JP2007253350A - Injection molding method and injection molding apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simultaneously make a plurality of times of continuous molding possible without receiving the spatial restriction of a resin molding mechanism in relation to the repeating pitch-narrowing of a continuum such as a lead frame. <P>SOLUTION: In the case of a resin injection molding accompanied by the conveyance of the lead frame 5, by making the conveyance of the lead frame 5 carried out next to each injection one pitch sending of N-1 times and next until the conveyance of N×(n-1)+1 pitch portions one cycle, a plurality of times of molding can be carried out simultaneously without receiving the spatial restriction (N is a molding mechanism arrangement period on the lead frame; and n is the number of the molding mechanisms). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an injection molding method and an injection molding apparatus for a resin portion disposed on a lead frame.

  In the conventional injection molding for molding thermoplastic resin, there is a torpedo that opens and closes the gate, and injection and stop of the thermoplastic resin kept in the molten state by the heat of the heater in the resin passage into the cavity. Some have been controlled by opening and closing the gates by topped (see, for example, Patent Document 1). FIG. 3 shows a conventional injection mold described in Patent Document 1. In FIG.

In FIG. 3, 110 is a fixed mold plate, 111 is a movable mold plate, 112 is a cavity, 113 is a fixed receiving plate, 114 is a band heater, 115 is a bush, 115A is a flange portion, 116 is a gate, 117 is a manifold, 118 is Gap, 119 is a guide hole, 120 is a resin passage, 120A is an upper portion of the passage, 120B is a lower portion of the passage, 121 is a depression, 122 is an annular groove, 123 is a topped, 123A is a conical portion, 123B is a gate closing portion, and 124 is a resin passage , Respectively.
As shown in FIG. 3, it has a fixed mold plate 110 and a movable mold plate 111, and a cavity 112 having a shape of a molded product is defined on the facing surfaces thereof. The fixed mold plate 110 is fixed to a fixed mounting plate (not shown) via a fixed receiving plate 113, and the movable mold plate 111 is fixed to a movable mounting plate (not shown).
Inside the fixed mold plate 110 and the fixed receiving plate 113, a cylindrical bush 115 provided with a band heater 114 is disposed downward so as to face the gate 116 communicating with the cavity 112, and its upper end flange portion 115A is fixed. In addition to being fixed to the manifold 117 disposed in the receiving plate 113, a heat insulating gap 118 is formed around the bush 115.

A guide hole 119 having a circular cross section along the central axis is formed inside the bush 115, and a resin passage 120 is formed around the guide hole 119. The upper portion 120A of the resin passage 120 communicates with a recess 121 formed at an eccentric position of the upper end surface of the flange portion 115A, and the lower portion 120B branches into four at the same location, and 90 ° around the guide hole 119. Each extends in parallel with the guide hole 119, and its side surface communicates with the guide hole 119 in a slit shape. In addition, all the areas of this communication port are equal.
These resin passage lower portions 120B are symmetrical to each other with respect to the central axis of the guide hole 119, all have a semicircular cross section, the flow passage cross-sectional areas are equal, and the molten resin flowing from the resin passage upper portion 120A It flows evenly into the resin passage lower part 120B. Further, the lower end of the resin passage lower portion 120 </ b> B is opened in an annular ring groove 122 formed coaxially with the guide hole 119 on the lower end surface of the bush 115.
On the other hand, inside the guide hole 119, a tope 123 extending through the manifold 117 is inserted so as to be vertically slidable, and is driven up and down by a moving plate (not shown).
The outer diameter of the topped 123 is slightly smaller (for example, about 0.003 to 0.005 mm) than the inner diameter of the guide hole 119 so that the inside of the guide hole 119 can slide. As a result, a cylindrical gate closing portion 123B having an outer diameter slightly smaller (for example, about 0.01 to 0.025 mm) than the opening diameter of the gate 116 is formed. When the topped 123 is raised, the conical portion 123A is connected to the lower end surface of the bush 115, and when lowered, the lower end surface of the gate closing portion 123B is flush with the upper surface of the inner wall of the cavity 112.
Further, a resin passage 124 communicating with the depression 121 is formed in the manifold 117 so that molten resin is injected from an injection nozzle (not shown).

