RU2745944C1 - 3d printer extruder with convection heating - Google Patents

Abstract

FIELD: mechanical engineering; 3D printers.SUBSTANCE: invention relates to the mechanical engineering field, namely to 3D printers, in particular to polymer extruders designed for installation on 3D printers of volumetric printing of various layout schemes for the purpose of manufacturing structures, including for modeling in various branches of mechanical engineering, printing layouts, forms and other products of simple and complex geometric shapes using additive technology. The extruder includes a case with a mounting device, a transport system for feeding granular plastic, which serves to feed the granular plastic into the plastic melt chamber, from which the plastic melt is extruded by a screw from the nozzle. The plastic melt chamber is located inside the convection heating chamber and is heated by convection by hot air heated by a heater and fan and fed to the convection heating chamber.EFFECT: increased power and speed of heating plastic to the molten state, the performance of the 3D printer, provision of uniform heating of the melt chamber, printing large-sized products with various granular plastics.3 cl, 1 dwg

Description

Technology area

The invention relates to the mechanical engineering field, namely to 3D printers, in particular to polymer extruders intended for installation on 3D printers of volumetric printing of various layout schemes for the purpose of manufacturing structures, including for modeling in various industries of mechanical engineering, printing models, forms and others products of simple and complex geometric shapes using additive technology.

State of the art

The basis of all known methods of 3D printing are the following steps: the formation of cross-sections of the manufactured object, the layer-by-layer imposition of these sections and the combination of layers, with the creation of a given geometry of the product, corresponding to a computer 3D model.

Depending on the selected technology of three-dimensional printing of products, various materials can be used: metal and ceramic powders, liquid resins, wax, plastic, various sheet materials, composite materials (from cellulose compounds, special fibers and other additives, a mixture of foundry sand and additives), construction mixtures based on cement, gypsum, chamotte clay. For example, the FFF (FDM) technology is characterized by printing with various types of plastics.

3D printing can be carried out in different ways and using different materials, which are based on the principle of layer-by-layer creation (growth) of a solid object, as a result of which the object is formed by layer-by-layer laying of building material to the height of the formed layer. FFF technology (FDM) - layering of molten plastic.

In all known cases of printing with polymer materials that require heating and melting, regardless of the printer design (gantry, with angular coordinates based on robotic manipulators), the printheads of printers are usually equipped with cartridge-type solid-state heaters, or with spiral heating elements in various options.

From the prior art, a method is known for forming a medium of a given temperature in a working chamber of a 3D printer using resistive heating elements, the power from which is removed by an air flow entering the working chamber of a 3D printer. (see [1] US6722872, IPC B29C 41/36; B29C 67/00, publ. 20.04.2004).

The disadvantages of this method are the wear and tear of resistive elements, for example, a metal wire, from which power is taken off; Resistive elements can overheat and deteriorate in the event of air supply failure or control errors.

From the prior art, there is a method of forming a medium of a given temperature in the working chamber of a 3D printer using heating elements with a positive temperature coefficient of resistance (PTC; posistors; semiconductor crystals), the power from which is removed by the air flow entering the working chamber of the 3D printer (see. [2] CN106738926, IPC B29C 64/20; B29C 64/295, publ. 05/31/2017)

From the prior art, there is a method of forming an environment of a given temperature in the working chamber of a 3D printer using flat heating elements with an external aluminum radiator, the power from which is removed by the air flow entering the working chamber of a 3D printer (see [3] US10265941, IPC B29C 67 / 00; B33Y 10/00, publ. 23.04.2019).

The disadvantages of these analogs are:

- uneven heating due to the local location of the heater relative to the melt zone;

- low power of the used heaters, which makes it impossible to print large-volume designs;

- high inertia of heating.

An alternative method of convection heating is not used in existing FFF 3D printers, due to the high power of the heaters, which require large energy consumption to cool the model when printing small products. However, when printing large linear sizes and volumes of products, convection heating of the 3D printer's extruder is justified. In addition, by means of convection heating with hot air, printing with free-flowing granular plastics is possible. From the state of the art there are known applied methods for convection heating of plastics in welding extruders.

