“GUILLOTINE SHUT-OFF VALVE FOR INJECTION MOULDING”

Description

“Guillotine Shut-Off Valve for Injection Molding” in the name of INglass Spa with sole shareholder, with headquarters in S. Polo di Piave (TV) Designated Inventors: Massimo Rossi, Alessandro Dario DESCRIPTION 5 The invention relates to a guillotine shut-off valve for controlling a flow of molten material during injection molding. It is known to control the flow of molten material exiting a gate into a cavity. mold by means of a stem (pin or shutter) which is linearly movable back and forth with movement consistent with the flow of the molten material. The presence and movement 10 alternating of the stem however increases the disturbances on the flow creating accumulation zones and stagnation of the material, so much so that for example the operation of changing the color of the material injected requires multiple purge injections with significant waste of material. Oblique stems as in EP520345 have the defect of pushing the material against the internal surface of the canal, compressing it further until the exit. This effect 15 of crushing causes the appearance of defects on the final piece. To try to solve the problem, the stem shutter has been replaced by a slide valve placed at the material output gate. This solution, adopted for the simultaneous control of opening and closing of multiple injectors placed in line and controlled by a single actuator, is e.g. shown in EP1409222 (fig. 13). However, a single movable guillotine involves the 20 crushing of the material towards the perimeter of the gate orifice, which is located at a lower temperature, thus causing defects in the printed product. WO2024095073 shows a better solution, i.e. using a rotor to control the shutter elements. The WO2024095073 system can also be improved. Main object of the invention, defined in the attached claims where those 25 employees define advantageous variants, it is to improve this state of the art. A particular aim is to improve the actuation of the moving shutter parts. At least one purpose is achieved by a shut-off valve to control a flow of molten material exiting from an injector gate into a mold cavity, including: 30 • a channel, for the molten material, which extends along a first axis up to the gate, • a mounted shutter element - movably along a respective second axis (orthogonal or inclined at an angle acute or obtuse with respect to the first axis) and - so that a free end of the shutter element can move towards, and reach a point inside the canal to narrow and / or close the canal thus regulating the said flow, • an actuator element having a portion coupled to the shutter so that a rotation of the actuator element causes a translation of the shutter along the 5 second axis from and / or to said point, where the actuator element comprises  a fixed annular stator on the mold, and  an annular rotor (rotatably placed inside or outside the stator) and coupled to the shutter, 10  a first circular series of magnetic poles installed in the rotor,  a second circular series of magnetic poles installed in the stator, the magnetic poles of the first and second circular series being relative to each other magnetically interacting to rotate the rotor relative to the stator via a field magnetic generated by them. 15 Such an actuator element avoids complex rotor control mechanisms, such as a rack-and-pinion transmission to an external motor, which in turn requires a reduction mechanism within it. Thus, it simplifies the system, the kinematics is shortened, transverse holes in the mold and actuators are avoided placed outside the mold. 20 Furthermore, the molding system becomes simpler, takes up less space, there is greater precision in positioning and control of the shutter. And there is greater responsiveness thanks to the reduction of mechanical play, because the chain kinematics is shorter (fewer components), simple and direct. The stator preferably has a ring shape and surrounds the rotor, or is placed 25 immediately above or below the rotor. Preferably the rotor comprises a profile, e.g. one or more grooves or reliefs, for the coupling and control of the respective shutters, a solution which further makes compact drive system and avoid additional parts, shortening the chain kinematics. In particular, one end of the shutter element comprises a pin or 30 protruding part slidably inserted into a peripheral groove of the rotor, so that a rotation of the rotor causes a rotation of the groove from which a push on the pin that slides the shutter element. The position of the protruding part and the groove can also be exchanged. It is sufficient that this profile acts as a cam on the end of the element shutter to convert a rotation of the rotor into a linear translation of the element shutter. Preferably one or each shutter is translated via connection mechanical direct to the rotor. 5 In a preferred variant the magnetic poles of the stator are permanent magnets or electromagnets, preferably fixed and / or placed on an annular cylindrical surface of the stator and facing inside the stator. In a preferred variant the magnetic poles of the stator are configured windings to generate a radial magnetic field whose polar axis is directed towards the center of the 10 stator. These windings can receive electrical signals via fixed brushes. in the stator. The actuator element can behave like a brushed motor or like a stepper motor via a suitable control unit. In a preferred variant the stator is fixed in a corresponding seat of an insert or a mold plate. 