JPH042034Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Application Field] The present invention relates to improvements in tape-reel molds. More specifically, the present invention relates to a tape reel mold having a fixed cavity core provided with a gate and a movable cavity core, in which the cooling efficiency of the fixed cavity core is improved. [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 cavity core and a movable 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 the resin is filled into the cavity. After cooling and solidifying, the mold is opened and a tape-reel molded product is taken out. However, in conventional tape and reel molding molds, the position of the cooling channels is inappropriate due to the constraints of the mold structure, so the cavity cooling efficiency in the fixed cavity core with a gate is poor, and the gap between the fixed cavity and the moving cavity is poor. The disadvantage was that there was a large temperature difference between them. To explain this using drawings, Fig. 1 is a schematic cross-sectional view showing an example of a conventional hot runner type tape reel molding die. It is the fixed side core with 1
3 is a fixed cavity core, 3 is a movable cavity core that can be moved toward and away from the fixed cavity core, and 4 is a movable core. 5 is a cavity formed when these cores are joined. The nozzle of the molding machine (not shown in the figure) is connected to the nozzle contact surface 6 of the mold.
The molten resin is injected into the mold from this nozzle, passed through the runner 7, heated by the hot chip 8, and filled into the cavity through the gate 9. The parting 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 1 and fixed side core 2, as well as the fixed side mounting plate 1.
1, manifold block 12, fixed side spacer block 13, fixed side receiving plate 14, fixed side template 1
Consists of 5th grade. On the other hand, the movable mold is composed of a movable mold plate 16, a movable receiving plate 17, an upper ejector plate 18, a lower ejector plate 19, a movable spacer block 20, a movable mounting plate 21, and the like. The hatched part is the cooling groove, 22 is for gate or hot chip cooling, 2
4 is for cavity cooling of fixed side cavity core,
26 is a cooling groove for cooling the moving side cavity core tape reel side plate, and 28 is a cooling groove for cooling the cylindrical core of the tape reel. Reference numeral 23 designates a cooling water inlet/output path to the cooling groove 22, 25 a cooling water inlet/outlet path to the cooling groove 24, 29 a cooling water inlet/outlet path to the cooling groove 26, and a cooling water inlet/outlet path to the cooling groove 28. FIG. 2 is a plan view of the stationary cavity core portion 1 shown in FIG. 1. 25
-1 is the entrance of the cooling water inlet/outlet passage 25, and 25-2 is the entrance of the cooling water inlet/outlet passage 25.
It shows the way out. The conventional mold shown in FIGS. 1 and 2 has a cooling groove 24 for cooling the cavity on the gate side.
Since it is not possible to process to bring it closer to cavity 5,
The cooling efficiency of the molded product is poor, and the temperature difference between the moving and stationary sides of the cavity is as large as 5°C to 15°C. Furthermore, if the molding cycle is shortened, the temperature of the stationary side cavity increases, causing problems such as surface run-out of the molded product and cylindricity of the tape core. [Problems to be Solved by the Invention] The object of the invention is to provide a hot runner type tape reel molding mold equipped with a cooling means that enables efficient and uniform cooling of the mold cavity. be. According to the tape reel mold of the present invention, it is possible to improve the surface runout and cylindricity of the tape reel, and to enable high-cycle manufacturing of the tape reel. [Means for Solving the Problems] That is, the present invention provides a hot runner tape reel mold consisting of a fixed cavity core provided with a gate and a movable cavity core joined to the fixed cavity core. The cavity core is divided into a plurality of blocks, and cooling grooves are provided on one or both sides of the divided surfaces. In this way, the cooling grooves can be easily machined and can be provided at any position, and the cooling grooves are formed by aligning the machined divided surfaces. The dividing surface is provided as close to and parallel to the tape reel side plate portion of the cavity as possible for machining the cooling grooves. Cooling grooves are provided on this divided surface close to the cavity so that the projected surface overlaps the reel side plate portion of the cavity. [Function] Thus, according to the hot liner type tape reel mold of the present invention, by sufficiently cooling the fixed side cavity, the temperature difference between the moving side and the fixed side cavity is reduced, and the surface runout of the tape reel is reduced. The cylindricity of the tape core is improved, and the molding cycle (injection + cooling time) can be shortened. As explained above, in the present invention, the stationary cavity core is composed of a plurality of blocks divided at one or more dividing planes provided close to and parallel to the tape reel side plate portion of the cavity. This relates to a tape reel mold in which cooling grooves are provided on the split surface close to the cavity so that the projected surface thereof overlaps with the reel side plate portion of the cavity. [Example] Next, the present invention will be explained with reference to FIG. 3 showing a preferred embodiment thereof. In FIG. 3, the gate side cavity core 1 is located at 1-1 and 1-2 at the dividing surface 30.
It is divided into two blocks, one of which is block 1.
-1 is machined with a cooling groove 24, and the other block 1-2 is provided with a cooling water inlet/outlet passage 25 to this cooling groove 24.
is processed. FIG. 4 is a plan view of the cavity core shown in FIG. 3, and 25-1 and 25-2 indicate cooling water inlets and outlets, respectively. The cooling groove 24 is installed close to the cavity 5, and by bringing the cooling groove close to the cavity in this way and performing efficient cooling, depending on the molding conditions such as the molding cycle,
The temperature difference with the moving side cavity can be as low as 2 to 8°C. The cooling groove should be installed as close to the cavity as possible so that its bottom is 2 mm or more away from the surface of the tape reel side plate of the cavity. If the thickness is less than 2 mm, it may be difficult to process. Preferably 30 mm or less, more preferably 5
Provided at an appropriate position within the range of ~20mm from the viewpoint of processing and mold strength. The width of the groove is such that the projected surface of the cooling groove overlaps the reel side plate of the cavity. In the tape reel mold of the present invention, the number of cooling grooves provided on the divided surfaces may be two or more as shown in FIG. 5, for example. In FIG. 5, two grooves 24-1 and 24-2 are provided on the dividing surface, and as shown in FIG. 6, cooling water is introduced from the cooling water inlet 25-1 and from the cooling water outlet 25-2. be discharged. The cross-sectional shape of the cooling groove is not particularly limited, but may be circular,
Polygons such as semicircles, ellipses, half ellipses, triangles, and quadrangles may also be used. In addition, in order to increase cooling efficiency,
Two or more dividing surfaces may be provided. Due to mold structure or processing, the dividing plane is generally provided parallel to the cavity plane as shown in the drawings. Further, in order to increase the cooling efficiency of the cavity, it may be provided so as to be completely close to the cavity surface. Also, a baffle plate may be provided in the cooling water groove. FIG. 7 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 a case using the mold of the present invention as shown in FIG. 3, and (B) is a case using a mold having conventional cooling grooves as shown in FIG. Regarding the molding cycle, surface run-out of the tape side plate, and cylindricity of the tape winding core when the cooling method is the conventional method (Fig. 1) and the two-block method (Fig. 3), which is an example of the present invention. It is shown in Table-1.

