EXTRUDER, GRANULE FEED, AND LIQUID ADDITIVE DISPENSER SYSTEM FOR 3D PRINTERS

Abstract

An extruder, granule feed, and liquid additive dispenser system for 3D printers, having a mobile print head (1) with a substantially vertical extruder barrel (17) and a throat (18) which, at the upper area whereof, includes a mobile funnel-shaped hopper (10′) for the receiving of the granules (2) and a rotating internal worm (19). The mobile hopper (10′) presents curved indentations (28) that progress inward in the rotational direction of the worm, seeking langency to the mouth (29). The worm (19) includes, as an extension to its thread (26), a drag shovel (20) complementary to the mobile hopper (10′) with a sloping internal thrust face (27) that links with its cavity (25) and draws inward the granules contained in the hopper (10′) via the indentations.

Claims

1. An extruder and granule feed and a liquid additive dispenser system for 3D printers comprising: a mobile print head (1) with a substantially vertical extruder barrel (17) and a throat (18) which, at an upper area comprises a mobile funnel-shaped hopper (10′) for receiving of the granules (2), and a rotating internal worm (19), wherein said mobile hopper (10′) includes curved indentations (28) that progress inward in a rotational direction of the rotation internal worm, seeking tangency to a mouth (29), and that said worm (19) comprises, as an extension to its thread (26), a drag shovel (20) complementary to the mobile hopper (10′) with a sloping internal thrust face (27) that links with its cavity (25) and draws inward the granules contained in the hopper (10′) via said indentations.

2. The extruder and granule feed and liquid additive dispenser system according to claim 1, wherein the thrust face (27) of the shovel (20) is configured to exert a downward and radial pressure force (P) on the granules in the hopper at all times.

3. The extruder and granule feed and liquid additive dispenser system according to claim 1, wherein a depth of the indentations (28) of the mobile hopper (10′) increases progressively in the rotational direction of the worm.

4. The extruder and granule feed and liquid additive dispenser system according to claim 1, wherein the throat (18) and/or the extruder barrel (17) have one or more side inlets (30) below the mouth of the hopper (10′) for the connection of auxiliary hoses (5′) for dispensing liquid additive into the barrel.

5. The extruder and granule feed and liquid additive dispenser system according to claim 1, wherein the feeding device includes a hopper (10) for receiving granules and a drum (11) in its inner lower part with inlet grooves (12) and outlet grooves (13), and a transport wheel (14) complementary to the hopper (10) and the drum (11) with shovels that are introduced in the hopper (10) through the inlet opening (12) configured for loading the material by rotation thereof and unloading it through the outlet groove (13) to a pressurized feeding hose (5) connected to the mobile hopper (10′).

6. The extruder and granule feed and liquid additive dispenser system according to claim 5, wherein the inlet groove (12) of the drum is located on a convex face of the hopper (10).

7. The extruder and granule feed and liquid additive dispenser system according to claim 5, wherein the wheel (14) with shovels is made of a soft material.

8. The extruder and granule feed and liquid additive dispenser system according to claim 1, wherein the hose (5) is attached to the print head (1) in a coupling with a ball joint (16).

9. The extruder and granule feed and liquid additive dispenser system according to claim 1, wherein the throat (18) and the mobile hopper (10′) have cooling elements.

10. The extruder and granule feed and liquid additive dispenser system according to claim 9, wherein the throat (18) presents radiator fins (23).

11. The extruder and granule feed and liquid additive dispenser system according to claim 1, wherein the barrel (17) and the throat (18) are two parts attached by an interrupted thread and a thermal washer (24).

12. The extruder and granule feed and liquid additive dispenser system according to claim 4, further including multiple connections (31) for auxiliary hoses (5′) before the side inlets (30).

13. The extruder and granule feed and liquid additive dispenser system according to claim 4, further comprising peristaltic-type liquid additive pumps.

14. The extruder and granule feed and liquid additive dispenser system according to claim 5, further comprising an air pump with a power regulator.

Description

DESCRIPTION OF THE DRAWINGS

[0023] The following figures are included in order to better understand the invention.

[0024] FIG. 1: General perspective view of the head of the extruder and the granule feeding and liquid additive dispensing system for 3D printers.

[0025] FIG. 2. Section of the extrusion head, according to a preferred example.

[0026] FIG. 3: Section of the dispensing device of the granule feed.

[0027] FIG. 4A shows a section view of the mobile hopper.

[0028] FIG. 4B shows a section view of the barrel.

[0029] FIG. 4C shows a section view of the worm.

[0030] FIG. 4D shows the collaboration between the elements according to the preferred example.

[0031] FIG. 5A shows a stage of transit of the granule from the hopper to the inside of the extruder barrel according to the preferred embodiment.

[0032] FIG. 5B shows another stage of transit of the granule from the hopper to the inside of the extruder barrel according to the preferred embodiment.

