Stop valve for controlling flow of molten material from gate of injector to mold cavity

Abstract

A shut-off valve for controlling the flow of molten material from a gate of an injector to a mold cavity is described. The valve includes a channel for molten material extending along a first axis to a gate; a gate member movably mounted along a respective second axis and enabling a free end of the gate member to move towards and to a point within the passage to throttle and / or close the passage to regulate the flow rate; and an actuation member, a portion of which is coupled to the gate member such that rotation of the actuation member causes translation of the gate member from and / or toward the point along the second axis. The actuation member includes an annular stator fixed to the mold and an annular rotor rotatably placed inside or outside the stator and coupled to the gate member.

Description

TECHNICAL FIELD

[0001] The present invention relates to a shut-off valve for controlling the flow of molten material from a nozzle of an injector to a mold cavity. BACKGROUND

[0002] It is known to control the flow of molten material from a nozzle to a mold cavity via a valve stem (pin or shutter) that can be moved linearly back and forth. However, the presence and alternating movement of the valve stem increases flow disturbances, creates accumulation and stagnation areas of material, causing for example color-changing operations of injected material to require multiple cleanings of the injector, with consequent waste of a large amount of material.

[0003] The oblique valve stem as shown in EP520345 presents the drawback of pushing the material against the inner surface of the channel, further compressing it to the outlet. This extrusion effect causes defects on the final product. This extrusion effect can cause defects on the surface of the final product. To solve the above problem, the valve pin has been replaced with a shutter valve placed near the material nozzle. This solution is used to control the opening and closing of multiple side-by-side placed injectors simultaneously by a single actuator, as shown for example in EP1409222 (figure 13). However, a single movable shutter valve can cause the extrusion of material to the edge area of the nozzle orifice, which is at a lower temperature, causing defects in the molded product.

[0004] WO2024095073 shows a better solution, i.e. the use of a rotatable member to control the shutter member. The system of WO2024095073 can also be improved. SUMMARY

[0005] The main object of the present invention is to improve this prior art, which object is defined in the appended claims, where the dependent claims define advantageous variants.

[0006] A specific object is to improve the actuation of the movable shutter member / obturator.

[0007] At least one object is achieved by a shut-off valve for controlling the flow of molten material leaving a nozzle of an injector into a cavity of a mold, the shut-off valve comprising:

[0008] • a channel for molten material extending along a first axis up to the nozzle,

[0009] • a shutter member, said shutter member being mounted:

[0010] - movable along a respective second axis (orthogonal to the first axis or inclined at an acute angle to the first axis), and

[0011] - This allows the free end of the gate component to move toward and reach a point inside the channel to throttle and / or close the channel, thereby regulating the flow rate.

[0012] • An actuating member, a portion of which is coupled to the gate member, such that rotation of the actuating member causes translation of the gate member along the second axis from and / or toward the point.

[0013] The actuating components include

[0014] - An annular stator fixed to the mold, and

[0015] - An annular rotor (rotatably arranged inside or outside the stator) and connected to the gate assembly.

[0016] -The first circular array of magnetic poles installed in the rotor

[0017] -A second circular array of magnetic poles installed in the stator.

[0018] The magnetic poles of the first and second circular arrays interact magnetically with each other to rotate the rotor relative to the stator through the magnetic field generated by them.

[0019] This actuation component avoids the complex control mechanisms of the rotor, such as rack and pinion drives facing the external motor, which in turn require an internal reduction gear. Therefore, the system is simplified, the motion path is shortened, and the need for transverse holes in the mold and external mounting of the actuator is eliminated.

[0020] Furthermore, the molding system becomes simpler, occupies less space, and offers greater precision in positioning and controlling gate components. And due to reduced mechanical backlash, feedback is faster because the kinematic chain is shorter (fewer parts), simpler, and more direct.

[0021] The stator is preferably annular and surrounds the rotor, or is placed directly above or below the rotor.

[0022] Preferably, the rotor includes a contoured structure, such as one or more grooves or protrusions, for connecting and controlling the corresponding gate components. This design further makes the drive system compact and avoids additional components, shortening the kinematic chain. Specifically, one end of the gate component includes a pin or protrusion slidably inserted into a circumferential groove in the rotor, such that rotation of the rotor causes rotation of the groove, thereby pushing the pin and causing the gate component to slide. The positions of the protrusion and the groove can also be interchanged.

[0023] By simply making the contour structure act as a cam at the end of the gate component, the rotational motion of the rotor can be converted into the linear movement of the gate component.

[0024] Preferably, one or each gate component is translated to the rotor via a direct mechanical connection.

