JP2005519793A - Nozzle gate valve for molding - Google Patents

Abstract

A novel nozzle for controlling the flow of a molding material is provided.
A molding nozzle (10) controls the flow of material from a source of plastic melt to an outlet communicating with a gate (30) to a mold cavity (12). The nozzle (10) houses a valve pin (38) having a guide section (40) and a valve section (42) and is advanced and retracted relative to the gate (30) to selectively open and close the gate (30). I can exercise. The valve pin (38) is a guide surface on the vane (62) that extends inwardly in the nozzle (10) such that the guide surface (64) engages the guide section (40) of the valve pin (38). 64) is guided to exercise. The valve end (42) of the valve pin (38) has a smaller diameter than the diameter of the guide section (40), so that the valve section (42) is capable of forming a flow line in the molded part. Freely float to allow an annular flow within the guide surface area to minimize performance.

Description

  The present invention relates to an injection molding nozzle incorporating a valve member to control the flow of molding material into a mold cavity. In particular, the invention relates to an injection generating nozzle having a guide sleeve with inwardly extending vanes for guiding the pin when the axially movable valve pin is properly aligned with the gate.

  Plastic injection molds often have a flow shut-off valve at the outlet end of the hot water runner to shut off the flow of molding material between successive injection phases of the machine cycle. The melt flow path begins within the plasticizing barrel of the injection molding machine and ends with a “gate” into the interior of the mold cavity. A pin-type valve member is often provided in the outlet nozzle adjacent to the gate to control the flow of molten plastic from the nozzle through the gate and into the mold cavity. In particular, a portion of the valve pin is movable into the gate to close the gate after filling the mold cavity to block any further flow of molten material through the gate.

  Various arrangements have been proposed for guiding the valve pin within the nozzle in order to properly align the pin with the gate and prevent the pin from causing damage to the outer end of the valve pin itself or the gate. . In runnerless mold constructions where the gate provides direct communication between the mold cavity and the injection nozzle, the valve pin is such that the end of the valve pin becomes part of the mold cavity surface and defines it. Enter the gate and close the gate.

  Previous valve pin guide arrangements are often located in the material flow path, and the incoming flow of molten plastic material is usually recombined into several independent streams that are recombined at a downstream point immediately adjacent to the gate. It had support elements that helped to break it up. As a result, the related molded parts often have areas that are not intermixable enough to allow independent streams of plastic to combine before entering the mold cavity to form a homogeneous stream of melt. Shows a disturbing flow line to give. For example, in US Pat. No. 5,700,499 (Patent Document 1 below) entitled “Valve Member Positioning Insert for Injection Molding Nozzle” issued December 23, 1997, an outer sleeve is disclosed. And a valve pin guide having a concentric inner sleeve, the inner sleeve being supported by radial connecting vanes extending from the outer sleeve to the inner sleeve. In that configuration, the plastic streams must be separated and combined downstream of the insert.

Another known valve pin guide for splitting a melt flow stream is U.S. Pat. No. 5, issued December 15, 1998 entitled "Injection molding apparatus with a one-part gate insert for positioning a cylindrical valve member". , 849,343 (the following Patent Document 2). The guide member disclosed in this patent specification has a flow passage that tapers from an inlet to a narrower outlet that defines a gate. Several axially extending vanes are located in the passage, these vanes extend from the inlet of the insert to the outlet of the insert, define a gate and lead to a mold cavity that leads to a flow line in the molded part Prevent recombination of several flow streams until
US Pat. No. 5,700,499 US Pat. No. 5,849,343

  A guide arrangement that avoids the formation of such flow lines while maintaining proper pin alignment because the flow lines in the molded part are disturbing in that they detract from the desired uniform surface appearance of the part. It is desirable to provide Accordingly, it is an object of the present invention to provide an injection molded nozzle with a valve pin guide that overcomes the disadvantages of prior devices and allows the formation of parts that are substantially free of flow lines.

