JPH03197112A - Injection molding device - Google Patents

Abstract

PURPOSE: To prevent mold damage generated by misalignment of a mold core and a mold cavity by generating fitting relation between a secondary cavity surface and a secondary core surface and forming a secondary surface to form a contact point or an obstructing surface effective when a main molding surface is detached from an aligning position. CONSTITUTION: Secondary surfaces 13, 14 are formed between the main molding surfaces 10, 15 of a core and a cavity determining the shape of a molded article and the secondary surface 13 becomes a guide surface and the secondary surface 14 becomes a guide device. A stepped part and a shoulder or lip 16, 17 are formed to the secondary surfaces 13, 14 having a gap smaller than the thickness of the core of the molded article therebetween and the accurate alignment of the core and the cavity is obtained by them. However, if mold parts move together to a position having possibility generating a damage and misalignment is generated, the stepped part 16 on the secondary surface comes into contact with the guide device 18 on the secondary surface to prevent the pressure contact of the mold parts. When interference or contact showing misalignment is generated in the stepped part 16, one of a large number of signals is outputted by triggering to stop a molding cycle.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an injection molding apparatus, particularly an injection molding machine with a relatively movable system and a precise tolerance, a mold for molding thin-walled articles or containers at high speeds. Related to core and cavity assembly.

The relative interlocking of the molds described above (fixed cavity and movable core, fixed core and movable cavity, or movable core and movable cavity) occurs along an axis common to the core and cavity.

The wall thickness of the article being molded, and therefore the gap between the core and the cavity, should be between 0.010 and 0.020 inches at the molding location.
25~0.5mm+) to maintain correct alignment between the core and cavity along a common axis to prevent mold damage caused by improper contact between the core and cavity during the molding cycle. It is necessary.

The prior art device which the present invention seeks to improve is described in a paper published by Brown (Pa.
U.S. Patent No. 4゜556 in the name of U.L.P. Brown
．． No. 377.

The above specification discloses an externally sloped cavity that cooperates with a ring 25 surrounding the core 20 with a mating taper A that guides the core into the cavity to maintain alignment of the core and the cavity.

The device shown in the above-mentioned patent specification No. 4,556,377 works well, but the wall pressure of the product is 0.010 to 0.0.
On the order of 20 inches (0.25 to 0.5 wn), this is not satisfactory.

Also, this device does not provide any means to reliably prevent damaging contact between the core and the cavity.

Accordingly, it is a feature of the present invention to provide a mold having a structure that prevents mold damage resulting from misalignment of the mold core and mold cavity.

Another feature of the present invention is that it provides a protective structure and safety scheme that is particularly useful for core and cavity assemblies that mold thin-walled articles.

Another feature of the invention is the provision of cooperating features or surfaces on the core and the cavity that prevent the core and the cavity from collapsing during high speed molding cycles before undesirable destructive contact occurs. The goal is to provide a structure that responds to alignment.

Another feature of the invention is the provision of a stepped or shouldered fitting structure on the exterior of the core and cavity, which structure provides a sliding fit with a clearance less than the wall pressure of the molded article.

An injection molding apparatus according to the present invention for performing the tasks described above is capable of injection molding thin-walled structural articles at high speeds using a reciprocating concentric mold core and mold cavity assembly having a constant stroke and continuous cycles, and Prevents damage to the core and cavity during reciprocating movement along the axis. This injection molding device consists of a mold core, a mold cavity in which the core and the cavity are movable relative to each other, a guide device provided in one of the core and the cavity, and a force of the guide device to supplement this. The core and one of the cavities include a stepped guide surface having a recess formed therein. The core and cavity molding surfaces do not come into destructive contact during the molding operation, and if destructive contact between the mold surfaces threatens to occur, the guide surface contacts the guide device to stop the molding cycle.

