CN211917720U - 3D printing device - Google Patents

Abstract

The utility model discloses a 3D printing device relates to 3D and prints technical field. The device comprises a material melting and extruding mechanism, a melting material conveying pipe and a printing head, wherein the melting material conveying pipe is of a bendable structure, one end of the melting material conveying pipe is connected with an output port of the material melting and extruding mechanism, the other end of the melting material conveying pipe is connected with a melting material input port of the printing head, the printing head is connected with a melting material flow control mechanism, the material melting and extruding mechanism is separated from the printing head, and the melting material is conveyed through the melting material conveying pipe. The material melting and extruding mechanism heats the solid particle raw material entering from the feeding hole into fluid, fully plasticizes the melting material and generates extruding pressure. The molten material is conveyed to the printing head through the molten material conveying pipe, and the molten material is finally controlled by the printing head, such as the printing flow or the cut-off flow of the material is adjusted, so that the running speed can be effectively improved, the extrusion flow of the material is increased, and the quality of the material is improved.

Description

3D printing device

Technical Field

The embodiment of the utility model provides a 3D prints technical field, concretely relates to 3D printing device.

Background

In principle, the current industrial manufacturing method of the real object only has 3 processes, namely material reduction manufacturing, material equal manufacturing and material increase manufacturing.

Reducing material manufacturing: in the age of stone products, a desired part is obtained by knocking a stone with another stone and subtracting the redundant part, and a whole material is cut by using a cutter of a conventional substitute machine tool to obtain a partial material to form a finished product.

And (3) material preparation: from pottery to bronze era, fluid or liquid is injected into a mould, and a finished product with the same volume as the mould is obtained after cooling or sintering, and various modern processes such as injection molding, casting and the like are all made of equal materials.

Additive manufacturing: the nature always uses additive manufacturing, from one seed to a large ginseng tree, from a fertilized egg to a complex animal body structure, the natural additive manufacturing principle is gradually used until the modern manufacturing field. Such as 3D printing, build the finished product by adding material layer by layer.

The three manufacturing modes have different characteristics, and the material reduction manufacturing needs to prepare a piece of material larger than a finished product firstly and then remove ten percent to ninety percent of the material, so that the waste is great, the labor and the time are wasted, and the accurate finished product can be obtained. The manufacturing of the materials requires that the mold is firstly prepared, the early investment is high, but the single-piece production efficiency can be high. Both of the above two methods cannot produce highly complex finished products at one time, because the material is 3-dimensional, when the material is removed, the cutter interferes, and the cutter has an inaccessible part blocked by the 3-dimensional structure of the finished product, and when the material manufacturing mold does not remove the material, the mold interferes, and the part blocked by the 3-dimensional structure of the finished product has an inaccessible part. Therefore, if a complex finished product is to be produced, the product design is divided into a plurality of unnecessary parts to be processed separately.

With the economic development and the technical progress, particularly the development of the computer technology information technology in recent times, products are more and more complex, the variety is more and more, the batch of single products is less and less, the defects of material reduction and equal material manufacturing are more and more obvious, and particularly in the field of complex and light-weight products. Additive manufacturing in this case shows natural advantages:

the core principle of 3D printing, which is a main technology of additive manufacturing, is dimension reduction, various interferences occur in a 3-dimensional object in a manufacturing process, the manufacturing process cannot reach the inside of a material, namely the interference occurs when a 3-dimensional structure on the surface of the material is complex, the 3D printing process is performed on a 2-dimensional surface, the 3-dimensional spatial interference problem does not exist, a complex 3-dimensional model is decomposed into a plurality of 2-dimensional sheet layers through special software, and the layers have thicknesses but are thin enough in the thickness direction and can be considered to be 2-dimensional approximately, so that the 3D printing method has natural advantages for complex products. However, as can be seen from the foregoing, the reduced material and the equal material are both surfaces related to the whole material and can be regarded as surface processing, and the 3D printing is related to the inside of the material and can be regarded as bulk processing, so that the efficiency of the 3D printing is much lower than the former two methods at the same moving speed, and the larger the size of an object is, the larger the ratio of volume to area is, and the lower the efficiency of the 3D printing is. In small and medium sizes such as less than one meter, the difference in efficiency is not obvious, but the 3D printing is obvious for the advantages of complex products, so that in the field of small and medium-sized complex products, 3D printing has developed a plurality of categories.

Most of the existing 3D printing technology categories are only suitable for small products, namely the size level from decimeter to meter, and the size of the 3D printing technology category cannot reach the size above the meter used in daily life (namely the size of the product designed according to the height of people), so that the 3D printing technology category cannot enter the mainstream market. Present 3D printing technology framework is difficult to accomplish into the size and is more than the meter level, because any kind of 3D printing technology is the integrated system of multiple technique, after the shaping size increase, its supplementary technique can not match with it, meter level size and decimeter level size are 10 times of the relation in size, nevertheless calculate with shaping volume (space), cubic meter is 1000 times of cubic decimeter, consequently printing apparatus need have nearly thousand times's promotion in the material volume theory that needs the processing in the same time, obviously not that simple enlarged structure can accomplish.

The following will briefly describe the reason principle that the currently mainstream SLA/DLP, SLS and FDM 3D printing processes cannot be large-sized.

1. SLA/DLP is a 3D printing technique using a light-curing (hardening) resin as a raw material, and is different from DLP in the way of using light. SLA uses UV light beam to scan photocuring resin and obtains the shape of printing the layer, can regard as the process of point to line, line to face shaping gradually, and DLP uses the projection principle of similar projecting apparatus, the required light of a printing layer of projection comes the curing resin, the process of point to line, line to face has been skipped to compare SLA technique, DLP is very many times faster than SLA on the individual layer shaping speed, DLP has also got rid of the required high-accuracy optics of SLA and has swung the mirror system, therefore DLP's cost is lower, at present, mass market mostly adopts DLP's technology to do photocuring 3D and print.

