JPWO2020025338A5 - - Google Patents

Description

The present invention relates to ultrasonic devices for polymer (eg thermoplastic polymer) extrusion devices. Ultrasonic devices act on molten or resoftened polymer (with or without additives) to improve the properties and quality of the resulting product.

Ultrasonic devices are well known in the polymer melting and fluidizing industry and include an ultrasonic transducer that produces ultrasonic vibrations and an ultrasonic head that propagates the vibrations.

It is known to insert the tip of an ultrasound device into a chamber. This configuration places the molten polymer in compression and allows the ultrasonic device to contact the molten polymer. Feeding the polymer into the chamber is done by an extrusion device with a helical conveyor. This helical conveyor compresses and melts the polymer and forces it into a chamber from which it is extruded through an exit opening. US Pat. No. 6,200,000 discloses a solution /device of this kind.

In this type of device, the tip of the ultrasound device (tip with respect to the ultrasound transducer) is inserted into the chamber through a sonotrode receiving bore. To prevent molten polymer from escaping from the sonotrode housing bore, a ring seal is placed holding it around the cross-section of the ultrasonic head. In order to reduce interference of the ring seal with vibration of the ultrasonic head, the ring seal is mounted in a nodal plane where the vibration amplitude of the ultrasonic head is zero at its root.
US6528554B1 EP1536936B1 US6036467A International Publication Pamphlet No. 2004/024415

The ring seal may or may not be circular. Often the ring seal radially retains the ultrasonic head. Therefore, if the ring seal covers the adjacent area of the nodal plane (where the vibration amplitude is not zero) in order to increase the contact surface between the ring seal and the ultrasonic head, the wear of the ring seal will increase. cause. US Pat. No. 6,300,002 discloses a solution of this kind.

According to another alternative solution, the ultrasonic head has a flange-shaped annular projection surrounding the nodal plane where the vibration amplitude is zero . Ring seals are placed above and below the flange to hold it and achieve a tight seal. US Pat. No. 6,300,005 discloses a solution of this kind.

However, said flange has a certain thickness and thus has an upper surface and a lower surface. A ring seal is mounted there, but it is adjacent to the nodal plane rather than coplanar with it. Therefore, the amplitude of vibration in these two planes is not zero, but there is some vibration, albeit small, that degrades the ring over time. Moreover, the manufacture of the ultrasonic head with said flange is complicated and expensive.

US Pat. No. 5,300,000 discloses a sonotrode device. A sealing flange located on the sonotrode is secured around the nodal plane of the sonotrode to prevent leakage of the polymer around the ultrasonic head.

The present invention relates to ultrasonic devices for extruders of molten or resoftened polymers (with or without additives).

An ultrasonic device is a device having an ultrasonic transducer which vibrates an ultrasonic head which is placed in contact with the molten polymer and which is extruded by means of an extrusion device. The vibrational and thermal effects generated by said vibrations alter the physico-chemical properties of the polymer.

A polymer extruder is a device that melts, mixes and feeds a polymer to an extrusion outlet. It is known in devices of this type to have an ultrasonic device in contact with the molten polymer, particularly at the root of the extrusion exit bore. As a result, the polymer is treated with an ultrasonic device before being extruded out of the extruder. Alternatively, the ultrasonic device can be positioned elsewhere along the extrusion device.

The ultrasonic device of the present invention has the following chamber, ultrasonic head and ring seal.
* The chamber has an inlet bore for compressed molten polymer, an outlet bore for compressed molten polymer, and a sonotrode containment bore. The chamber can be connected to or integrally formed with a polymer extrusion device that supplies compressed molten polymer to the inlet bore.
*The ultrasonic head has a sonotrode. The ultrasonic head has a tip and a root separated by a first nodal plane where the vibration amplitude is zero . The tip consists entirely of the sonotrode and is inserted projecting into the chamber through the sonotrode receiving bore. The tip maintains contact with the compressed molten polymer in the chamber. The root comprises a second nodal plane, at least partially formed by the sonotrode, outside the chamber, maintained in contact with the ultrasonic transducer, and having a zero vibration amplitude . The second nodal surface is in a parallel state away from the first nodal surface.
* The ring seal contacts the ultrasonic head at the first nodal plane and is configured to seal the sonotrode receiving bore of the chamber containing the compressed molten polymer.