  Briefly, according to one aspect of the present invention, a nozzle is provided that controls the flow of molding material from a melting source to an outlet in communication with a gate that provides an entry point into the mold cavity. The nozzle includes a nozzle body having a material inlet, a material outlet, and radially inwardly extending guide vanes with a guide surface. The valve pin is located within the nozzle body and can move axially so that the end of the valve can engage the gate to selectively open and close the gate. More specifically, the valve pin is in a retracted position such that the valve pin is spaced from the gate to allow material flow through the nozzle, and an extended position in which the valve pin closes the gate and blocks material flow. In the nozzle body. The valve pin has a cylindrical guide section that has an outer diameter that allows engagement between the guide section and the guide surfaces of the guide vanes in the nozzle body. The cylindrical pin section of the valve pin is axially aligned with the guide section and has a foremost end with a cross-section corresponding to the cross-section of the gate, so that the valve section has a closing valve for the gate. Define.

  In accordance with another aspect of the present invention, for guiding a gate valve closure pin within a tubular nozzle body between an open position and a closed position to selectively permit and block material flow through the gate. A method is provided. The method includes moving the valve pin axially from the retracted position to the first internal position toward the gate without contact between the valve pin and the inwardly extending guide surface associated with the nozzle body. The valve pin is then engaged with a guide surface in the nozzle to reliably guide the valve pin as it continues to move axially toward the gate. In particular, the valve pin is guided by the engagement between the periphery of the valve pin and the guide surface of the nozzle body. When the valve pin is guided to engage the front end of the valve pin with the gate, the gate is eventually closed, blocking the flow of material.

