CN116787757A - Miniature screw gear pushing mechanism special for three-dimensional printer - Google Patents

Abstract

A miniature screw gear pushing mechanism special for a three-dimensional printer belongs to the technical field of machinery. The structure comprises: a pushing motor with a tubular rotating shaft, a pushing gear, a supporting member, a transmission gear and a swing arm; a screw-shaped external thread is processed at the extending part of the pushing motor shaft, and the pushing gears on the 1 supporting members and the pushing gears on the 1 swing arms are synchronously rotated in opposite directions through 2 transmission gears; after passing through the tubular rotating shaft of the pushing motor, the material wire is clamped by 2 pushing gears, and when the tubular rotating shaft rotates clockwise or anticlockwise to drive the driving turbine, the pushing gears are simultaneously driven, so that the material wire can displace along the axial direction; ejecting from a heated nozzle of an extrusion nozzle; is widely applied to the manufacture of small and simple FDM-3D printers.

Description

Miniature screw gear pushing mechanism special for three-dimensional printer

Technical Field

The invention belongs to the technical field of machinery; specifically a pushing mechanism component used on an FDM-3D printing (material wire) extruder.

Background

The most mature 3D printing technology is: the fused deposition modeling (Fused Deposition Modeling, FDM) rapid modeling technology is a method for heating and melting various wires (such as engineering plastics ABS, polycarbonate PC, etc.) and further accumulating and shaping layer by layer, which is called FDM for short. Most FDM rapid prototyping techniques can employ a wide variety of modeling materials, such as modified paraffins, (acrylonitrile/butadiene/styrene) copolymers (ABS), nylon, rubber, and other thermoplastic materials, as well as multiphase blends, such as metal powders, ceramic powders, staple fibers, and other blends with thermoplastic materials. Wherein PLA (polylactic acid) has the advantages of lower shrinkage, easier shaping of a printing model, biodegradability and the like.

The basic construction and operation principle of the FDM-3D printer are expressed as follows:

the extruder comprises a pushing mechanism and a melt extrusion nozzle part; a mechanical stage for carrying 2-dimensional or 3-dimensional (horizontal X-axis Y-axis movement and vertical Z-axis driving) movement of the extruder (extrusion nozzle part), or the vertical direction of the extruder (Z-axis direction) is kept stationary, and the movement in the Z-axis direction is completed by lifting and lowering an independent carrying workbench; the 3-dimensional mechanical system addressed by the driving extruder of the current FDM-3D printer is divided into: a mechanical arm 3-dimensional displacement system, a belt or screw-driven (X, Y-axis) 2-dimensional mechanical transmission + (Z-axis) lifting carrying workbench system, a vertical 3-screw-driven (commonly called as delta mode) displacement driving system which is connected with an extruder platform by using a connecting rod, and the like. Also structural shells, etc. that hold the above-described kinematic construction; there are also electronic control systems that support the movement of the mechanical system, etc.

It should be noted that: the extruder (2 major components) comprises: a pushing mechanism and a melt extrusion head portion, which may be closely assembled together (known as a short-throw extruder); the device can also be assembled separately, and a material guiding hose is used for connecting a material pushing mechanism and a melt extrusion nozzle part, so that the material pushing mechanism can be fixed on a certain part of a printer shell in a static way, and the melt extrusion nozzle part is carried by a mechanical carrier with 2-dimensional or 3-dimensional movement (called as a remote material pushing extruder, and one of the purposes is to lighten the inertia mass of the movement carrying mechanism); but the remote pushing has a certain influence on the extrusion capacity, which is due to the elasticity and resistance of the guiding hose.

The prior art has the following defects: for the extruder of the FDM-3D printer, a motor pushing mechanism without a speed reduction design is often used for directly driving a material wire by utilizing tangential thrust of a gear on a motor shaft; the motor can not rotate relatively fast, the mechanical efficiency is low, and the volume and the weight are large.

