JPS58158232A - Molding method using ring gate - Google Patents

Abstract

PURPOSE:To mold the highly accurate product having true circularity without welded lines, by inserting a metallic rod shaped protruding member, forming a unitary body, and uniformly injecting a fused molding material through the ring gate between the inserted part and a metal mold. CONSTITUTION:A metallic shaft 12 having the size and shape corresponding to the central shaft of the product is arranged as the inserted part. The protruded part 12a at the lower side is positively held by the metal mold 11. A lower end surface 13a of a runner core 13 is coupled with an upper end surface 12c of the inserted shaft 12. A cylindrical runner 15 is formed between the outer surface of the runner core 13 and the inner surface of a metal mold 14. The ring shaped gate 17, which is contacted with a molding part 10, is formed at the lower part of the runner. The fused molding material, which is flowed in from the spool through a runner 21, becomes the flow only in the direction of the ring gate 17, and fills the inside of the molding part 10 at the uniform pressure. Thus a product 23, wherein the shaft 12 is inserted in the center as a unitary body, is molded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is applicable to molded products that require highly accurate roundness,
J This invention relates to a molding method suitable for use in molding products that are undesirable from the generation of weld lines from the standpoint of strength, and which have a metal rod-shaped protruding member such as a central shaft at a predetermined position.

Conventionally, for molding synthetic resin molded products such as annular parts and gears, as shown in FIG.
2), the molten synthetic resin material was injected into the molding part (3). For this reason, the injected molding material flows in the direction of the arrows in each molding part (3), creating a central joining part, and in this part, a so-called weld line (4), which is a weak joint with insufficient mechanical strength, is formed. was occurring. In addition, several injection ports (2
) The inflow pressure of the molding material injected from the molding part (3:
Because it is not uniform inside, gears, flywheels, etc.
It has been extremely difficult to mold products that require accurate shapes and highly accurate roundness. In addition, especially when iron powder or the like is mixed into a synthetic resin material in order to increase the mass, the iron powder is likely to be distributed unevenly, resulting in uneven weight balance. Moreover, in the case of gears, flywheels, etc. formed in this manner, the shaft (6) is fitted into the shaft hole (5) after machining the shaft hole (5) to form an integral unit, which requires a large amount of manufacturing man-hours.

The present invention was made in view of the above-mentioned circumstances, and its purpose is to insert and integrally mold a metal bar-shaped protruding member that will be integrated with a future product such as a shaft, and to uniformly spread the molten molding material. To provide a molding method capable of molding a product without weld lines or a product with highly accurate roundness and uniform filling by injecting it into a molding part.

In order to achieve this purpose, in the molding method of the present invention, a metal rod-shaped protruding member such as a shaft that will be integrated with a future product is placed at a predetermined position in the molding part as an insert part, and the protruding insert part is In addition to holding at least one end, a ring opening gate is formed between the outer circumferential surface of the protruding part and the inner circumferential surface of the mold by using the protruding part of the insert part, and communicating with the molding part. The first embodiment of the present invention will be described below with reference to Fig. 2 and Fig. 6. The explanation will be based on.

First, the metal microdevice used in this first embodiment will be explained. The symbol aO is a molding part formed in the movable koji mold aIJ, and in the center of this molding part (101, a metal shaft aδ of a size and shape corresponding to the central axis of the product is arranged as an insert part, The downward protrusion of this axis a2 (1
Note that the upper surface (10 m) of the molding part (1 (1) is almost at the same level as the upper surface of the mold aυ.

On the other hand, the lower end surface (13a) of the runner core Q31 is the upper end surface (
This is a frusto-conical rond with a small taper that has the same shape as runner core a31 or its lower end 11i (13m).
1, and fixed to the other end by a fixed thin metal plate (not shown).

In this case, the upper end surface (12c) of the insert shaft a2 is provided with a protrusion # (12d) as shown by the chain line in Fig. 112,
This protrusion (12d) is fitted into the recess 8tl (13b) formed at the lower end of the runner core a3, and the runner core (1
2+ and insert with even higher precision) 4
Holding 11 (121 also turns red).

Next, the runner core a3 is surrounded by a fixed 11 first mold 041 having a predetermined thickness, and a cylindrical launch (151
An upper runner 7 lange saθ is formed, and the above-mentioned molded portion (ring-shaped goo communicating with IQ) an is formed at the lower part of this runner a9.

On the other hand, there is a linear horizontal runner a8, a circular horizontal runner ridge branching from one end of the horizontal runner a8, and an inlet (20a) that connects the end of the horizontal runner acJ to the runner 7 lung portion 061, respectively. 2, Ob) or the fixing I [formed on the upper surface of the first mold (14+). One end is connected to the upper sprue (not shown), and the other end is connected to the end of the horizontal runner a8. A fixed side second metal mold 4 having a vertical runner (211 formed inside) connected to the first mold (14
1 and fixed thereto.

In the mold device configured as described above, the flow of molten molding material flowing from the sprue to the runner 7 flange portion t161 via the runners (2〃α8a pier (20a) (20b)) flows downward while going around the periphery. The flow in the upper part of the runner (151) is a combination of the circumferential flow and the downward flow, and some of the flow in the circumferential direction remains.However, the flow in the upper part of the runner (U5) In this case, the above-mentioned molding material finishes going around the runner core a3 and flows only in the direction of the ring gate an.

Therefore, the molten molding material flows radially and uniformly into the molding part (101) through this ring gate a'r), and is filled into the molding part (101) with uniform pressure, with the axis a21
A circular molded product (c) is formed by integrally inserting the In addition, in this embodiment, the runner is hollow and has a very small volume, so the molding cycle is short.
Material costs can be significantly reduced.