The DLP technology is difficult to realize large-scale, because the projection resolution adopted by the DLP technology is limited (usually 1920 x 1080), the projection resolution is about 0.1mm when the DLP technology is used in a decimetric scale, after the DLP technology is large-scale, the volume is enlarged by 1000 times, the area of a single layer is enlarged by 100 times, in order to keep the size of the single pixel to be 0.1mm, the total pixel quantity of the DLP is also enlarged by 100 times, namely the resolution is required to reach 19200 x 10800, otherwise, the edge of a forming layer is provided with sawteeth (similar to sawteeth after picture enlargement), and the prior art cannot achieve the extremely high resolution. The light-cured resin material used in the light-curing technology must be cured by light reaction, in order to ensure that the resin material is fully cured, the thickness of each layer cannot be too thick, the maximum thickness cannot exceed 2mm, otherwise, light cannot penetrate through the excessively thick material to cure the material, and the thickness of the 2mm layer is relatively too thin when a large-size object is molded, so that the total layer number is increased, and the integral molding efficiency is sharply reduced. The photo-curing material has high production cost, is not durable (easy to decompose), has toxicity and insufficient mechanical properties (cannot meet daily use), particularly the photo-curing resin material has high cost which is 0.6 yuan/g on average at present, the weight of objects commonly used by human bodies is 10kg-50kg (such as sofas, chairs, tables and the like), and the material cost can reach 6000 ion 50000 yuan only by simple calculation. Therefore, the photocuring 3D printing technology is only suitable for small-sized 3D models, cannot be used in practice, can only be used for exhibition and appreciation, and cannot realize large-scale and practical use.

2. The SLS process (selective laser sintering), which is a process for mainly manufacturing metal products, uses a high-energy laser beam to scan and process the material powder into extremely fine material powder, so that the material powder heated instantly is melted and bonded, the forming process is similar to SLA, and is a process of gradually forming point-to-line and line-to-surface, and the whole forming process is linear, so that the forming volume is increased, and the forming speed of a single piece is reduced by 3 times. Most SLS processes can be used after the metal or thermoplastic resin is powdered, the raw material requires additional powder processing cost, usually 5 times the raw material cost after being powdered, and the material powder can cause the surface of the SLS molded object to form powder particles, the surface is usually rougher than other 3D printing technologies, and the roughness is related to the layer height and the particle size of the powder. The SLS process enables the material powder to fill the whole forming space, and the unsintered material becomes a support, so the SLS process can not print a support structure independently, the utilization rate of the powder material can almost reach 100%, and no waste is caused.

The SLS process requires heating of the material powder to a temperature slightly below the melting temperature of the material when printing the product, thereby reducing the required output power of the laser and reducing the internal stresses due to linear fabrication cooling. After the enlargement, the volume is enlarged by 1000 times, and assuming that the enlarged volume is about 12m3(2m × 3m × 2m), it takes tens of tons to fill the whole molding space with the plastic material powder, and even tens of tons to one hundred tons if the metal powder is used, the material is heated and kept at 100 degrees or more. In order to solve the problem of material powder generation after large-scale production, the original mechanical structure design and process of the SLS process become very complicated, the total cost of materials is very high, and the energy consumption is also very large.

The SLS process uses the laser power and is closely related to the forming speed, the maximum power of the SLS process is generally between 0.4kw and 1kw, according to the principle of geometric amplification, the product volume is amplified by 1000 times, theoretically, the maximum power of the SLS process is also amplified by 1000 times correspondingly, otherwise, the SLS process is equivalent to using a tiny light spot to carve a picture which is increased by thousand times, the efficiency is unacceptably low, or the maximum power of a matched laser needs 400kw to 1000kw, according to the current laser technology, the common power is below 6kw, and 400kw can only be realized in the military field, so that the SLS process is difficult to realize at present.

3. The FDM process (fused deposition modeling), also called fuse deposition, mainly uses the thermoplastic plastic wire with the diameter of 1mm-3mm as the printing material, the printing head (3) melts the wire to coat and form the shape of each layer, and is also the process of point-to-line and line-to-surface gradual modeling, the technology required by the FDM process is the simplest of all 3D printing process types, except that the moving structure only needs the wire feeding mechanism and the heating head (printing head), compared with the SLS process and the DLP process, the FDM process does not use expensive materials and expensive technology, the modeling principle is simpler, and the FDM process has the possibility of large-scale.

The FDM process is a linear molding. The volume is increased, and the forming speed of the single piece is reduced by 3 times. Therefore, the printing speed must be increased when the FDM is realized in a large scale, and the printing efficiency of the FDM process is related to the material extrusion flow and the movement speed of a printing head.

After the forming volume is enlarged by 1000 times, the diameter of the wire needs to be enlarged by 10 times to reach 10mm-30mm, the extrusion speed of the wire needs to be enlarged by 10 times, and the wire is difficult to bend due to the enlarged diameter of the wire, the bendable diameter is very large, the wire is difficult to bend into a coil, the production is not easy, and extra processing cost is needed. And the thermal conductivity of the material is limited, when the diameter of the wire is increased, the area of the outer surface of the wire is increased by a square, the volume is increased by a cube, the melting heating mode of the mini-machine only heats the outer surface of the wire, the melting efficiency of the wire is seriously reduced, and the printing head of the mini-machine is not applicable any more. The small-size conventional FDM printer uses crowded material gear and silk material surface meshing roll to produce and extrudes thrust, and after silk material line footpath became thick 10 times, the silk material sectional area enlargies 100 times, and extrusion speed need improve 10 times simultaneously, and the extrusion resistance of silk material becomes very big, and the intensity of silk material epidermis is difficult to bear the thrust of crowded material gear, leads to the epidermis to burst, and crowded material gear skids the idle running. The feeding mechanism of the small-sized machine and the melting structure of the printing head are not suitable after being enlarged. In general, the FDM process needs to realize high-speed movement and large-flow and accurate and controllable extrusion of materials to achieve truly practical large 3D printing.