Ring seals may be circular or other closed shapes.

A polymer extrusion device compresses and extrudes molten polymer into a chamber through an inlet bore. The chamber is thus filled with compressed molten polymer, which is extruded through the exit bore. The chamber is located behind or integral with the extrusion device. Said chamber is located between two parts of the extrusion device or traverses a portion of the extrusion device.

The ultrasonic device alters the properties of the polymer before it is extruded, homogenizing the texture of the polymer so that no pellets or unmelted particles are present, and dispersing additives within the molten polymer. improve the mixing conditions of various types of polymers, increase productivity, reduce polymer degradation, and reduce energy consumption of production machinery.

The ultrasonic device has an ultrasonic transducer that contacts the ultrasonic head to generate ultrasonic vibrations. This ultrasonic head transmits vibrations to an internal part that protrudes into the chamber. The chamber is in contact with the polymer.

Polymer extrusion equipment typically has an inlet for pelletized or powdered material at the end of a cylindrical melt chamber. This chamber has a spindle. In this type of device, rotation of the spindle compresses, transports, kneads and mixes the polymer with additives (if any). A heater may be included to raise the temperature of the polymer and allow it to melt. A molten polymer stream is introduced into the chamber through the inlet bore and processed. The chamber contains the tip portion of the ultrasound system. Said chamber is located at the end of the cylindrical melting chamber of the extruder or in the middle part thereof. As a result, the spindle can pass through the chamber of the ultrasound system.

The molten polymer passes through the chamber of the ultrasonicator and exits through the exit bore. It is driven by pressure applied to the extrusion device. This polymer is then directed to a forming die where the polymer is extruded into the desired shape.

When the ultrasonic device chamber is connected to the end of the extrusion device, the forming die is placed in the exit bore of the chamber. Conversely, if the chamber of the ultrasonic device is incorporated in the middle part of the extruder, the polymer is transferred from the chamber with the extruder. The extruder directs the polymer to an extruder outlet that is connected to a shaping die.

The ultrasonic head is divided into a tip part and a root part. The tip is contained within the chamber and the root is outside the chamber. The entire ultrasound system is subjected to ultrasonic vibrations in the form of stationary waves.

Within an object exposed to ultrasonic vibrations in the form of a standing wave, one or more planes are created in which the vibration amplitude is zero. These planes are known as nodal.

Between the tip and root there is a first nodal plane where the vibration amplitude is zero . The root of the ultrasonic head has a second nodal plane where the vibration amplitude is zero . This second nodal plane is parallel to and spaced from the first nodal plane.

In this device, the tip of the ultrasonic device is in the chamber in contact with the compressed molten polymer. A ring seal is placed around the ultrasonic head coincident with the first nodal plane (the plane where the vibration amplitude is zero ) to prevent molten polymer from escaping through the sonotrode housing bore instead of the exit bore. . This prevents the ring seal from interfering with the vibration of the ultrasonic head and avoids wear of the ring seal due to vibration.

The ultrasonic device of the present invention proposes the following novel features.
* The first nodal surface is coplanar with the first annular surface of the ultrasonic head on which the annular surface of the ring seal lies parallel.
* The second nodal plane is coplanar with or close to the second annular plane of the ultrasonic head. The second annular surface is parallel to the first annular surface. The fixation device contacts or rests on the second annular surface.
*Furthermore, the ultrasound device of the present invention includes a pressure device. The pressurizing device includes the locking device and applies pressure in a direction perpendicular to the first annular surface to compress the root between the locking device and the ring seal and transmit pressure to the ring seal. to form a seal in the chamber.

The ultrasonic head has a first annular surface coplanar with the first nodal surface. The vibration amplitude is therefore zero at all points of the first annular surface. It also has a second annular surface. The second annular surface, whether annular or not, is coplanar or adjacent to the second nodal surface. The first and second planes are therefore parallel to each other.

The second annular surface may consist of a flange-shaped annular projection around the ultrasonic head or an annular slot or step formed in said ultrasonic head.

A pressure device applies pressure to the second annular surface of the ultrasonic head through the fixture . The fixation device is attached to or disposed on the second annular surface of the ultrasound head. Since the second annular surface corresponds to or is near the second nodal surface, the vibration amplitude is zero or reduced.

