WO2023201444A1

WO2023201444A1 - Apparatus and method for 3d printing

Info

Publication number: WO2023201444A1
Application number: PCT/CA2023/050556
Authority: WO
Inventors: Roger HEISE
Original assignee: Heise Roger
Priority date: 2022-04-23
Filing date: 2023-04-24
Publication date: 2023-10-26

Abstract

A 3D printing apparatus for sand molding for foundry metal casting, the apparatus comprising a frame, the frame defining a printing area disposed within the frame; a 3D printbar mounted on the frame, the 3D printbar comprising a plurality of printheads, the printbar dimensioned to cover a full width of the printing area and capable of bi-directional linear movement along the frame over the width and length of the printing area; a pair of sand spreaders, each sand spreader mounted to opposite sides of the printbar, and each sand spreader capable of independent operation based on direction of movement of the printhead; wherein the printbar and sand spreaders are operative to produce a printed binder layer from the printbar and a sand layer from one of the sand spreaders in a single pass over the printing area.

Description

APPARATUS AND METHOD FOR 3D PRINTING

FIELD OF THE INVENTION

[0001] The present specification relates generally to 3D printing, and more particularly to an apparatus and method for 3D printing.

BACKGROUND OF THE INVENTION

[0002] The following includes information that may be useful in understanding the present disclosure. It is not an admission that any of the information provided herein is prior art nor material to the presently described or claimed inventions, nor that any publication or document that is specifically or implicitly referenced is prior art.

[0003] The traditional process for manufacturing cast metal parts involves the making of forms or patterns of the part to be produced. The patterns are placed in a box configured so that sand prepared with a binder is packed around the pattern. The prepared sand is allowed to harden or set such that the pattern can be removed from the hardened sand, leaving a void or mold in the shape of the part. The mold can then be filled with liquid metal which is allowed to cool and solidify. The part is then removed from the mold, and the used sand can be further processed for re-use, disposed of in a landfill or applied to another industrial use.

[0004] About twenty years ago, a new method was developed to use computerized ink-jet printing technology to print a binder (glue) in a predetermined pattern on thin layers of sand. Subsequent layers are then built up over time to produce a 3D printed mold, along with associated passages for the liquid metal and mold inserts or cores to create specified voids in the final casting, similar to a traditional mold.

[0005] This 3D sand printing process has evolved into serving a market niche for relatively low volume castings. Sand is spread into a thin layer followed by a subsequent computer-controlled jetting application of the binding agent. The printheads are moved in a zig zag, or rastering manner until the entire surface of the sand has been covered where desired. The initial sand layer is spread onto the movable bottom of an open box with the bottom moved up to the highest point of the box sides. Prior to each subsequent layer the bottom is lowered by a constant predetermined distance and the process repeated until the box is filled. The full box is then extracted from the machine to a cleaning position where the solidified parts are removed from the sand bed. The loose unprinted sand is removed and recycled for use in subsequent printing jobs. The quantity of boxes produced may be increased by printing into an additional box while the completed box contents are removed. The overall cycle time is slow, and the precise manipulation of an increasing mass of sand in the boxes requires heavier equipment be integrated into the printer.

[0006] Accordingly, there remains a need for improvements in the art to address the limitations and deficiencies found in the current state of the art.

SUMMARY OF THE INVENTION

[0007] In accordance with an aspect of the invention, there is provided an apparatus and method for 3D printing of molds for foundry metal casting.

[0008] According to an embodiment of the invention, there is provided a 3D printing apparatus comprising: a frame, the frame defining a printing area disposed within the frame; a 3D printbar mounted on the frame, the 3D printbar comprising a plurality of printheads, the printbar dimensioned to cover a full width of the printing area and capable of bi-directional linear movement along the frame over the width and length of the printing area; a pair of sand spreaders, each sand spreader mounted to opposite sides of the printbar, and each sand spreader capable of independent operation based on direction of movement of the printhead; wherein the printbar and sand spreaders are operative to produce a printed binder layer from the printbar and a sand layer from one of the sand spreaders in a single pass over the printing area. [0009] The apparatus may further comprise a pair of sand spreader troughs coupled to each sand spreader, each sand spreader trough operative to store and provide sand for each sand spreader. The 3D printing apparatus may also further comprising an electronic adjustment mechanism coupled to at least one of the sand spreader troughs, the electronic adjustment mechanism enabling and producing movement of the coupled sand spreader trough. Additionally, the printbar may be coupled to power, cooling and binder sources via quick connect couplings.