What is shown in FIGS. 4 and 5 is a second embodiment of the present invention, which is suitable for molding small products with high precision. Since this 1g2 71 example differs in the metal W device from the first example, the mold device will be explained first.

A molding 5001 is formed in a movable mold Gυ, and a metal 41i (to) having a size and shape corresponding to the central axis of the product is placed in the center of this molding S hook as an insert part.
The tip 4s of the upper protrusion 5 (52a) of this shaft movement is securely held by the runner core (to). The runner core (to) is a conical rod with a small taper that has an obtuse conical surface on its lower end surface (33 m), and the recess (33 b) bored in the center of its lower end surface (35 m) has the above-mentioned shape. After lowering the tip of the protruding part (32J1) of the insert shaft C12+ so that it is coaxial with this shaft 0, insert it vertically with a predetermined gap between it and the molded part □□□. Fixed.

Next, a fixed mold 11@1 with a predetermined thickness is placed around the runner core (to), and the lower end surface (35a) of the runner core (to) and the inside of the mold (2) are A conical runner is formed between the two. and,
The protruding shaft (3) is placed in the lower part of this launch (c), that is, in the gap between the molded part (to) and the lower end facing the runner core.
A ring-shaped gate communicating with the molding part is formed between the outer circumferential surface of mold (2a) and the inner circumferential surface of mold (2).

On the other hand, at the opposite positions of the upper end of the conical launch (to), there is a runner core (to) connected to this runner (c).
Runners (, 57a, 57a, 57b, 57a, 57a, 37b) are formed along the outer peripheral surface of the runners with a predetermined ring and a predetermined thickness, and the upper ends of these launches (C57a), CB7k) are connected to semicircular horizontal runners (to), respectively. . The **-shaped horizontal runner c19, the vertical runner, and the gold W (41) of the fixed 11!2 connected to this semicircular launch are exactly the same as in the first embodiment. Runner (37a) (371m) of the mold device configured as above.
) The molten molding material that has flowed into the conical runner flows into the conical runner@ And, also in this second embodiment, before the molding material that has flowed in reaches the ring gate ■, the lower end surface of the runner core can (3!ia ), the molded product is formed by flowing only in the direction of the ring gate (toward), as in the first embodiment. Also, the shape of the lunch is slightly different from that of the first embodiment, but
The hollow shape as shown in FIG. 5 is also the same as in the embodiment *i. Therefore, in this second embodiment as well, the same effects as in the first embodiment can be achieved.

The one shown in Iris 6FItJ is a third embodiment of the present invention, and parts having the same or the same functions as those in the first embodiment are given the same reference numerals and their explanations will be omitted. The third embodiment differs from the first embodiment in that a runner core is not used. Therefore, in this third embodiment, the metal part structure is simple, and the point that the molten molding material is injected into the molding part aQ through the ring gate recirculation η is the same as in the first embodiment. It is clear that a molded article of quality similar to that of the example is molded. However, since this third embodiment does not use a runner core, when the molded product becomes large and the diameter of the ring gate aη becomes very red, the volume of the runner (c) becomes very large and the molding cycle becomes longer. However, there is a disadvantage that a large amount of unnecessary synthetic resin remains in the lunch box, making the material cost uneconomical.

In addition, in these embodiments, the insert shaft a's
a and ring gate a? Although the shape of ) (to) is circular, it is clear that this shape may be polygonal and the same effects as described above can be achieved.

First, the molten molding material is injected radially and uniformly into the molding part through the darts formed between the insert part and the mold, so the inflowing molding material is filled into the molding part with uniform inflow pressure. Ru. Therefore, not only do weld lines not occur in the molded products, but the molded products are also uniform in their internal filling, and 114 products have been molded with accurate shapes and highly accurate roundness and shapes. Ru.

Moreover, since the metal bar-shaped protruding members, such as the shaft, which will be integrated with this product in the future, are integrally molded as insert parts, the number of manufacturing steps can be significantly reduced, resulting in lower costs.

[Brief explanation of the drawing]

FIG. 1 is an explanatory schematic diagram showing a conventional molding method, 1112
3 is a perspective view of the molded product and runner of the first embodiment, and Figure 4A is a longitudinal cross-sectional view of the metal device used in the embodiment of @1 of the present invention. FIG. 4B is a vertical sectional view of the gold layer device used in the example, and FIG. 6 is a reduced perspective view of the dust removal device shown in FIG.
The reason is a longitudinal sectional view of the @3 embodiment of the present invention. In addition, in the symbols used in the drawings,
−−−−・−・・・・・−・Movable cylinder metal a plowing・・・・・
・－・・・・・・Insert shaft A grade－・・・・・・・・・・
・・・・Fixed side first mold a■・・・・−・−・・−
...-It is a ring gate. Agent Masaru Ueya Yoshio Tsunekazu Toshiki Sugiura Figure 1 Figure 2 j I 3 Figure 4 A Figure 5 Figure 6 (Voluntary) procedural amendment letter May 10, 1980 Mr. Commissioner of the Japan Patent Office 1, of the case Display Patent Application No. 41105 of 1982 2, Title of invention: Molding method using ring dart 6, Number of inventions increased by amendment 7, Subject of amendment (1), Page 10, lines 6 to 7 of the specification "The molded product is uniform and uniform."
is corrected as ``The density inside the molded product is also more uniformly distributed than in the gate area.'' One or more -

Claims (1)

[Claims] An insert component that protrudes from at least one end of the molded part formed in the mold is placed at a predetermined position of the molded part, and at least one end of the insert part is held, and the outer circumferential surface of the protruding part of the insert part is held. A ring-shaped gate communicating with the molding part is formed between the inner peripheral surface of the mold and the mold, and the molten molding material is injected into the molding part through the ring gate. Forming method using a gate.