NL1043467B1 - Method, 3d manufacturing system and print head therfor - Google Patents

Abstract

The present invention discloses a method of operating a 3D printer of a 3D printing based manufacturing system in which a filament of printing material is driven into a printer head, in which the filament is driven into a printer head so as to be expelled therefrom in motten form, the method comprising the steps of driving the filament into a heater block thermally separated from a feeder element by means of a connection between feeder element and heating block centrally comprising a thermally isolating separator or distance member through which the filament is fed. By including a thermally not or minimally conducting distance holder in the feeding or entry path of the filament, the invention realizes that the heat path to which the filament is subjected is effectively elongated, i.e. the filament is instantly brought into contact with a heater block part of a maximum possible temperature level.

Description

METHOD, 30 MANUFACTURING SYSTEM AND PRINT HEAD THERFOR Field and background of the Invention S [0091] The present invention relates to an improvement in a so-called 3D device manufacturing system, in popular sense also known as a 312 printer, an improved print head and manner of using or operating a print head, [00021 So called 3D printing based device manufacturing systems have been out in the art ever since 1982, however have presently not only become popular in amateur or 1 hobbyist areas for various purposes, but have also in industry become established as a professional means of producing devices or spare parts. The economic significance of these systems not only resides in the ability to relatively easily create special shapes orto quickly create prototypes for testing purposes, but alse in on demand supply, saving various forms of costs like in storage, transport and administration.

153 (0003) The print head of such systems very often is derived from preceding plastic molding technology, be it that the conventional melting technology thereof is often developed for receiving and welting granulate material rather then filament material, In the respect of a 3D printer departing from the use of filament material as presently at stake, UN104647751A of May 2015 discloses a heat conductive material attached on the inner side wall of the hole passing through a heating block of the print head and the center of the nozzle. In the annexed figure, plastic string 1 may be noticed, fed by extruder 9 into a heater block 3, feeding molten plastic into a nozzle 4. The plastic heating system is improved by the insertion of a “plate heater 7” in a “heating chamber” having mmteroal copper walls and external insulating material 3. Where the application of the plastic heating system may be shaped or described differently, the undedying problem of uniformly melting plastic for a subsequent application or use thereof in molten form is a generic one of melting and is in many cases essentially not solved differently than already known from this CN publication. One example of such may e.g. be the embodiment of WO2016047732, published 31 march 2016, which teaches to provide the hole with a division into a large centralized hole section and a lower section (3) with multiple holes (see Figure 5). While the latter poblication is dedicated to 3D printing, it in fact utilizes known solutions of uniformly melting plastic in a manner of a straight forward carry over of existing techuology to 3D printers. Another, generic example of a 3D printer system coping with the necessity of melting a filament of material may se amongst others be found in US92335065 relating to a Hguefier assembly for use in additive manufacturing system,

BRIEF SUMMARY OF THE INVENTION 3 [0004] In the present invention various essential improvements have been made to the known 3D printer, both in various constituent parts, which, as will become clear may often also be applied independently from one another, as well as © the method of operating such 3D printer, if not to a method of 312 printing, all in view of promoting either or both of the speed and the guality of printing.

1

BRIEF DESCRIPTION OF THE DRAWINGS 0005) Varipus aspects of the invention and an example of part of an embodiment of the invention is Hlustrated tn the drawings which depart from the general and wide spread knowledge of 3D printing system and extruders therefor, and in which: iS [oog] PIG, 1 schematically depicts a certain cross sectional view of a print head in accordance with the present invention: doon) FIG 2 is another cross sectional view of the same, further clarifying the print head design of the invention 00081 FIG. 3 thastrates from a perspective view the upper end of the heater in accordance with the present invention; [60091 FIG. 4 analogously tnstrates the bottom distal end thereof, with a print nozzle attached, 00101 FIG. § schematically illnstrstes an invention according to which the filament receiving chamber of a heater block splits up into different channels for guiding and heating flavaent material; joa) FIG. SA provides an external, perspective view of the preceding 0012] BIG. 6 and 64, in a perspective view ilusirste yet an other invention, here cooperating with the invention of FIG, §, according to which the print nozzle is screwed to an external thread of the heater block.

