RU182393U1 - 3D print head - Google Patents

Abstract

A print head for a 3D printer, including a housing with two extruders located inside it, with height-adjustable nozzles connected to the supply channels of the consumable material, with the lift cable of the left extruder and the lift cable of the right extruder located in the upper part of the housing, and the print head housing itself is attached to the base, on the sides of which there are slides for the movement of the print head along the XY coordinate axes, while the slide for the movement of the print head along the Z axis is perpendicular to the base and attached vertically to the side of the printhead housing, and the extruder is switched to the active or inactive position using a switching module, including a control board and a switching mechanism with an electric motor connected to the extruder hoist cables, and the desired extruder is lifted for by pulling the desired cable with the electric motor and withdrawing the inactive extruder to the position in which the nozzle of the inactive extruder is It rises above the print plane.

Description

Application area

The utility model relates to the technology of manufacturing a three-dimensional product using a digital 3D model by the method of layer-by-layer printing with molten polymer filament (FDM), namely, to an improved 3d print head.

The technical field to which the utility model belongs.

The utility model relates to the technology of manufacturing a three-dimensional (bulk) product (physical object, or layout, or model) using a digital 3D model by rapid prototyping methods, which can be implemented by extrusion deposition of a sequence of layers in the cross section of the product. Extrusion 3D printers can be used in various fields of human activity, for example, in the production and development of new products - for the rapid manufacture of prototype models.

The level of technology.

3D printing is the construction of a real object based on a 3D model created on a computer. Then the digital three-dimensional model is saved in the format of the STL file, after which the 3D printer, on which the file for printing is output, forms the real product.

The printing process itself is a series of repeating cycles associated with the creation of three-dimensional models, applying a layer of consumables to the printer desktop, moving the desktop down to the level of the finished layer and removing waste from the surface of the table.

The cycles continuously follow one after another: the next layer is applied to the first layer of material, the elevator is lowered again and so on until the finished product is on the desktop.

3D printing can be carried out in different ways and using different materials, which are based on the principle of layer-by-layer creation (growing) of a solid object, in particular, using FDM (Fused Deposition Modeling) technology of layer-by-layer printing with molten polymer filament (or a method of layer-by-layer deposition or modeling deposition method), as a result of which the object is formed by layering on the surface of the working table (work surface) of a layer formed by molten thread from a fusible building material Methods and material (consumable or modeling material), for example, plastic, with stepwise displacement desktop down to a height formed layer.

The principle of operation of a 3d printer is based on the principle of gradual (layer-by-layer) creation of a solid model that “grows” from a certain material, which will be discussed a bit later. The advantages of 3D printing over the usual, manual methods of building models are high speed, simplicity and relatively low cost.

For example, to create a 3D model or any part manually, it can take quite a lot of time - from several days to months. After all, this includes not only the manufacturing process itself, but also the preliminary work - drawings and diagrams of the future product, which still do not give a complete vision of the final result.

As a result, development costs significantly increase, the time period from product development to serial production increases.

3D technologies can completely eliminate manual labor and the need to make drawings and calculations on paper, because the program allows you to see the model in all angles already on the screen, and eliminate the identified shortcomings not in the process of creation, as it happens with manual manufacturing, but directly in the development and create a model in a few hours.

In this case, the possibility of errors inherent in manual work is practically eliminated.

A 3D printer is a peripheral computer device that, according to a digital volumetric model, creates a material object by layer-by-layer application of rapidly hardening material. For the operation of such a device, a three-dimensional computer model is required, executed in any of the 3D editors or obtained on a 3D scanner. Today, there are several varieties, depending on the technology used.

The claimed utility model is used for 3D printing using FDM 3D printers.

This method of 3D printing is carried out by extrusion, based on the forcing of the molten material through a thin hole in the extruder.

FDM printing technology consists in the following: a temperature-controlled printhead (or extruder) heats a thread from a fusible material to a fluid state, and with high accuracy delivers the molten material in thin layers onto the working surface of a 3D printer. The layers are applied to each other, joined together and harden, gradually forming the finished product. The print head squeezes the liquid material layer by layer, moving freely both in the plane of the layer and vertically. To position the print head, a Cartesian coordinate system is used, according to which in the design of the printer the print head or the desktop on which the product is formed are moved along three mutually perpendicular guides.