[0010] The 3D printing apparatus may further comprise a printhead cleaning system, the printhead cleaning system comprising a removable non-contact cleaning trough operative to apply cleaning fluid to the printheads. The application of cleaning fluid to the printheads may be provided via a spray mechanism.

[0011] According to a further embodiment of the invention, the 3D printing apparatus further comprises a moveable machine base disposed within the frame, the machine base operative to provide a platform for 3D printing. The machine base may further comprise one or more closeable openings operative to collect sand within the machine base and further comprising a one-way pushing apparatus within to the machine base, the pushing apparatus operative to push sand within the machine base to one end of the machine base. The base may further comprise a collection device coupled to the machine base operative to collect sand pushed by the pushing apparatus into a storage container

[0012] According to a still further embodiment of the invention, there is provided a method of 3D sand printing using sand and a binder, comprising: defining a printing area on a moveable machine base disposed within a frame; printing a sand mold on the machine base via the method of: simultaneously dispensing the binder from a printbar comprising a plurality of printheads and sand from a sand spreader coupled on one side of the printbar onto the machine base as the printhead moves along the frame over the machine base; indexing the printbar vertically when the printbar reaches one end of the frame; simultaneously dispensing the binder from the printbar and sand from a second sand spreader trough couple on the opposite side of the printhead as the printbar moves along the frame over the machine base in an opposite direction; indexing the printbar vertically when the printbar reaches an opposite end of the frame; and repeating the dispensing and indexing steps to form a sand mold for casting.

[0013] The method may further comprise 3D printing of box walls around the around the sand mold as part of the method of printing the sand mold. The method may also comprise collecting loose sand within the machine base via one or more closeable openings within the machine base. The loose sand may be collected from the machine base into one or more storage containers. The method may further comprise moving the machine base outside of the frame.

[0014] For purposes of summarizing the invention, certain aspects, advantages, and novel features of the invention have been described herein. It is to be understood that not necessarily all such advantages may be achieved in accordance with any one particular embodiment of the invention. Thus, the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein. The features of the invention which are believed to be novel are particularly pointed out and distinctly claimed in the concluding portion of the specification. These and other features, aspects, and advantages of the present invention will become better understood with reference to the following drawings and detailed description.

[0015] Other aspects and features according to the present application will become apparent to those ordinarily skilled in the art upon review of the following description of embodiments of the invention in conjunction with the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Reference will now be made to the accompanying drawings which show, by way of example only, embodiments of the invention, and how they may be carried into effect, and in which:

[0017] Figure 1 is a block diagram of a 3D printer assembly according to an embodiment;

[0018] Figure 2 is a bottom plan schematic view of the printbar assembly according to an embodiment;

[0019] Figure 3 is a perspective view of the printbar assembly according to an embodiment;

[0020] Figure 4 is an end view of Figure 3;

[0021] Figure 5 is a side view of Figure 3;

[0022] Figure 6 is a perspective view of the printbar and frame according to an embodiment;

[0023] Figure 7 is a top view of a sand trough according to an embodiment;

[0024] Figure 8 is a side view of Figure 7;

[0025] Figure 9 is a perspective view of Figure 7; and

[0026] Figure 10 is a front view of Figure 7.

[0027] Like reference numerals indicate like or corresponding elements in the drawings. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The present invention relates generally to 3D printing, and more particularly to an apparatus and method for 3D sand printing for molds for metal casting.

[0029] As used herein “sand” describes the loose substrate used for the 3D printing process, and may be natural sand, artificial sand, an aggregate material, or any similar fine particle material that may be formed using a binder to create a mold.

[0030] As used herein, a “binder” is an adhesive material which is used to bind sand particles together as part of the 3D printing process. The binder may be a liquid glue which binds the flowable sand into a solid to create the mold.

[0031] As shown in Figure 1 , a 3D printing device 100 is formed from a full width printbar 110 mounted in a frame 120. The printbar 110 covers the full width of the frame 120 and is moveable along the long axis of the frame 120. The frame 120 is moveable longitudinally along a base 130 to perform multiple consecutive printing operations as described further below.