Referring now to the drawings and in particular to FIG. 1, a nozzle 10 is shown through which a molten plastic material rotates a plasticizing screw to convert solid plastic particles or pellets into a flowable plastic melt. It flows into mold cavity 12 from a source (not shown) such as a conventional injection molding machine plasticizing apparatus having an elongated heated barrel freely received therein. The nozzle 10 has a tubular nozzle body 14 that includes a melt channel 16 from which molten plastic material is introduced into the channel from a melt source. The downstream end of the nozzle body 14 has an axially extending bore 20 for receiving a tubular nozzle tip 22. An outlet opening 24 is provided in the nozzle tip 22 through which the molten material enters the mold cavity 12 and eventually fills the cavity.
Nozzle tip 22 is in contact engagement with a first mold half 26 having a circular opening 28 that defines an entrance to a cylindrical gate 30, which gate is connected to melt channel 16 and mold cavity 12 of nozzle 10. Allow communication between. The nozzle outlet opening 24 is axially aligned with the opening 28 and the gate 30. The second mold half 32 abuts the first mold half 26 and the mold cavity 12 is defined between the mold halves 26, 32. Mold cavity 12 allows molten plastic to flow through gate 30 into mold cavity 12 to fill the cavity and form a molded part upon cooling of the molten plastic in the mold cavity as is known in the art. Located in the second mold half 32 to allow communication with the gate 30.
As shown in FIG. 1, the first mold half 26 has a recess 34 for receiving the nozzle 10 therein. A heater 36 surrounding the nozzle body 14 supplies heat to the nozzle body 14 to maintain the plastic melt at a desired temperature when the plastic melt enters the mold cavity 12. Although illustrated as a band heater, other types of heating elements can be used as will be appreciated by those skilled in the art.
The nozzle 10 has a valve pin 38 that is axially positioned within the melt channel 16 and moves axially to control the flow of molten material into and through the gate 30. Can do. The valve pin 38 is cylindrical with a diameter smaller than the outer diameter of the melt channel 16 to define an annular passage for conveying the flow of plastic melt along the valve pin 38 and into the nozzle tip 22. The guide section 40 is included. At its downstream end, the valve pin 38 is also cylindrical and has a valve section 42 that is coaxial with the guide section 40. The valve section 42 has an outer diameter that is smaller than the diameter of the guide section 40 and terminates at the foremost end 43. In this regard, the outer diameter of the valve section 42 substantially corresponds to the diameter of the opening 28 and the gate 30, so that the valve section 42 advances into the opening 28 when the valve pin 38 is fully extended forward with respect to the nozzle tip 22. To close the gate 30. When the valve pin 38 is in its retracted position, ie, the part shown in FIG. 1, the gate 30 opens and molten plastic flows from the melt channel 16 into the opening 28 and through the gate 30 into the mold cavity 12. Can do.
The valve pin 38 can be actuated to move axially within the nozzle body 14 by a suitable actuating mechanism (not shown) to move the valve pin back and forth relative to the opening 28. Known actuation mechanisms for such valve pins have a piston carried adjacent the upstream end of the valve pin 38 for movement within the cylinder for hydraulic or pneumatic actuation. Other valve pin actuation configurations may be of mechanical nature such as rack gear connected to the valve pin 38 that engages the rack and rotatable pinion gear for axial movement of the valve pin 38. it can.
The guide sleeve 44 carried in the nozzle tip 22 also has a generally tubular shape. The nozzle tip 22 has a first inner counterbore 46 defining a first inner step 48 with respect to the nozzle outlet 24 and a second inner step 52 defining a second inner step 52 with respect to the first counterbore 46. And an inner counter bore 50. The second inner step 52 is axially spaced upstream from the first inner step 48 to define a stepped container carrying the guide sleeve 44 therein. The guide sleeve 44 has a downstream end 54 that is received within the inner counterbore 46 and abuts the first inner step 48. The enlarged upstream end 56 of the guide sleeve 44 is received in the outer counterbore 50 and has an outer step 58 that abuts the second inner step 52. An annular seal member 60 is provided in the outer counterbore 50 between the upstream end 56 of the guide sleeve 44 and the nozzle body 14 to provide a seal, so that the molten plastic passes from the melt channel 16 to the guide sleeve 44. And then through the nozzle outlet 24.
The inner diameter of the guide sleeve 44 includes a plurality of radially inwardly extending guide vanes 62, each vane having an innermost guide surface 64 extending axially inwardly toward the central axis of the sleeve 44. As shown in FIGS. 1 and 2, four such guide vanes 62 can be provided. However, as few as three guide vanes 62 are sufficient for the guide function described later. The guide surface 64 of each guide vane 62 is defined by an arc, and each arc of the guide surface 64 lies on a virtual circle having a diameter that is only slightly larger than the diameter of the guide section 40 of the valve pin 38. When the valve pin 38 is pulled back with respect to the nozzle tip 22 as shown in FIGS. 1 and 2, the outer surface of the valve section 42 of the valve pin 38 is in the guide sleeve 44 but is spaced inward of the guide surface 64.
The guide vanes 62 as shown in FIGS. 1 and 2 extend axially with respect to the longitudinal axis of the guide sleeve 44 to facilitate centering of the valve pin 38 when the guide section 40 moves axially into the sleeve 44. It has an inclined inlet surface 66. The inlet surface 66 may have a V-shaped cross section to allow a smooth flow of molten plastic material as the molten plastic material flows through the guide sleeve 44. The downstream end 68 of the guide vanes 62 also allows for a smooth recombination of the portions of material flowing between the guide vanes as the plastic melt flows along the guide vanes 62 toward the nozzle outlet 24. It can be tapered with a V-shaped cross section. FIG. 3 shows the guide surface 64, the inlet surface 66 and the downstream end 68 of the guide vane 62.