The technology was invented in the late 80s by Scott Kramp (company Stratasys).

In particular, from the patents US 5121329, US 5340433, US 5738817, US 5764521, US 6022207 of the company Stratasys (Stratasys, Inc), the technology of constructing a 3D object by a model for computer-aided design (CAD) by layer-by-layer extrusion deposition is known flowing building material (modeling material). In this case, the building material is fed through the tip (nozzle) of the print (extrusion) head and deposited as a sequence of tracks on the substrate in the XY plane. Then the print head rises relative to the substrate along the Z axis (perpendicular to the XY plane) by one step, and the process is repeated to form a 3D object similar to a CAD model.

Building material is typically loaded into the machine as an elastic thread wound on a feeding reel, as described in US Pat. No. 5121329. As a building material, a hardening material is used that adheres to the previous layer with adequate adhesion after hardening and which can be fed as an elastic thread. The feed rollers driven by an electric motor feed a strand of filaments into a heating element mounted on an extrusion head. In the heating element, the thread is heated to a pour point. Fluid building material is extruded from the tip at the far end of the heating element and deposited on the base (desktop surface). The consumption of material displaced from the tip depends on the speed of advancement of the thread with the extrusion head. The controller controls the movement of the extrusion head in the horizontal XY plane, the movement of the worktable in the vertical Z direction, and the feed rate of the filament by the feed rollers. With the simultaneous control of these technological variables, the building material is applied in layers in the form of “rollers” along the tool paths defined by the model of the computer-aided design system. The displaced material is deposited on the previously deposited material and hardens with the formation of a three-dimensional product according to the model from the computer-aided design system.

As a result of layer-by-layer formation of the product, stripes are formed on its outer surface. In general, curved and curved surfaces have a “stepped” appearance, which is caused by the layer-by-layer representation of their sections with a rectangular configuration of faces. The serrated effect is more pronounced as the layer thickness increases. Although dentation does not affect the strength of an object, it impairs its aesthetic perception. The surface roughness of objects obtained on the basis of layer-by-layer manufacturing technologies is also the result of errors in the process of layer building.

State of the art

At present, printers with a double extruder, that is, including a print head containing two extruders at once, are increasingly used. (http://homecnc.ru/3d-printer/92-pechatayushaya-golovka-3d-printera).

Printers with a double extruder find application in creating support structures and in printing two-color objects, since they can use two types of plastic. One of them can dissolve in ordinary water and is used to print support parts, and a working PLA or ABS thread is already fed into the second extruder.

The disadvantage of printers with a print head containing two extruders is that both extruders are mounted on the same print head, and therefore simultaneous printing is inferior: the printer has to use the extruders individually, as needed.

The technology is still "raw", which is manifested in a decrease in the speed of the device due to an increase in the size and weight of the print head. In addition, during operation, a nozzle that does not participate in printing, at best, leaves traces of filament on the surface of the object being drawn, and in the worst case, can deform it.

From RU 161249 (priority 04.09.2015) a printhead of an inkjet 3D printer is known comprising a movable platform made in a single housing with two nozzles with heaters placed on it and a nozzle switching mechanism. The position of the head is determined by the position sensor of the moving platform and is limited by a position limiter. The print head of the 3D inkjet printer is equipped with a nozzle valve configured to deflect, locking one of the nozzles and opening the other when switching nozzles.

From RU 171905 (priority 07.03.2017) a printhead of an inkjet 3D printer is known, a 3D inkjet printer including a base on which a feeding mechanism for printing material is fixed, an engine configured to rotate an eccentric that drives a single platform, valves configured to locking the inactive extruder, a single platform that contains two easily removable extruders with heating elements, a self-locking switching mechanism configured to position the ate in the working position, and spring-loaded rollers, made with the possibility of pressing the material to the feed mechanism for the currently active extruder. The self-locking mechanism is made in the form of a plate with a profiled cut-out with the possibility of self-locking of an eccentric fixed in one of the working positions in the profiled cut-out of the plate mounted on a single platform.

