JPS5818900B2 - Elastomer cable - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates generally to transfer molding, injection molding, and compression molding, and more particularly to systems for transferring elastomeric material from an injection unit or the like to a multi-cavity mold.

This invention relates to an improvement of the present invention in which a one-way valve part or check valve is disposed between the injection unit and the chamber in which the heat insulating plate is confined.

The check valve allows unidirectional flow of elastomeric material from the chamber of the injection unit into the chamber enclosing the insulation plate.

However, the check valve is not activated when the piston of the injection unit is retracted to replenish material, for example, during a curing cycle in which the injection unit and the mold are held tightly together. The insulating plate prevents the elastomeric material from flowing back from the confined chamber to the injection unit chamber even if the internal pressure decreases.

The present invention reduces the amount of time required to produce molded articles over the course of multiple injection cycles.

This is accomplished by refilling the substantially empty injection chamber with elastomeric material during the curing cycle, rather than after, during which the mold and injection unit are held rigidly together.

Accordingly, the time traditionally required for such restocking operations may be saved.

In some cases, the replenishment operation does not need to be performed as a separate operation after a specified number of injection cycles, but can be performed during the time that the elastomer material hardens in the mold cavity.

In this regard, the present invention provides that the piston of the injection unit continuously applies pressure (necessarily) to the elastomer material within the injection chamber to hold the mold and injection unit tightly together. Eliminate.

Thus, the piston of the injection unit can be controlled independently of the mold, for example for elastomer material feeding purposes, while at the same time maintaining the clamping pressure required to keep the mold in a closed working condition during the mold curing cycle. maintained.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention may be briefly described as an apparatus for molding elastomeric materials having a multi-cavity mold in which the elastomeric material is molded into a cavity and cured.

An elastomeric material injection unit is coupled to the mold so that elastomeric material can be cyclically injected into the empty cavities of the kettle for final curing.

A plate with a plurality of holes, preferably in the form of a heat insulating plate, is arranged between the mold and the injection unit.

The plate is enclosed in a chamber that communicates directly with the chamber of the injection unit.

Between the chamber in which the movable plate is confined (hereinafter referred to as the secondary chamber) and the injection chamber (hereinafter referred to as the secondary chamber), the flow of the elastomer material is directed from the secondary chamber to the secondary chamber. A valve is placed that allows only one direction into the interior.

The movable plate may engage the mold and define a separation line therewith.

The mold moves relative to the movable plate to transfer the movable plate inwardly into the secondary chamber, thereby transferring elastomeric material from the secondary chamber to each mold cavity aligned with the hole in the movable plate. The valve can be pushed into the movable plate as follows.

That is, during the inward movement of the movable plate, for example, the piston of the injection unit is retracted for the purpose of replenishing the previous chamber with additional elastomeric material to continue a plurality of blank mold cavity filling cycles. The valve is associated with the movable plate to prevent backflow of elastomeric material from the secondary chamber to the primary chamber even if a pressure drop occurs between the primary and secondary chambers during the period of time.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be better understood - by consideration of the detailed description set forth below in conjunction with the accompanying drawings.

With particular reference to FIG. 1 of the accompanying drawings, the present invention relates to a transfer molding, injection molding or compression molding apparatus generally designated by the reference numeral 10.

The forming apparatus 10 has a platform 12 on which an upright support block 14 carrying a plurality of horizontal guide rods 16 is mounted.
is provided, and a toggle link device support zero bursting mechanism 18 is arranged adjacent to the stand 12.

The mechanism 18 moves the mold assembly 22 along the horizontal guide rod 16 toward or away from a stationary injection unit 24 coupled to the opposite end 25 of the guide rod 16 and supporting them. It is operatively coupled to a conventional toggle link device array 20 for movement.

An elastomeric material delivery source 26 is operatively coupled to the injection unit 24 and communicates with the injection unit 24 via an injection cylinder 28 within which a movable piston 30 is disposed. Trapped (Figure 2).

The piston 30 is associated with a support block and piston actuator 32 for movement relative to the interior of the injection cylinder 28, as will be seen later.

The injection cylinder 28 has an adapter 34, which
4 is a piston confinement chamber 36 inside the injection cylinder 28.
It communicates in the axial direction.

An intermediate chamber or constriction 38 is defined between chamber 36 and the enlarged interior of adapter 34 and communicates therewith.