In order to allow smooth centering of the guide section 40 of the valve pin 38 as it enters the guide sleeve 44, the valve pin 38 has a frustoconical transition section 70 between the guide section 40 and the valve section 42. The inclination angle of the transition section 70 with respect to the longitudinal axis of the valve pin can advantageously be approximately the same as the inlet surface inclination angle. Further, the valve pin 38 is connected at its upstream end to an actuator (not shown) that moves the valve pin 38 in the axial direction in the nozzle body 14, and the downstream end of the valve pin 38 is As shown in FIG. 1, it is not supported in the retracted position.
In operation, molten plastic material is introduced into the melt channel 16 in the nozzle 10 and flows downstream toward the nozzle tip 22 and nozzle outlet 24. In this regard, the melt channel 16 is an annular channel defined between the inner surface of the tubular nozzle body 14 and the outer surface of the cylindrical valve pin 38. The flow of plastic melt enters the guide sleeve 44, passes over and around the guide vanes 62, and passes around the valve section 42 of the valve pin 38. As is apparent, the central inner portion of the melt flow stream is maintained in an annular shape as this stream flows between the guide surface 64 of the guide vane 62 and the outer surface of the valve section 42 of the valve pin 38. The The remaining outermost portion of the flow stream adjacent to the inner surface of the nozzle body 14 flows into the space between adjacent guide vanes 62 while remaining connected to the annular flow stream of the central inner portion. Thus, in the structure disclosed herein, the melt stream is not divided into several independent discontinuous flow streams that must be recombined later, but into a single continuous flow stream.
The molten material flows along the valve section 42 of the pin 38, passes through the foremost end 43, adjacent the opening 28, between the outer end of the nozzle tip 22 and the recess 34 of the first mold half 26. It flows into the gap 72. The material travels through the opening 28 and proceeds into the gate 30 and then into the mold cavity 12. When the mold cavity 12 has been filled, the valve pin 38 moves axially toward the mold cavity 12, causing the foremost end 43 of the valve section 42 to enter the opening 28, thereby causing the gate 30 to move. Close to block further flow of molten material into the mold cavity. The movement of the valve pin 38 ends when the surface at the foremost end 43 is flush with the associated mold cavity surface. The material in the mold cavity is then cooled and this cooling is accelerated by providing cooling elements (not shown) in the mold halves 26, 32 adjacent to the mold cavity 12. When the molded part has been sufficiently cooled, the mold is opened by separating the mold halves 26, 32 and the part is removed from the mold cavity 12. The mold halves 26, 32 can be moved back into contact and the molding cycle can be repeated.
1 and 2 show the present invention with the valve pin 38 in its retracted position and the plastic melt can freely flow through the nozzle body 14, nozzle tip 22 and nozzle outlet 24 into the opening 28. Show. As the valve pin 38 moves from its retracted position toward its extended position, the valve pin 38 is substantially centered within the nozzle body 14 by the flowing molten plastic material.
As the valve pin 38 moves toward the mold cavity 12 during its extension stroke, the transition section 70 enters the guide sleeve 44 as shown in FIGS. When the valve pin 38 is somewhat eccentric, contact of the transition section 70 with the inlet surface 66 of the guide vane 62 causes centering of the valve pin 38 within the sleeve 44. The additional axial movement of the valve pin 38 toward the opening 28 causes the valve pin guide section 40 to be received between and contact the innermost guide surfaces 64 of the respective guide vanes 62, which It serves to guide the valve pin 38 axially with respect to the nozzle tip 22 so that the foremost end 43 is axially aligned with the opening 28.
When the valve pin 38 is further extended toward the opening 28, the foremost end 43 of the valve section 42 enters the opening 28. The movement of the valve pin 38 continues until the valve pin completely fills the gate 30 and the end face of the foremost end 43 is flush with the adjacent surface of the mold cavity 12 in the position shown in FIGS. As is apparent from FIG. 7, there is continuous and uninterrupted communication between the molten material in the gap 72 and the molten material in the upstream portion of the melt channel 16. As a result, when the valve section 42 closes the opening 28 and enters the gate 30, any molten material extruded by the downward movement of the guide section 40 of the valve pin 38 may flow upstream toward the molten material source. There is no undue compression that could cause possible leakage between the respective parts defining the melt flow channel 16.
Although illustrated and described based on the guide vanes 62 extending in a direction parallel to the longitudinal axis of the nozzle, the orientation of the guide vanes can be varied if desired. As an alternative, the guide vanes can be oriented in the guide sleeve such that the guide vanes are inclined with respect to the axis of the guide sleeve, as shown in FIG. In this regard, the guide sleeve 74 has a tubular shape similar to the guide sleeve 44 shown in FIGS. However, each guide vane 76 is similarly shaped and similarly oriented so as to be inclined with respect to the axis of the sleeve 74. As a result, the guide vanes 76 provide a vortex effect in the plastic melt flow stream, which serves to assist in the mixing of the material as it passes through the vanes 76, and thereby within the molded part. Further minimize the possibility of forming flow lines. The angle of inclination of the guide vane 76 relative to the axis of the guide sleeve 74 can be on the order of about 10 ° to about 60 °. To further optimize performance, the width of the vane 76 can be increased, as shown, and a radius can be provided where the vane 76 is attached to the sleeve 74.

