“GUILLOTINE SHUT-OFF VALVE FOR INJECTION MOULDING”

Description

“Guillotine Shut-Off Valve for Injection Molding” on behalf of INglass Spa 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 ones as in EP520345 have the defect of pushing the material against the surface inside the canal, compressing it further until the exit. This effect of 15 crushing causes the appearance of defects on the final piece. In an attempt to solve the problem, the stem shutter was replaced by a slide valve placed at the material exit gate. This solution, adopted for the simultaneous opening and closing control of multiple injectors placed in line and controlled by a single actuator, is shown for example in EP1409222 (fig. 13). 20 However, a single moving guillotine causes the material to be crushed towards the perimeter of the gate orifice, which is at a lower temperature, thus causing defect in the printed product. A better solution, as in EP1064138, is to use two opposing guillotines which have the closing point in the centre of the channel, because the temperature is higher there. 25 EP1064138 however provides two planar guillotines operated by a single actuator placed on the distant perimeter of the mold, with considerable complications in the movement and imprecise control of the position of the guillotines. Complex and The installation is also expensive, since the proximity of the guillotines to the gate (orifice of exit of the plastic material), and therefore to the cavity of the mould, requires small thicknesses of 30 containment of the same or very resistant and expensive materials. However, Despite the efforts, it remains impossible to eliminate the witness (small protuberance (cylindrical shape) that this solution leaves on the printed piece. Main object of the invention, defined in the attached claims where those employees define advantageous variants, is to improve this state of the art. A particular aim is to improve the actuation of the moving shutter parts. Another particular purpose is to improve the performance and / or characteristics of an injector (or nozzle) for injection molding. At least one purpose is achieved by a shut-off valve to control a flow 5 of molten material exiting from a gate into a mold cavity, the valve including: - a channel for the molten material extending along a first axis, - a shutter element having a first free end and movably mounted for move along a second axis so as to get closer to the first axis so that the first 10 free end can move and reach a point inside the channel to strangle the channel and limit said flow, - a mounted actuator element movable back and forth along a third axis, where the shutter element and the actuator element are coupled by a plane inclined configured to convert a linear displacement of the actuator element into 15 a displacement of the shutter element. The inclined plane allows for good contact between the actuator element and shutter element. The contact surface between the two can be increased, therefore the the pressure of the molten material is distributed over a larger area and the risk of damage these mutual contact surfaces. Reducing the risk of seizure or wear, 20 the possibility arises of using less performing and less hard, i.e. less expensive, materials. It is then possible to move the positioning point of the actuator element away from the critical area of ​​the mold, because the inclined plane allows freedom to position and relatively direct the actuator element and the shutter element. Furthermore, with such kinematics it is easy to compact the dimensions of the 25 system. In a preferred variant, said shutter movement is linear and / or curvilinear. In a preferred variant, the actuator element is configured to slide within a plane orthogonal to the first axis, or a plane passing through the first axis. In a preferred variant, the inclined plane is integral or integral with the element 30 actuator and / or shutter element. In a preferred variant, the second axis and the third axis are orthogonal to each other. In a preferred variant the second axis and the third axis identify a plane, and such plane is parallel or orthogonal to the first axis. In a preferred variant the inclined plane is a groove present in the element actuator and / or in the shutter element. In a preferred variant the actuator element and the shutter element comprise each a respective inclined plane, and such inclined planes are in sliding contact one with the other. 5 In a preferred variant the or each inclined plane develops along a direction between the second axis and the third axis. In a preferred variant the valve comprises two or more coupled shutter elements to a respective actuator element via an inclined plane, where each element shutter and each actuating element include one or more of the features 10 above defined, the two or more shutter elements being positioned to move along - the diagonals of an imaginary polygon, preferably regular, whose center is placed on the first axis; or - the same straight line, or 15 - the edges of a pyramid having as its base the said imaginary polygon and vertex on the first axis (as in WO2024095074). In a preferred variant the shutter element has the shape of a straight stem which has a free end and the opposite end is coupled to the actuator element. In a preferred variant the actuator element is movably installed inside a 20 cavities of a mold plate. In one variant, said opposite end includes a hole and is threaded into a lateral slot of the actuator element, the hole being crossed by a pin which protrudes from said opposite end in opposite directions with two heads, such heads being slidingly engaged in two linear grooves which are facing and obtained in the 25 body of the actuator element at the internal walls of the slot. The grooves develop along an axis that follows a bisector of the angle formed from the direction of advance of the shutter element and from the direction of advance of the actuator element. In a preferred variant, said opposite end has a slider protruding from the 30 profile of the shutter element, and the actuator element includes a slot which engages two sides and penetrates one edge transversally, the crack having two side walls substantially parallel to each other and a rear wall in correspondence of a T-shaped widening of the crack cross-section, the widening having a profile corresponding to that of the cursor, so as to form a track for the cursor. In a preferred variant, the valve comprises two or more actuator elements with respective shutter element, the actuator elements having axes of movement between them parallel and being