[0032] The printbar 110 is comprised from multiple printheads 140, with the printheads 140 arranged in a pattern suitable to provide printhead coverage over the full length of the printbar 110. One suitable pattern would be a staggered pattern of alternating printhead positions as shown in Figure 2. The number and density of the printheads 140 is determined by the size of the printbar 110. As an example, a 52-inch printbar may be covered by 20 printheads arranged in a staggered pattern as described above. Thus, the printbar 110 is capable of printing over the entire width of the print area in a single pass, without the need for rastering as is necessary with smaller printbars and printheads.

[0033] Mounted on either side of the printbar 110 are sand spreaders 150 coupled to sand troughs 160. The sand troughs 160 may have a variable spreader opening to allow for different sizes of substrates to be used with the same trough. The sand spreaders 150 are integrated with the printhead assembly in the printbar 110 such that a single pass of the printbar results in a printed layer containing both the binder for the printheads 140 and the sand layer from the sand spreaders 150. After each pass, the printbar 140 is raised (e.g. 1/1000^th of an inch) and the next printing pass is made in the opposite direction.

[0034] As shown, the printbar 110 includes a sand spreader 150 on either side of the printheads 140 so that each subsequent layer of sand and binder can be spread following the movement of the printbar 110 in either direction along the frame. Accordingly, the printing process may be twice as fast as the rastering processes known in the art, or possibly faster when compared to specific rostering processes.

[0035] With the bi-directional sand spreading process, in order to prevent the lead spreader 150 from disturbing the unprinted layer, it may be raised at the beginning of each change in print direction, then lowered into position for spreading the next layer when the direction of motion changes (and vice-versa for the other sand spreader 150).

[0036] The general known practice is to convey the sand into a spreader trough, then use a mechanical means to level the sand along the trough length. The present device 100 uses a chute 170 positioned above the spreader troughs 150 to provide a continuous sand feed from the bulk sand supply into the two spreader troughs 150 moving with the printbar 110. The chute 170 may be designed as a collapsible length of pipe connected to the bulk sand tank above and both troughs below. The eliminates the need to pause the printing process every few cycles to replenish the troughs with fresh sand, as it done in the known art.

[0037] The printhead may be clamped into position on a three point locator with positive position location features. The electrical, cooling, and binder lines may be joined at the end of the printhead with quick connect couplings, allowing the printhead to be rapidly removed for any major servicing or maintenance requirements.

[0038] As the printbar 110 consists of multiple printheads 140, cleaning may be performed using a removable non-contact cleaning trough 180 which will spray cleaning fluid on the bottom of the printheads while activating the cleaning function on each printhead. Preferably, there may be no moving parts involved in the cleaning. The cleaning trough 180 may be positioned at either end of the frame 120. The cleaning trough 180 may comprise a tray with perforated hoses which spray fluid up onto printheads, and then uses gravity and vacuum pressure to remove the fluid. The printbar 140 may be moved to one end of frame120 and the cleaning trough 180 manually attached and removed to printbar as needed for cleaning.

[0039] In operation, as the printbar 110 is moved vertically rather than the bottom base 130 which is under an increasing sand load as print progresses, the heavy mold handling construction found in the known art is eliminated, as the loaded printbar 110 and sand spreader 150 assembly weight will be less than five percent of the maximum sand weight, reducing overall weight, and thereby cost of the entire device 100.

[0040] The printbar 110 is designed to print within a printing area on a flat surface provided by base 130. Removable walls may be positioned around the desired printing area of the base. Alternatively, the device may print box walls as part of the printing cycle. When a print job is complete, the frame 120 will index to a second position along the base 130, exposing the completed printing job for part and sand removal.

[0041] Following frame indexing to the second position, openings in the base will allow loose sand to flow under gravity into the base. The sand may be removed using a one way pushing apparatus (i.e. an auger) to push it to the end of the base, where it will be collected in a hopper for conveying to storage tanks for re-use on a subsequent print job. The openings will then be closed before indexing the printer back to the previous position. Additionally, multiple bases may be aligned adjacent to each other such that the printing apparatus may be indexed over an adjacent base to commence a new printing process while part and sand removal takes place on the first base.