Enclosed in said intermediate chamber or waist 38 is a movable ball 39 or the like, said ball 39 being larger than the narrowest area of said waist 38 and having an end flange in the wider opposite area of said waist 38. It has a larger diameter than the opening formed in 41.

The end flange 41 itself is open at its center or elsewhere, thereby providing continuous communication between the enlarged chamber of the adapter 34 and the constriction 38 when the ball 39 engages the end flange 41. enable.

This will be discussed in more detail later.

The end flange 41 serves to prevent the ball 39 from escaping from the constriction 38.

The adapter 34 has a cylindrical flange or wall 40 that connects internally with a generally frustoconically outwardly tapered wall 42 that is centrally connected to the midchamber waist 38. The constriction 38 gradually opens into the interior of the adapter 34 from a point at the end of the piston confinement chamber 36 .

The wall 42 of the adapter 34 is formed with a plurality of heating passages 43 in which suitable heating media, such as steam, electric heating coils, etc., are arranged.

A heat resistant flexible end insulation plate 44 having an enlarged exposed flange 46 is operatively mounted to the adapter 34 and positioned opposite the mold assembly 22 .

As shown in FIG. 2, the exposed flange 46 of the heat insulating plate 44 is provided with a series of axially extending recesses 48 spaced apart from each other in the circumferential direction; The heads 50 of each mounting bolt 52 are slidably housed.

Each mounting bolt 52 terminates at an opposite end 54;
The opposite end 54 is threaded or otherwise secured to the cylindrical wall 40 of the adapter 34.

The hidden diameter body portion 56 of the heat insulating plate 44 is connected to the adapter 34.
is slidably received within a field circle of a cylindrical flange or wall 40 .

Alternatively, the insulation plate 44 may be simply held frictionally along its periphery by the adapter 34, as shown in FIGS. 3-6, without being provided with a flange 46.

The heat insulating board 44 is made of a mixture of flexible asbestos fibers and thermosetting resin, such as phenolic resin.

Further, the heat insulating plate 44 has a plurality of openings 58 arranged in a row, and a low-friction (for example, Teflon) annular insertion piece 60 is trapped in each of these openings 58, and these insertion pieces 60 are generally It has a T-shaped cross section and communicates with the mold assembly 22.

The mold assembly 22 is provided with an end plate 62, and a heat-resistant heat insulating plate 64 is placed along the end plate 62.

Insulating plate 64 is constructed of any suitable insulating material having a suitable thickness to prevent end plate 62 from heating as a result of heat generated by heating platen 66 disposed thereon.

A heating platen 66 is provided with a heating passageway 68 for heating the mold assembly 22 and is disposed along a surface of the insulation plate 64 opposite the surface that contacts the end plate 62 of the insulation plate 64.

End plate 62 is attached to a fluid actuated ram 70 enclosed within housing 72.

The ram 70 is moved axially as fluid is introduced into the housing through the input lower 4, as will be described below.

Overlying the heating platen 66 is an assembly of templates including a bottom or inner template 80, a middle plate 82 disposed on the inner template 80, and a top plate 82. It is constructed with an outer mold plate 84 disposed at.

These templates 80, 82, 84 are each drilled with a plurality of aligned apertures, with the apertures in each alignment coaxially aligned with each aperture in the other alignment.

Each group of aligned openings has a plurality of inner mold inserts 86.
, one of the plurality of center cavity defining mold inserts 88 , and one of the plurality of wound opening mold inserts 90 , each of which inserts overlap each other to form a respective mold. Cavities are defined into which elastomeric material can be injected and cured.

the mold inserts 86, 88, 90 are arranged in groups of burr-free or locally deflectable nature;
By slightly moving relative to each other, they serve to seal all separation lines between them.

A plurality of circumferentially spaced bolts 92 secure the inner mold plate 80 to the heated platen 66 while the intermediate mold plate 82
and outer mold plate 84 are removably coupled to each other and to inner mold plate 80 and perforated plate 94, respectively.

The forming plates 94 face-to-face engage the insulation plates 44 and are used to periodically remove any runner scrap from the runners or openings of the insert 90 after curing.

In one mode of operation, the toggle linkage array 20, shown only schematically, is comprised of a plurality of links that can be moved to an ejector locking position to inject the mold assembly 22, as is commonly understood. It acts to move it toward the cylinder 28.