[0025] In a preferred variant, the stator's magnetic poles are permanent magnets or electromagnets, preferably fixed and / or placed on an annular cylindrical surface of the stator facing inwards.

[0026] In a preferred variant, the stator poles are configured as windings that generate a radial magnetic field, the pole axis of which points towards the center of the stator. These windings can receive electrical signals via brushes fixedly arranged in the stator. The actuation mechanism can be configured to operate as a brushed motor or a stepper motor via a suitable control unit.

[0027] In a preferred variation, the stator is fixed in a corresponding housing in the insert or plate of the mold.

[0028] In other variations, the components constituting the magnetic poles may be interchanged with those described above, or replaced by other technologies.

[0029] Preferably, the actuating component is placed near the gate.

[0030] The actuation system for the gate component of a valve is independent of the number and configuration of the gate components; advantageously, there can be more than one gate component.

[0031] In a preferred compact variant, the stator and rotor extend around (and for example, also around) a first axis and / or channel.

[0032] In a preferred variation, the rotor has a rotation axis parallel to the first axis; in particular, for maximum compactness, the rotatable member has a rotation axis coaxial with the first axis.

[0033] In a preferred variant, the valve comprises two or more gate members, the respective second axes of which are coplanar and arranged as follows:

[0034] • Arranged in a radial pattern relative to the points, or

[0035] • Arranged along the diagonal of a polygon (either a regular or irregular polygon), where the point is the center of the polygon.

[0036] In a preferred variant, the valve comprises only two gate members that are movable along the sides of an angle whose vertices are located at the point, wherein the plane containing the angle is orthogonal to or through the first axis.

[0037] In the case of two or more gate components, with respect to the translation of the gate components (and with respect to the second axis), the point becomes a common convergence point, or the closing point of the channel.

[0038] In a preferred variation, the valve comprises three or more gate components, each with its second axis arranged along the lateral edge of an imaginary pyramid, the convergence point forming the apex of the pyramid. In a more preferred variation, the imaginary pyramid is arranged such that its base intersects the first axis and the channel; more specifically, the base is orthogonal to the first axis.

[0039] In a preferred variant, the performance of the syringe is improved, and the valve includes two or more gate members, which are actuated by a rotor and mounted as follows:

[0040] It can move along a corresponding second axis that is inclined at an acute angle to the first axis, and

[0041] This allows the free ends of each gate component to move and converge toward the same convergence point within the channel.

[0042] The free ends of the gate components can be joined together at the convergence point to form a barrier for molten material.

[0043] In a preferred variant, the gate component has the shape of a straight rod, one end of which is a free end, and is connected to an actuating component at the opposite end. Attached Figure Description

[0044] The advantages of the present invention will become more apparent from the following description of the preferred valve, wherein

[0045] Figure 1 A cross-sectional view of the shut-off valve is shown;

[0046] Figure 2 A three-dimensional view of the valve assembly assembled into the actuation system is shown;

[0047] Figure 3 Shown in exploded view Figure 2 A 3D view of the components.

[0048] In the figure, the same elements are represented by the same reference numerals, and in order to avoid the drawing becoming crowded, sometimes only some elements are numbered. Detailed Implementation

[0049] Reference Figure 1The diagram shows the end 18 of a known syringe 10 for injecting molten material into a mold cavity 12. The syringe 10 is typically mounted within one or more plates 500 constituting the mold and is fixed to a known manifold (not shown, which is also mounted within the plate 500) for dispensing molten material. The syringe 10 includes and defines an axial cavity 16 extending longitudinally along a central axis Y (which is preferably also the axis of polar symmetry of the syringe 10). The end 18 of the syringe 10 rests on a mold insert 20 having an orifice defining a gate 98, and the molten material can flow within the cavity 16 to the gate 98. In general, the structure of the syringe 10 is known and need not be repeated.

[0050] Unlike known syringes, cavity 16 does not have a valve pin arranged in a straight line with axis Y. Figure 2 The following details the system for regulating the flow of molten material through gate 98.

[0051] A gate member 32 in the form of a straight rod 34 is installed in the mold insert 20 or in the channel 30 connected to another plate of the mold insert. The straight rod has a free end 36 and an opposite end 38 connected to the actuating device 100. Figure 2 and Figure 3 An example of an actuation device is shown. The channel 30 and the gate member 32 preferably have complementary shapes.

[0052] The actuating device 100 is used to translate the gate component 32 along the axis Z, and the actuating device is in the form of an electric motor, preferably installed in the cavity surrounding the gate 98 of the mold insert 20.

[0053] The actuation device 100 includes an annular stator 110 fixed to the mold and an annular rotor 150 located inside the stator 110 for rotating about axis Y2.