The closest analogue to the claimed invention in terms of a set of features taken as a prototype is a method and device for a manual extruder for welding plastics (see [4] RF patent for a useful model No. 189590, IPC В29С 48/15, publ. 28.05.2019). The application provides a description of a hand held extruder for welding plastics. In this solution, it is proposed to heat the plastic using a stream of hot air.

The design of a hand-held plastic welding extruder does not include:

- use of the principle of convection heating by hot air of a hand-held extruder for welding plastics in a device for forming products using additive technology by the method of layer-by-layer growth, incl. in 3D printers;

- the use of stepper motors, servo drives or similar variable drives as a drive for the feeding screw, which makes it possible to control the speed of extrusion of molten plastic in CNC systems, incl. in 3D printers (FFF);

- automatic control and management of heating temperature;

- changing the heating temperature by means of CNC systems.

The essence of the invention

The technical problem facing the invention is to eliminate the disadvantages of analogs and expand the functionality.

The technical result of the claimed invention is a significant increase in the productivity of 3D printers (FFF), the ability to print large-sized products (currently FFF printers have a construction volume of no more than 1.5 cubic meters), a significant reduction in the cost of printing, the ability to print with various granular plastics.

According to the invention, the technical problem is solved, and the technical result is achieved due to the fact that the extruder of a 3D printer with convection heating consists of a housing with a fastening device that allows the extruder to be fixed on the printer actuators, a transport system for feeding granular plastic, which serves for feeding granular plastic into the plastic melt chamber, from which the plastic melt is extruded by a screw from the nozzle, while the plastic melt chamber is located inside the convection heating chamber and is heated by convection by hot air heated by a heater and fan and supplied to the convection heating chamber, which allows increasing the power and speed of heating the plastic to molten state and, accordingly, increase the productivity of the 3D printer, make the heating of the plastic melt chamber uniform.

Also, the technical problem is solved, and the technical result is achieved due to the fact that the screw drive, which extrudes the plastic melt from the nozzle, forming a layer of the printed product, is rotated by a CNC drive (stepper motor, servo drive or similar variable drive), which makes it possible to dose the plastic melt when extrusion.

Also, the technical problem is solved, and the technical result is achieved due to the fact that the heating temperature in the convection heating chamber is controlled by a temperature sensor integrated into the plastic melt chamber, which allows using a CNC control system to maintain or change the temperature of the heated air of the air heater.

Also, the technical problem is solved, and the technical result is achieved due to the fact that extruders of a similar design can be used on all types of FFF (FDM) 3D printers, regardless of the layout (portal, delta, with angular coordinates and printers based on robotic manipulators).

Also, the technical problem is solved, and the technical result is achieved due to the fact that the heating of the chamber and the melting of the plastic is carried out by convection heating it with hot air.

Also, the technical problem is being solved, and the technical result is achieved due to the fact that stepper motors, servo drives or similar variable drives are used as a drive for the feeding screw, which makes it possible to control the speed of extrusion of molten plastic in CNC systems, incl. in 3D printers (FFF).

Also, the technical problem is solved, and the technical result is achieved due to the fact that the regulation of the heating temperature is controlled by a temperature sensor and is carried out automatically.

Also, the technical problem is solved, and the technical result is achieved due to the fact that the heating temperature is changed by means of CNC systems (controllers of various types).

Brief Description of Drawings

FIG. 1 is a side view (in section) of a convection heated 3D printer extruder.

The following positions are indicated in the figures:

1 - case;

2 - fastening device;

3 - transport system for feeding granular plastic;

4 - convection heating chamber;

5 - plastic melt chamber;

6 - auger;

7 - CNC drives (stepper motor, servo drive or similar variable drive);

8 - temperature sensor;

9 - air heater;

10 - fan;

11 - nozzle with an outlet for extruding molten plastic.

12 - granular plastic;

13 - plastic melt;

14 - printed product.