When the toggle link in-progress array 20 is fully extended, the mold assembly 22 is placed in an operative position in which it is ready to engage the insulation plate 44 via the forming plate 94.

Elastomeric material is then introduced into the piston confinement chamber 36 of the injection cylinder 28.

The amount is in excess of that required to fill all of the mold cavities.

The heating medium in the heating passage 43 fills the interior of the adapter 34 when the elastomer material is acted upon by the piston 30 and exerts a uniform pressure against the insulation plate 44, forcing it to its axially outermost position (FIG. 3). ) to impart fluidity to the elastomer material.

When the piston 30 is protruded, the ball 39 moves into the constriction 38.
It will be appreciated that this allows the elastomeric material to fill the chamber of the adapter 34.

When the insulation plate 44 is moved to its axially outermost position, it engages and similarly exerts a uniform pressure on the plate 94 mounted on the mold assembly 22.

The ram 70 is then pushed out slightly to increase the pressure on the insulation plate 44 through the plate 94.

Since the forming plate 94 is flexible to a certain extent, the mold insertion piece 86.8
8.90, thereby locally deflecting the mold inserts relative to each other and eliminating any gaps that may be formed at the line of separation between them. It acts to close.

As the gap at the separation line between the mold inserts 86, 8890 is reduced, the potential for formation of flash on the portion of elastomeric material transferred into the mold cavity is similarly reduced.

Further movement of the ram 70 in the direction of the insulation plate 44 (FIG. 4) forces a defined amount of the elastomeric material through the low friction annular insert 60 and
Injected into the mold cavity.

The portion of elastomeric material transferred into the mold cavity is then cured by heat provided by a heating medium confined within heating passages 68 of heated platen 66.

However, because a heat insulating plate 44 is disposed between the mold cavity and the interior of the adapter 34, the remainder of the elastomeric material within the area of the adapter 34 is removed from the heated mold assembly 22 during the fixed injection process. Despite continuous engagement with unit 24, curing is prevented.

At the end of the curing process, or at least in the very final stages of curing, the mold assembly 22 is completely retracted.

Accordingly, the toggle link in-progress array 20 operates to fully retract the mold assembly 22 and move it away from the insulation plate 44, thereby allowing removal of the molded product from the mold cavity. Figure 6).

At the end of the curing process, the plate 94 can be used to simultaneously remove scrap of cured elastomer within the sprue area of the outer sprue insert 90 and then the mold cavity is removed from the injection mold cavity. It will be appreciated that cylinder 28 may be emptied for recirculation operation in conjunction with it operatively.

Once emptied, the mold cavity, along with the recovered plate 94, can be moved back into the vicinity of the insulation plate 44 via the toggle link in-process array 20.

The piston 30 is then extended slightly to fill the chamber of the adapter 34, thereby moving the insulation plate 44 outwardly of the chamber of the adapter 34, thereby causing the insulation plate 44 to engage the plate 94. .

The chamber of the adapter 34 is thereby refilled for the next mold cavity filling process.

Ram 70 is then ejected again to move insulation plate 44 inwardly into the chamber of adapter 34, thereby causing
Extrusion and transfer of the trailing portion of the elastomeric material into the mold cavity can occur without any further movement of the piston 30.

The above cycle is repeated many times until the piston confinement chamber 36 of the injection cylinder 28 is nearly empty.

A condition in which the confinement chamber 36 becomes nearly empty occurs, for example, when the piston 30 occupies a position within the injection cylinder 28, such as that illustrated in FIG.

Therefore, the piston confinement chamber 36 must be refilled with elastomer material before a subsequent mold cavity filling cycle can be performed.

A freely movable valving ball 39 is therefore arranged in said constriction 38 of the adapter 34 so that after the final injection cycle, for example, the ram 70 moves the insulation plate 44 into the chamber of the adapter 34. After moving the elastomeric material from the chamber and into the mold cavity so that the insulation plate 44 assumes the position generally shown in FIG.
The piston 30 can be fully retracted, allowing additional supply of elastomer material into the empty or near-empty piston confinement chamber 36 by conventional means, not shown.

When the piston 30 is retracted, the pressure to lock the mold in an operationally closed condition is not reduced.

The reason is that during the retraction of the piston 30, the ball 39 moves towards the narrow end portion of the constriction 38 and the adapter 34
Elastomeric material within the expanded chamber of the constriction 38
This is because it is prevented from flowing backward through the piston 30 and into the empty space formed by the retracted piston 30.