The FDM process is large-sized to a certain extent by a few companies in the industry, a truss type moving structure (similar to a gantry machining center) is generally adopted, a material melting mechanism and a material extrusion head are arranged on a lower probe arm shaft (Z shaft), the material melting mechanism generally uses a screw type extrusion head similar to an injection molding machine, raw materials use granular raw materials, and the raw materials do not need additional processing (such as processing into wires). In order to achieve certain material extrusion efficiency, the material melt extrusion mechanism mounted at the tail end of the moving structure is heavy, usually weighing several hundred kilograms, so that the rigidity of the mechanical moving structure for mounting and bearing the molten material melt extrusion mechanism must be designed to be strong enough, the inertia of the whole structure participating in the movement is also large, and since a product to be printed is usually complex, a lot of local details are generated in the printing process, short-distance reciprocating motion is required, the printing head must be accelerated and decelerated repeatedly, and the moving structure has high inertia load due to the weight of the extruder and the mechanism, so that the average acceleration is low, the moving speed is low, the energy consumption is high, the printing quality is reduced, and the mechanical abrasion is accelerated. On the contrary, if the weight of the material melt extrusion mechanism is reduced, the whole motion structure is lightened, which will cause that the material extrusion efficiency is not high, the extrusion flow is not enough, and the whole printing efficiency is still not high. Although the framework realizes the large-scale FDM process size, the movement speed and the discharge flow cannot be simultaneously improved, and the printing efficiency is difficult to improve.

In summary, in order to realize an efficient large FDM printing process, it is necessary to simultaneously increase the movement speed and the discharge flow.

Disclosure of Invention

Therefore, the embodiment of the utility model provides a 3D printing device to solve the problem that FDM prints technology printing efficiency low among the prior art.

In order to achieve the above object, the embodiment of the present invention provides the following technical solutions:

according to the utility model discloses in the first aspect, this 3D printing device includes material melting extrusion mechanism, molten material transmission pipe and beats printer head, the molten material transmission pipe is flexible structure, the delivery outlet of material melting extrusion mechanism is connected to the one end of molten material transmission pipe, the molten material input port of beating printer head is connected to the other end of molten material transmission pipe.

Further, a heating wire is wound on the molten material delivery pipe.

Furthermore, the outside of the molten material conveying pipe is coated with an insulating layer.

Further, material melt extrusion mechanism include melting shell, screw extrusion mechanism and melting heating circle, screw extrusion mechanism rotates and sets up in the melting shell, the winding of melting heating circle sets up in the outside of melting shell, screw extrusion mechanism connects the melt extrusion power supply that drives its rotation.

Further, screw extrusion mechanism include engaged with initiative taper screw and driven taper screw, the driving gear is installed in the connection of the screw shaft upper end of initiative taper screw, driven gear is installed in the connection of the screw shaft upper end of driven taper screw, the driving gear meshes with driven gear mutually, the melting reduction gear is connected to initiative taper screw, and the power supply is extruded in the melting of melting reduction gear connection. The power source can adopt various power structures such as an electric motor, a hydraulic motor and the like.

Furthermore, the lower end of the printing head is provided with a printing nozzle, and the printing head is connected with a molten material flow control mechanism.

Furthermore, the molten material flow control mechanism comprises a material control rod arranged in the printing head in a lifting mode and a lifting mechanism for driving the material control rod to lift. The adjustment of the caliber of the printing nozzle is realized by utilizing the lifting of the material control rod, so that the flow is adjusted, and the structure is simple.

Furthermore, the lifting mechanism comprises an electric cylinder and an electric cylinder servo motor which are connected, and the electric cylinder is fixedly connected with the upper end of the material control rod.

Furthermore, the lower end of the material control rod is provided with a transverse flow channel and a vertical flow channel, the transverse flow channel transversely penetrates through two sides of the material control rod, the lower end of the vertical flow channel penetrates through the material control rod, and the upper end of the vertical flow channel is communicated with the transverse flow channel. More accurate adjustment can be realized through horizontal runner and vertical runner, and when the material control lever was in printing nozzle top completely, the bore of printing nozzle was printout bore promptly, and in the material control lever lower extreme got into printing nozzle, the material was exported behind horizontal runner and vertical runner in proper order, and vertical runner bore was printout bore promptly, continues to move down and just can close printing nozzle when the material control lever.

Furthermore, the lower end of the printing head is provided with a tail end heating ring.

The embodiment of the utility model provides a have following advantage:

1. improve functioning speed, the embodiment of the utility model provides a with material melting extrusion mechanism with beat printer head separation, both transmit the fused material through the fused material transmission pipe. The material melting and extruding mechanism heats the solid particle raw material entering from the feeding hole into fluid and generates extruding pressure on the melting material. The molten material is conveyed to the printing head through the molten material conveying pipe, and the printing head performs final control on the molten material.

Due to the characteristics of 3D printing, the product is generally complex, each layer contains a large number of reciprocating filling lines, and the requirements on the movement speed and acceleration of the printing head are high. Therefore, the printing efficiency can be greatly improved by only improving the high mobility and high acceleration of the tail end movement of the printing device. In a limited printing stroke, the highest speed of the movement is determined to a certain extent by higher acceleration, and for the FDM printing process, the acceleration is increased, so that the comprehensive movement speed of the printing can be increased, and the printing efficiency of a printed product can be improved.