The pressure applied by the pressure device is perpendicular to the first and second annular surfaces of the ultrasonic head and pushes the second annular surface toward the first annular surface.

A first annular surface of the ultrasonic head contacts and presses against the annular surface of the ring seal. The pressure applied by the pressurizing device provides a seal between the two surfaces that is unaffected by vibrations of the ultrasonic head. This is because the first annular plane coincides with the first nodal plane, so the vibration amplitude is zero on all planes.

According to one embodiment of the invention, the root of the ultrasonic head is at least partially composed of the sonotrode plus an ultrasonic amplifier sandwiched between the sonotrode and the ultrasonic transducer. In this case, the second nodal plane should not coincide with the junction of the ultrasonic amplifier and the sonotrode. This is because there are high stresses in this area that can damage the joint.

Alternatively, the entire root portion of the ultrasonic head may consist of a sonotrode. However, this is the case without an ultrasonic amplifier.

In either case, the tip of the ultrasonic head has a smaller cross-section than its root. In the transition region between the tip and root, an annular first annular surface of the ultrasonic head is formed coincident with the first nodal surface.

A third annular surface may also be positioned opposite the first annular surface of the ultrasonic head around the sonotrode-receiving bore of the chamber and in contact with another annular surface of the ring seal.

In such case, the ring seal is a tubular body held between the first annular surface and the third surface, but not necessarily circular. The pressure applied by the pressurizing device can avoid polymer leakage from both gaskets.

The space between the ultrasonic head tip and the surrounding ring seal is filled with a polymer and forms part of the chamber.

The third surface forms an annular seat and provides precise positioning of the ring seal.

Ring seals are either metallic or ceramic. This allows it to withstand higher temperatures and vibrations to a greater extent than other materials, including many plastic materials for example. Metal or ceramic can be used to form the ring seal because it contacts the ultrasonic head precisely formed at the first nodal plane where the vibration amplitude is zero. Affixing the ring seal to the other surface of the ultrasonic head, even if it is adjacent to the first nodal surface, exposes the ring seal to vibration and a material having some degree of flexibility. (e.g. certain plastics, rubbers) must be used. This causes wear due to vibration and temperature, and leakage of molten polymer.

According to another embodiment, the ring seal forms the interior space. The cross-section of this internal space is larger than that of the tip of the sonotrode. The difference in cross-section between both elements is less than 2.5 mm.

This size difference allows the tip to vibrate within itself without interfering with the wall of the ring seal disposed therearound. Further, this space forms a tubular duct which communicates with the rest of the chamber and extends the tubular duct and is filled with polymer. In the tubular duct, the vibration amplitude of the tip decreases to zero as it approaches the first nodal plane. This means that the polymer contained within the tubular duct can solidify in the area coinciding with the first annular surface of the ultrasonic head and cooperate with the sealing of the gasket to avoid leakage of the polymer therethrough. do.

The pressure device, according to one embodiment, comprises a plurality of connectors . These connectors are connected at one end to the fixation device and at the other end to the body containing the chamber. Pressure applied by the connector compresses the root of the ultrasonic head to ensure a precise seal of the chamber. Preferably the force generated by the pressure device is adjustable.

In one embodiment , the pressure device consists of a plurality of bars and a plurality of clamping devices. These bars are positioned perpendicular to the first and second nodal planes around the ultrasonic head and act as guides for axial displacement of the fixation device. These clamping devices apply a predetermined amount of stress to the ultrasonic head. For example, the fixation device is a flat plate with holes parallel to the first and second nodal planes. A hole in the plate allows a portion of the ultrasonic head to pass therethrough and supports a second annular surface of the ultrasonic head at the perimeter of the hole.

If the flat plate that constitutes the fixation device contains a plurality of through-holes around its perimeter through which the bar is inserted as part of the pressure device, the bar will be able to accommodate the axial displacement/displacement of the fixation device. It is possible to guide movement. Additionally, if the bar is threaded and includes a nut as a tightening device, the nut can be adjusted to adjust the pressure experienced by the ultrasonic head.

Other possible solutions include the use of pistons or springs.

