JPH03261528A - Mold - Google Patents

Abstract

PURPOSE:To omit waste of material and to prevent deterioration of resin in a hot runner by forming an undercut part in the tip part of a sprue bush and providing a recessed part into which the tip part of the sprue bush is freely inserted to the rear of an insert die regardless of presence of the cavity of the insert die. CONSTITUTION:Since an undercut part 44 is formed in the tip of a sprue bush, a runner branch is tightly stuck to a fixed plate side and gate cut due to mold opening is performed without especially providing a runner lock pin. Moreover since the position of a runner hole is freely changed in a range within the width of a recessed part 59 in the rear of an insert die, the degree of freedom for designing the gate position is increased. Further since only the small runner branch described hereunder is provided between a runner stripper plate 36 and the rear of the insert die, waste of material can be reduced. The runner branch is formed of a sprue bush resin path 57, a runner 60, the recessed part 59 of the insert die 38 and the undercut part 55 of the sprue bush 53. Furthermore since the same recessed part 59' as the molding insert die 38 is formed to the rear of the insert die substitute, resin in a hot runner block 49 is not stagnated and deterioration and decomposition of resin are not caused.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a molding die.

(Prior Art) There is a three-plate type molding mold that allows a molded product and a runner to be taken out separately at the same time as the mold is split.

FIG. 4 shows a conventional three-plate mold.

10 is a movable type, 11 is an intermediate type, and 12 is a fixed type. For example, four nesting molds 14 are inserted and fixed into the intermediate mold 11 to form both bottoms of the cavity 13 when the movable mold 10 and the mold are closed. Each nesting mold 14 has a runner hole 15 for introducing resin into the cavity 13. The fixed mold 12 is provided with a hot runner block 17 that melts and holds the resin injected from the nozzle 16 in a heated state, and the tip of the hot runner block 17 faces the center of the back surface of the intermediate mold 11. Then, the nested mold 1 was fixed to the back side of the intermediate mold 11.
In order to guide the resin from the hot runner block 17 into each cavity 13, the receiving plate 18 holding the hot runner block 17 and each runner hole 15
Runner grooves 19 are radially cut out to communicate with each other. Reference numeral 20 denotes a runner stripper plate, which moves toward and away from the fixed die 12 and the fixed die base 21 with a slight stroke. A runner lock pin 22 that protrudes from the fixed base 21 and has an undercut portion at its tip is inserted into the runner stripper plate 20 .

The mold is then closed, and molten resin is supplied from the nozzle 16 into the cavity I3 through the real runner block 17, runner groove 19, and runner hole 15 to form the bottom. When the mold is opened after molding, the space between the intermediate mold 11 and the runner stripper plate 20 first opens, and as a result, the runner is cut at the position of the molded product and the gate, and is held by the undercut portion of the runner lock pin 22 to form the runner stripper. It remains attached to the plate 20 side. Next, the space between the movable mold 10 and the intermediate mold 11 is opened to expose the molded product, and the molded product is ejected by an appropriate ejection pin (not shown).

In the runner technique, the runner is dropped by opening the space between the runner stripper plate 20 and the fixed base 21.

(Problems to be Solved by the Invention) However, the conventional molding die described above has the following problems.

That is, in the runner technique, a long cold runner is formed corresponding to the runner groove 19 extending radially from the tip of the hot runner block, resulting in a large amount of wasted material. Particularly in the case of small-sized molded products, the runner technique accounts for a large proportion of the molded product, which poses the problem of increased material loss.

In addition, if the number of nesting molds is smaller than the specified number, for example, three, a substitute nesting mold without a cavity or runner hole is inserted and fixed in the empty space of the intermediate mold 11 to form a bottom. In this case, too, runner grooves 19 extending to the substitute nesting mold are formed with runner grooves in exactly the same way, resulting in a large amount of wasted material.

To reduce the number of cold runners and reduce material waste,
It is conceivable to extend the hot runner block to a position close to each nested mold to minimize the number of runners formed.

When a substitute nesting mold is used, it is conceivable to close the resin outlet of the hot runner block with the detaching surface of the substitute nesting mold so that no runner pattern is formed in this part.

However, if the resin outlet of the hot runner block is blocked with the substitute nesting mold as described above, the resin in the corresponding hot runner block will decompose and deteriorate due to high temperature, which may cause problems such as interfering with the next bottom shape. found.

Therefore, the present invention has been made to solve the various problems mentioned above, and its purpose is to provide a hot runner.
To provide a molding die that eliminates wastage of materials and does not cause deterioration of resin in a hot runner.