Compare current large-scale FDM 3D and beat printer head framework, the embodiment of the utility model provides a designed material melting extrusion mechanism and beat the structure of printer head separation, made material melting extrusion mechanism need not to design at printer motion structure end, and in the structure of the low accelerated motion in the mechanism, does not participate in the high acceleration motion of beating printer head. Or at a fixed position outside the moving structure of the printer without participating in any movement. The moving part (printing head) at the tail end of the printer only needs part of the heating device and the material control structure, and the total weight of the printing head is reduced. The inertia of the end moving part is reduced, the moving structure of the whole printer can also reduce the weight and improve the moving acceleration, the limit of the end moving speed of the existing large FDM 3D printing framework is only about 5000 mm/min, and theoretically, the end moving speed of the novel FDM 3D printing framework can be improved by 20 times or more compared with the end moving speed.

2 increasing the material extrusion flow and improving the material quality

The material melt extrusion mechanism can be placed on a low acceleration motion structure or a non-motion structure, so that the size and weight of the molten material melt extrusion mechanism no longer have a large influence on the printing efficiency (in a low acceleration motion position in the machine), or have no influence (in a fixed position), and the design of the molten material melt extrusion mechanism is more free. In the novel framework, a large extruder with mature technology can be used as a melting material melting and extruding mechanism, materials can be fully plasticized and uniformly mixed by means of pressure and shearing force generated by rotation of a long-stroke double screw of the extruder, impurities such as water vapor, low molecular weight substances and the like in the materials are discharged, the melted materials are very uniform, dense and free of air holes, the material extrusion flow of the large extruder can reach 1-10 kg/min, the material extrusion flow is 5-10 times that of a light single screw extrusion head commonly adopted by the existing large FDM process and 1000 times that of a small wire FDM printer, and therefore the requirements of high-speed printing of 3D printing can be met.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. It should be apparent that the drawings in the following description are merely exemplary, and that other embodiments can be derived from the drawings provided by those of ordinary skill in the art without inventive effort.

The structure, ratio, size and the like shown in the present specification are only used for matching with the content disclosed in the specification, so as to be known and read by people familiar with the technology, and are not used for limiting the limit conditions which can be implemented by the present invention, so that the present invention has no technical essential significance, and any structure modification, ratio relationship change or size adjustment should still fall within the scope which can be covered by the technical content disclosed by the present invention without affecting the efficacy and the achievable purpose of the present invention.

Fig. 1 is a schematic view of a 3D printing apparatus provided in embodiment 1 of the present invention;

FIG. 2 is an enlarged view of a portion of FIG. 1 at A;

fig. 3 is a schematic view of a material melt extrusion mechanism according to embodiment 1 of the present invention;

fig. 4 is a schematic view of a print head according to embodiment 1 of the present invention;

FIG. 5 is an enlarged view of a portion of FIG. 4 at B, showing a material control lever in position I;

fig. 6 is a state diagram ii of the material control lever according to embodiment 1 of the present invention;

fig. 7 is a state diagram iii of the material control rod according to embodiment 1 of the present invention;

fig. 8 is a schematic view of a practical application of the 3D printing apparatus provided in embodiment 1 of the present invention;

FIG. 9 is an enlarged view of a portion of FIG. 8 at C;

fig. 10 is a schematic view of a practical application of the 3D printing apparatus provided in embodiment 2 of the present invention;

in the figure: 1-material melt extrusion mechanism 2-molten material conveying pipe 3-printing head 4-melt heating ring 5-melt speed reducer 6-melt extrusion power source 7-power source controller 8-electric cylinder 9-electric cylinder servo motor 10-temperature controller 11-heating wire 12-tail end heating ring 13-heat insulation layer 14-melt shell 15-output port 16-driving conical screw 17-driven conical screw 18-driving gear 19-driven gear 20-printing nozzle 21-molten material input port 22-fixing seat 23-transverse flow channel 24-vertical flow channel 25-bearing 26-material control rod 27-heat insulation pad 28-frame machine tool 29-industrial robot 30-raw material bin 31-feed pipe 32-total controller 33-feed inlet.

Detailed Description

The present invention is described in terms of specific embodiments, and other advantages and benefits of the present invention will become apparent to those skilled in the art from the following disclosure. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention. In the present specification, the terms "upper", "lower", "left", "right", "middle", and the like are used for the sake of clarity only, and are not intended to limit the scope of the present invention, and changes or adjustments of the relative relationship thereof are also considered to be the scope of the present invention without substantial changes in the technical content.

Example 1

Referring to fig. 1-2, the 3D printing apparatus includes a material melt extrusion mechanism 1, a molten material delivery tube 2 and a printing head 3, the molten material delivery tube 2 is a bendable structure, one end of the molten material delivery tube 2 is connected to an output port 15 of the material melt extrusion mechanism 1, the other end of the molten material delivery tube 2 is connected to a molten material input port 21 of the printing head 3, and the printing head 3 is connected to a molten material flow control mechanism.

The molten material delivery tube 2 in this embodiment may be a high temperature resistant hose. It can also be a hard tube with multi-joint structure. A heating wire 11 is wound around the outside of the molten material transfer pipe 2 to ensure that the molten material is not hardened during the transfer, and an insulating layer 13 is coated on the outside of the molten material transfer pipe 2.

The material melting and extruding mechanism 1 comprises a melting and heating ring 4 wound on the outer side, the lower end of the printing head 3 is provided with a tail end heating ring 12, the melting and heating ring 4 and a heating wire 11 are connected to a temperature controller 10, the material is kept in a proper temperature environment all the time, and 3D printing is finally achieved after the material is melted and transmitted and is discharged from the printing head 3.