The overall working principle of the FDM-3D printer is as follows: under the control of an electronic system, the extruder moves in an X-Y plane according to the section profile information of the product parts, the height of a carrying workbench is adjusted, the workbench plane is positioned at the nozzle position of a hot melting nozzle at the beginning of printing, thermoplastic thread-like materials are sent to the hot melting nozzle by a thread supplying mechanism, heated and melted into a semi-liquid state in the nozzle and then extruded out, selectively coated on the workbench, and a layer of sheet profile with the thickness of about 0.1-8 mm is formed after rapid cooling. And after the forming of one layer of section is finished, the workbench is lowered by a certain height, and then the cladding of the next layer is carried out, so that the section and the outline are 'drawn' layer by layer, and the cycle is performed, and finally, the three-dimensional product part is formed. Often 1 special nozzle is used to lay the support material (the support material is generally water-soluble, and is washed away after printing is finished); in the printing process, the displacement of the printing head on the plane and the up-down displacement of the printing platform form a three-dimensional space, the printing head and the printing platform print according to the generated path, after the printing head finishes a printing task on the plane, the printing platform automatically descends one layer, the printing head continues to print, and the printing head is cycled until the finished product is finished. Or the Z-axis motor is not used for driving the printing object platform to lift, the printing object platform keeps static in the Z-axis direction, and the Z-axis motor is used for driving the extruder to move up and down; or 3 vertical screws are used for driving 3 sliding blocks which vertically move, the 3 sliding blocks are all hinged with the extruder, and the purpose of three-dimensional displacement addressing is achieved through an algorithm (the position coordinates of the 3 sliding blocks in the Z-axis direction determine the 3-dimensional space position of the extruder). The temperature of the printing head is higher, and the temperature of the printing head is relatively different according to the difference of materials and the design temperature of the model. In order to prevent the problems of edge curling of a printed object, the printing platform is generally heated, and the printing platform is generally covered with adhesive paper so as to facilitate the stripping of a printed finished product.

The structural details are described as follows:

the component of the extruder that is the core of the FDM rapid prototyping technique is the extruder, and the components of the extruder are: the plastic wires are extruded from the nozzle under the action of the pressure of a subsequent wire feeding (piston) and extruded onto a printing table, the throat in the extruder is made of stainless steel, the stainless steel throat is internally lined with teflon for reducing the heat conduction performance, the temperature in the throat is increased due to long-term heating printing of the extruder, the material in the throat is in a molten state, after the printing and cooling are stopped, the material is bonded in the throat, the adhesive in the pipe cannot be melted immediately when the printing is restarted next time, the choke plug phenomenon occurs in the throat, the material in the throat cannot be melted and adhered, and the problem can be greatly improved. Meanwhile, the cooling fin and the fan are additionally arranged on the extruder by the author, so that the temperature of the upper part of the throat pipe is reduced, the problem of choke plug is prevented, and the heat of the extruder can be dissipated. The heated and melted plastic filaments are extruded from the nozzle onto a printing table, and if the plastic is subjected to edge lifting, shrinkage and other adverse phenomena due to temperature rapid reduction, a hot bed printing table can be used to reduce the plastic is subjected to edge lifting, shrinkage and other adverse phenomena due to temperature rapid reduction. There are four general types of orifice diameters located at the lowest nozzle of an extruder: the jet nozzle with the maximum application range of 0.2mm,0.3mm,0.4mm and 0.5mm in the market is provided with a nozzle with the maximum application range of 0.4mm, and after the diameter of the nozzle is selected, corresponding parameters such as printing layer height, printing speed and the like in slice software are set in software during printing, so that the printing quality and precision are higher.

Compared with a single extrusion head, the double extrusion head adopts two extruders to be arranged in parallel, the printing speed is higher, the efficiency is higher, the inertia generated during operation is higher due to the larger mass, and the rigidity requirement on the guide rail is higher. This reduces the accuracy of printing. Compared with a single extrusion head, the double extrusion heads are arranged in parallel by adopting two extruders, and the relative positions are fixed, and as two spray heads are arranged on the sliding block, the double extrusion heads are connected with the guide rail by the sliding block, and the diameters of the spray nozzles at the lowest end of the extruders are of four types: the nozzles with the diameters of 0.2mm,0.3mm,0.4mm and 0.5mm are the most widely applied in the market, and of course, the nozzles with different diameters can be purchased according to actual needs, and it should be noted that after the diameters of the nozzles are selected, corresponding parameters, such as the printing layer height, the printing speed and the like in slice software, are set in software during printing, so that the quality and the precision of printing are higher.