The disadvantage of these analogues is, in the first case, the technologically complex design of the device, which affects the reliability of the device as a whole, and in the second case, the adhesion of plastic residues to the self-locking mechanism plate, which can lead to problems with printing or artifacts on the model.

The closest analogue of the claimed device is a print head for a 3d printer, described in electronic sources (httpe3d_n1_dual_ot_rec /: //raise3d.ru/application_experience/obzor_3d-printera_rais; https://3deshnik.ru/blogs/tiger/chestnyj-obzor-ot-tiger -raise-vs-picasso.).

The print head of an inkjet 3D printer, an inkjet 3D printer including a housing, inside of which at the top there are two stepper motors, the FDM material is fed directly to one or the other extruder of the print head, made in a single housing and containing a platform with two nozzles placed on it heaters.

Significant disadvantages of such a device is that the height calibration of the nozzle of the extruder, which must be taken out of work, is done manually. To do this, park the printer to zero, unscrew the screw holding the desired extruder, and calibrate the extension, followed by touching the nozzle of the table extruder and twisting the extruder back. In addition, for the subsequent height calibration of this extruder, it will be necessary to re-calibrate the height manually.

The objective of the claimed device is to eliminate these significant drawbacks of printers with a print head containing two extruders, which allows to obtain high quality external surface of the 3D model. At the same time, the task is also to eliminate the calibration of the nozzle height manually, which greatly simplifies the printing technology and significantly reduces printing time, by eliminating unnecessary operations when calibrating the nozzle height.

The technical result, which is provided by the claimed device, is the high quality of the external surface of the 3D model, as well as a significant reduction in printing time to obtain the finished product, which is ensured by the removal of the system for switching the print head extruders into a separate device, thus eliminating manual nozzle height calibration, since in this case, the nozzle switching is carried out using the switching module of the active extruder, in which the switching mechanism contains engine.

Also, the technical result is a significant simplification of the design of the print head, due to the removal of the switching module in a separate unit, which significantly reduces the number of breakdowns and malfunctions of the device when it is used, and also eliminates printing problems associated with the ingress of residual molten material onto the manufactured model from the nozzle, out of work.

Also, the use of the claimed device allows the printing of extremely complex parts with cavities closed for machining, by printing support with specialized, soluble material, while work can be carried out with high-temperature engineering plastics.

Brief Description of the Drawings

The design features of this print head FDM (FFF) 3D printer are illustrated in figure 1.

The figure shows the print head FDM (FFF) 3D printer with two extruders. The 3D printer's print head includes a housing (1), with two right extruder (3) and a left extruder (2) located inside it, with height-adjustable nozzles (10) connected to the supply channels of the consumable (15). In the upper part of the housing are the lifting cable of the left extruder (5) and the lifting cable of the right extruder (4), the active extruder is returned to the lower position using springs (6).

The housing of the print head (1) is attached to the base (7), on the sides of which there is a slide (8) for moving the print head along the XY coordinate axes, and the slide for moving the print head along the Z axis (9) is perpendicular to the base and attached vertically to the right side of the printhead housing.

Design features of the switching module of the active extruder are illustrated in figure 2.

The switching module of the active extruder includes a control board (11), a switching mechanism with an electric motor (12), a lift cable for the left extruder (5) and a lift cable for the right extruder (4).

The figure 3 shows the location of the print head relative to the print surface relative to the coordinate axes XYZ.

The figure 4 shows the location of the print head (13) relative to the print surface (14) relative to the coordinate axes XY.

The figure 5 shows the location of the print head (13) relative to the print surface (12) relative to the coordinate axes XZ.

The figure 6 shows the height of the nozzle, which corresponds to 3 mm, which eliminates the problems with printing associated with the ingress of residual molten material onto the manufactured model from the nozzle taken out of operation. It was revealed that it is this lift height of the inactive nozzle that is optimal and allows you to get the manufactured model, on which there are no residues of molten material flowing from the nozzle taken out of work.