  Those skilled in the art will appreciate that the nozzle and nozzle valve structures shown and described herein provide distinct advantages over previously used structures. The structure according to the invention described here is believed to minimize the formation of flow lines in the molded part. The reason is due to the integrity of the flowing material as it passes through the nozzle, and when the inner guide vanes in the guide sleeve terminate at a point sufficiently upstream of the nozzle outlet and the flow stream enters the nozzle outlet passage. This is because it allows a sufficient distance to return the flow stream to its purely annular shape. Further, when the valve is in its fully open state as shown in FIG. 1, the foremost end of the valve pin will be reiterated, minimizing the possibility of flow lines in the molded part. In order to achieve this, the flow stream is separated from the gate by a distance sufficient to allow the flow stream to transition from an annular shape to a cylindrical shape having a circular cross section before entering the gate.

  While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the inventive concept. Accordingly, all such claims and modifications falling within the spirit of the invention are intended to be covered by the following claims.

1 is a schematic longitudinal sectional view showing a configuration of an injection-molded high-temperature runner gate valve according to the present invention. It is sectional drawing in the 2-2 line of FIG. It is a front view of the guide surface carry | supported by the guide blade provided in the guide sleeve which concerns on this invention. FIG. 2 is a cross-sectional view similar to FIG. 1, showing the position of the valve pin relative to the gate when the guide segment of the valve pin engages the guide surface of the guide sleeve. FIG. 5 is a cross-sectional view taken along line 5-5 in FIG. FIG. 5 is a cross-sectional view similar to FIG. 4 showing the components at their relative positions when the valve pin has fully extended so that the foremost end of the valve pin is received into the gate to close the gate. It is. It is sectional drawing in the 7-7 line | wire of FIG. FIG. 6 is a cross-sectional view of another embodiment of a guide sleeve according to the present invention in which the guide sleeve has guide vanes that are inclined to vortex the molten material.

Claims (15)

