JPH0155976B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a synthetic resin molded product, such as a synthetic resin molded product, in which a large number of solid rod-like bodies, such as cylindrical pieces for accommodating the ends of electric wires, are connected in parallel via intermediate pieces. The present invention relates to a method and apparatus for manufacturing continuous cylindrical pieces for electrical terminals, and more particularly to a method and apparatus for manufacturing continuous cylindrical pieces when these cylindrical pieces are press-deformed into an elliptical cylindrical shape during use.

[Prior art]

In the conventional method for manufacturing the above-mentioned cylindrical pieces for electrical terminals by injection molding of synthetic resin, the sixth
As shown in the figure, a gate 10 that is perpendicular to the direction in which the cylindrical cavities 12 are continuous, but oblique to the axial direction of these cavities, is provided on one side of the two-part mold, for example, and the gate 10 is inserted through the gate. It has been common practice to inject molten resin into each of a series of cavities 12 each having a shape corresponding to the cylindrical piece.

[Problem that the invention seeks to solve]

Therefore, according to the conventional method, the gate marks 14 of the molded product that has been gate trimmed are located at right angles to the continuous direction of the cylindrical pieces 40 as shown in FIG. 7, and are therefore highly visible from the outside and spoil the aesthetic appearance. Particularly, when these continuous band-shaped cylindrical pieces 40 are used for manufacturing electric terminals, they are pressed from a direction perpendicular to the continuous direction and the axial direction of the cylindrical pieces as shown in FIGS. In order to fix the terminal metal piece 18 inside the cylindrical piece, the intermediate piece 34 is removed and simultaneously deformed into a flat shape, so the gate mark 14 is
Not only does this expand due to elongation stress, further impairing the aesthetic appearance, but also causes other problems such as the following. That is,
When molten resin is injected into the cylindrical cavity 12 of the mold, this resin splits in two directions from the gate 10 and joins on the opposite side of the gate to form a so-called weld line 20. Pressing concentrated stress in the elongation direction, leading to breakage of the cylindrical piece and lowering the yield rate of non-defective products. The present invention therefore seeks to eliminate the above-mentioned drawbacks.

[Means to solve the problem]

The present invention relates to a method for manufacturing a continuous band-shaped cylindrical piece for electrical terminals, etc. by injection molding of thermoplastic synthetic resin, in which a plurality of cavities arranged parallel to each other along a mold parting line are continuous. A method characterized by supplying molten resin to each cavity from a direction oblique to the direction and also oblique to the cavity axis direction, and a device directly used in this method are provided as means for solving the above problem. .

More specifically, in the method of the present invention, the molten resin is supplied to the cavity of the mold from a direction oblique to the continuous direction of the cavity along the parting line, so that the gate marks on the individual cylindrical pieces are A continuous band-shaped cylindrical piece for an electric terminal or the like is manufactured in which a line connecting the cylindrical piece and the weld line obliquely intersects the continuous direction of the cylindrical piece when viewed from the axial direction of each cylindrical piece. In addition, in order to enable the above method to be carried out in the apparatus of the present invention, the structure of the mold loaded into the injection molding machine is specialized, and includes a runner that receives molten resin via a sprue and each of the above cavities. The angle of the gate connecting between the two and゜ (supplementary angle 135゜).

[Effect]

If the above method is carried out using the above device,
The molten thermoplastic synthetic resin is applied to the cylindrical space formed between the walls of multiple cavities parallel to each other in the direction of the parting line of the two molds and the circumferential surface of the pin inserted into each of these cavities. After the molten resin is cooled and hardened, 2
When the two molds are separated from each other and the pin is pulled out, and the molded product is extruded by the ejector pin, the protruding piece at the gate is also removed, leaving a gate mark, as in the past, but this gate mark and weld line The line connecting these lines obliquely intersects the continuous direction of the cylindrical pieces at the above-mentioned angle, which is in very good contrast to the conventional molded products of this type in which the above-mentioned line and the above-mentioned continuous direction were perpendicular to each other.

〔Effect of the invention〕

When the continuous cylindrical piece for electrical terminals, etc. manufactured by the method and apparatus of the present invention is used to make an electric terminal, for example, by the apparatus shown in FIGS. The press tool 50, which moves in the direction shown in FIG. At this time, since the gate marks are located at or near the contact position with the surface of the press tool, the area does not expand as much as in conventional products, and therefore not only does it not spoil the aesthetic appearance of the final product, but also prevents welding. Since the lines are located in areas where the generation of tensile stress is relatively small, or where compressive stress is applied, there is no risk of breakage at the weld line during the press crushing process mentioned above, and the yield rate of good quality products is increased. is significantly improved. In FIG. 5, reference numeral 54 is a sprocket for feeding the cylindrical piece, 54' is a pedestal, and 56 is a drive mechanism for raising and lowering the press tool 50 and rotating the sprocket 54.

The above effect is most pronounced when the angle of the gate is approximately 45°.

In addition, when the cylindrical piece is used without being flattened and the intermediate piece is not cut out, the aesthetic appearance is most improved when the angle of the gate is close to about 30°.
This is because the gate mark is located close to the intermediate piece and is difficult to visually recognize.