Referring to fig. 3, the material melt extrusion mechanism 1 in the present embodiment includes a melting housing 14, a screw extrusion mechanism rotatably disposed in the melting housing 14, and a melt heating ring 4 wound around the outside of the melting housing 14, and the screw extrusion mechanism is connected to a melt extrusion power source 6 for driving the screw extrusion mechanism to rotate. The lower end of the melting shell 14 is an output port 15, and both sides of the upper part of the melting shell 14 are respectively provided with a feed inlet 33.

The screw extrusion mechanism comprises a driving conical screw 16 and a driven conical screw 17 which are meshed with each other, the upper end of the driving conical screw 16 is connected with a driving gear 18, the upper end of the driven conical screw 17 is connected with a driven gear 19, the driving gear 18 is meshed with the driven gear 19, and the upper parts of the driving conical screw 16 and the driven conical screw 17 are respectively connected with a bearing 25. The driving conical screw 16 is connected with a melt extrusion power source 6 through a melt reducer 5. The screw extrusion mechanism can also be a single screw structure driven by a hydraulic motor or other structures capable of generating extrusion pressure. The melt extrusion power source 6 is a servo power source, and the servo power source is matched with the double screws to achieve better extrusion effect and efficiency. The driving gear 18, the driven gear 19 and the bearing 25 are arranged in a box body shell, in order to facilitate the assembly and maintenance of the integrated synchronous and supporting mechanism, the box body shell is divided into two parts by taking a plane formed by the axes of the two screw rods as a parting surface, and lubricating grease can be injected into the box body shell to lubricate the bearing and the gear.

Referring to fig. 4, the lower end of the printing head 3 is provided with a printing nozzle 20, and the printing head 3 is further connected with a molten material flow control mechanism for controlling the flow of the molten material, the embodiment of the present invention innovatively uses an extrusion mode of a counter-rotating conical twin-screw structure, improves the synchronous structure and the supporting structure of the twin-screw to integrate them, the integration level of the driving structure is improved, and the servo driving is used as an accurate driving mode, so that the extruder with the counter-rotating conical double-screw structure can be applied to a 3D printer and can be used in screw gaps, except for the mechanical pressure of extrusion, the thermal expansion pressure component of the melting material is not controlled by a screw, the tail end printing head is improved, the printing head is connected with a melting material flow control mechanism, the throttling control on the melting fluid can be realized, the control precision and the real-time performance are further improved, and the requirement of a high-efficiency large FDM 3D printing process is met.

The molten material flow control mechanism includes a material control rod 26 which is provided in the print head 3 and an elevating mechanism which moves the material control rod 26 up and down. Elevating system is including electronic jar servo motor 9 and electronic jar 8 that from top to bottom connect gradually, and electronic jar 8 is connected with material control rod 26 upper end, and the structure is very simple, in order to avoid beating printer head 3 in the heat transfer of molten material to electronic jar 8, originally be equipped with heat insulating mattress 27 between electronic pole 8 of stand and the printer head 3. Certainly the embodiment of the present invention provides an elevating system can also adopt other power supplies. One side of the print head 3 is provided with a fixing base 22 for connecting a moving mechanism.

Referring to fig. 5 to 7, a transverse flow channel 23 and a vertical flow channel 24 are formed at the lower end of the material control rod 26, the transverse flow channel 23 transversely penetrates through two sides of the material control rod 26, the lower end of the vertical flow channel 24 penetrates through the material control rod 26, and the upper end of the vertical flow channel 24 is communicated with the transverse flow channel 23. The lower end of the material control rod 26 is provided with the transverse flow channel 23 and the vertical flow channel 24, and the position of the material control rod 26 is controllable by the electric cylinder 8, so that the printing head 3 has at least two output calibers and can be completely closed.

When the material control lever 26 is in the states i and ii, there is a passage for material from the chamber of the printhead 3 to the print nozzle 20, and the printhead 3 is in the open state. When the material control lever 26 is in state iii, there is no passage for material from the chamber to the print nozzle 20 and the printhead is in a closed state. Specifically, when the position of the material control lever 26 is in the state i, a certain gap exists between the material control lever 26 and the print nozzle 20, and the molten material flows into the print nozzle 20 from the gap, and the aperture of the print nozzle 20 is in the maximum opening state as the final output aperture of the material. When the position of the material control rod 26 is in the state ii, there is no gap between the material control rod 26 and the printing nozzle 20, and the molten material flows out only from the horizontal flow channel 23 and the vertical flow channel 24, and the caliber of the vertical flow channel 24 at this time is used as the final output caliber of the material.

The electric cylinder servo motor 9 and the melt extrusion power source 6 are connected with a power source controller 7 to control the extrusion pressure of the molten material, the flow rate of the material or the cut-off flow rate. The power source controller 7 and the temperature controller 10 are connected with a master controller 32. The melting extrusion power source 6 drives the driving conical screw 16 and the driven conical screw 17 to rotate through the melting speed reducer 5, solid particle raw materials entering from a feeding hole are heated into fluid, the material is fully plasticized through the rotation of the screws and extrusion pressure on the molten material is generated, the molten material is conveyed into the printing head 3 through the molten material conveying pipe 2, the electric cylinder servo motor 9 drives the material control rod 26 to lift through the electric cylinder 8, the opening degree of the printing nozzle 20 is further adjusted, and the flow of the material is adjusted or the printing nozzle 20 is directly closed.

The embodiment of the utility model provides a separate material melting extrusion mechanism 1 and printer head 3, both transmit the fused material through melting material transmission pipe 2. The material melt extrusion mechanism 1 heats the solid particulate raw material entering from the feed port into a fluid and generates extrusion pressure on the molten material. The molten material is transported to the print head 3 through the molten material transport pipe 2, and the print head 3 performs final control on the molten material, such as adjusting the flow rate of the material or stopping the flow rate.