According to this, the torpedo 123 is directly supported by the side wall surface of the guide hole 119 and the position thereof is regulated. Therefore, even if the pressure of the molten resin is applied at the time of resin injection, the torpedo 123 is less likely to be shaken. Deterioration of the injection balance into the cavity 112 was prevented, and molding abnormalities such as whiskers and burrs due to the deterioration of the injection balance could be prevented.
JP-A-2-243314

However, in the conventional configuration, space for the configuration of the bush, the heater, the manifold, the toped, etc. is indispensable as a mechanism for injecting and stopping the resin into the cavity while keeping the resin in a molten state. When forming multiple resin molding parts on a continuous body such as a frame, considering the simultaneous molding with multiple cavities in accordance with the lead frame pitch, there is a restriction on the space that is indispensable for the mechanism configuration. Therefore, there was a limit to narrowing the pitch between the cavities in accordance with the lead frame pitch.
The present invention solves the above-mentioned conventional problems, and keeps the resin in a molten state and secures a space for a mechanism configuration for injecting and stopping the resin into the cavity, and to a continuous body such as a lead frame. An object of the present invention is to provide an injection molding method and an injection molding apparatus capable of simultaneously forming a resin in a plurality of cavities in accordance with the pitch of the resin molding portion.

In order to solve the above-mentioned conventional problems, the injection molding method of the present invention heats the runner part of a resin molding die, and injects the resin part disposed on the lead frame while keeping the thermoplastic resin in a fluid state. An arbitrary number of n gates and cavities arranged at equal intervals are provided in accordance with one cycle for every N pitches of an arbitrary number of resin molding scheduled portions of the lead frame to be The injection molding method is characterized in that N-1 pitch feed is performed during the N-th injection molding from the first injection molding to the next N × (n-1) +1 pitch feeding as one cycle.
According to this, a plurality of simultaneous moldings are possible even if there is a limit to the miniaturization of the injection molding apparatus accompanying the narrowing of the lead frame pitch.

The injection molding apparatus of the present invention is an apparatus that heats a runner portion of a resin molding die and injects and molds a resin portion that is disposed in a lead frame while keeping the thermoplastic resin in a fluid state. An injection molding apparatus provided with an n number of gates and cavities, which are arranged at equal intervals, in accordance with one cycle for every N pitches of an arbitrary number of molding target portions.
According to this, a plurality of simultaneous moldings are possible even if there is a limit to the miniaturization of the injection molding apparatus accompanying the narrowing of the lead frame pitch.

It is good also as a structure which has an air permeable cavity part in the space | interval of a gate and a cavity. This is because the heat history to be applied to the resin and the lead frame can be reduced.
A mechanism for allowing cooling air to pass through the air-permeable cavity may be provided. This is because the thermal history to be applied to the resin and the lead frame can be further reduced.

  As described above, according to the injection molding method and the injection molding apparatus of the present invention, the resin is formed in accordance with the pitch of the resin molding portion to the continuous body such as the lead frame without being restricted by the space of the injection mechanism. This can be done simultaneously in multiple cavities.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional view illustrating a molding process for explaining an example of an injection molding method according to an embodiment of the present invention, in which 1 is a first cavity, 2 is a second cavity, and 3 is a first injection mechanism. 4 is a second injection mechanism, 5 is a lead frame, 6 is a resin molding scheduled part, 7a is a first resin molding part, 7b is a second resin molding part, and 7c is a third resin molding part. ing.

FIG. 1A shows the first cavity 1, the first injection mechanism 3, the second cavity 2, and the second injection mechanism at positions separated by three pitches between the resin formation scheduled portions 6 of the lead frame 5. 4, the first cavity 1 is filled with resin from the first injection mechanism 3, and the second cavity 2 is filled with resin from the second injection mechanism 4. The first injection molding is shown in a state where the first resin molding portion 7 a is molded in the first cavity 2 and the second cavity 2.
In FIG. 1B, the lead frame 5 of FIG. 1A is conveyed by one pitch, and the resin molding scheduled part 6 adjacent to the first resin molding part 7a is moved to the first cavity 1 and the second cavity 2. The first cavity 1 is filled with resin from the first injection mechanism 3, and the second cavity 2 is filled with resin from the second injection mechanism 4. The second injection molding is shown in a state where the second resin molding portion 7b is molded in the cavity 2.
In FIG. 1C, the lead frame 5 of FIG. 1B is conveyed by one pitch, and the resin formation scheduled portion 6 adjacent to the second resin molding portion 7b is moved to the first cavity 1 and the second cavity 2. The first cavity 1 is filled with resin from the first injection mechanism 3, and the second cavity 2 is filled with resin from the second injection mechanism 4. The third injection molding is shown in a state where the third resin molding portion 7c is molded in the cavity 2.
FIG. 1 (d) conveys the lead frame 5 of FIG. 1 (c) by 4 pitches, the first cavity 1 and the second cavity 2 are opened, and the resin molding planned portion 6 is positioned in both the cavities. In this state, conveyance at the end of the cycle is performed.
Here, the first cavity 1 and the second cavity 2 are closed, and the same injection molding as in FIGS. 1A to 1D is performed again and the lead frame 5 is conveyed in one cycle. If it repeats, it is possible to form the resin molding part sequentially.

