CN1295067C - Transfer molding machine with features for enhanced cull removal - Google Patents

Abstract

A transfer molding machine (10) with an injection mold plate (12). The injection mold plate has ejection pins (22,24) for ejecting a cull in a first direction (40). Each of the ejection pins (22,24) has a sprue abutment (50) with a notch (52). The notch is oriented to enable dislodging of the cull in a second direction (54), substantially normal to the first direction (40) and away from the sprue abutment (50). A method (100) for cull removal by transfer molding machine (10) upon curing a molding ends with the cull being moved out of the transfer molding machine (10) using a movable bar (200) with stubs (202).

Description

Transfer molding machine with enhanced excess material removal feature

technical field

The present invention relates to a model component. More particularly, the present invention relates to a transfer molding machine having enhanced excess material removal features.

Background technique

Transfer molding machines with patterns forming the cavities are known art. Such a transfer molding machine is used in a molding process to form a molded product shaped according to a cavity. Models generally include at least two templates that are clamped during part molding. Molding compound in molten state is injected into the cavity. When sufficient time has passed for the molding compound to cure, the formwork is separated to enable ejection of the molded product formed of the molding compound.

In the process of conveying the molding compound from the mold tank to the cavity, one or more channels formed by runners are generally used to convey the molding compound. As a result, when the die plate forming the cavity is separated, the molding compound inside the sprue or in the bonding surface between the sprue and the mold pot is also solidified, but an undesired molded portion is formed. This unwanted molded portion is often referred to as excess material.

Excess material must be removed from the transfer molding machine so that another molding cycle can be performed. However, cutouts can be cumbersome, thereby reducing the throughput of the transfer molding machine. Furthermore, removal of excess material should not cause the excess material to break into small pieces or fragments. These small pieces of excess material or pieces of excess material adversely affect the subsequent molding of the transfer molding machine, and may even cause the subsequent molding production to stop.

In addition to the above problems, excess material removal is a common problem for existing transfer molding machines that mold by direct gating. A straight gate generally results in excess material being formed with one or more raised portions called gates. Such gates can become entangled with each other during cutout, or with parts of the transfer molding machine. As a result, the presence of the gate limits excess material removal in sprue molding.

Accordingly, there is an apparent need for a transfer molding machine having enhanced excess material removal features to enable increased molding throughput of the transfer molding machine. This feature should also enable the ability to cut excess material from the transfer molding machine with gates formed as a result of sprue molding.

Contents of the invention

It is an object of the present invention to provide a transfer molding machine and a method for cutting excess material by the transfer molding machine when a molded product is cured.

Therefore, in one aspect, the present invention provides a transfer molding machine comprising:

at least one formwork having at least one ejector pin for ejecting excess material from the at least one formwork in a first direction, each of the at least one ejector pin having a sprue bond;

Wherein the gate junction includes a notch, the direction of the notch is such that at least one excess material can be removed from the gate junction in a second direction, the second direction being substantially orthogonal to the first direction.

In another aspect, the present invention provides a method of removing excess material by a transfer molding machine when a molded product is cured, the method comprising the steps of:

separating the plurality of templates to remove the molded product from at least one ingate of one or more of the plurality of templates;

ejecting at least one excess material associated with the molded product in a first direction using at least one ejector pin having the notched gate junction; and

One less excess material is removed from the gate land in a second direction that is substantially orthogonal to the first direction and based on the orientation of the notch.

Description of drawings

Preferred embodiments of the present invention are described in more detail below by way of illustration with reference to the accompanying drawings, wherein:

Figure 1 is a simplified cross-sectional view of a transfer molding machine according to a preferred embodiment of the present invention;

Figures 2A, 2B and 2C are isometric, plan and side views, respectively, of the gate junction of the ejector pin of the transfer molding machine of Figure 1;

Figure 3 is a cross-sectional view of the tapered cavity of the transfer molding machine of Figure 1;

4 is a flow chart of a method of removing excess material by the transfer molding machine of FIG. 1;

Figure 5 is a side view of the transfer molding machine of Figure 1 showing an excess material removal member; and

6A, 6B and 6C are front, side and bottom views, respectively, of an excess material removal member.