[0054] A circular array of windings 112 is mounted on the stator 110, configured to generate a magnetic field with a polar axis radially relative to the axis Y2. A circular array of permanent magnets 152 is mounted on the rotor 150, the polar axis of which is radially relative to the axis Y2. The windings 112 and the permanent magnets 152 interact magnetically so that the magnetic field they generate causes the rotor 150 to rotate relative to the stator 110 about the axis Y2 in a known manner. Therefore, the rotor 150 can be rotated in a controlled manner about the axis Y2, which is preferably parallel to or even coincides with the axis Y.

[0055] The rotor 150 is connected to the gate component 32 to move it back and forth.

[0056] In a preferred variant, end 38 is engaged, for example, via a protruding pin 200 in a groove 160 formed in the periphery of rotor 150.

[0057] The groove 160 has a profile that follows an arc centered on the axis Y2, such as a helical arc or a circumferential arc, or a profile that follows a circumferential arc located on a plane orthogonal to the axis Y2 and having a center offset from the axis Y2. This profile is sufficient to act as a cam at the end 38 to convert the rotation of the rotor 150 into a linear translation of the gate member 32.

[0058] Then, by means of the electrically controlled winding 112, the rotor 150 can be rotated about the axis Y2, and thus the groove 160 is moved, thereby moving the end 36 and causing the gate member 32 to translate back and forth according to the rotation direction of the rotor 150.

[0059] The end 38 can then be pushed back and forth along the Z-axis, causing the gate member 32 to slide proportionally within the channel 30, thus causing the end 36 to protrude more or less into the channel of the gate 98. This protrusion determines the degree of closure of the gate 98.

[0060] The positions of winding 112 and permanent magnet 152 can be interchanged.

[0061] The rotor 150 can also operate more than one gate component at a time, for example, two opposing gate components that can move along the same axis Z. A corresponding number of grooves 160 can be provided.

[0062] However, by installing more actuators 100, more than two gate components can be moved simultaneously.

[0063] In these examples, the angle between axis Z and axis Y is a right angle, but not mandatory: it can be an acute or obtuse angle. In fact, the actuator 100 or axis Z can be oriented differently to obtain the tilt trajectory of the gate member 32. For example, three or more gate members 32 can be arranged to resemble the edges of a regular pyramid whose axis coincides with axis Y.

[0064] In order to block the stator relative to the mold plate in which the stator 110 is mounted, a key 290 can be used that is inserted into the peripheral notch 292 of the stator 110.

Claims

1. A shut-off valve for controlling the flow rate of molten material from the gate of an injector to a mold cavity, the shut-off valve comprising: • A channel for molten material extending along the first axis to the gate. • Gate component, which is installed as follows: -Able to move along the corresponding second axis, and - This allows the free end of the gate component to move toward and reach a point inside the channel to throttle and / or close the channel, thereby regulating the flow rate. • An actuating member, a portion of which is connected to the gate member, such that rotation of the actuating member causes the gate member to translate along the second axis from the point and / or toward the point. The actuating member includes: - An annular stator, which is fixed to the mold. - An annular rotor, rotatably positioned inside or outside the stator and connected to the gate component. -A first circular array of magnetic poles installed in the rotor - A second circular array of magnetic poles installed in the stator. The magnetic poles of the first circular array and the magnetic poles of the second circular array interact magnetically with each other to rotate the rotor relative to the stator by the magnetic field generated by them.

2. The shut-off valve according to claim 1, wherein, The stator is annular and configured to surround the rotor.

3. The shut-off valve according to claim 1 or 2, wherein, The rotor includes one or more grooves for connecting and controlling the corresponding gate components.

4. The shut-off valve according to claim 1, wherein, The magnetic poles of the stator are permanent magnets or electromagnets.

5. The shut-off valve according to claim 4, wherein, The permanent magnet or electromagnet is fixed to and / or placed on an annular cylindrical surface of the stator facing the interior of the stator.

6. The shut-off valve according to claim 1 or 2, wherein, The magnetic poles of the stator are windings configured to generate a radial magnetic field, the polar axis of which is oriented toward the center of the stator.

7. The shut-off valve according to claim 3, wherein, The magnetic poles of the stator are windings configured to generate a radial magnetic field, the polar axis of which is oriented toward the center of the stator.

8. The shut-off valve according to claim 1, wherein, The stator is fixed in the corresponding housing of the insert or plate of the mold.

9. The shut-off valve according to claim 1, wherein, The stator and the rotor extend around and around the first axis and / or the channel.

10. The shut-off valve according to claim 1, wherein, The rotor has a rotation axis parallel to the first axis; The gate component has the shape of a straight rod, the straight rod has a free end and the straight rod is connected to the actuating component at its opposite end.

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