Thus, the ball 39 acts as a check valve to maintain the pressure within the expanded chamber of the adapter 34 and, therefore, the pressure required to fasten the mold and injection cylinder 28 together. Work.

Therefore, not only is no pressure lost during the retraction of the piston 30, but there is also a period during which the piston confinement chamber 36 of the injection cylinder 28 is refilled with additional elastomeric material (this period is during the curing of the material in the mold cavity). There is also no loss of time (which would otherwise occur).

The stages during one cycle of operation of a device according to the invention, the treading forces associated with such a device between such steps and the time economies achieved by such a device are:
This can be clearly understood by referring to FIGS. 7 to 9 below.

The horizontal axes of each of the three graphs illustrated in these figures indicate the time interval for each operating phase, while the respective vertical axes indicate the pressures that various device elements experience between such operating phases.

FIG. 7 is a graph showing the change in pressure that occurs in the expanded chamber of the interior 5 of the adapter 34 during a single cycle;
The figure is a graph showing the variation in pressure exerted by the piston 30 on the elastomeric material of the piston confinement chamber 36 of the injection cylinder during a single cycle; FIG. It is a graph showing changes in pressure applied to.

The graphical analysis of FIGS. 7-9 shows that the injection cylinder 28 is already completely filled with elastomeric material;
It is assumed initially that the piston 30 is being extruded through said constriction 38 to inject the elastomeric material into the enlarged chamber of the adapter 34 .

Therefore, the ball 39 has been moved from the position where it blocks the fin 38.

The pressure initially exerted by piston 30 is only sufficient to move insulation plate 44 outwardly to assume the position generally shown in FIG.

The initial pressure of the piston 30 is referenced P. is insufficient to cause release of elastomeric material through the openings in the insulation plate 44.

Additionally, toggle link in-progress array 20 is fully extended to the position shown in FIG. 3 and ram 70 is fully retracted (pressure P).

) condition, i.e., allowing said outward movement of the insulation plate 44 to its outermost position, thereby maximizing the elastomeric material packing of the expanded chamber of the adapter 34. be done.

The initial position of ram 70 limits the range of outward movement of insulation plate 44 through mold assembly 22 and thus initially functions as an abutment element.

The above operating steps are performed at time intervals t in each of FIGS. 7-9.

-11.

The next stage is the cavity filling stage from tl to 12.

During this stage, the pressure exerted by the ram 70 on the mold assembly 22, the insulation plate 44, and the elastomeric material within the expanded chamber of the adapter 34 increases to the level of Pl at time t2, 39 is returned to a position blocking said constriction 38.

The change in pressure exerted by ram 70 is illustrated in FIG. 9, while the change in pressure against the elastomeric material inside the expanded chamber of adapter 34 is illustrated in FIG.

At time t2, the device 10'' and in particular the insulation plate 44
is in a state as shown in FIG.

When the mold cavities are filled, ie at time t2, curing of the elastomeric material within these mold cavities may be effected by heated platen 66.

Curing in the mold cavity continues further in time interval 13-14, in which the fifth
As illustrated in the figure, if the piston confinement chamber 36 of the injection cylinder 28 is near empty and requires refilling of additional elastomer material, the piston 30 is fully retracted to fill the piston confinement chamber 36. Restocking may take place.

After refilling the piston confinement chamber 36, the piston 30 is ejected to compact the newly refilled elastomer material within the piston confinement chamber 36.

The pressure exerted by the piston 30 against the elastomeric material within the piston confinement chamber 36 is represented in FIG. 8 by the solid waveform curve.

However, if a push screw or the like is used instead of piston 30, such a pressure change would be represented as a dashed line in FIG. 8 during the time interval t3-t4.

The ball 39 blocks said constriction 3B during the retraction of the piston 30 to allow replenishment of additional elastomer material, so that the elastomer flows from the enlarged chamber of the adapter 34 into the empty piston confinement chamber of the injection cylinder 28. It will also be clear that no backflow of material occurs.

With respect to time economy - so importantly, the piston confinement chamber 36 is used during the curing period during which time the elastomeric material cures within the mold cavity 12-1. is refilled with additional elastomer material for a shorter period of time.

Accordingly, the time traditionally required for such operation is not required by the present invention.