15 In other variants, the components that make up the magnetic poles are swapped compared to what was said above, or are replaced by other technology. Preferably the actuator element is placed close to the gate. The drive system for the valve shutter elements is independent of the number and configuration of the shutter elements, which can advantageously 20 be more than one. In a preferred compact variant, the stator and rotor extend around (e.g. also surround) the first axis and / or the channel. In a preferred variant, the rotor has an axis of rotation that is parallel to the first axis, in particular for maximum compactness the rotating element has a rotation axis 25 coaxial to the first axis. In a preferred variant, the valve comprises two or more shutter elements whose respective second axes are coplanar and arranged • radially around the said point, or • like the diagonals of a polygon (regular or not), where the said point identifies the center 30 of the polygon. In a preferred variant, the valve comprises only two movable shutter elements along the sides of an angle with vertex at the said point, where the plane of the angle is orthogonal to the first axis or passing through the first axis. In the case of two or more shutter elements, this point becomes a common point of convergence, or closing point of the canal, for the translation of the obturator elements (and for the second axes). In a preferred variant, the valve comprises three or more shutter elements and respective second axes are arranged like the edges of an imaginary pyramid, called 5 convergence point forming the vertex of the pyramid. In a more preferred variant, this imaginary pyramid is arranged so that its base intersects the first axis and the channel, more specifically, is orthogonal to the first axis. In a preferred variant, which improves the performance of the injector, the valve comprises two or more shutter elements that are actuated by the rotor and mounted 10 movably along a respective second axis inclined at an acute angle with respect to the first axis and so that one free end of each shutter element can move and converge towards the same point of convergence within the channel, the free ends of the shutter elements can match at the 15 said convergence point to compose a blocking bulkhead for the molten material. In a preferred variant, the shutter element has the shape of a straight stem which at a one end is free and the opposite end is coupled to the actuator element. The advantages of the invention will be made even clearer by the following description of a preferred actuator, in which 20  Fig. 1 shows a sectional view of a shut-off valve;  Fig. 2 shows a three-dimensional view of valve components assembled at the implementation system;  Fig. 3 shows a three-dimensional view of the components of fig. 2 in exploded view. In the figure equal elements are indicated by equal numbers, and in order not to crowd the 25 drawings sometimes only some elements are numbered. Referring to figure 1, the end 18 of a known injector 10 used for inject molten material into a mold cavity 12. The injector 10 is usually mounted inside one or more plates 500 that make up the mold and which is fixed to a known molten material distribution manifold (the so-called manifold, also mounted 30 inside said plates 500, not shown). The injector 10 comprises and defines a cavity axial 16 which extends longitudinally along a central axis Y (which preferably it is also the polar symmetry axis for the injector 10). The end 18 of the injector 10 rests on a mold insert 20 having an orifice which determines a gate 98, and the molten material can flow in cavity 16 to gate 98. Overall, the construction of injector 10 is known, and there is no need to repeat it. Unlike the known injectors, there is no stem shutter in cavity 16 (valve pin) arranged in accordance with the Y axis. The system for regulating the flow of molten material passing through gate 98 is illustrated in detail in Fig. 2 and 5 following. In a tunnel 30 of the insert 20, or of another plate connected to it, a shutter 32 in the form of a straight stem 34 which has a free end 36 and the opposite end 38 is coupled to an actuator means 100, an example of which is shown in fig. 2 and 3. The tunnel 30 and the shutter 32 preferably have a shape 10 complementary. The actuator means 100 serves to translate the shutter 32 along a Z axis, and is in the shape of a motor, preferably installed in a cavity of the insert 20 around the gate 98. The actuator means 100 comprises an annular stator 110 fixed on the mold and a 15 annular rotor 150 placed inside the stator 110 so as to rotate around a Y2 axis. Mounted on the stator 110 is a circular array of windings 112 configured to generate a magnetic field with a polar axis that has a radial direction with respect to to the Y2 axis. A circular array of permanent magnets 152 is mounted on the rotor 150 with 20 polar axis which is radial to the Y2 axis. The 112 windings and the magnets permanent 152 are magnetically interacting to rotate - in a known way - the rotor 150 with respect to the stator 110 around the Y2 axis via a magnetic field from them generated. Therefore the rotor 150 can rotate in a controlled manner around the Y2 axis, which preferably it is parallel or even coincident with the Y-axis. 25 The rotor 150 is coupled to the shutter 32 to make it move back and forth. In a preferred variant the end 38 is engaged, e.g. by a pin protruding 200, in a groove 160 obtained in the peripheral edge of the rotor 150. The groove 160 has a profile that follows an arc, e.g. spiral or circumference, centered on the Y2 axis or a circular arc lying on an orthogonal plane 30 to the Y2 axis and has a center offset from the Y2 axis. It is sufficient that this profile acts as a cam on the end 38 to convert one rotation of the rotor 150 into one linear translation of the shutter 32. Then, by electrically controlling the windings 112, the rotor 150 can be rotated. around the Y2 axis and then move the groove 160, which moves the end 36 and causes the shutter 32 to move back and forth in the direction of rotation of the rotor 150. You can then push end 38 back and forth along the Z axis to get a proportional sliding of the shutter 32 inside the tunnel 30, followed by the greater or minor protrusion of the end 36 inside the gate channel 98. This protrusion 5 determines the degree of closure of gate 98. The position of the windings 112 and the permanent magnets 152 can be interchanged. The 150 rotor can also operate more than one shutter at a time, for example two opposing shutters that can move along the same Z axis. It is sufficient provide a respective number of grooves 160. 10 However, it is possible to move more than two shutters simultaneously by installing more actuators 100. In the examples the angle between the Z-axis and the Y-axis is right, but not necessarily: It could be sharp or blunt. In fact, it is sufficient to orient the means differently actuators 100 or the Z-axis to obtain inclined trajectories of a shutter 32. E.g. three or 15 plus 32 shutters could be arranged like the edges of a regular pyramid having axis coinciding with the Y axis. To lock the stator 110 with respect to the mold plate in which it is installed, it is possible to use a key 290 inserted into a perimeter notch 292 of the stator 110. * * *