The guide surface is offset to form a shoulder that prevents contact with the guide device and prevents movement between the core and the cavity if damage to the mold could occur due to misalignment. The guide device extends parallel to the axis, and the length of the guide device is
Determine the location on said axis where interference occurs in the event of misalignment. The length of the guide device and the clearance between said guide device and the guide surface determine the axial position at which disturbance occurs in the event of misalignment. Furthermore, a device is provided for interrupting and stopping the molding cycle in the event of the above-mentioned disturbances, this device being, for example, a pressure sensor.

The wall thickness is 0.010~0.020 inch (0°25~
0.5■), and the gap between the guide device and the guide surface is 0.0
0.04 inch (0.1 m) and the tolerance is ±0.002 inch (0.05 no). A guide device surrounds and forms part of the core, and a guide surface surrounds and forms part of the cavity.

A method for preventing damage to a main molding surface according to the present invention comprises an injection molding machine having a main molding surface for molding a thin-walled article and comprising a mold core and a mold cavity that move relative to each other along a cyclical common axis. In the apparatus, generating a mating relationship between a secondary cavity surface and a secondary core surface, and forming the secondary surface so that the primary molding surface is out of alignment and the mold is damaged. forming a potential contact point or interfering surface when there is a risk of interference.

This method of preventing damage to the primary molding surface includes the step of using the occurrence of contact as a signal to interrupt and stop the molding cycle to prevent damage to the primary molding surface. Further, a step is added to form a gap smaller than the thickness of the thin wall between the secondary surfaces when the main molding surfaces are properly aligned.

A protrusion is formed on one of the secondary surfaces and a complementary recess with a shoulder is formed on the other one of the secondary surfaces. The protrusions cyclically fit into the recesses when the main molding surfaces are correctly aligned, and when the main molding surfaces are out of alignment, the shoulder prevents the protrusions from being fitted, thereby preventing the interfering surface forming process. achieved.

A stop signal is generated by a surge in power demand due to closed contact between the secondary surfaces.

The molding apparatus of the present invention has a mold core and a cooperating mold cavity for molding thin-walled articles, the mold core and mold cavity having a primary molding surface and a secondary molding surface. A device is provided on the secondary surface to prevent the mold core and mold cavity from coming into contact if they are misaligned to such an extent that damage to the primary forming surface may occur.

Raw-1 For example, the wall thickness of a thin-walled article is 0.010~0°020
On the order of inches (0.25 to 0.5 m), the clearance between the mating steps, shoulders, or lips is allowed to be ±0. OO2 inch (0,025m) 1'O,OO4 inch (0,0
5m).

Accordingly, the present invention provides a configuration of the secondary surfaces of the core and cavity such that preventive interference occurs with the secondary surfaces of the mold before destructive interference occurs with the inner surface or primary molding surface of the mold during high speed molding cycles. It's about deciding.

The term "primary molding surface" above refers to the mold surface on the core and cavity used in molding the article, and the term "secondary surface" refers to the surface of the core and cavity other than the primary molding surface.

Core and cavity assemblies used to mold thin-walled articles typically have a coarse guide or alignment device that operates between molding cycles to allow the core to fit into the cavity without undue interference or contact. Introduction (or introduction of a cavity on the core)
can do.

The invention provides a precise guide or alignment device that prevents damage to the mold, if any, after initial installation, and prevents relative movement between the core and the cavity.

The present invention provides an improved method of providing accurate guidance.

The method of the present invention provides precise guidance to prevent mold damage of a core cavity assembly reciprocating over a constant stroke for forming thin-walled articles.
forming a tight fit between the mating secondary surfaces; determining the size of the gap between the secondary surfaces to a value smaller than the wall thickness of the article; and shaping these mating secondary surfaces. The method includes the step of determining the likely interference zone to correct core-to-cavity misalignment and inhibit relative movement between the core and the cavity to prevent mold damage.

The molding device that performs accurate guidance and guidance to prevent damage to the mold includes a core, a cavity, and a stepped guide device that surrounds the core, in which these cores and air conditioners move relative to each other through a constant stroke for molding thin-walled products. , the secondary surface of the cavity is formed with a stepped guide surface into which the reciprocating guide device fits, and the gap between the guide device and the guide surface is smaller than the wall thickness of the article, so that the core and The cavities are properly aligned to prevent mold interference and damage during high speed molding operations.