connected solidly by a common connecting element mounted around the injector. Preferably the common connecting element 5 comprises a bracket or plate with a central hole into which the injector is inserted, and two or several actuator elements are connected on opposite ends of the bracket or plate. The advantages of the invention will be made even clearer by the following description of a preferred actuator, in which  Fig. 1 shows a cross-sectional diagram of an injector; 10  Fig. 2 and 3 show a plan view of a shut-off valve;  Fig. 4 shows a partial three-dimensional view of a drive for shut-off valve;  Fig. 5 shows a partial exploded three-dimensional view of the drive in fig. 4; 15  Fig. 6 shows a partial three-dimensional view of a second drive for shut-off valve;  Fig. 7 shows a partial exploded three-dimensional view of the drive in fig. 6;  Fig. 8 shows a cross-sectional diagram of a second injector; 20  Fig. 9 shows a partial three-dimensional view of a third drive for shut-off valve;  Fig. 10 shows a cross-sectional diagram of a third injector equipped with the system of fig. 9. In the figure equal elements are indicated by equal numbers, and in order not to crowd the 25 drawings sometimes only some numbers are reported. 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 mounted inside one or more 500 plates that make up the mold and is fixed to a known manifold of distribution of the molten material (the so-called manifold also mounted inside the 30 plates 500, not shown). The injector 10 comprises an innermost hollow body 14 which defines an axial cavity 16 that extends longitudinally along a central axis Y (which preferably is also of polar symmetry for the tip 10). The end 18 of the tip 10 rests on a mold insert 20 with an orifice that determines a gate 98, and the molten material can flow in cavity 16 up to gate 98. Overall, the 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). The system for regulating the flow of molten material passing through the gate 98 is illustrated in detail in fig. 2 and following. 5 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 is free at one end 36 and at the opposite end 38 is coupled to an actuator means, an example of which is shown in fig. 4 and 5. The tunnel 30 and the shutter 32 preferably have a shape complementary. 10 The end 38 is connected to an actuator element 44 (e.g. a shaft) which is movably installed inside a cavity 48 of the insert 20 close to the cavity 16, and is there translatable along an axis W. The end 38 includes a hole 50 and is inserted into a lateral slot 56 of element 44. The hole 50 is crossed by a pin 52 which protrudes from end 38 in opposite directions with two heads. These heads are slidable 15 engaged in two linear grooves 54 which are facing and obtained in the body of the actuator element 44 at the internal walls of the slot 56. The grooves 54 are accessible from the outside via the slot 56, and are developed along an axis S which, in plan as in fig. 2, follows a bisector of the angle formed from the Z-axis and the W-axis. 20 During a translation of the actuator element 44 along the axis W, orthogonal to a plane passing through the Y axis, the grooves 54 translate and push the heads of the pin 52 along the walls of the grooves 54. These walls act as an inclined plane for the pin 52, which is forced to slide in the grooves 54 along the axis S. This corresponds to a translation of the shutter 32 along the Z axis. 25 It follows that the grooves 54 convert a linear displacement of the element actuator 44 in a proportional linear displacement of the shutter 32. It can then push end 38 back and forth along the Z axis obtaining a proportional sliding of the shutter 32 inside the tunnel 30, which results in the greater or lesser protrusion of the end 36 inside the channel of the gate 98. This protrusion determines the 30 degree of closing of gate 98, from fully open (fig. 2) to fully closed (fig. 3). Intermediate positions are however possible. In the example shown the angle between the Z axis and the W axis is right, but not necessarily: it could be sharp or dull. Another example of actuation for the shutter 32 is shown in fig. 6 and 7. This time the end 38 has (fig. 7) a cursor 60 protruding from the profile of the stem 34, while a cooperating actuator element 70, homologous to the actuator element 44, has a slot 62 that engages two adjacent sides of the actuator element 70 and penetrates a corner transversely. The slot 62 has two side walls 63 5 substantially parallel to each other and a back wall 64 in correspondence with a T-shaped widening 66 of the slot section 62. Widening 66 has a profile corresponding to that of the cursor 60, so as to form a track for the cursor 60. Then the cursor 60 can slide linearly within (and along) the enlargement 66. The wall 64 is inclined with respect to the axis W like the grooves 54 and of a certain 10 angle, and the cursor 60 is inclined with respect to the Z axis by a complementary angle. The cursor 60 corresponds in function to the pin 52 and the enlargement 66 to the grooves 54. In particular, the wall 64 constitutes an inclined plane on which the cursor 60 can slide. Due to the geometry of the parts, a translation of the actuator element 70 results in a 15 translation of the shutter 32, along the Z axis, as explained in fig. 2 and 3. Fig. 8 shows another example of actuation for shutter 32. This time the element actuator 44 is mounted inside a cavity 72 that extends parallel to the cavity 16 and is movable back and forth along a W axis parallel to the Y axis. The operation with respect to the shutter 32 of fig. 1 is the same. 20 Fig. 9 Illustrates a variant of the system that allows more than one shutter to be moved at a time, in the example two 32-inch shutters facing each other that can move along a same line. However, it is possible to move more than two objects simultaneously. shutters replicating the mechanisms. Each shutter 32 is controlled in position by a respective actuator element 44 25 and related kinematic chain, as described in fig. 4 and 5. The two actuator elements 44 have parallel W axes and are connected solidly by and to a bracket 80. Moving By moving the bracket 80 back and forth, the two shutters 32 move simultaneously. by moving its ends 36 closer or further apart at gate 98. Fig. 10 illustrates an example to implement the system of fig. 9 together 30 to injector 10. The bracket 80 is mounted around the injector 10, where the body 14 is inserted into a hole central 82 of the bracket 80. The axes W of the two actuator elements 44 are parallel to the Y-axis (but in other variants they may not be). * * *