Claims

CLAIMS 1. A shut-off valve for controlling a flow of molten material exiting an injector gate into a mold cavity, comprising: • a channel for the molten material extending along a first axis to the gate, • a shut-off element mounted - movably along a respective second axis and - so that a free end of the shut-off element can move to, and reach, a point within the channel to throttle and / or close the channel thereby regulating said flow, • an actuating element having a portion coupled to the shut-off element so that a rotation of the actuating element causes a translation of the shut-off element along the second axis to and / or to said point, where the actuating element comprises - an annular stator fixed on the mold, - an annular rotor rotatably located inside or outside the stator and coupled to the shut-off element, - a first circular set of magnetic poles installed in the rotor,- a second circular set of magnetic poles installed in the stator, the magnetic poles of the first and second circular sets being magnetically interacting with each other to rotate the rotor relative to the stator via a magnetic field generated by them.

2. A valve according to claim 1, wherein the stator is ring-shaped and structured to surround the rotor.

3. Valve according to any of the preceding claims, wherein the rotor comprises one or more grooves for coupling and controlling respective shutters.

4. Valve according to any of the preceding claims, wherein the magnetic poles of the stator are permanent magnets or electromagnets.

5. Valve according to claim 4, wherein the permanent magnets or electromagnets are fixed and / or placed on an annular cylindrical surface of the stator and facing towards the inside of the stator.

6. A valve according to any of claims 1 to 3, wherein the magnetic poles of the stator are windings configured to generate a radial magnetic field whose polar axis is directed towards the center of the stator. Eng. Massimiliano Citron (Registration 1215B) 7. A valve according to any of the preceding claims, wherein the stator is fixed in a corresponding seat of an insert or a mold plate.

8. A valve according to any preceding claim, wherein the stator and rotor extend around and surround the first axis and / or the channel. 5 9. A valve according to any preceding claim, wherein the rotor has an axis of rotation that is parallel to the first axis.

10. Valve according to any of the preceding claims, wherein the shutter element has the shape of a straight stem which has a free end and is coupled to the actuator element at the opposite end.