Other important advantages of the present invention are obtained during mold making and during injection molding. First, when manufacturing a mold, the long trunk runner before branching can be brought closer to the cavity than before, increasing the degree of freedom in mold design. If necessary, the length of the end runner after branching can be shortened, which shortens the overall length of the runner, reducing resin loss, and also speeds up resin filling, contributing to shortening of the process. Furthermore, the angle at which the trunk runner transitions from the terminal runner is conventionally 90 degrees, but in the present invention it becomes obtuse to 150 degrees to 120 degrees (as described above), so that the flow of the high viscosity molten resin becomes smooth. That is, since there is no risk of dead space being created, the contamination of thermally degraded residual resin can be avoided and the product can be made more uniform.

〔Example〕

The present invention will be explained in more detail below with reference to the illustrated embodiments.

In the injection mold according to the apparatus of the present invention shown in FIG. 1, a runner 30 that receives molten resin from an extruder via a spool is connected to each cavity 12 via a gate 32. Reference numeral 13 designates a thin plate-like cavity for the intermediate piece.

In this embodiment, the angle (θ) between each gate 32 and the continuous direction of the cylindrical piece cavity 12 is approximately 45°. Therefore, even though the end runner 30 itself can be made short, the distance between the runner and the cavity 12, that is, the length of the gate 32, is
If it is unavoidable in the mold design that the angle (θ) is considerably longer than the case of 90° (prior art), the pressure loss when high-viscosity molten resin flows through the gate will be extremely large. To prevent an increase in extruder discharge pressure from increasing power costs or causing insufficient resin supply, the gate diameter should be made slightly larger than the conventional one. For example, if the gate length is 1.4 times, the gate diameter should be set to √1.4. (approximately 1.2) times. Increasing the diameter of the gate to this extent does not make it very difficult to remove a portion of the gate after the resin is cooled and solidified.

The above-mentioned mold is operated according to a conventional method, and the continuous strip produced therefrom has a shape in which several cylindrical pieces (5 pieces in the example of FIG. 1) are connected via an intermediate piece 34, The endless piece shown in FIG. 3, which is obtained by sequentially welding the end pieces 36 and 38 to the end pieces of another strip, can be advantageously applied to a continuous press as shown in FIGS. 4 and 5. In this pressing operation, each cylindrical piece 40 of the molded product has its gate mark 1
4 and the weld line 20 are in contact with the press tool 50 and the receiving tool 52, respectively, so when the cylindrical piece 40 is pressed and flattened, it receives almost no stress in the elongation direction, but rather receives stress in the compression direction. tend to receive it. Therefore, there is no risk that the area of the gate trace 14 will expand, and there is no risk that it will burst at the weld line 20. The stress in the elongation direction is generated at the location indicated by the symbol E in FIG. 6, and from this fact, the above-mentioned drawbacks of the conventional molded product can be understood.

[Another example]

In another embodiment of the present invention, the angle (θ) of the gate is approximately 60°, and since the gate length is only slightly increased, the gate diameter can be almost the same as that of the conventional product. The cylindrical piece produced with this mold is suitable for use when the degree of flattening is relatively small.

In yet another embodiment, the above angle (θ) of the gate
is said to be approximately 30°. In this case, if the gate length is approximately doubled, the gate diameter should be multiplied by √2 (approximately 1.4
It is desirable to increase the Even in this case, it hardly becomes difficult to remove the protruding piece of the gate portion.
This strip is suitable if it is to be extremely flattened during use.

In yet another embodiment, the runners, gates, and cavities are arranged symmetrically as shown in FIG. 2, and the molten resin is supplied from the direction of arrow A, so that the flow of resin toward each cavity 12 is It becomes extremely smooth.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part showing an apparatus according to one embodiment of the present invention, FIG. 2 is an explanatory diagram of another embodiment, and FIG.
The figure is a perspective view of a molded product manufactured according to the present invention.
Fig. 4 is a front view of the main parts of a device for manufacturing electrical terminals using the molded product or a conventional molded product, Fig. 5 is an enlarged sectional view thereof, and Fig. 6 is a sectional view of the main parts of the conventional device. , FIG. 7 is a perspective view of a molded product manufactured using a conventional apparatus. 12... Cavity for the cylindrical piece, 13...
Cavity for intermediate piece, 30...Runner, 3
2...Gate, 40...Individual cylindrical piece, θ...Angle between the continuous direction of the cylindrical piece and the direction of the gate.

Claims (1)

[Claims] 1. A method for manufacturing a continuous cylindrical piece in which a large number of cylindrical pieces are connected in parallel via intermediate pieces, the method comprising: a direction in which a cavity 12 having a shape corresponding to the cylindrical piece 40 is continuous; A method characterized by injection molding by injecting molten resin into each cavity 12 from an oblique direction. 2. An apparatus for manufacturing a continuous cylindrical piece in which a large number of cylindrical pieces are connected in parallel via intermediate pieces,
Cavity 12 having a shape corresponding to the cylindrical piece 40
The direction in which the runners are continuous through the cavity 13 for the intermediate piece 34 and the direction in which the end portion of the runner 30 and the gate 32 connected thereto extend are oblique to each other, and the cylinder Apparatus characterized in that it comprises an injection mold in which each of the cavities 12 for the shaped pieces communicates with a respective runner 30 via a gate 32. 3. The angle (θ) between the direction of the distal end of the runner 30 and the gate 32 and the continuous direction of the cavity 12 is about 30° to about 60°.
Equipment described in Section. 4. Apparatus according to claim 3, wherein said angle (θ) is approximately 45°.