(Summary of the invention) In order to solve the above problems, the present invention has the following configuration.

That is, a three-plate molding tool in which a plurality of sets of nested molds are inserted into a set of mold bases, and the bottom shape is formed by supplying molten resin from a hot runner block to the cavity of each nested mold. In the mold, a resin path connected to the hot runner block is opened at the tip, and when the mold is closed, an undercut portion that protrudes from an appropriate runner stripper plate fixes a sprue bush provided on the outer periphery of the tip to the fixed mold base. At the same time, a recessed portion into which the tip of the sprue bushing having the undercut portion is loosely inserted is provided on the back surface of the nesting mold inserted into the mold base, regardless of the presence or absence of a cavity of the nesting mold. It is characterized by

(effect) Next, we will discuss the effect.

1 and 2, when the molten resin is injected from the nozzle 52 after the mold is closed, the molten resin flows through the hot runner 56.
, the cavity 45 is filled through the resin path 57 of the sprue bush 53, the recess 59, and the runner 60, and the bottom is shaped.

Similarly, resin is also injected into the recess 59'' of the substitute nesting mold 38''. The mold is opened and the molded product is taken out, but at the same time the part that is discharged as a runner is the recess 59.
Since this is a cold runner technique for the runner 60 part, waste of materials can be avoided. Also, a long runner is formed in the recess 59' and discharged, but the amount thereof is small. By providing a part of the rotary runner, the molten resin does not remain in the hot runner flock 49 corresponding to the 38° substitute nesting mold, so that decomposition and deterioration of the resin are suppressed.

Note that the setting of the gate position is variable within the range of the width of the recess 59.

(Example) Hereinafter, preferred embodiments of the present invention will be described in detail based on the accompanying drawings.

In FIG. 1, 30 is a fixed type, 31 is an intermediate type, and 32 is a movable type. The fixed mold 30 includes a fixed base 34 fixed to a fixed platen 33, and a runner stripper plate 36 connected to the fixed base 34 by a limiting bolt 35 so as to be movable toward and away from the fixed base 34 by a predetermined stroke.

The intermediate mold 31 is inserted into the U-shaped space of the intermediate mold base 37, which has a substantially U-shaped front shape, by a fixing mechanism to be described later.
The nesting mold 38 is inserted and fixed, and the restriction bottle 39
It is connected to the runner stripper plate 36 so that it can move toward and away from the runner stripper plate 36 by a predetermined stroke. Further, the intermediate mold 31 is urged in a direction away from the runner stripper plate 36 by a spring 40.

The movable mold 32 includes a movable platen 41 that is moved toward and away from the intermediate mold 31 and the fixed mold 30 by an appropriate hydraulic cylinder (not shown), and a movable base 42 that is fixed to the movable mold 141.
, and a movable nesting mold 43 fixed to the U-shaped portion of the movable mold base 42 by a fixing mechanism described later.

Note that this movable mold 32 is also restricted to the intermediate mold 31 by the restriction bin 44.
The intermediate die 31 is connected to the intermediate die 31 so as to be in contact with the intermediate die 31 for a predetermined stroke.

The nesting mold 38 of the intermediate mold 31 and the movable nesting mold 4 opposing it
3 to define a molding cavity 45. In the illustrated example, one set of the nesting mold 38° and the movable nesting mold 43° are shown as substitute nesting molds that do not form any cavities.

Reference numeral 46 denotes a protruding bottle for ejecting a molded product, which is inserted through the movable nesting mold 43, and is protruded by a protruding frame 48 driven against the biasing force of a spring 47.

Next, 49 is a hot runner block, which is disposed within the aforementioned fixed mold 30 via a heat insulating material 50. One end of this hot runner block 49 faces a nozzle entry hole 51 provided in the fixed platen 33, and a nozzle 52 is touched. The other end of the true runner block 49 is branched, and each branched end is connected to a corresponding intermediate mold 31 from the fixed mold base 34.
It protrudes in the direction of the nested mold 38.

Reference numeral 53 denotes a sprue bush, which is formed in a cap shape to cover each branch end of the hot runner block 49, and is fixed to the fixed base 34 by a fixing plate 54 at its base end. An undercant portion 55 for locking the runner's technique is provided around the outer periphery of the tip of this sprue bush.

Further, a resin path 57 is opened at the tip of the sprue bush 53 and communicates with the hot runner 56, which is a resin path of the hot runner block 49. The sprue bush 53 is fitted into the through hole 58 provided in the runner stopper plate 36, and when the mold is closed as shown in FIG. It is set to protrude from the surface.

