Screw pump module for the extrusion of plastic materials

Abstract

This concerns a screw pump for the extrusion of plastic materials, which is extremely compact and so it can be inserted in-line in a plastic material filtration system, encapsulating within it a duct parallel to the axis of the screw.

Claims

1. A screw pump module for extrusion of plastic materials, comprising: a drive motor; a body with an inlet and an outlet for a molten plastic material; a hollow cylinder with an inlet and an outlet; a screw with a helical thread around a circumference of the screw; a first connection conduit between the inlet of the hollow cylinder and the inlet of the body; or a second connection conduit between the outlet of the hollow cylinder and the outlet of the body; wherein said screw is rotated by said drive motor; wherein inside said hollow cylinder said screw with the helical thread rotates; wherein the molten plastic material enters from the inlet of the hollow cylinder and, following the rotation of said screw with the helical thread, exits from the outlet of said hollow cylinder; wherein said inlet of the body and said outlet of the body is at a common end of said body; wherein said inlet of the body and said outlet of the body are respectively equipped with a flange for the inlet of the body and a flange for the outlet of the body of the molten plastic material, and wherein the flanges are positioned with a coincident axis; wherein inside said body is said first connection conduit through which the molten plastic material that enters from the inlet of the body reaches the inlet of the hollow cylinder; or through said second connection conduit the molten plastic material leaving the hollow cylinder reaches the outlet of the body; and wherein said first connecting conduit is positioned with an axis thereof substantially parallel to a main axis of the screw.

2. The screw pump module of claim 1 wherein said pump module has a single-function screw.

3. The screw pump module of claim 1 wherein a support for a terminal end of the screw includes a bushing or a bearing.

4. The screw pump module of claim 1 wherein said drive motor of the pump module is designed to provide a power corresponding to a force required for operation of the screw.

5. The screw pump module of claim 1 wherein said inlet of the body and said outlet of the body each include a flange, and are positioned at 90° with respect to the main axis of the screw.

6. The screw pump module of claim 1 wherein said hollow cylinder has a cover cap axially coincident with the main axis of the screw, the cover cap sized to allow the screw to be inserted in and removed from the hollow cylinder, thereby providing access to the screw.

7. The screw pump module of claim 1 wherein the screw inside the hollow cylinder can be replaced with a corresponding screw having a different helical thread.

8. The screw pump module of claim 1 further including a plurality of cover caps, one cover cap covering each of an end part of the screw, the outlet of the hollow cylinder, a reducer side at an initial part of the screw, the inlet of the hollow cylinder, and an end part of the first connection conduit, where said cover caps are openable.

Description

DESCRIPTION OF THE DRAWINGS

(1) The technical characteristics of the invention, according to the aforementioned objects, can be clearly seen from the content of the claims below and the relative results will be apparent in the detailed description that follows with reference to the drawings, which illustrate a purely exemplary and non-limiting embodiment, in which:

(2) FIG. 1 shows a perspective view of the pump module that is the object of the invention placed above a wheeled support;

(3) FIG. 2 shows a different perspective view of the pump module of FIG. 1;

(4) FIG. 3 shows a front view of the pump module of FIG. 1 with the flanged inlet and outlet set at the same height;

(5) FIG. 4 shows a partially sectioned view of the pump module of FIG. 2;

(6) FIG. 5 shows a partially sectioned view of the pump module of FIG. 1;

(7) FIG. 6 shows a top section view of the pump module, with the exception of the screw, with clear paths of the molten material from inlet to outlet;

(8) FIG. 7 shows an example of a perspective view of a screw with a helical thread; and

(9) FIG. 8 shows a view, corresponding to FIG. 6, with the screw further sectioned.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(10) With reference to the drawings, the object of the innovation revolutionizes the system of feeding the pump of a screw extruder by optimizing energy consumption, which is certainly lower due to there being less friction and taking into consideration the total energy required for a pump made from different corresponding elements placed in series.

(11) Above all, with the system of the invention, it is possible to split what traditionally was the single screw of the pump, which was tasked with the compression, plasticization, degassing, etc., in various modules, each specifically specialized for a limited set of functions and preferably for a single function.

(12) The object of the invention also allows you, given the modularity of the pump module, to place the various modules in series, and it has not increased the total length, as would have been expected for a number of elements in series, but actually limits its overall length due to the presence of the connection duct, which is a return or recovery duct, that connects the inlet of the module with the initial part of the hollow cylinder, or which connects the outlet with the final part of the hollow body.

(13) Preferably by placing the inlet and outlet of the pump module on the same side, the inlet and outlet flanges are kept coaxial.

(14) Preferably by placing the screw with the main axis at 90° to the axis of the in-line connection of the inlet and outlet, the system becomes even more compact.

(15) Advantageously, each screw of each pump module is powered by a single motor using a suitable reduction gear, thus it is possible to calculate the power of the motor much more precisely for the required needs, and also it is possible to individually vary the torque and the number of revolutions specifically for the required use and the specific function to be performed.