  In the embodiment of the present invention, two cavities and injection mechanisms are provided as an example, and the two cavities and injection mechanisms are for three feeds of the resin molding scheduled portion 6 on the lead frame 5, that is, three pitches. Although explained in the separated form, the present invention is not limited to this. Based on the resin molding scheduled portion 6 of the lead frame 5, it matches one period for every N pitches that is an arbitrary number and is equally spaced. An arbitrary number of arranged cavities and injection mechanisms are provided, and the lead frame 5 is fed one pitch N-1 times during the process cycle from the first injection molding to the Nth injection molding. The process until the lead frame 5 for the next N × (n−1) +1 pitch is sent as one cycle is repeated.

According to such a configuration, the resin is molded into a continuous body such as a lead frame without being restricted by the space of the injection mechanism for the mechanism configuration that controls the injection and stop of the resin into the cavity while keeping the resin in a molten state. It is possible to adopt an injection molding method in which the resin can be formed in accordance with the pitch of the portions simultaneously in a plurality of cavities.
An injection molding apparatus for realizing such an injection molding method can be referred to FIG.
In FIG. 2, 1 is the first cavity, 2 is the second cavity, 3 is the first injection mechanism, 3a is the resin passage, 3b is the heater, 3c is the topped, 3d is the gate, 3e is the bush, 4 is the first Second injection mechanism, 4a is resin passage, 4b is heater, 4c is topped, 4d is gate, 4e is bush, 8 is fixed side mold, 9 is movable side mold, 10 is lead frame fixing pin, 11 is hollow Each part is shown.

In FIG. 2, a known first injection mechanism 3 having a resin passage 3a, a heater 3b, a torpedo 3c, a gate 3d and a bush 3e and a first cavity 1 are formed in pairs, and a resin passage 4a A known second injection mechanism 4 and a second cavity 2 provided with a heater 4b, a torpedo 4c, a gate 4d, and a bush 4e are formed in pairs, and each of the pair of the first injection mechanism 3 and the first The cavity 1 and the second injection mechanism 4 are separated from the second cavity 2 by a distance corresponding to the N pitch (3 pitches in FIG. 1) of the resin formation scheduled portion 6 of the lead frame 5 shown in FIG. .
The first cavity 1 and the second cavity 2 are both divided into a fixed mold 8 including a first injection mechanism 3 and a second injection mechanism 4 and a movable mold 9. The movable side mold 9 is moved and opened by a mold opening / closing mechanism (not shown).
Further, a transport mechanism (not shown) for intermittently transporting the lead frame 5 by a distance corresponding to the pitch of the resin molding scheduled portion 6 of the lead frame 5 shown in FIG. 1 and lead frame fixing for positioning and fixing the lead frame 5 And a pin 10.
Further, a cavity 11 having air permeability is formed around the first cavity 1 and the second cavity 2 even when the fixed mold 8 and the movable mold 9 are clamped.

According to this, the fixed mold 8 and the movable mold 9 are opened by a mold opening / closing mechanism (not shown), and the resin molding scheduled portion of the lead frame 5 shown in FIG. 6 is set in the first cavity 1 and the second cavity 2, and the movable side mold 9 is moved by a mold opening / closing mechanism (not shown) to fix the fixed side mold 8 and the movable side mold. 1 is clamped between the lead frame 5 and the first injection into the first cavity 1 and the second cavity 2 formed in the resin molding scheduled portion 6 of the lead frame 5. After the thermoplastic resin (not shown) is filled by the mechanism 3 and the second injection mechanism 4 and the resin in the first cavity 1 and the second cavity 2 is cured, the fixed mold 8 and the movable mold The mold 9 is opened by a mold opening / closing mechanism (not shown), and the transfer mechanism (not shown) is used. It can be continuously injection molded at repeating the operation to position the lead frame 5 by pitch feeding the next resin molding scheduled portion 6 to the first cavity 1 and the second cavity 2.
More specifically, in order to repeat the cycle as shown in FIGS. 1A to 1D, the opening and closing between the fixed side mold 8 and the movable side mold 9, the conveyance of the lead frame 5, and the injection mechanism. This is an injection molding apparatus in which the entire apparatus is controlled by mechanical and electrical mechanisms (not shown) that control the order and timing of each operation of resin injection.