poi) BIG. 6A is provides the view with the nozzle removed, and farther Hhustrates a preferred embodiment in which the heater block is split up into four separate chamiels debouching into a normally conically shaped plenum of the here not depicted print nozzle;

[00141 FIG, 7 illustrates yet another independently applicable invention and measure, according to which the heater block is split up into an outer section carrying electric heater elements and an inner, detacheable section in which the receiving sections for the filament to be liquefied;

[0913] Figure 8 illustrates that the latter invention may be applied in conjunction with other inventions and measures mentioned here such as the invention in accordance with figure 3, the one measure thus becoming an aspect of the other, while still also independently being applicable if so preferred or desired;

[016] FIG, 9 and FIG. 9A illustrate the latter design of figure 7 and 8 from different perspective views.

100171 FIG. 10 and IOA from an outer perspective view and from a cross sectional view illustrate the invention of providing a standing layer of air around the heater block, in particular by providing the heat sink circurnferentiad to rather than in line with the heater block, As in figure 1 and 2, FIG. 10A also illustrates the invention of providing a thermally isolating distance member between the heat sink, be it the upper wall thereof, or the lower end thereof as In prior art designs,

[0018] FIG, 11 and 11A illustrate the latter design in a perspective view with an without the print nozzle attached, and also showing a measure to have the electric heating elements partially protruding from, Le. through the outer heat block part; mom} FIG. 12 lustrates an embodiment in which the heater block section accommodating the separate channels is designed of greater height that than the first section with central receiving chamber for the filament, [00201 FG. 12A illustrates the invention relating to the thermally decoupling distance member applied in an otherwise largely conventional printer head design; 10921} FIG, 13 illustrates the application of the invention of a standing layer of air, or circomferentially applied beat sink to an otherwise largely conventionally designed heater block.

[0022] FIG. 134 illustrates the application of circumferentially distributed screws between beater block and feeder element in an otherwise conventionally designed printer head, as well as the measure of having in this case four electric heater elements protruding from the heater block;

[0023] FIG. 14 and 14A illustrate different perspective views of the design according to | FIG. 13,

fe joo24} FIG, 15 illustrates a print head carrying system according to another aspect of the present invention according to which the print head is supported by what may be called a corapliant joint, comprising upwardly extending lugs attached to the print head, articulating with an intermediary block over a first zus, the intermediary block S articulating with a support rod over a second axis otlented transverse 1e the fist axis, hotly parallel io an roaginary of previewed work piece wea, the invention taking away lag from the system; [0251 FIG 16 and 16A illustrate the same from a top and bottom view respectively, and both FIG. 15 and 16, along with figure 1 tlustrating another aspect of the invention, in 16 which the print bead accommodates cooling or ventilation means, further controlling and trpproving the process and work piece to bo delivered.

DESCRIFTION OF ILLUSTRATIVE EMBODIMENTS ooms) FHS. 1 and further disclose a method of operating a 30 printer of a 3D printing iS based mannlacturiug system in which a filament of printing maternal ta driven info a printer head, in which the filament is driven into a printer head so as to be expelled therefrom in molten form, the method comprising the steps of driving the filament into a heater block thermally separated from a feeder element! by means of 2 connection between feeder element and heating block centrally comprising a thermally isolating separator or distance member through which the filament is Ted. By including a theymally not or minimally conducting distance holder in the feeding or entry path of the filament, the invention realizes that the heat path 10 which the filament is subjected is effectively sdongated, Le. the filament is Wwstantly brought into contact with a heater block part of a maximum possible temperature level, Hence this measure increases the meliing capacity 23 of the beater block, and therewith improves both quality and speed of the print head. [00271 Yet a further, in fact also independently applicable measure sccording to the present invention holds the receiving and heating of the filament in a fest receiving section inchided as a common chamber for receiving Hlament and filament material, and subsequently dividing the filament material within a second, further filament receiving 3} section of the heater block info separate streams of material, With such a method of 3D printing and with a 3D printer adapted thereto, high heating temperature may be attained as well as a controlled transition from solid filament stags to a gradually melting at least due to increased temperature environment, sofiening of the filament. This softened

-5- filament may be pressured further into separate channels where the material may be heated through and through since the thickness of the material relative to the surrounding heat wall is much more favorable than in in the first section. This is unlike many prior art designs where the core of the filament may still be crumble at least not as flnid as in the circumferential parts of the filament to be spelled out.