In general terms, the claimed device the claimed device is a printhead for a 3D printer, including a housing, with two extruders located inside it, with height-adjustable nozzles connected to the supply channels of the consumable material, and the elevator cable of the left extruder is located in the upper part of the housing and the right extruder lift cable, and the print head housing itself is attached to the base, on the sides of which there are slides for the movement of the print head along the axes of the XY axis, while the slide for moving the print head along the Z axis is perpendicular to the base and attached vertically to the side of the print head housing, and the extruders are switched to the active or inactive position using a switching module including a control board and a switching mechanism with an electric motor, connected to the hoist cables of the extruders, and the desired extruder is lifted by pulling the desired cable by the electric motor and removing some active extruder to a position in which the nozzle of the inactive extruder is above the printing plane.

Exercise

The print head of a 3D printer consists of two extruders 5 and 6, one of which is the main extruder that prints the main material with a heating temperature of up to 500 ° C and an auxiliary extruder designed to print support materials with a heating temperature of up to 300 ° C.

The board controls the switching module, and it, in turn, switches the extruders using the extruder hoist cables. By pulling the desired cable, the switching module diverts the inactive nozzle to a position located above the print plane. Switching occurs by means of an electric motor according to the corresponding signal. The desired (active) nozzle is lowered to the lower position, and the unnecessary (inactive) nozzle is retracted upward. The return of the active extruder to the lower position guarantees the elastic force of the springs 6. The diagram shows the position in which the second extruder is lowered to the operating position, the first extruder is raised, that is, it is inactive. The lift cable of the second extruder is weakened, and that under the action of the elastic force of the springs 6 lowers to a lower fixed point.

The feed mechanism of the printing (consumable) material can be performed in any design. The switching mechanism with an electric motor can be made in the form of an electric motor and controlled by a printer control module or control unit.

The printing process is as follows: preparation of 3 d-models, preparation of the printer, printing process, removing the finished model from the printer, processing the finished model or removing supporting elements if necessary.

Preparing a 3d model involves transforming it from a set of surfaces of any order and a set of coordinates that the printer understands. This is done using programs called slicers.

The preparation of the printer consists in starting up the unit, preparing supplies and printing surface, warming up the print head, table and camera, fine-tuning, if necessary.

Next, the printing process starts. The layer that lies on the printed surface is called the first layer. In most cases, the model’s body is first printed with the main material, i.e. the first extruder is in the lower position, the second is retracted above the printing plane by a distance h (as indicated in the diagram). When the printing of the model body in this particular layer is completed, a command is sent to the control board of the switching mechanism of the active extruder. The mechanism pulls the lift cable of the first extruder, lifting it. It becomes inactive. In this case, the second extruder is lowered, which in turn becomes active. The process of building elements supporting the main body is ongoing. When the printing of supporting elements in this particular layer is completed, a command is sent to the control board of the switching mechanism of the active extruder. The mechanism pulls the lift cable of the second extruder, raising it above the printing plane. It becomes inactive. In this case, the first extruder is lowered, which in turn becomes active. The active nozzle of the print head extruder changes and the process is repeated layer by layer until the printing process is completed. This solution can significantly improve the surface quality of the resulting models due to the withdrawal of the inactive nozzle from the print layer.

Removing the finished model from the printer is done some time after the completion of the printing process. This is due to the need to comply with safety regulations when working with the unit.

Processing of the finished model or the removal of supporting elements is carried out as necessary.

The claimed device allows you to get 3D models, and the technology itself due to the removal of the switching module outside the body of the print head greatly simplifies the design itself, reduces the number of breakdowns and allows you to optimize the process by eliminating manual extruder settings from it. The process allows to obtain models with a minimum percentage of defects associated with the sticking of residual material from an inactive extruder to the manufactured model.

Claims (1)

A print head for a 3D printer, including a housing with two extruders located inside it, with height-adjustable nozzles connected to the supply channels of the consumable material, with the lift cable of the left extruder and the lift cable of the right extruder located in the upper part of the housing, and the print head housing itself is attached to the base, on the sides of which there are slides for the movement of the print head along the XY coordinate axes, while the slide for the movement of the print head along the Z axis is perpendicular to the base and attached vertically to the side of the printhead housing, and the extruder is switched to the active or inactive position using a switching module, including a control board and a switching mechanism with an electric motor connected to the extruder hoist cables, and the desired extruder is lifted for by pulling the desired cable with the electric motor and withdrawing the inactive extruder to the position in which the nozzle of the inactive extruder is It goes above the print plane.

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