The body, including the chamber, can also be formed in a single piece or assembled from complementary halves. If the body is formed in two halves or more, the inlet and outlet bores may be partially formed in one or the other of the joining surfaces of the two halves. . As a result, by separating these parts, the interior of the inlet and outlet bores can be easily accessed and cleaned of any polymer left therein.

Preferably, when the sonotrode receiving bore is formed in one of the halves and the pressure device is attached to the halves, the halves, the ring seal, the fixation device and the ultrasonic head are combined into one combined assembly. configure. This allows the halves to be separated, allowing cleaning and maintenance of the interior of the chamber and bore without removing the ultrasonic head from the halves.

Sectional drawing of the ultrasonic device of this invention. The figure does not show a polymer extrusion device. Arrows indicate the direction in which molten polymer travels from the extruder to the exit bore. FIG. 2 is an exploded view of the ultrasonic device of FIG. 1;

According to one embodiment of the present invention, the ultrasonic device of the present invention is particularly adapted for use with polymer (with or without additives) extrusion devices.

Said extrusion device comprises a device for compressing and forcing molten polymer into chamber 10 through inlet bore 11 . Chamber 10 has an inlet bore 11 , a sonotrode housing bore 13 and an outlet bore 12 . This exit bore 12 is connected/coupled (hereinafter collectively referred to as "connection") to the forming die. This shaping die defines the shape of the polymer product produced by the extrusion device.

Inlet bore 11 and outlet bore 12 may or may not be aligned. The polymer extrusion apparatus comprises, in this example, a cylindrical melting chamber 10 and an inlet bore 11 for polymer particles. This melting chamber 10 has one or more spindles. Said inlet bore 11 is arranged at the beginning of the chamber 10 . Other implementations are also possible. In this type of device, rotation of the spindle compresses, conveys, mulls, and mixes the polymer with additives (if any). A heater may also be included to raise the temperature of the polymer to aid in its melting. This molten polymer stream is introduced into chamber 10 through inlet bore 11 . This chamber 10 accommodates the tip of the ultrasonic head 20 .

A chamber containing the tip of the ultrasonic head may be connected to the end of the pusher through an inlet bore. Conversely, the chamber may be constructed integrally (integrated) with the intermediate portion of the extrusion device. As a result, vibrations generated by the ultrasonic head are applied to the polymer within the extruder. In this embodiment, the spindle preferably extends through the chamber. The spindle may be placed before or after the chamber.

The ultrasonic device of the present invention is formed by an ultrasonic transducer 25 that produces vibrations. An ultrasonic transducer 25 is associated with the ultrasonic head 20 to transmit the generated vibrations.

The ultrasonic head 20 is formed by an ultrasonic amplifier 24 and a sonotrode 23 . Ultrasonic amplifier 24 is in direct contact with ultrasonic transducer 25 . The sonotrode 23 is connected to an ultrasonic amplifier 24 .

A distal end 21 of the ultrasonic head 20 corresponds to a portion of the sonotrode 23 and is contained (enters) the chamber 10 . This tip 21 projects cantilevered into the chamber 10 via the sonotrode housing bore 13 . Tip 21 maintains contact with the compressed molten polymer and imparts vibrations to the polymer, altering its properties before it exits through exit bore 12 of chamber 10 .

The remainder of the ultrasonic head 20 constitutes a root portion 22 which remains outside the chamber 10 .

The ultrasonic transducer 25 produces sinusoidal vibrations. This vibration spreads in the ultrasonic head 20 as a standing wave. An object exposed to a standing wave forms one or more nodal planes whose vibration amplitude is always zero.

The ultrasonic head 20 of the present invention is configured such that the first nodal plane PN1 is formed between the tip portion 21 and the root portion 22 . Thereby, corresponding to the first nodal plane PN1, the ring seal 30 is positioned around and in contact with the ultrasonic head 20, sealing the sonotrode receiving bore 13, and the compressed air contained within the chamber 10. The melted polymer is prevented from flowing out of the chamber 10 therethrough.

The ring seal 30 affects the vibration of the ultrasonic head 20 or the vibration affects the sealing by the ring seal 30 . For this reason, the ring seal 30 is constituted by a tubular body through which the distal end portion 21 of the ultrasonic head 20 passes. This tubular body has the annular surface of the ring seal 30 . This annular plane is parallel to and coplanar with the first nodal plane PN1 of the ultrasonic head 20 . The ultrasonic head 20 has a first annular surface S1. This first annular surface S1 is complementary to the annular surface of the ring seal 30 and is coplanar with the first nodal surface PN1.