[0028] An optimising feature in accordance with the preceding holds that the inner wall of the first receiving section is provided with grooves spiraling towards the lower end of the section. In this manner the partly heated filament may already mechanically be somewhat mixed or split up, especially if more than one grooves is carved or otherwise at least largely shaped. An even further improvement in pre-mixing and flow of heated if not largely molten plastic is attained if the grooves each spiral towards an opening in the second receiving section for realizing said separate streams.

100281 According to yet a further, and in fact also independently applicable method step, the heated material is and expelled from the heater block via a printer nozzle, receiving 13 said separate streams and recombining the same for at least in part, the nozzle thereby maintained in futimate thermal contact with said heater block. In this manner it is assured that final mixing is with certainty performed on thoroughly softened if not molten material, since all expelled from a relatively small diameter heater channel, gud since the nozzle itself in fact is virtually integrated with the heat block due to its large, circumferential and screwed thermal contact with the block. In that manner it is assured that the thoroughly heated material will not solidify at arriving In contact with a nozzle which in prior art design may be found to be of relatively lower temperature, e.g. due to the nozzle normally be screwed to an inner thread of the heater block, The nozzle according to the invention is heuce provided for adhering to the heater block via screw thread provided to the outer side, i.e. circumference of an end part of the heater block. In this manner the thermal contacting surface may, with the thread even further be increased. Yet another measure to the nozzle, in fact to even further support the latter heat effect, holds that tightening of the nozzle to the heater block causes an end face of the heater block to intimately contact an at least largely corresponding, opposing face 39 provided within the nozzle, therewith further iucreasing the thermal contact between heater block and nozzle. Where the latter is made of a messing type of material, internal transfer of heat is optimized.

fin 0030] It is remarked that in a further development of the method in accordance with the inventor, the thermally separated connection between feeder element and beating block comprises radially outward disposed screws, firmly connecting the feeder element to the heater block, of course under maintaining the pre-mentioned thermally decoupling § mechanical distance holder, Where the latter may be made of a composite or ceramic material, the screws are of a stainless steel, may be maintained relatively small so as thereby equally minimizing heat transfer over the screws, Where any local loss of heat level could be remarked, this will in the present, new design be relatively remotely from the central section housing and beating the fHament, thereby maintaining a relatively high I) temperature al entry of the filament, at least {eraperatom wise favorable condition, when compared to prior art designs. So as to promote this remoteness of a potential heat bridge, the three screws are regularly distributed disposed for said fom connection, preferably the screws incorporated in a flange-like pan for the feeder element, A favorable side effect of this design is that simoltaneously the rigidity or bending stiffuess in the connection between feeder cloment and heating block is optimized, if not improved relative to many prior art designs, The presently discussed feature may hence, whether ov not even only for the latter advantage, or mm conjunction with ot solely for the thermal effect, hence also be applied either in conjunction with the preceding for further optimization, but also independently.

03) In yet a hwther development of the present invention, and also equally independently applicable measure, the heater block is incladed in the print head ina manner surrounded by a standing volume of air. In this manner, despite continuous movement of the print head a continously stable thermal environment is created for the heater block, increasing i's capacity to maintain a high and constant heat level, therewith increasing controllability of the printer head and of the privting process, In particadar both the speed and the quality thereof, In a most favorable embodiment, this feature is realized by having the a volume of standing atv surrounding the hester block provided by way of a heat sink included in the print head circumferentaliy to the beater block. Another important effect of having the heat sink circumferential to the heater black rather than preceding it, 18 that the height of the heater block may relatively easily be increased, therewith allowing for even further improvement and control of the melting process of a filament at entry thereof into the heater block, Also for this reason alone the beat sink may be included citeumferentialiy to the heater Block.

Je {6032} In a further development of the latter, the surrounding heat sink is closed to its upper distal end by an upper wall. An upper wall part of the heat sink may form a flange part to the feeding element. In such design, the feeder element favorably is centrally screwed into an upper wall part of the cireumferential heat sink, 3 10033} Further to the preceding it may be noted that the feeder element is favorably formed by a mainly tubular or prismatic part, abutting to the thermaliy isolating distance member by a distal end face. Internally, in a preferred embodiment the inner channel thereof may at some point or gradually be formed tapered, The feeder element preferably is further secured in the print head by way of a counter acting nut, screwed to the outer side of the tubular part and abutting the flange like part to which the feeder element is secured, e.g. by the part being screwed into the flange like part via an inner screw thread thereof.