(16) Structurally, each individual pump module 1 can be supported by a suitable support 2, possibly trolley-mounted with wheels 3, which makes it extremely simple and practical to move for an easy and quick installation. Furthermore, a pump module 1 supported in this way makes it very inexpensive to maintain and/or replace in the event of breakages or scheduled interventions.

(17) Said support 2 comprises a base 4 provided with height adjusters 5 in order to be able to reach, fix and maintain the pump module 1 at the correct height for its installation in the system.

(18) The pump module 1 is connected through a spacer collar 6 to a gear motor 7 directly connected to the screw and driven by a suitable drive motor 8.

(19) An advantage of the system is precisely that of having a dedicated motor 8, so that it can be adjusted according to contingent needs, for example, if installed after an extruder, the pump module can increase the pressure of the molten plastic for the use of the component, whatever it is.

(20) However, this pump module can also be mounted between a rougher filter changer and a finisher filter changer.

(21) The capacity of this pump module is that it can bring the working pressure from a pressure of a few bars, of the molten material leaving the previous machine, to the pressure required by the next machine.

(22) The pump module 1 comprises an inlet flange 9 for the entry of the molten material, and an outlet flange 10 for the exit of the molten material.

(23) Said inlet flange 9, and possibly also the outlet flange 10, is preferably positioned at 90° to the main axis of the compression screw 11, allowing you to significantly limit the space between the inlet and outlet of the material.

(24) Advantageously, said inlet flange 9 and said outlet flange 10 are positioned with their main axis coinciding, allowing you to maintain the linear implementation and connection of the previous machines and the machines following the pump module.

(25) To obtain the aforementioned characteristic, the pump module 1 comprises a connection duct 12 which hydraulically connects the inlet flange 9 with the inlet 13 of the hollow cylinder 14 within which the screw 11 rotates.

(26) Said connection duct 12 feeds the screw 11 with the molten material coming from the inlet of the inlet flange 9. It has been found that along said connection duct 12, there is no appreciable increase in pressure or any other form of alteration of the plastic material involved.

(27) To make it easier to maintain the pump module 1 near the inlet of the hollow cylinder 13, there is a removable plug (plug towards gear motor) 15 for accessing and inspecting the end part of the connection duct 12 that opens on the inlet of the hollow cylinder 13.

(28) In this way, said connection duct 12 can easily be accessed at its ends even in the event that it becomes obstructed or needs to be inspected.

(29) Preferably, said connection duct 12 is parallel and laterally spaced from the screw 11, outside the hollow cylinder, keeping the space occupied by the hollow cylinder 14 to a minimum.

(30) This configuration is also optimal for heating, for maintaining the temperature of the molten material and also for reducing heat loss, in fact the outer surface of the module is only slightly higher compared to a configuration that includes only the hollow cylinder, and the temperature of the molten material is kept at the same level for the material present in the connection duct 12 and also for the material processed by the screw 11 with the various electric heating elements placed on the perimeter surfaces of the pump module 1.

(31) The screw 11 located within the hollow cylinder 14 has a helical thread 16 on the circumference for shifting the material from the inlet of the hollow cylinder 13 to the outlet of the hollow cylinder 17.

(32) During this displacement of the molten material, from the inlet to the outlet of the hollow cylinder 14, the plastic material undergoes an increase in pressure and/or plasticization or other modifications related to the function of the screw itself and to the configuration of the helical thread 16.

(33) These functions can be finely adjusted by modifying the torque and the number of revolutions of the motor 8 that rotates the screw 11 using the gear motor 7.

(34) This peculiarity of having a motor 8 dedicated to the single screw 11 inside the pump module not only optimizes the result at the outlet from the outlet flange 10, as regards the characteristic parameters of the molten material, such as, for example, temperature, pressure, degree of plasticization, but also achieves that flexibility and compactness that are the purposes of the invention.

(35) Advantageously, in fact, the motor 8 is positioned orthogonally to the axis of the screw and preferably vertically, and has a series of accessory elements that are, given the powers, limited to the motor only, of limited size (electrical panel, cable sizing, etc.)

(36) In fact, a screw 11 of limited length, such as the one inside the pump module that is the object of the invention, is not subject to high levels of friction on the hollow cylinder 14 and can be supported in a cantilevered position by the spacer collar 6.

(37) Advantageously and for greater safety, it is possible to support the end of the screw 11 near the outlet of the hollow cylinder 17 using a bearing in the cover cap 18 of the hollow cylinder 14. Said covering cap 18 can easily be removed and allows axial access to the inside of the hollow cylinder 14 for any maintenance and/or other inspection operations, or even facilitating the replacement of the screw.

(38) However, considering the large sections of the inlet and outlet openings and the limited friction, said pump module is not subject to any drawbacks, and can process and manage contaminated material without modest limits, both in terms of size and percentage of contamination of the usual pumps and especially those with gears.