Detailed ways

A transfer molding machine according to a preferred embodiment of the present invention and a method of cutting excess material by the transfer molding machine when a molded product is cured are explained below. In the following description, details are provided to illustrate preferred embodiments. However, it will be understood by those skilled in the art that the present invention may be practiced without these details. In order not to obscure the present invention, some details have not been described in detail.

The present invention has many advantages. An advantage of the present invention is that the transfer molding machine forms excess material. This excess material will not break into pieces. Thus, excess material removal is enhanced by the present invention, thereby eliminating production stoppages for removal of excess material fragments.

Another advantage of the present invention is that the transfer molding machine is provided with one or more ejector pins. In addition to ejecting excess material, these ejector pins include features that make removal of the excess material formed from the molded product ingate and from the plate easier than with existing transfer molding machines.

Yet another advantage of the present invention is that the transfer molding machine provides automatic removal of excess material with gates formed as a result of sprue molding. Therefore, the problem of entanglement of these excess materials in the transfer molding machine can be eliminated.

Referring now to FIG. 1 , there is shown a simplified cross-sectional view of a transfer molding machine 10 in accordance with a preferred embodiment of the present invention. Transfer molding machine 10 includes a transfer platen 12 , an intermediate platen 14 and a complementary platen 16 .

The product to be molded is conveyed by the transfer molding machine 10 in the outflow direction indicated by the arrow 18 . These products may be, for example, semiconductor molds (not shown) placed on the conveyor belt 20, for example.

The transport formwork 12 has at least one ejector pin, two ejector pins 22 , 24 are shown in FIG. 1 . When ejecting excess material, the ejector pins 22 , 24 protrude beyond the surface 25 of the conveying formwork 12 . A transfer plunger 28 is used to inject molding compound (not shown) from a mold pot 26 . The transfer plunger 28 advances molding compound from the mold pot 26 into excess material cavities 30 formed on the intermediate formwork 14 .

The intermediate template 14 also has two conical cavities 32 , 34 . Conical cavities 32, 34 connect excess material cavity 30 to two cavities 36, 38 of intermediate die plate 14, respectively.

It should be noted that when a molded product has been formed using the molding compound, the ejector pins 22 , 24 eject excess material from the delivery plate 12 in a first direction indicated by arrow 40 . In describing the preferred embodiment, the ejector pin 22 and the tapered cavity 34 are illustrated by way of example to illustrate details relating thereto.

Referring now to FIGS. 2A to 2C , the ejector pin 22 has a gate junction 50 including a notch 52 . The notch 52 is suitably oriented so that excess material can be removed from the gate land 50 in the second direction indicated by arrow 54 . The second direction is substantially orthogonal to the first direction.

The notch 52 includes a first surface 56 oriented obliquely relative to the exit direction of the transfer molding machine 10 (direction indicated by arrow 18 ) as shown in FIG. 2B . As shown in FIG. 2C , the first surface 56 is inclined at an angle 57 of approximately 15 to 20 degrees relative to the longitudinal axis 58 of the ejector pin 22 .

The notch 52 further includes an end surface 59 and a second surface 60 . The end surface 59 and the second surface are parallel to each other and normal to the first direction (shown by arrow 40).

It should be noted that the excess material formed by the transfer molding machine 10 when curing the molded product has a gate having an end (not shown) that abuts the gate junction 50 of each ejector pin 22,24 . Each end abuts complementary to the gate land 50 so as to have an indentation opposite to the indentation 52 .

The cross-sectional view of Figure 3 shows details of the tapered cavity 34 and cavity 38 (not shown to scale). Tapered cavity 34 includes a sprue 70 positioned within an ingate portion 72 of cavity 38 . Ingate portion 72 has an ingate depth 74 for excess molding compound that may remain after degating. The ingate depth 74 is not greater than 0.2 mm. Also shown is a tundish 76 at the end of the tapered cavity 34 . The tundish 76 has a height of no greater than 0.1 mm.

Cutting off excess material as the molded product cures using the transfer molding machine 10 is performed by the method 100 shown in the flow diagram of FIG. 4 .