On the other hand, on the outer surface of the nesting mold 38 of the intermediate mold 31, there is a recess 59 having a depth and width sufficient to cover the tip of the sprue bushing 53 protruding from the surface of the runner stopper plate 36 when the mold is closed. It is formed. A runner 60 is formed which communicates the recess 59 and the cavity 45 via a gate. In this case, the gate position can be varied within the range of the width of the recess 59, which has a relatively wide area, so when replacing the nesting mold 38 according to various molded products, there is freedom in designing the gate position. The degree becomes large. Furthermore, the present invention is characterized in that a recess 59'' similar to the above-mentioned recess 59 is formed on the back surface of the substitute nested mold 38'.

This concave portion 59° forms a dummy runner pattern each time the bottom shape is formed as shown in the figure.

FIG. 3 shows a nested fixing mechanism. In addition, since the fixing mechanism of the nested mold in the movable mold 32 and the intermediate mold 31 is the same, the fixing mechanism in the movable mold 32 is shown in the figure.

4 (The 1 m movable nesting mold 43 has a rectangular front external shape, and the movable mold base 4 is arranged in two rows with their walls touching each other.
It is incorporated in the U-shaped space of 2.

Further, the upper and lower surfaces of the movable nesting mold 43 are formed into step-like stepped surfaces, and the adjacent upper and lower movable nesting molds 43 engage with the unevenness on the stepped surfaces (Fig. 1). The convex portion of the movable mold base 42 slides into a concave groove provided on the wall surface of the movable mold base 42, and the convex portion of the lower surface of the lower movable nested mold 43 engages with the wall step portion 61 of the movable mold base 42 (the Figure 1), movable nesting mold 4
Key grooves 62 are formed in the upper and lower surfaces of the movable base 42 and the wall step portion 61 of the movable base 42 so as to coincide with each other.
By fitting the key 63 into the movable insert molds 43, the movable insert molds 43 are prevented from being displaced from each other. One end of the key 63 is connected to the movable base 42
The other end is secured to the wall surface in a hole provided in a holding member (described later) (FIG. 3).

In FIG. 3, reference numeral 64 denotes a holding member, which is slidably guided in the U-shaped open portion of the movable die base 42 in the direction in which the movable nesting die 43 is tightened.

65 and 66 are clamp cylinders, and the movable base 4
Clamps 67 and 68 provided at both ends of the U-shape 2 and at the rond ends thereof are provided with slopes, and these slopes abut against the slopes provided on the presser member 64. Therefore, when the clamp cylinders 65 and 66 are driven, the presser member 64 is pushed and the two rows of movable insert molds 43 are simultaneously clamped.

69 is also a clamp cylinder, and its clamp 70
can press the upper surface of the movable nesting mold 43 in the upper row.

71.72 is a cooling water circuit. The cooling water circuit 71 passes through the inside of the movable nesting mold 43 in the upper row, through a holding member 64 and a turn block 73 fixed to this holding member 64, and -
It reciprocates and opens on the wall surface of the movable base 42. Similarly, the cooling water circuit 72 passes through the movable nesting mold 43 in the lower row through the holding member 64 and the turn block 74 fixed to the holding member 64, and reciprocates to the movable mold base 42.
It opens into the wall. A cooling water supply pipe and a cooling water discharge pipe are respectively connected to these openings (not shown).

The cooling water circuits 71 and 72 are provided with removable female circuits between the movable nested mold 43 and the movable mold base 42, between the movable nested molds 43, and between the movable nested mold 43 and the presser member 64. Kabra 7
5. Connected with salt cap 76. Therefore, when assembling the movable nesting mold 43, if the male and female couplers 75, 76 are placed in predetermined positions and then the movable nesting mold 43 is tightened, the cooling water circuits 71, 72 are installed simultaneously with the movable nesting mold 43. is connected.

Next, the operation will be explained.

The movable nesting mold 43 and the nesting mold 38 are connected to the movable mold 32 as described above.
, incorporated into the intermediate mold 31.

After the mold is clamped, the hot runner 56 is passed through the nozzle 52.
Molten resin is injected into the cavity 45 through the resin path 57, the recess 59, and the runner 60 to form the bottom.