In the assembled position, the ultrasonic head 20 is positioned so that its first annular surface S1 rests in contact with the annular surface of the ring seal 30. As shown in FIG.

If the annular surface is coplanar with the first nodal surface PN1, the vibration amplitude will be zero on all points of the annular surface. As a result, the seal created between both members is unaffected by vibrations of the ultrasonic head 20 .

The ultrasonic head 20 generates a second nodal plane PN2 at the root portion 22 . The second nodal surface PN2 is parallel to and separated from the first nodal surface PN1. Preferably, the second nodal plane PN2 is away from the coupling portion of the sonotrode 23 and the ultrasonic amplifier 24 to avoid exposing this coupling portion to excessive stress. This overstress can damage the connection parts (eg screw connections).

The ultrasonic head 20 has a second annular surface S2 that is parallel to the first annular surface S1 and coplanar with or adjacent to the second nodal surface PN2. As a result, the vibration amplitude in the second annular surface S2 is zero or extremely small.

The second annular surface S2 may be formed by a plurality of second partial surfaces. All of these partial surfaces are coplanar with each other and form an annular, discontinuous surface. This configuration does not affect the invention (components).

The fixing device 40 is in this example a flat plate with a central through hole. A portion of the ultrasonic head 20 penetrates through this through hole. This plate is placed in contact with the second annular surface S2 of the ultrasonic head 20 thereon. A peripheral portion of the through hole maintains contact with the second annular surface S2 of the ultrasonic head 20 .

The pressurizing device 41 applies pressure to the fixing device 40 in a direction perpendicular to the first nodal plane PN1 and the second nodal plane PN2. This pressure is transmitted to the ultrasonic head 20 through the second annular surface S 2 and forces a portion of the ultrasonic head 20 against the ring seal 30 . Thus, the pressure of the molten polymer within the chamber 10 eliminates leakage between the ring seal 30 and the first annular surface S1 of the ultrasonic head 20. FIG. The pressure applied by pressurizing device 41 is greater than that of the molten polymer in chamber 10 .

The placement of the first annular surface S1 and the shape of the ring seal 30, along with the direction of compression applied to the ultrasonic head 20, form an axial seal between the ultrasonic head 20 and the ring seal 30. FIG. In the prior art, it was from the radial direction.

In this embodiment, the pressurizing device 41 is composed of a plurality of bars (rod-like members). These bars are parallel to each other and perpendicular to the first nodal plane PN1 and the second nodal plane PN2 of the ultrasonic head 20 . The ultrasonic head 20 has two ends. One is attached to the body containing the chamber 10 and the other passes through a through hole in the fixing device 40 . This makes it possible to guide the fixation device 40 in the axial direction defined by the bar.

Said bar is a threaded bar and has nuts as clamping device 42 . This causes the fixation device 40 to move toward the body containing the chamber 10 and compress the ultrasonic head 20 that is sandwiched. Alternatively, the threaded bar may be rotated by a motor. The nut may be threaded onto the fixation device 40 or may be of integral construction.

Ring seal 30 may be a separate component from the body containing chamber 10 . This facilitates maintenance and inspection. In such a case, the body including the chamber 10 may have a third annular surface S3 around the sonotrode receiving bore 13 . The third annular surface S3 is parallel to and faces the first annular surface S1 of the ultrasonic head 20 . A ring seal 30 also has an annular flat surface and is positioned on the third annular surface S3 to retain the ring seal 30 between the ultrasonic head 20 and the body containing the chamber 10. As shown in FIG. The pressure applied by the pressurizing device can ensure sealing of the gaskets on both sides of the ring seal 30 to avoid the release (leakage) of molten polymer.

The above description relates to one embodiment of the present invention, and those skilled in the art can conceive of various modifications of the present invention, all of which are within the technical scope of the present invention. be. The numbers in parentheses after the components in the claims correspond to the part numbers in the drawings, are attached for easy understanding of the invention, and are not used for restrictive interpretation of the invention. (Article 24-4 of the Patent Act Enforcement Regulations and Form 29-2, "Remarks" 14-b) . Also, even if the number is the same, the part names in the specification and claims are not necessarily the same. This is for the reason described above. With respect to the term "or", for example, "A or B" includes selecting "A only", "B only", as well as "both A and B". Unless otherwise specified, the number of devices or means may be singular or plural.