After starting at step 102 , method 100 proceeds to step 104 where delivery template 12 , intermediate template 14 and complementary template 16 are separated. Separating these die plates 12 , 14 , 16 disengages the molded product (not shown) from the sprues of the tapered cavities 32 , 34 .

It should be noted that in the separation step 104, the notch 52 passes through a complementary engagement gate (not shown) formed from the cured molding compound remaining in the notch 52 of the excess material cavity 30, the tapered cavities 32, 34 and the sprue junction 50. out) maintains a surplus of material. Thus, notches 52 aid in the removal of excess material from the molded product.

Thereafter, in step 106 , the excess material is ejected in a first direction (direction indicated by arrow 40 ) using the ejector pins 22 , 24 . Ejection requires that the ejector pins 22 , 24 protrude beyond the delivery formwork 12 , thereby exposing the notches 52 above the upper surface 25 . Each ejector pin 22 , 24 continues to abut a gate (not shown) at gate junction 50 as excess material is ejected.

The method 100 ends at step 108, where excess material is removed from the sprue junction 50 in a second direction (direction indicated by arrow 54). As shown in FIGS. 2A and 2B , the second direction is substantially orthogonal to the first direction (direction indicated by arrow 18 ) and is based on the orientation of notch 52 .

Removal step 108 includes pushing excess material away from sprue junction 50 in a second direction with an excess material removal member. In the preferred embodiment, the excess material removal member is a movable bar 200 shown in the transfer molding machine 10 side view. Using the movable rod 200, the cutting step 108 includes the step of aligning the movable rod 200 with the excess material to be pushed.

6A, 6B and 6C show details of the movable rod 200 . The movable bar 200 has a plurality of stubs 202 that push excess material at portions of the runner such as connecting adjacent gates. This pushing action provides a force that cuts each gate away from each gate bond 50 in the direction of arrow 54 .

It should be understood that although a preferred embodiment has been described in detail, various modifications and improvements can be made by those skilled in the art without departing from the scope of the present invention.

Claims (11)

1. A transfer molding machine comprising: at least one formwork having at least one ejector pin for ejecting at least one excess material from said at least one formwork in a first direction, each said at least one ejector pin having a sprue combination department, Wherein said gate land includes a notch, said notch is oriented such that said at least one excess material can be cut away from said gate land in a second direction, said second direction being substantially the same as said first Orthogonal in one direction; said indentation further comprises a first surface oriented obliquely with respect to a discharge direction of said transfer molding machine and also oriented obliquely with respect to said second direction; Wherein said at least one template comprises a delivery template, a complementary template and an intermediate template having at least one tapered cavity. 2. The transfer molding machine of claim 1, wherein said indentation further includes a second surface aligned with a plane substantially normal to said first direction. 3. The transfer molding machine of claim 1, wherein each of said at least one tapered cavity has an ingate angle in the range of 55 degrees to 60 degrees. 4. The transfer molding machine of claim 1, wherein each of said at least one tapered cavity has a tundish. 5. The transfer molding machine of claim 1, wherein said at least one intermediate platen includes an ingate portion with an ingate depth for overmolding compound. 6. The transfer molding machine of claim 1, wherein the transfer molding machine further comprises an excess material cutting device for cutting off the at least one excess material. 7. The transfer molding machine of claim 6, wherein said excess material removal means comprises a movable rod. 8. The transfer molding machine of claim 7, wherein the movable rod comprises at least one stud. 9. A method of removing excess material by a transfer molding machine when a molded product is cured, said method comprising the steps of: separating a plurality of templates to remove the molded product from at least one gate of one or more of the plurality of templates; At least one excess material associated with the molded product is ejected in a first direction using at least one ejector pin having a gate junction with a notch, the at least one ejector pin being associated with the plurality of at least one combination of templates; and cutting the at least one excess material from the gate land in a second direction substantially orthogonal to the first direction and based on the orientation of the notch; Wherein said indentation further comprises a first surface oriented obliquely with respect to the discharge direction of said transfer molding machine and also oriented obliquely with respect to said second direction. 10. The method of claim 9, wherein the cutting step includes the step of pushing the at least one excess material away from the gate land in the second direction. 11. The method of claim 10, wherein said removing step further comprises the step of aligning a movable rod of said transfer molding machine with said at least one excess material for said pushing step.

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