Implementation of the invention

The extruder of a 3D printer with convection heating is designed to heat plastic to the melting temperature with high performance, dosing it by controlling the rotation speed of the drive (stepper motor, servo drive or similar variable drive) of the screw by means of CNC systems (controllers of various types) and extruding molten plastic through nozzle, maintaining, regulating and changing the heating temperature by means of CNC systems (controllers of various types).

The extruder of a 3D printer with convection heating consists of a body (1) with a mounting device (2), a transport system for feeding granular plastic (3), which serves to feed granular plastic (12) into the plastic melt chamber (5) located inside the convection chamber heating (4) with hot air. The air heated by the heater (9) is fed by the fan (10) into the convection heating chamber (4) and heats up the plastic melt chamber (5) located inside the convection heating chamber (4). Inside the plastic melt chamber (5) there is a plastic melt supplying screw (13) (6) driven by a CNC drive (stepper motor, servo drive or similar variable drive) (7). The plastic melt (13) is extruded from the nozzle (11), forming the layer of the printed product (14). The heating temperature is controlled by a temperature sensor (8) integrated into the plastic melt chamber (5), which allows using a CNC control system (controllers of various types) to maintain or change the temperature of the heated air of the air heater (9).

The device works as follows.

The extruder body (1) of a 3D printer with convection heating is fixed by means of a fastening device (2) on the actuators for moving the 3D printer. Granular plastic (12) is loaded (supplied) by means of a transport system for feeding granular plastic (3) into the plastic melt chamber (5), where it is melted to a liquid plastic melt (13), allowing the melt to be extruded through a nozzle with an outlet for extruding molten plastic (11) into the product layer, which is formed by controlling the 3D printer actuators controlled by a CNC control system (controllers of various types). The plastic melt chamber (5) is located inside the convection heating chamber (4), blown and heated by hot air, which is supplied from the air heater (9) to the convection heating chamber (4) by a fan (10). The plastic melt supply (13) auger (6) is located inside the plastic melt chamber (5) and is driven by a CNC drive (stepper motor, servo drive or similar variable drive) (7). The melt of plastic (13) under the pressure of the turns of the screw (6) is extruded from the nozzle (11), forming a layer of the printed product (14). The heating temperature is controlled by a temperature sensor (8) integrated into the plastic melt chamber (5), and allows, through a CNC control system (controllers of various types), to maintain or change the temperature of the heated air of the air heater (9).

The causal relationship between the technical result and the essential features of the claims is as follows:

- an increase in the productivity of 3D printers (FFF) due to the use of a convection heating method in the extruder of a 3D printer, which made it possible to increase the power and speed of heating the plastic to the molten state, to make the heating of the plastic melt chamber (5) uniform;

- obtaining the ability to print large-sized products by increasing the productivity of 3D printers (FFF) when using the convection heating method in the extruder of a 3D printer;

- a significant reduction in the cost of printing due to the possibility of printing with granular plastics, including granular plastics of recycling, the cost of which is on average 8-20 times cheaper than the filament usually used in FFF - (FDM) 3D printers

Claims (3)

1. Extruder of a 3D printer with convection heating, consisting of a body (1) with a fastening device (2), a transport system for feeding granular plastic (3), which serves to feed granular plastic (12) into the plastic melt chamber (5), from which the plastic melt (13) is extruded by the screw (6) from the nozzle (11), characterized in that the plastic melt chamber (5) is located inside the convection heating chamber (4) and is heated convectionally by hot air heated by the heater (9) and the fan ( 10) and supplied to the convection heating chamber (4), which allows increasing the power and speed of heating the plastic to the molten state and, accordingly, increasing the productivity of the 3D printer, making the heating of the plastic melt chamber (5) uniform. 2. Extruder 3D printer with convection heating according to claim 1, characterized in that the screw drive (6), which extrudes plastic melt (13) from the nozzle (11), forming a layer of the printed product (14), is rotated by a CNC drive ( 7), which makes it possible to dose the plastic melt (13) during extrusion. 3. Extruder of a 3D printer with convection heating according to claim 1, characterized in that the heating temperature in the convection heating chamber is controlled by a temperature sensor (8) integrated into the plastic melt chamber (5), which allows maintaining or changing temperature of the heated air of the air heater (9).

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