According to such a configuration, the resin is molded into a continuous body such as a lead frame without being restricted by the space of the injection mechanism for the mechanism configuration that controls the injection and stop of the resin into the cavity while keeping the resin in a molten state. It is possible to provide an injection molding apparatus that can simultaneously mold the resin in accordance with the pitch of the portions in a plurality of cavities.
Further, by providing the cavity 11 around the first cavity 1 and the second cavity 2 of the first injection mechanism 3 and the second injection mechanism 4, the heat dissipation of the periphery of the cavity 11 is improved. I can get it. Thereby, the heat of the heater 3b and the heater 4b included in the first injection mechanism 3 and the second injection mechanism 4 is conducted to the first cavity 1 and the second cavity 2, and the first cavity 1 is transmitted. And the thermoplastic resin injected into the inside of the second cavity 2 and the surrounding lead frame 5 are prevented from continuing to be heated, and are molded and out of the first cavity 1 and the second cavity 2. Since the conveyed resin molding part is rapidly cooled, the heat history to be applied to the resin molding part and the surrounding lead frame 5 is reduced, the oxidation of the resin molding part and the lead frame 5 is reduced, and the resin molding part and the lead frame are reduced. Since the inhibition of mutual adhesion due to the difference in coefficient of thermal expansion from 5 can be reduced, it is possible to improve the reliability.
Furthermore, if the cavity 11 is provided with an opening to the outside of the apparatus and also has a mechanism for allowing air to pass therethrough, it is possible to further improve the heat dissipation and to make it highly reliable. By using nitrogen or the like instead of air, oxidation of the lead frame and the molded product can be prevented, which is more effective.

  In the embodiment of the present invention, two cavities and injection mechanisms are provided as an example, and the two cavities and injection mechanisms are for three feeds of the resin formation scheduled portion 6 on the lead frame 5, that is, three pitches. Although described in the separated form, the present invention is not limited to this. Based on the resin formation scheduled portion 6 of the lead frame 5, it matches one period for every N pitches of an arbitrary number and is equally spaced. An arbitrary number of arranged cavities and injection mechanisms are provided, and the lead frame 5 is fed one pitch N-1 times during the process cycle from the first injection molding to the Nth injection molding. The operation is repeated with one cycle until the lead frame 5 corresponding to N × (n−1) +1 pitch is sent next.

  It is useful as injection molding using a thermoplastic resin, and is particularly suitable for a lead frame having a narrow pitch.

Sectional drawing which shows the order of the formation process in embodiment of this invention. Sectional drawing which shows the injection molding apparatus in embodiment of this invention. Sectional drawing which shows the conventional injection molding apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st cavity 2 2nd cavity 3 1st injection mechanism 3a, 4a, 120 Resin passage 3b, 4b Heater 3c, 4c, 123 Toped 3d, 4d, 116 Gate 3e, 4e, 115 Bush 4 2nd injection Mechanism 5 Lead frame 6 Resin molding planned part 7a First resin molding part 7b Second resin molding part 7c Third resin molding part 8 Fixed side mold 9 Movable side mold 10 Lead frame fixing pin 11 Cavity part 110 Fixed Mold plate 111 Movable mold plate 112 Cavity 113 Fixed receiving plate 114 Band heater 115A Flange portion 117 Manifold 118 Air gap 119 Guide hole 120A Passage upper portion 120B Passage lower portion 121 Depression 122 Annular groove 123A Conical portion 123B Gate closing portion

Claims (4)

In the injection molding of the resin part disposed in the lead frame while keeping the thermoplastic resin in a fluid state by heating the runner part of the resin molding die,
An arbitrary number of N gates and cavities arranged at equal intervals are provided in accordance with one period for every N pitches of an arbitrary number of resin molding scheduled portions of the lead frame,
While performing the Nth injection molding from the first injection molding, with N-1 times pitch feed,
Next, the injection molding method is characterized by repeating N × (n−1) +1 pitch feeding as one cycle. In an apparatus that heats the runner part of the resin molding die and injects and molds the resin part disposed in the lead frame while keeping the thermoplastic resin in a fluid state,
An arbitrary number of n gates and cavities arranged at equal intervals in accordance with one period for every N pitches of an arbitrary number of resin molding scheduled portions of the lead frame. Characteristic injection molding device.   The injection molding apparatus according to claim 2, wherein a breathable cavity portion is provided between the gate and the cavity. The injection molding apparatus according to claim 2 or 3, further comprising a mechanism for allowing cooling air to pass through the air-permeable cavity.

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