In a nozzle (10) for controlling the flow of molding material from the source chamber to the outlet communicating with the gate (30) to the mold cavity (12),
Nozzle body having at least two radially inwardly directed guide vanes (62) with a material inlet and a material outlet and having an innermost guide surface (64) located on a virtual circle having a first diameter (14) and;
A valve pin (38) positioned in the nozzle body (14) for axial movement and having an end (43), the end of the valve pin (38) being connected to the gate (30). A pull-back position spaced from the gate (30) to allow flow of material through) and the end (43) of the valve pin (38) to block flow through the gate (30). Sized to be accommodated within the gate (30) such that it can move within the nozzle body between an extended position located within the gate (30) and blocking flow through the gate; A cylindrical guide segment having an outer diameter slightly smaller than the first diameter so that the valve pin (38) allows sliding movement of the guide segment (40) along the guide surface (64). (40) and align with the guide section in the axial direction. A cylindrical valve section (42) connected thereto, the valve section (42) having a diameter smaller than the first diameter, corresponding to the cross section of the gate (30). A valve pin such as having a foremost end (43) defining a closing valve for the gate (30);
Nozzle characterized by having.   The tubular guide sleeve (44) carried in the nozzle body (14), wherein the guide vane (62) is carried by the guide sleeve (44). Nozzle (10).   The nozzle (10) according to claim 1, wherein the downstream end (68) of the guide surface (64) terminates in an axial position spaced from the gate (30).   The upstream end (66) of the guide surface (64) is such that the guide section (40) of the valve pin (38) is in the guide surface (64) when the valve pin (38) is in its retracted position. ) Axially spaced from the upstream end (66) and the valve section (42) of the valve pin (38) allows an annular flow of material through the nozzle (10). The terminal end (43) of the valve pin (38) terminates in an axial position such that it is unguided and is free to float with respect to the guide surface (64). The nozzle (10) of claim 1.   The upstream end (66) of the guide surface (64) is located on the side of the guide surface (64) during the closing stroke of the valve pin (38) when the guide section (40) of the valve pin (38) is closed. The valve pin (38) terminates in an engaged position such that it disengages from the gate (30) when first contacted with the end (66), the guide surface (64) When the valve section (42) moves from a guide surface engagement point to a position such that the valve section (42) engages the gate (40) to block the flow of material through the gate (30), the guide surface The nozzle (10) according to claim 1, characterized in that it extends in the axial direction by a distance sufficient to maintain the engagement between (64) and said guiding section (40).   The nozzle (10) according to claim 1, characterized in that the cross-sectional flow area along the axial extent of the guide surface (64) in the nozzle body (14) is a uniform flow area.   The guide sleeve (44) has a plurality of radially inwardly extending guide vanes (62) that are uniformly spaced circumferentially from one another and extend axially with respect to the nozzle body (14). The nozzle (10) according to claim 2.   The guide vanes (62) are circumferentially spaced apart from each other and extend in a helical direction with respect to the longitudinal axis of the nozzle so as to impart a vortex component of motion to the material flowing through the sleeve (44); 3. Nozzle (10) according to claim 2, characterized in that   The nozzle (10) of claim 8, wherein the guide vanes (62) extend at an angle of about 10 ° to about 60 ° with respect to the longitudinal axis of the nozzle body (14).   The nozzle (10) according to claim 1, wherein the guide surface (64) is defined by an arc having its center located on the longitudinal axis of the nozzle body (14).   A nozzle (10) according to claim 2, characterized in that the guide surface (64) is defined by an arc having its center located on the longitudinal axis of the guide sleeve (44).   The nozzle (10) according to claim 1, wherein the guide surface (64) has an axially tapered leading edge (66).   The nozzle (10) according to claim 1, characterized in that the guide surface (64) has an axially tapered trailing edge (68).   13. A nozzle (10) according to claim 12, wherein the guide surface (64) has an axially tapered trailing edge (68). In a method of guiding a gate valve closure pin within a tubular nozzle body (14) between an open position and a closed position to selectively permit and block material flow through the gate (30),
Providing a stepped cylindrical valve pin (38) having a guide section (40) and a valve end (42) having a diameter smaller than the diameter of the guide section (40);
When the valve pin (38) is in a retracted position with respect to the gate (30) to allow passage of material through the gate (30), the valve pin with respect to the nozzle body within the nozzle body (14). Allowing the valve end (42) of (38) to be free floating;
A first axial position from the retracted position toward the gate (30) without contact of the valve pin (38) with an inwardly extending guide surface (64) carried on the nozzle body (14). Moving the valve pin (38) axially by a first distance up to;
A guide surface (64) carried on the nozzle body (14) for reliable guidance of the valve pin as the valve pin (38) continues to move axially toward the gate (30). Engaging the guide segment (40) of the valve pin (38) with respect to
When the valve end (42) of the valve pin (38) approaches the gate (30), the valve pin (38) is in contact with the guide surface (64) carried on the nozzle body (14). Guiding the valve pin (38) by engagement of the guide section (40);
With the guide section (40) of the valve pin (38) guided by the guide surface (64), the valve end (42) of the valve pin (38) is blocked to prevent material flow. Closing the gate (30) by inserting it into the gate (30);
A method characterized by comprising:

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