[0042] Thus, in operation, the printbar 110 moves along the frame 120 to provide bidirection printing via binder dispensed from printheads 140 and sand dispenser from sand spreaders 150. Cleaning of the printheads 140 may be performed by cleaning trough 180 as needed.

[0043] It should also be noted that the steps described in the method of use can be carried out in many different orders according to user preference. The use of "step of" should not be interpreted as "step for", in the claims herein and is not intended to invoke any statutory interpretation provisions. It should also be noted that, under appropriate circumstances, considering such issues as design preference, user preferences, marketing preferences, cost, structural requirements, available materials, technological advances, etc., other methods are taught herein.

[0044] The embodiments of the invention described herein are exemplary and numerous modifications, variations and rearrangements can be readily envisioned to achieve substantially equivalent results, all of which are intended to be embraced within the spirit and scope of the invention. Further, the purpose of the foregoing abstract is to enable the Patent and Trademark Office and the public generally, and especially the scientist, engineers and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application.

[0045] The present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Certain adaptations and modifications of the invention will be obvious to those skilled in the art. Therefore, the presently discussed embodiments are considered to be illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than the foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

What is claimed is:

1 . A 3D printing apparatus, comprising: a frame, the frame defining a printing area disposed within the frame; a 3D printbar mounted on the frame, the 3D printbar comprising a plurality of printheads, the printbar dimensioned to cover a full width of the printing area and capable of bi-directional linear movement along the frame over the width and length of the printing area; a pair of sand spreaders, each sand spreader mounted to opposite sides of the printbar, and each sand spreader capable of independent operation based on direction of movement of the printhead; wherein the printbar and sand spreaders are operative to produce a printed binder layer from the printbar and a sand layer from one of the sand spreaders in a single pass over the printing area.

2. The 3D printing apparatus of claim 1 , further comprising a pair of sand spreader troughs coupled to each sand spreader, each sand spreader trough operative to store and provide sand for each sand spreader.

3. The 3D printing apparatus of claim 1 , further comprising an electronic adjustment mechanism coupled to at least one of the sand spreader troughs, the electronic adjustment mechanism enabling and producing movement of the coupled sand spreader trough.

4. The 3D printing apparatus of claim 1 , wherein the printbar is coupled to power, cooling and binder sources via quick connect couplings.

5. The 3D printing apparatus of claim 1 , further comprising a printhead cleaning system, the printhead cleaning system comprising a removable non-contact cleaning trough operative to apply cleaning fluid to the printheads. The 3D printing apparatus of claim 5, wherein the application of cleaning fluid to the printheads is provided via a spray mechanism. The 3D printing apparatus of claim 1 , further comprising a moveable base disposed within the frame, the machine base operative to provide a platform for 3D printing and defining the printing area. The 3D printing apparatus of claim 7, wherein the base further comprises one or more closeable openings operative to collect sand within the base and further comprising a one-way pushing apparatus within the base, the pushing apparatus operative to push sand within the base to one end of the base. The 3D printing apparatus of claim 8, further comprising a collection device coupled to the base operative to collect sand pushed by the pushing apparatus into a storage container. A method of 3D sand printing using sand and a binder, comprising: defining a printing area on a moveable base disposed within a frame; printing a sand mold on the base via the method of: simultaneously dispensing the binder from a printbar comprising a plurality of printheads and sand from a sand spreader coupled on one side of the printbar onto a printing area on the base as the printhead moves along the frame over the base; indexing the printbar vertically when the printbar reaches one end of the frame; simultaneously dispensing the binder from the printbar and sand from a second sand spreader trough couple on the opposite side of the printhead as the printbar moves along the frame over the base in an opposite direction indexing the printbar vertically when the printbar reaches an opposite end of the frame; and repeating the dispensing and indexing steps to form a sand mold for casting. The method of claim 10, further comprising setting removable walls on the base to defining the printing area on the base. The method of claim 10, further comprising collecting loose sand within the machine base via one or more closeable openings within the machine base. The method of claim 12, further comprising collecting the sand within the machine base into one or more storage containers. The method of claim 10, further comprising moving the base outside of the frame when printing is complete. The method of claim 10, wherein the vertical indexing is 1/1000^th of an inch.