Due to the characteristics of 3D printing, the product is usually complex, each layer contains a large number of reciprocating filling lines, and the moving speed and acceleration of the printing head 3 are high. Therefore, the printing efficiency can be greatly improved by only improving the high mobility and high acceleration of the tail end movement of the printing device. In a limited printing stroke, the highest speed of the movement is determined to a certain extent by higher acceleration, and for the FDM printing process, the acceleration is increased, so that the comprehensive movement speed of the printing can be increased, and the printing efficiency of a printed product can be improved.

Compare current large-scale FDM 3D and beat printer head framework, the embodiment of the utility model provides a designed material melting extrusion mechanism 1 and beat the structure of printer head 3 separation, made material melting extrusion mechanism 1 need not to design at printer motion structure end, and in the structure of the low accelerated motion in the mechanism, did not participate in the high acceleration motion of beating printer head 3. Or at a fixed position outside the moving structure of the printer without participating in any movement. The moving part at the tail end of the printer, namely the printing head 3, only needs part of the heating device and the material control structure, and the total weight of the printing head 3 is reduced. The inertia of the tail end moving part is reduced, the moving structure of the whole printer can also reduce the weight, and the moving acceleration is improved. The limit of the terminal movement speed of the existing large FDM 3D printing framework is only about 5000 mm/min, and theoretically, the terminal movement speed of the novel FDM 3D printing head framework can be improved by 20 times or more compared with the terminal movement speed.

The material melt extrusion apparatus 1 can be placed on a low acceleration movement structure or a non-movement structure, whereby the size and weight of the molten material melt extrusion apparatus 1 no longer have a great influence on the printing efficiency at a low acceleration movement position in the machine, or at a fixed position, the design of the molten material melt extrusion apparatus 1 is more free. In the novel framework, a large extruder with mature technology can be used as the molten material melting and extruding mechanism 1, materials can be fully plasticized and uniformly mixed by means of pressure and shearing force generated by rotation of a long-stroke double screw of the extruder, impurities such as water vapor, low molecular weight substances and the like in the materials are discharged, the molten materials are very uniform, dense and free of air holes, the material extrusion flow of the large extruder can reach 1-10 kg/min, the material extrusion flow is 5-10 times that of a light single screw extrusion head commonly adopted by the existing large FDM process and 1000 times that of a small wire FDM printer, and therefore the requirements of high-speed printing of 3D printing can be met.

Referring to fig. 8 ~ 9, the utility model discloses 3D printing device installs on walking machine tool 28, and the 3D who is applicable to high-speed, large-traffic, high motion stability prints and uses, can use the structure of external large-scale extruder, is fit for jumbo size or super large-size 3D and prints the product. The material melting and extruding mechanism 1 is fixed on a machine tool base, a raw material bin 30 for supplying materials to the material melting and extruding mechanism 1 is arranged on one side of a row frame type machine tool 28, a melting material conveying pipe 2 is arranged along the machine frame, and a printing head 3 is arranged on a row frame capable of moving horizontally and vertically.

The utility model discloses 3D printing device has following advantage:

1. reducing the total weight of a melt extrusion apparatus

The structure of a large-scale melt extruder in the traditional industry is optimized, so that the conical double-screw extruder can be applied to a large-scale 3D printer, the driving structure of the melt extruder is specifically improved, the complex structure of a screw, a synchronous mechanism, a reduction gearbox and multistage connection of the traditional extruder is simplified, and the improvement is a direct-drive mode. The embodiment of the utility model provides an in, the screw rod to and high-accuracy speed reducer between not have unnecessary transmission axis body, thrust support bearing group, journal bearing etc. direct mount epaxial at the screw rod, make whole drive structure compacter, the volume is littleer, weight is also lighter.

2. Increasing the output flow of a melt extrusion apparatus

The different-direction double-screw extruding structure is different from the conveying mechanism of a single-screw extruding structure used in the current 3D printing industry. The solid conveying process in the single-screw extrusion structure is friction drag, the melt conveying process is viscous drag, and the magnitude of the friction coefficient between the solid material and the metal surface and the viscosity of the melt material determine the strength of the conveying capacity of the single-screw extruder to a great extent. In the single-screw structure, a spiral passage exists from the feeding hole to the final discharging hole, which means that the pressure building limit of the single screw to the material is lower, when the pressure of the molten mass reaches a certain degree, the molten mass can leak and release pressure from the spiral passage and other gaps, so that the single-screw structure does not form effective positive displacement conveying to the material any more, the final output flow can not be continuously improved, and the output flow can not correspond to the rotating speed of the motor.

The meshing type counter-rotating double-screw extruder is similar to a gear pump and a double-screw pump in the principle of forcedly conveying molten fluid materials, a section of double C-shaped closed chambers can be formed by a meshing structure, the number of the C-shaped closed chambers is the same as the number of turns of screw threads, when the screws rotate, shafts of the double C-shaped closed chambers move forwards (towards a discharge port), the screws rotate for one turn, and the closed chambers move forwards by a lead, so that the materials are forcedly pushed forwards by the mutually meshed threads, and the degree of forcedly-displacing and conveying depends on the meshing gap between the screw ridge of one screw and the screw groove of the other screw and the matching gap between the screws and screw jackets.

The utility model discloses the crowded structure of incongruous rotatory toper double screw of closely meshing that adopts, the less fit clearance of screw rod and screw rod overcoat, the maximum possible reduction hourglass flow phenomenon obtains the biggest positive displacement and carries the effect. The maximum output flow under the conditions of the driving force limit and the mechanical limit of the screw can be realized.

According to the 3D printing principle, the internal filling volume accounts for about 90% of the total volume, only the shell curved surface influencing the appearance effect of the printed product is formed, and the internal filling does not influence the appearance effect of the printed product, so that the line width and the line height (layer height) can be increased in the printing process, and the internal filling is rapidly completed at the maximum flow. For a part of the plane perpendicular to the horizontal plane in the outer surface or a curved surface with small curvature change and approaching the vertical horizontal plane, the printing can be rapidly carried out by using a larger layer height and a larger flow rate, and the appearance effect (curved surface fitting effect) of the product is the same as that of the small layer height. A larger flow rate therefore means a higher average efficiency 3D printing.