10: Chamber 11: Inlet Bore 12: Outlet Bore 13: Sonotrode Receiving Bore 20: Ultrasonic Head 21: Tip 22: Root 23: Sonotrode 24: Ultrasonic Amplifier 25: Ultrasonic Transducer 30: Ring Seal 40: Fixing device 41: Pressure device 42: Tightening device

Claims (12)

In an ultrasonic device for a polymer extrusion device,
having a chamber (10), an ultrasonic head (20), a ring seal (30), a fixing device (40) and a pressure device (41);
* Said chamber (10) has an inlet bore (11) and an outlet bore (12) for compressed molten polymer and a sonotrode containment bore (13) to supply molten polymer to said inlet bore (11). connectable to or integrally formed with a polymer extrusion device that
* The ultrasonic head (20 ) has a sonotrode (23), and the ultrasonic head (20) has a tip (21) and a root ( 22) is divided into
Said tip (21), composed entirely of said sonotrode (23), projects into said chamber (10) through said sonotrode-receiving bore (13) to displace the compressed molten polymer in said chamber (10). maintain contact with
The root (22) is in contact with the ultrasonic transducer (25) and is at least partially composed of the sonotrode (23) and is outside the chamber (10) and has a second node of zero vibration amplitude . contains a face (PN2),
the second nodal surface (PN2) is parallel to and away from the first nodal surface (PN1);
* The upper annular surface of the ring seal (30) contacts the ultrasonic head (20) at the first nodal surface (PN1) and the lower annular surface contacts and seals the sonotrode housing bore (13). ,
said first nodal surface (PN1) being parallel and coplanar with a first annular surface (S1) of said ultrasonic head (20) contacted by an upper annular surface of said ring seal (30) ;
Said second nodal surface (PN2) is coplanar with or adjacent to a second annular surface (S2) of said ultrasonic head (20), said second annular surface (S2) being the first annular surface. is parallel to (S1),
* said fixation device (40) contacts or rests on said second annular surface (S2);
* Said pressurizing device (41) is connected to said fixing device (40) and applies pressure in a direction perpendicular to said first annular surface (S1) so that said fixing device (40) and ring seal (30) An ultrasonic device for a polymer extruder, characterized in that it compresses the root (22) between and transmits pressure to said ring seal (30) to form a seal in said chamber (10). Ultrasonic device according to claim 1, characterized in that the root (22) comprises an ultrasonic amplifier (24) between the sonotrode (23) and the ultrasonic transducer (25). 3. The ultrasound system of claim 2, wherein the second nodal plane (PN2) is remote from the junction of the sonotrode (23) and the ultrasound amplifier (24). 2. Ultrasonic device according to claim 1, characterized in that the whole root part (22) is constituted by the sonotrode (23). Ultrasonic device according to any one of claims 1 to 4, characterized in that the tip (21) has a smaller diameter than the root (22). Ultrasonic device according to claim 5, characterized in that the transition region between the tip (21) and the root (22) forms a first annular surface (S1). Said chamber (10) has a third annular surface (S3) around said sonotrode receiving bore (13), said third annular surface (S3) facing said first annular surface (S1). , in contact with a lower annular surface of said ring seal (30), said ring seal (30) defining a tubular body, said tubular body having said first annular surface (S1) and said third annular surface; (S3). 8. The ultrasonic device of claim 7, wherein said third annular surface (S3) forms an annular seat providing accurate positioning of said ring seal (30). Ultrasonic device according to claim 7 or 8, characterized in that the ring seal (30) is made of metal or ceramic. Ultrasonic device according to any one of claims 7-9, characterized in that the cross-sectional area of the inner space of the ring seal (30) is larger than that of the tip (21). Said pressurizing device (41) comprises a plurality of connectors, said plurality of connectors being attached at one end to said fixing device (40) and at another end to a body containing said chamber (10). The ultrasonic device according to any one of claims 1 to 10. Ultrasonic device according to any one of claims 1-11, characterized in that the pressure exerted by the pressure device (41) is greater than that of the molten polymer in the chamber (10).