Other features and advantages of the invention will become apparent from the following description, which is illustrated in the accompanying drawings, in which an exemplary embodiment is shown.

1-4, the mold cavity is indicated at 11, and the core is indicated at 12 as it moves from the molding position shown in FIG. 1 to the article ejection position shown in FIG.

The core has a main molding surface 10, and the cavity has a main molding surface 15.
has.

Regardless of the cooperation between the primary forming surfaces 10 and 15 of the core and cavity which determine the shape of the molded article, the core and cavity have a mating, i.e. nesting, relationship with secondary surfaces, i.e. the cavity. Reference numeral 13 and reference numeral 14 formed on the core.

For the purposes of the invention, the secondary surface 13 is a guiding surface;
The secondary surface 14 becomes a guiding device.

The term "thin wall" means 0.010 to 0.020 inches (0,2
5 to 0.50 m) (Figure 1B).

On the other hand, the gap between both surfaces 13 and 14 at the molding position in FIG. 1 is 0°004 inch (0, Olm) ±0.002 inch (0,005 mm), as shown by A in FIG.
This is the order.

As noted above, the present invention provides a reliable method and apparatus for preventing mold damage during high speed molding operations, and allows thin wall structural articles such as those described above to be molded.

Many conventional core cavity assemblies, also referred to as coarse core/cavity alignment devices, require precision guiding or alignment devices and the core cavity to avoid damage to the mold surface during critical portions of the molding cycle. Introduction (or introduction of type into core)
There is a need in the art for a method that operates between operations that perform the following steps.

3, the secondary surfaces 13 and 14 with a gap smaller than the thickness of the core of the molded article as shown in FIG. 1 have steps, shoulders or lips 16 and 17. are formed and these provide the correct alignment as shown in FIG.

However, if the mold parts move together to a position where damage may occur and misalignment (often the result of improper product ejection) occurs (contact with the primary molding surfaces 10 and 15), the secondary A step 16 on the next surface contacts a guide device 18 on the second surface 14 to prevent pressure-tight contact of the mold parts, as shown in FIG.

Therefore, even if some alignment is achieved between the cavity and the core with a coarse alignment device (not shown), there is often a residual misalignment that is detected by the precision guide device and the present invention. Further progress of the molding cycle is inhibited to prevent significant mold damage.

Of course, the guide device! 18 (and fitting recess 19) height Y (
3) to change the point of interference of the step, lip or shoulder 16, thereby independently controlling the gap between the secondary surfaces 13 and 14 and the deflection of the shoulder 16 (A in FIG. 1). , or in combination,
The stop position can be varied depending on the mold design, product wall thickness, mold stroke and cycle speed.

Also, a guide device! 18 and shoulder 16 are inverted, i.e. cavity 1
A guide device i18 is formed on the core 12, and a shoulder 1 is formed on the core 12.
6 is also included in the present invention.

In the event of interference or contact indicating misalignment of the steps 16, as shown in FIG. 3, one of a number of haiku will be triggered to stop the molding cycle in a known manner.

For example, as shown in FIG. 4, if a sudden increase in hydraulic pressure would occur due to interference in the position of a step in a hydraulically actuated molding device, a suitable pressure sensor in this hydraulic device would immediately be activated by a switch device. The molding cycle is stopped using the stop pump P.

It is clear that the present invention provides an injection molded anti-collision device which achieves the objects and advantages mentioned above.

The present invention provides the advantage that a high speed injection molding apparatus and method can detect misalignment between the core and cavity of the mold, detect the molding operation, and continue the correct molding operation.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of the main parts of the injection mold at the molding position of the present invention, Fig. 2 is a cross-sectional view similar to Fig. 1 of the injection mold at the product ejection position, and Fig. 3 shows the core and '! 1! FIG. 4 is a cross-sectional view showing a state in which the molding apparatus is stopped due to misalignment of the parts, and FIG. 4 is a schematic diagram of the apparatus for stopping the molding cycle when the misalignment of the parts shown in FIG. 3 occurs. 10. Main molding surface 11. ,, hollow, 12...
Core 13..., secondary surface (guide surface), 14. ,
, secondary surface (guiding device I).