[Table] The molding conditions in Figure 7 and Table 1 are made using polyacetal resin (Polyplastics VC-10).
was used to inject a VHS type VTR tape reel with a diameter of 89 mm at an injection pressure of 700 Kg/ ^cm2 , an injection speed of 3 m/min, and a mold temperature of 40°C.
The molding conditions were as follows. Surface runout was measured using a surface roughness measuring machine manufactured by Koita Institute (SE-
4A), and the value is the upper part of the side plate,
This shows the difference between the highest point and the lowest point of downward deformation. The tape reel mold according to the present invention is a hot runner type, and the cooling groove provided close to the cavity according to the present invention is effective in the hot runner type tape reel mold. 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, ABC resin, etc. are suitable. [Effects of the invention] By using the tape-reel mold of the invention, the following remarkable functions and effects are exhibited. (1) By reducing the temperature difference between the moving and fixed cavities and by providing sufficient cooling,
Surface runout and cylindricity are improved. (2) High-cycle molding becomes possible, reducing costs. (3) By dividing the cavity core into two parts, the cooling grooves can be easily machined and placed in any position.

[Brief explanation of drawings]

Fig. 1 is a schematic sectional view of an example of a conventional hot runner type tape reel molding die, Fig. 2 is a plan view of the main part of Fig. 1, and Fig. 3 is a schematic illustration of an embodiment of the present invention. A sectional view, Figure 4 is a plan view of the main part of Figure 3, and Figure 5 is a plan view of the main part of Figure 3.
The figure is a schematic cutaway sectional view of another embodiment of the present invention, No. 6.
The figure is a plan view of the main part of FIG. 5, and FIG. 7 is a graph showing the test results of the conventional cooling method and the cooling method of the present invention. 1...Fixed side cavity core, 24, 24-
1, 24-2... Cooling groove, 1-1, 1-2... Divided block, 25, 25-1, 25-2... Cooling inlet/outlet passage, 5... Cavity.

Claims (1)

[Scope of utility model registration request] In a hot runner type tape reel mold comprising a fixed core and a fixed cavity core on the gate side and a movable core and a movable cavity core opposing these, the fixed cavity core is close to the tape reel side plate portion of the cavity. In addition, it is composed of a plurality of blocks divided at one or more dividing planes provided parallel to this, and cooling grooves are formed in the cavity in such a way that the projected plane overlaps the reel side plate part of the cavity. Tape and reel molds installed in close proximity.