When the movable mold 32 is opened by driving a hydraulic cylinder (not shown), the intermediate mold 31 and the runner stripper plate 36 are first opened because the intermediate mold 31 is biased by the spring 40 . Runner technique is Sprubunsch 5
Since it is held by the undercut part 55 of 3, the molded part is cut at the gate part, and the runner stripper plate 3
Stay on the 6th side.

Similarly, the runner technique corresponding to the substitute nested mold 38" is the runner stripper plate 3 as a dummy runner technique.
Stay on the 6th side.

When the movable mold 32 is further opened, the intermediate mold 31 is attached to the restriction pin 39.
, the space between the intermediate mold 31 and the movable mold 32 opens, and the molded product adheres to the movable mold 32. This molded product is ejected by protruding the ejecting pin 46, and is dropped and collected.

The runner technique and the dummy runner technique are regulated by the limit pin 44, limit pin 39, and limit bolt 35, and the space between the runner stripper plate 36 and the fixed base 34 is opened, and the sprue bush is pushed by the runner stripper plate 36. 53 fell from the tip and was recovered.

(Effects of the Invention) As described above, in the present invention, a sprue (sprue bushing resin path), a runner, a recessed part of the nesting mold, and an undercut part of the sprue bushing are formed between the runner stripper plate and the back of the nesting mold. Since only small runners are formed, material waste can be reduced compared to conventional cold runners, and the effort required for post-processing of the runners can also be reduced.

Furthermore, even when using a substitute nesting mold that does not have a cavity or a runner hole, a recess similar to that of the bottom nesting mold is formed on the back of the substitute nesting mold, so a dummy runner is formed in the recess. The corresponding resin in the hot runner bronck does not stagnate, and the resin does not deteriorate or decompose.

Furthermore, since an undercut part is formed at the tip of the sprue bushing, gate cutting can be performed by fixing the runner to the stationary plate side and opening the mold without the need to provide a runner lock pin. Since the runner hole position can be changed freely within the range, the degree of freedom in designing the gate position is increased, and it is effective in being able to handle a variety of nested types such as nested center gates and nested side gates.

Although the present invention has been variously explained above with reference to preferred embodiments, the present invention is not limited to these embodiments, and it goes without saying that many modifications can be made without departing from the spirit of the invention. It is.

[Brief explanation of drawings]

Fig. 1 shows a preferred embodiment of the molding die according to the present invention, showing a sectional view of the mold in an open state, Fig. 2 a sectional view of the mold in a closed state, and Fig. 3 a front view of the movable mold. FIG. 4 is a partially cutaway explanatory view of a conventional molding die. 10...Movable type, 11...Intermediate type, 12...
Fixed type, 13... Cavity, 14... Nested type, 15... Runner hole, 16... Nozzle, 1
7...Hot runner block, 18...Socket plate,
19... Runner groove, 20... Runner stripper plate, 21... Fixed base, 22
...Runner lock pin, 30...Fixed type, 31
...Intermediate type, 32...Movable type, 33...Fixed plate, 34...Fixed type base, 35...Limiting bolt,
36...Runner stripper plate, 37
...Intermediate type base, 38.38°...Nested type, 3
9...Limiting pin, 40...Spring, 4
1... Movable plate, 42... U-shaped part, 43.4
3'...Movable nesting type, 44...Restriction pin, 45
...Cavity, 46...Protrusion pin, 47
...Spring, 48...Protruding rod, 49.
...Hot runner block, 50...Insulation material,
51... entry hole, 52... nozzle, 53...
Sprue bush, 54...Fixing plate, 55...Undercut portion, 56...Hot runner-57...
Resin path, 58... Through hole, 59.59'... Recessed part, 60... Runner 61... Wall step part,
62... Key groove, 63... Key 64... Pressing member, 65. 66... Clamp cylinder, 67.
68...Clamp, 69...Clamp cylinder,
70...Clamp, 71.72...Cooling water circuit, 73.74...Turn block, 75'...Female coupler, 76...
・Salt coupler.

Claims (1)

[Claims] 1. Three plates in which multiple sets of nested molds are inserted into one set of mold bases, and molten resin is supplied from a hot runner block to the cavity of each nested mold to perform molding. In this type of mold, the resin path connected to the hot runner block is opened at the tip, and a sprue bush is fixed on the outer periphery of the tip with an undercut portion that protrudes from an appropriate runner stripper plate when the mold is closed. In addition to being fixed to the base, a recess into which the tip of the sprue bushing having the undercut portion is loosely inserted is formed on the back of the nesting mold inserted into the mold base, depending on whether there is a cavity in the nesting mold or not. A molding die characterized by being provided regardless of the condition.