[0033] FIG. 5C shows another stage of transit of the granule from the hopper to the inside of the extruder barrel according to the preferred embodiment.

[0034] FIG. 5D shows another stage of transit of the granule from the hopper to the inside of the extruder barrel according to the preferred embodiment.

EMBODIMENTS OF THE INVENTION

[0035] An embodiment of the invention is briefly described below as an illustrative and non-limiting example of the invention.

[0036] The embodiment (shown in FIG. 1) is an extrusion head (1) for extruding plastic granules (2) for 3D printers which is connected to a feeding device (3) and a storage reservoir (4) by means of a hose (5) or semi-rigid conduit, and to other reservoirs (6) and liquid additive dispensing devices (7) with other auxiliary hoses (5′). The extrusion head is assembled in a carriage of a Cartesian or polar displacement system either on guides or suspended from a 3D printing machine by cables.

[0037] The feeding device has one or more level sensors (8) located in a receptacle (9) or reservoir in the extruder head (1) which indicate the start of the filling program. It dispenses and transports the required amount of material from the storage reservoir to the extrusion head (1) via a feeding hose (5) by means of pressurized air. This is achieved via a dispensing unit (shown in FIG. 3) that consists of a hopper (10) for receiving material in the lower part of the storage reservoir, which comprises therein a drum (11) with inlet grooves (12) and outlet grooves (13), and a wheel (14) with shovels located inside the drum and with a width similar thereto. The rotation of the mentioned wheel (14) introduces the material in a controlled manner into the pressurized conduit, preventing blockages. The use of a soft material, such as rubber, in the shovels of the wheel prevents impingement with the granule and reduces pressure loss of the system.

[0038] The extrusion head (shown in FIG. 2) consists of a mounting plate (15) and a rigid or flexible ball joint (16) for connecting the hose (5) allowing it to rotate and tilt. The extruder consists of a substantially vertical extruder barrel (17) and a throat (18) which, at the upper area whereof, comprises a mobile funnel-shaped hopper (10′) for the receiving of the granules, and a rotating internal worm (19), with a drag shovel (20) complementary to the mobile hopper (10′) that introduces the granules into the cavity of the worm (19) where they are subsequently heated and compacted in the barrel (17), and extruded through the nozzle (21) in the lower part.

[0039] The barrel (17) is heated by an electrical resistor or other means and comprises one or more temperature sensors. It is generally protected by an outer ceramic cover (22) or another type of cover in order to reduce heat losses and prevent burns to the skin from direct contact.

[0040] The mobile hopper (10) of the extruder is cooled by air flows or by a water cooling system so that the heat coming from the barrel (17) does not partially melt the granules. The cooling is assisted by radiator fins (23) when fluid flow passes between them.

[0041] The attachment between the throat (18) and the rest of the barrel (17) can be a threaded attachment, preferably with a discontinuous or interrupted thread and a thermal washer (24) to reduce heat transfer.

[0042] The air pressure of the blower can be regulated by means of a potentiometer for the use of different lengths of feeding hose (5) depending on the dimensions of the printer where it is installed.

[0043] The worm can be seen in FIGS. 2, 3, and 4. As is common in the art, it has a helical notch forming its cavity (25) and threads (26). However, it has, in correspondence with the mobile hopper (10′), a drag shovel (20) thrusting the granules from outside the worm. Said shovel (20) is an extension of the thread and has a shape similar or complementary to the mobile funnel-shaped hopper (10′), as well as a sloping lower thrust face (27) that links with the worm cavity and presses the granules against the indentations (28) of the hopper (10′), producing the drawing effect. This solution causes the granules to enter the worm in a manner independent of the pressure from the weight of material on the hopper (9′), and ensures that no residues adhered to the thread.

[0044] FIG. 5 shows, by means of multiple sections of the extruder, the transit of the granule from the mobile hopper (10) to the inside of the barrel (17) as it is captured by the thrust face of the shovel (20). The angle of incidence of the thrust face of the shovel (20) on the granules directly influences the efficiency of the system. The definition of this face exerts a downward force (P) on the granule at all times, describing acute angles with respect to the displacement vector (Dtg) tangent to the indentations.

[0045] In this way, the granular material enters the extruder barrel smoothly, abundantly, and continuously, resulting in a homogeneous, fluctuation-free extrusion. As a result of this smooth tangential displacement of the granule towards the mouth (29) of the mobile hopper (10′), the required rotational torque is less.

[0046] The throat (18) additionally has one or more side inlets (30) for connecting auxiliary hoses (5′) or tubing for dispensing liquid additives. These side inlets (30) are arranged below the mobile hopper (10′). Preferably, a single side inlet is provided with a multiple front connection (31) for the premixes of various additives. The incorporation of the liquid additive directly into the barrel offers rapid material change and better base material/additive mixture homogenization.