Claims (14)

[Claims] (1) High-velocity injection molding of thin-walled structural articles using a reciprocating concentric mold core and mold cavity assembly with constant stroke and continuous cycles, and In an injection molding device for preventing damage to the cavity, a mold core, a mold cavity in which the core and the cavity are movable relative to each other, a guide device provided in one of the core and the cavity, and a mold in which the guide device fits together and a stepped guide surface having a recess formed in one of the core and the cavity to supplement the above-mentioned core and the cavity molding surface so that no destructive contact occurs during the molding operation, and no destructive contact occurs between the mold surfaces. An injection molding apparatus characterized in that the guide surface contacts a guide device and stops the molding cycle if there is a possibility that this may occur. (2) the guide surface is offset to form a shoulder that impedes contact with the guide device and prevents movement between the core and the cavity in case damage to the mold is likely to occur due to misalignment; The injection molding apparatus according to item (1). 3. The injection molding apparatus of claim 2, wherein the guide device extends parallel to the axis, and the length of the guide device determines the location on the axis where interference occurs in the event of misalignment. 4. The injection molding apparatus of claim 3, wherein the length of the guide device and the gap between the guide device and the guide surface determine the axial location at which disturbance occurs in the event of misalignment. (5) The injection molding apparatus according to claim (2), further comprising a device for interrupting and stopping the molding cycle when said disturbance occurs. (6) The injection molding apparatus according to claim (5), wherein the device for interrupting and stopping the molding cycle is a pressure sensor. (7) The wall thickness is 0.010 to 0.020 inches (0.010 to 0.020 inches).
25 to 0.5 mm), the gap between the guide device and the guide surface is 0.004 inch (0.1 mm), and the tolerance is ±0.0
The injection molding apparatus according to claim 1, which has a diameter of 0.02 inch (0.05 mm). (8) The injection molding apparatus according to claim (1), wherein the guide device surrounds the core and forms a part of the core, and the guide surface surrounds and forms a part of the cavity. (9) In an injection molding apparatus including a mold core and a mold cavity having a primary molding surface for molding thin-walled articles and moving relative to each other along a common axis in a cyclic manner, the injection molding apparatus comprises a secondary cavity surface and a mold cavity. creating a mating relationship with a secondary core surface, forming said secondary surface to provide a potential contact point or A method for preventing damage to a main forming surface, comprising: forming an interfering surface. (10) The method for preventing damage to the main molding surface according to claim (9), further comprising the step of using the occurrence of the contact as a signal to interrupt and stop the molding cycle to prevent damage to the main molding surface. (11) The method for preventing damage to a main molding surface according to claim (9), further comprising the step of forming a gap smaller than the thickness of the thin wall between the secondary surfaces when the main molding surface is properly aligned. . (12) forming a protrusion on one of the secondary surfaces and forming a complementary recess with a shoulder on the other one of the secondary surfaces;
The protruding portion cyclically fits into the recess when the main molding surface is properly aligned, and when the main molding surface is out of alignment, the shoulder prevents the fitting, thereby interfering with the above. A method for preventing damage to a main molding surface according to claim 9, wherein the surface forming step is performed. 13. Claim 10 wherein said stop signal is generated by a surge in power demand due to closed contact between said secondary surfaces.
) Method for preventing damage to the main molding surface. (14) A forming apparatus having a mold core and a mold cavity cooperating therewith for molding thin-walled articles, wherein the mold core and the mold cavity have a primary molding surface and a secondary surface, and the mold core and the mold cavity have a primary molding surface and a secondary surface; If the mold cavity and mold cavity are misaligned to such an extent that damage to the main forming surface is likely to occur, a device for preventing contact is provided in the second mold cavity.
A molding device characterized in that the molding device is provided on the next surface.