3. Accurate flow control

3D printing process has very high requirement to the stability of the extrusion flow of material, the embodiment of the utility model provides an incorgruous toper two xuan extrusion structures that adopt have the compulsory transport characteristic of extremely low hourglass, therefore mechanical structure possesses the condition of accurate control flow, can calculate out the relation function of rotational speed and extrusion capacity according to this characteristic. The utility model discloses use servo drive mode, cooperation high accuracy planetary reducer directly drives the structure with synchronous case and constitutes numerical control screw extruder, and the screw shaft becomes the numerical control axle, realizes accurate control flow and rapid instruction response ability, and this is that the single screw rod that generally adopts in the current large-scale FDM 3D printing field extrudes the structure and does not have.

4. Real-time flow control

Because the servo motor controls the flow rate by pressure, the screw has a forced conveying characteristic, but the molten material has expansion pressure, the material is separated from the control of the screw when approaching the output port 15, the pipeline material and the molten material in the transmission process have elasticity, and under the action of the thermal expansion pressure, the screw does not move, and has certain pressure, so the flow rate is controlled only by the screw, when the material is extruded continuously and unchangeably, the thermal expansion pressure is in a steady state, and the flow rate is stable, but the 3D printing product generally has certain complexity, during the printing process, the flow rate is repeatedly switched on and off and changes in size, when the screw stops rotating or moves in a variable speed, the actual flow rate of the end printing nozzle 20 does not immediately respond to the change of the instruction under the action of the thermal expansion force of the molten material, but needs to wait for the thermal expansion pressure to be completely consumed, the flow just can be stabilized again, leads to actual flow and instruction to produce the hysteresis, and the real-time of flow is difficult to guarantee, so the utility model discloses a terminal throttle control and servo motor control's screw rod cooperation, just can solve the flow and be not only the space volume accurate, also accurate in time.

The position of the material control rod 26 is controllable, when the position of the material control rod 26 is transited from the state i to the state ii, the sectional area of a material flow channel formed by the material control rod 26 and the printing nozzle 20 is gradually reduced along with the movement of the material control rod 26 towards the printing nozzle 20, otherwise, the sectional area is increased, the flow resistance is changed in real time by matching with the flow regulation of the extrusion device, the flowing flow is not only related to pressure but also related to resistance, and therefore, the tail end of the printing output flow is continuously and accurately regulated in real time under the control of control system software.

5. Improving the effect of material output by a melt extrusion device

In 3D printing process applications, the extrusion effect of the melt extrusion device on the material directly determines the final printing effect. Two main factors affecting the material effect are the plasticizing degree and the impurity removal degree (moisture, air, low molecular weight vaporized impurities, etc.). If the plasticizing degree of the material is insufficient during extrusion, the material is unevenly distributed and has loose multiple layers, and finally, the mechanical property of a printed product is poor. If the impurity removal degree is not enough when the material is extruded, particularly when moisture and air are not completely removed, the molten material containing gas and moisture enters a normal-temperature normal-pressure state (after being extruded from a printing nozzle), the pressure is suddenly reduced, the moisture in the material can be vaporized, so that the printing line expands, and after water vapor is discharged, the printing line shrinks, so that the printing line width and the line height are uncontrollable, the printing line has more air holes, and the printing effect is seriously reduced.

Compared with a single-screw structure commonly used in the industry, the double-screw extruding structure has good mixing, stirring, plasticizing and impurity discharging effects, a printing line is compact and uniform in plasticizing, and the printing effect is good. Due to the mixing and stirring characteristics of the double-screw extruding structure, various auxiliary agents such as a toughening agent, a plasticizer, a filling agent, glass fibers, carbon fibers and the like can be added into a main material, so that the main material is modified and enhanced or other properties are added, the counter-rotating double-screw extruder has the forced extruding characteristic, powdery raw materials can be used, and the double-screw extruding structure has the advantage of material selection diversity compared with a single-screw extruding structure.

6, the printing head with high integration can be closed and the caliber can be switched

6.1 opening and closing of print nozzles

The small FDM 3D printer uses a wire printing mode, is simple in structure and only comprises a heating head and a wire extruding device. The printing head cannot be completely closed in the printing process or after printing is finished, only negative pressure generated in short-distance retraction of the printing line is utilized to suck the fluid material back into the printing nozzle, but the negative pressure cannot be continued, if the fluid material is not printed again in a short time, partial material overflows from the printing nozzle 20 and remains in other positions of a product, and the printed product has local defects. Such defects are reduced in the case of compact printers due to the relatively small size of the product. But to large-scale 3D printing, the volume increase is 1000 times, and its defect also will be enlarged, consequently any unnecessary material remains all can't ignore to large-scale printer, the utility model discloses beat fine solution of printer head 3 and printed the problem that the in-process material spills over, when not needing output material, material control rod 26 penetrates in printing nozzle 20, and material control rod 26 outer wall only has minimum fit clearance with printing nozzle 20 inner wall, and the clearance is less than the overflow limit value of molten material, makes the material unable overflow.