Claims

CLAIMS 1. A gate valve for controlling a flow of molten material exiting a gate into a mold cavity, the valve comprising: - a channel for the molten material extending along a first axis to the gate, - a gate element having a first free end and being movably mounted to move along a second axis so as to approach the first axis so that the first free end can move and reach a point within the channel to restrict the channel and limit said flow, - an actuator mounted to move back and forth along a third axis, the gate element and the actuator element being coupled via an inclined plane configured to convert a linear displacement of the actuator element into a displacement of the gate element.

2. Valve according to claim 1, wherein said displacement of the shutter element is linear and / or curvilinear.

3. A valve according to any preceding claim, wherein the actuator element is configured to slide within a plane orthogonal to the first axis, or a plane passing through the first axis.

4. Valve according to any preceding claim, wherein the inclined plane is integral with or integral with the actuator element and / or the shutter element.

5. Valve according to any preceding claim, wherein the second axis and the third axis are orthogonal to each other.

6. A valve according to any preceding claim, wherein the second axis and the third axis define a plane, and such plane is parallel or orthogonal to the first axis.

7. A valve according to any preceding claim, wherein the inclined plane is a groove in the actuator element and / or in the shutter element.

8. A valve according to any preceding claim, wherein the actuator element and the shutter element each comprise a respective inclined plane, and such inclined planes are in sliding contact with each other.

9. A valve according to any preceding claim, wherein the or each inclined plane extends along a direction between the second axis and the third axis.

10. Valve according to any preceding claim, comprising two or more actuator elements with a respective shutter element, the actuator elements having parallel displacement axes and being integrally connected by a common connecting element mounted around an injector in which said channel is present.