FIG. 3 shows the molding die shown in FIG. 1, with cooling grooves 24 in the stationary cavity core 1 on the gate side extending above the side plate of the tape reel, and the cavity 5
It's closer to Suke and others. FIG. 4 is a plan view of essential parts showing the positional relationship between the cooling grooves 24 and the cavity 5 in the AA' cross section of the cavity core in FIG. 3. FIG. 25-1 and 25-2 respectively indicate a cooling water inlet path to the cooling groove 24 and an outlet path from the cooling groove 24. The cooling groove 24 of the conventional hot runner type tape reel mold was not located so that its projected surface overlapped with the cavity of the reel side plate (that is, within the outer circumferential end 31) as shown in FIG. In the present invention, by providing the cooling groove 24 so as to overlap the cavity of the side plate portion (that is, so that at least a portion thereof enters the outer circumferential end 3I) and bringing it close to the cavity, efficient cooling can be achieved. Although it depends on the molding conditions such as molding cycle, the temperature difference between the fixed side and the moving side should be 0 to 1.
The temperature can be as low as 0°C.

The cooling grooves should be installed as close to the cavity as possible, with the bottom part separated from the surface of the cavity by 2+am or more. 2+ue or less may be difficult to process. Preferably 30m+a or less, more preferably 5~
It is provided at an appropriate position within a range of 20 mm from the viewpoint of processing and mold strength. Also, the width of the groove is determined so that the projected surface of the cooling groove overlaps the reel side plate portion of the cavity. Cooling # shown in Figure 3
The center position of I24 is, for example, 15m from the cavity surface.
It is m.

FIG. 5 shows an example of the relationship between the molding cycle (injection+cooling time) and cavity temperature for the conventional method and the cooling method of the present invention. (A) is when the mold of the present invention shown in FIG. 3 is used, (B)
) is a case using a mold having conventional cooling grooves as shown in FIG.

Molding cycle, surface runout of the tape side plate, and cylindricity of the tape winding core when the cooling method is a conventional method (Fig. 1) and when a close cooling method, which is an example of the present invention, is used (Fig. 3) The details are shown in Table-1.

Table 1 The molding conditions shown in Figure 5 and Table 1 are as follows:
H5 type VTR tape reel 89mm diameter injection pressure 0
0 Kr/cm2 Injection speed 3m/sin, mold temperature 40
The molding was carried out under the conditions of ℃.

Surface runout was measured using a surface roughness measuring machine (SE-4A) manufactured by Koita Research Institute, and the value indicates the difference between the highest and lowest points of deformation toward the top and bottom of the side plate. be.

The mold used in the present invention can be used regardless of the gate position, ho/ ) runner, or cold runner.
This is particularly effective when using a hot runner. Further, the resin molded by the tape-reel mold of the present invention is not particularly limited as long as it is a thermoplastic resin that can be injection molded, but polyacetal resin, polyester resin, ABS resin, etc. are suitable.

[Effects of the Invention] By using the tape-reel molding method of the present invention, the following remarkable functions and effects are exhibited.

(1) Surface runout and cylindricity are improved by reducing the temperature difference between the moving and fixed cavities and by providing sufficient cooling.

(2) Fast cycle molding becomes possible, reducing costs.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of an example of a conventional hot runner type tape reel molding mold, FIG. 2 is a plan view of the main part of FIG. 1, and FIG. 3 is an example of a mold used in the present invention. FIG. 4 is a schematic cross-sectional view of the embodiment, FIG. 4 is a plan view of the main part of FIG. 3, and FIG. 5 is a graph showing test results of the conventional cooling method and the cooling method of the present invention. l...Fixed side cavity core 24.24-1.24-2...Cooling groove 1-1.1-2
...Divided block 25.25-1.25-2...Cooling water inlet/outlet passage 5...
Cavity applicant's agent Kaoru Furuya

Claims (1)

[Claims] Consisting of a fixed core and a fixed cavity core on the gate side, and a movable core and a movable cavity core opposing these, the cooling groove provided in the fixed cavity core is arranged so that it is close to the cavity and its projection surface. However, by using a tape reel mold that overlaps the cavity of the reel side plate, the temperature difference during molding between the stationary side cavity core and the moving side cavity core is maintained within the range of 0 to 10°C, and the resin is A tape-reel molding method characterized by injection molding.