{0034} In a further favorable development of the method according to the invention, the heat sink is produced in an aluminum material, keeping centrifugal forces down for as far iS as increased by the more remote positioning of the weight of the heat sink. Egually if not more important is that the heater block is in the present invention also produced in aluminum, & was recognized that with the preceding measure of the invention, to generally raise and equally distribute the heat within the heat block, the filament material becomes soft in a much cartier stage, therewith reducing both internal resistance, even when in fact increased to some extend by the splitting thereof into separate streams, as well as it’s abrasive effect. It is for this reason recognized that the heat block may be produced in aluminum material, This is all the more so if at least part of the inner wall of anyone of the chamber sections is provided with a diamond, in particular nano-diamond coating. Maintaining a low weight in the print head supports swift and smooth manipelation and movement of the print head and therewith speed and quality as performance factors of a print head.

[on3s] In yet a further development the beater block is provided in a two part form comprising of a circumferential outer block part provided with receptacles for electric heater elements, and a central nner part provided with said first and second section receiving chambers. Preferably and favorably, the central portion is screwed into the outer portion, hence may be released, i.e. taken away therefrom e.g. for replacement, the portions thereto being provided with Inner and outer screw thread respectively.

[00361 In yet a further development if the method of 3D printing, in accordance with the present vention, the heater block is provided with at least one heat sensor, This measure altows for improved comrol of the printer characteristic, in that the temperature may be maintained relatively low if relatively slow printing speeds are desired for any particular section of a work piece, e.g. for high quality or accuracy, and relatively high where large volumes of material may be expelled, e.g. for reason that quality may locally not be of concern or be guaranteed also under such increased printing speeds.

The printing method 1s oven further improved in that the 3D printer system of the present invention is provided with a pressure sensor.

This may be for directly or indirectly sensing feeding pressure of the filament.

Where such a sensor could e.g. also be incladed in the extruder of the filament or to a motor shaft thereof, It may also be the case that a receiving chamber or receiving chamber part is provided with a pressure sensor, A major advanlahe of having such pressure sensor is not only in controlling delivery of a constant stream of material and al certain pressore, but also the possibility to timely control towards a so-called iS retraction action of the filament, in which, at jumps over the work piece, no material is meanwhile expelled as in prior art designs or leaked at such instance, so that with gertainty clean work may be delivered at all times. 00371 It hence goes without saying that the 31 printer according to the present invention is provided with a controller controlling pressure and temperature in conjunction, 1.0. 85 8 function of the local nature of the work piece to be printed, and that different parts of a werk piece may be printed with different speed, volume of flow and/or temperature of delivery,

<9.

Clauses

1. 3D printer, in particnlar for a 3D printing based manufacturing system in which a filament of printing material is driven into a printer head, in which the filament is S driven into a printer head so as to be expelled therefrom in molten 5 form, the method comprising the steps of driving the filament info a heater block thermally separated from a feeder element by means of 8 connection between feeder element and heating block centrally comprising a thermally isolating separater or distance member through which the filament is fed.

2, Printer in accordance with any of the preceding claims, in which the thermally separated connection between feeder element and heating block comprises radially outward disposed screws, firmly connecting the feeder element to the heater block.

3. Printer according to the preceding claim, in which three, regularly distributed screws are disposed for said firm connection, preferably the screws incorporated in a flange-like part for the feeder element,

4. Printer according to any of the preceding claims in which an upper wall part of the heat sink forms a flange part to the feeding element.

3. Printer according to any of the preceding claims in which the feeder element is centrally screwed into an upper or lower wall part of the circumferential heat sink.

6. Printer according to the preceding claim in which the feeder element is formed by a mainly tubular or prismatic part, abutting to the thermally isolating distance member by a distal end face.

7. Printer according to any of the preceding claims, in which the feeder element is further secured in the print bead by way of a counter acting nut screwed to the outer side 23 of the tubular part and abutting the flange like part to which the feeder element is secured, e.g. by the part being screwed into the flange like part via an inner screw thread thereof.

Claims (3)

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