Subsequently, at time t4, the ram 70 can be returned to a position corresponding to the position illustrated in FIG.

The return of ram 70 is accomplished by reducing its pressure from Pl to P2 (FIG. 9).

This is achieved by a corresponding pressure increase by the piston 30 and a pressure increase in the enlarged chamber of the adapter 34 (FIG. 7).

Time interval 14-1. By the ejection of piston 30 and the return of ram 70 in (FIG. 8), additional elastomeric material is "dispensed or squeezed" into the interior of the enlarged chamber of adapter 34, thereby causing the ejection or outward movement of insulation plate 44. cause movement.

This time interval is referred to as the 0-distribution phase, during which the expanded chamber of adapter 34 is completely refilled for at least one additional injection cycle.

It will be appreciated that the distribution pressure Pd is greater than the ram 70 pressure P2.

Curing continues until time t5, or for a short time after time t, and then, as illustrated in FIG. 6, toggle link in-progress array 20 is moved from its fully extended position. This allows the mold to be opened and the mold cavity to be emptied.

When the mold cavity is emptied, the toggle link in-process array 20 is again moved to the position shown in FIG. 3, and the next cycle begins at time t in FIGS.
.

may be started and repeated.

In the above, the present invention cooperates with a movable insulation unit.
According to the invention, the adapter itself is provided with a non-return valve, the non-return valve being trapped. A device may also be provided which is adapted to prevent backflow of elastomeric material from said adapter when the injection unit is withdrawn from communication with the waist.

Thus, a clamping pressure can be maintained between the crosshead to which the adapter is fixed and the mold, and elastomer material cannot flow back through the constriction.

Therefore, the valved adapter of the present invention is not limited to operative coupling to a movable insulation unit.

The valved adapter can also be operatively coupled to a fixed insulation unit, ie one that cannot be moved axially relative to the adapter or relative to the injection or transfer device.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view of the device according to the present invention; FIG. 2 is an enlarged sectional view of essential parts of the device according to the present invention; FIGS. 3 to 6 are operation of the device schematically illustrated in FIG. 2. Cross-sectional views of the main parts of the device at successive stages: Figures 7 to 9 show (a) the relationship between pressure and time in the secondary chamber that confines the movable end plate, and (b) the relationship between pressure and time in the piston of the injection unit. FIG. 3 is a graph diagram illustrating the relationship between pressure and time in a ram that moves the mold toward or away from the movable end plate of C. In the above drawings, 10 is a "molding device"; 22 is a "molding device";
Mold assembly 1. 24 is "injection unit"; 34 is "adapter"; 36 is "piston confinement chamber"; 30 is "piston"; 28 is "injection cylinder"; 38 is "constriction";
39 is a "ball"; 41 is an "end flange"; 44 is a "insulation plate"; 70 is a "ram"; 72 is a "housing".

Claims (1)

[Claims] 1 An apparatus 10 for molding elastomeric material, comprising: a mold 22 having at least one cavity for molding the elastomeric material into the shape of the cavity and curing; a primary chamber in which the elastomeric material is placed; an elastomer material injection unit 24 having an elastomeric material injection unit 24 from which the material can be transferred under pressure; an adapter device 34 defining a secondary chamber communicating with said primary chamber; and between said secondary chamber one and said secondary chamber; Arranged valve devices 38, 39, 4
1 to permit unidirectional flow of elastomeric material from the secondary chamber to the secondary chamber; an end plate 44 defined with an aperture carried by the adapter device in facing relation to the mold; the single opening interconnects the secondary chamber with the mold cavity, and is at least partially disposed in the secondary chamber to reduce the axial dimension of the secondary chamber. an exposed end that is freely movable axially relative to the secondary chamber to cause the mold to move, and that is engaged with the mold and defines a separation line with the mold; engaging an end plate thereby moving the end plate inwardly into the secondary chamber to reduce the axial dimension of the secondary chamber and forcing elastomeric material through the end plate and into the mold cavity. a device for moving the injection unit and the mold relative to each other so as to eject the elastomer; allowing material to flow in one direction from the secondary chamber to the secondary chamber, the valve arrangement cooperating with the end plate during inward movement of the end plate to reduce pressure in the secondary chamber. An apparatus for forming an elastomeric material, characterized in that a backflow of the elastomeric material from the secondary chamber to the secondary chamber is prevented even if a drop occurs.