6.2 bore switching of print heads

In a large FDM 3D printing process, the nozzle aperture of the print head 3 is not a fixed size, but a plurality of nozzles with different apertures are provided, and the flow control of the nozzles with different apertures in cooperation with extrusion can realize the line width and line height of different output print lines. According to the foregoing analysis, it is generally only necessary that the exterior curved surface (visible to the human eye) of the printed product have some appearance effect, while the interior (not visible to the human eye) solid portion thereof is generally not required unless the product has special requirements for its interior structure. A larger bore nozzle, i.e. a larger flow rate, is used for filling the interior of the printed product. The printing line is widened and heightened to reduce the density of the reciprocating filling line of the current printing layer, the principle of the printing line is similar to that a painting brush is used for coloring a graph with a certain area, the painting brush with a wider pen point can use fewer reciprocating times and shorter total path length to color the graph, the reciprocating acceleration and deceleration times can be reduced for 3D printing, the average movement speed of printing can be improved, the path length is also reduced, and therefore the forming speed of a printing product is improved. The contradiction between the efficiency and the appearance quality is greatly optimized.

In the current FDM 3D printing field, the current variable caliber of the printing head in the industry is usually realized by a structure of a plurality of independent printing nozzles with different calibers, the printing head is required to be shifted when different printing nozzles are switched, and the printing nozzle after being replaced is moved to the position of the printing nozzle before being replaced so as to continue printing. If a plurality of independent printing nozzles are at the same height relative to the printing object plane, the printing is interfered, and therefore the unused printing nozzles need to be lifted to a higher position to avoid scratching the surface of the printing layer. Finally, the structure of the existing multiple printing heads becomes complex, the integration level is poor, the total weight is increased due to the structure of the multiple independent printing heads, and the printing head is not suitable for high-speed and high-efficiency printing.

The embodiment of the utility model provides an in beat printer head 3 and material control rod 26's structure use concentric nested mode, the less vertical runner of embedded bore in print nozzle 20 inside. In the example, the nested structure is a dual-aperture nest, and can also be a multi-aperture nest. It is not necessary to shift the position of the print head 3 during switching of the print head 3 because all the printing nozzles are concentric. Except the outmost (also the maximum caliber) printing nozzle, other printing nozzles are hidden inside the current printing nozzle along with the material control rod 26 in the unused state, so that the problem of printing interference does not exist, and the problem of scratching the surface of the printing layer does not occur. The novel structure beat printer head 3 and realize printing nozzle 20's the closure and printing nozzle 20's bore switching, improved the integrated level, reduced weight, improved printing efficiency.

Example 2

Referring to fig. 10, the 3D printing apparatus in the present embodiment is applied to an industrial robot 29, a raw material bin 30 is provided on one side of the industrial robot 29, the raw material bin 30 is connected to a material melt extrusion mechanism 1 through a feeding pipe 31, the material melt extrusion mechanism 1 is fixed to a robot arm of the industrial robot 29, and a printing head 3 is fixed to a manipulator. The device is generally suitable for medium-high-speed and medium-flow 3D printing applications, can be integrated on a load arm of the industrial robot 29 by using a light extruding device, and is suitable for medium-size 3D printing products.

Although the invention has been described in detail with respect to the general description and the specific embodiments, it will be apparent to those skilled in the art that modifications and improvements can be made based on the invention. Therefore, such modifications and improvements are intended to be within the scope of the invention as claimed.

Claims (10)

1. The utility model provides a 3D printing device which characterized in that: the 3D printing device comprises a material melting and extruding mechanism (1), a molten material conveying pipe (2) and a printing head (3), wherein the molten material conveying pipe (2) is of a bendable structure, one end of the molten material conveying pipe (2) is connected with an output port (15) of the material melting and extruding mechanism (1), and the other end of the molten material conveying pipe (2) is connected with a molten material input port (21) of the printing head (3).

2. The 3D printing device according to claim 1, characterized in that: the molten material conveying pipe (2) is wound with a heating wire (11).

3. 3D printing device according to claim 1 or 2, characterized in that: the outside of the molten material conveying pipe (2) is coated with an insulating layer (13).

4. The 3D printing device according to claim 1, characterized in that: the material melting and extruding mechanism (1) comprises a melting shell (14), a screw extruding mechanism and a melting and heating ring (4), wherein the screw extruding mechanism is rotatably arranged in the melting shell (14), the melting and heating ring (4) is wound on the outer side of the melting shell (14), and the screw extruding mechanism is connected with a melting and extruding power source (6) for driving the screw extruding mechanism to rotate.

5. The 3D printing device according to claim 4, characterized in that: screw extrusion mechanism include engaged with initiative taper screw (16) and driven taper screw (17), the epaxial end of screw of initiative taper screw (16) is connected and is installed driving gear (18), the epaxial end of screw of driven taper screw (17) is connected and is installed driven gear (19), driving gear (18) and driven gear (19) are engaged with each other, melting reduction gear (5) are connected in initiative taper screw (16), melting extrusion power supply (6) are connected in melting reduction gear (5).

6. The 3D printing device according to claim 1, characterized in that: the lower end of the printing head (3) is provided with a printing nozzle (20), and the printing head (3) is connected with a molten material flow control mechanism.

7. The 3D printing device according to claim 6, characterized in that: the molten material flow control mechanism comprises a material control rod (26) arranged in the printing head (3) in a lifting mode and a lifting mechanism for driving the material control rod (26) to lift.

8. The 3D printing device according to claim 7, wherein: the lifting mechanism comprises an electric cylinder (8) and an electric cylinder servo motor (9) which are connected, and the electric cylinder (8) is fixedly connected with the upper end of the material control rod (26).

9. The 3D printing device according to claim 7, wherein: the material control rod is characterized in that a transverse flow channel (23) and a vertical flow channel (24) are formed in the lower end of the material control rod (26), the transverse flow channel (23) transversely penetrates through two sides of the material control rod (26), the lower end of the vertical flow channel (24) penetrates through the material control rod (26), and the upper end of the vertical flow channel (24) is communicated with the transverse flow channel (23).

10. The 3D printing device according to claim 1 or 6, characterized in that: the lower end of the printing head (3) is provided with a tail end heating ring (12).

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