The near-end wire feeding is to install the extruder on the printing head, the material is extruded into the throat directly by the gear, melted in the aluminum block and ejected out of the nozzle for printing. The mounting mode is characterized in that the extruder moves together with the printing head, the printing head has large mass, large inertia during printing, inaccurate printing is easy to cause, and the rigidity requirement of the guide rail by adopting the near-end wire feeding is higher. The far-end wire feeding is to install the extruder at a position far away from the extruder, the driving motor is generally installed on the printer frame, and the wire is fed by the guide pipe; rather than being mounted on an extruder, the distal wire feed requires a greater torque to extrude material into the printhead than the proximal wire feed.

Or the material used is no longer wire; the extrusion device can directly use particle raw materials such as ABS/PLA and the like, pour the particle raw materials into a feeding cabin, become liquid after melting at high temperature, and then realize the extrusion of 3D printing materials under the control of a pneumatic system.

The circuit part includes: the circuit part includes: the 3D printer circuitry portion functions in the printer to control the coordinated, orderly, complete operation of the entire printing process. A typical circuit part of the FDM type 3D printer mainly comprises an Arduino mega2560 main control board, a Ramps 1.4 expansion board and a stepping motor driving board. Their basic parameters and roles are described below. The micro controller of the Arduino Mega2560 main control board is atm ega2560, the working voltage is 5V, the number of digital I/O pins is 54, the number of analog input pins is 16, the direct current of each I/O pin is 50 milliamperes, the main control board is the brain of the 3D printer, and the main control board is responsible for controlling the whole printer to complete specific actions, such as printing specific files and the like. It should be noted here that the extended version of the diode supplying power to the main control board is not welded, that is, the mega2560 main control board is required to be supplied with power independently, and the USB 5V is directly used or the power is supplied through the power connector. Arduino is a convenient and flexible open source electronic prototype platform which is convenient to use, comprises hardware (Arduino plates of various types) and software (Arduino IDE), opens circuit diagram design of source codes, downloads program development interfaces for free, and can be modified according to personal needs, thereby meeting the needs of different people for creating creative ideas. Before the 3D printer operates, marlin firmware needs to be downloaded in an Arduino IDE, and partial parameters of the firmware need to be modified according to the needs to meet the printing requirements. The expansion board Ramps 1.4 is inserted on the main control board and is connected with the main control board through the contact pin, so that the expansion board Ramps are better connected and controlled with other hardware and play a role of a transition bridge. The expansion board needs to be connected with two 12V power supplies, one is 11A and supplies power to the heating bed, the other is 5A and supplies power to the extruder, the motors of each shaft, the fans and other elements, and the author does not use the heating bed, but only uses one 12V and 5A power supply. The fan output and the heating rod output indication LEDs are arranged on the Ramps 1.4 expansion board, the extruder and each shaft motor are controlled by the main control board through the stepping motor driving board A4988, and as the author adopts a single-head printer, the motor interface of the extruder 2 is not required to be provided with A4988, and the extruder is positioned at the upper right corner of the expansion board, and is provided with a X, Y, Z limit switch, so that the origin of each working time of the printer can be controlled. The A4988 stepping motor driving plate is used for being connected with a stepping motor, so that the control of the stepping motor by the main control board is realized, and the actions of the XYZ shaft motor and the extruder are realized. The A4988 stepper motor driving plate is characterized in that the driving plate has only a simple stepper and direction control interface and has 5 different stepper modes: the adjustable potentiometer can adjust the maximum current output to obtain higher stepping rate, and has the functions of overheat closing circuit, undervoltage locking and cross current protection, and the functions of grounding short-circuit protection and loading short-circuit protection. The driving board is connected to the corresponding interface in the expansion board through pins.

Disclosure of Invention

The purpose of the invention is that: in order to solve the defects that the extruder of the 3D printing extruder is large in size, the working rotating speed of a stepping motor is too low (output matching performance) and the like.

The invention is characterized in that: simple structure, reliable operation, small volume and good motor power matching performance.

The basic structure of the associated FDM-3D printer includes: a pushing mechanism part and an extrusion nozzle part: the miniature screw gear pushing mechanism comprises a pushing motor with a mesoporous rotating shaft, a pushing gear, a transmission gear and a supporting member; the extrusion nozzle part comprises a heating aluminum block, a heating rod and a nozzle.

The integral matching and assembling working relation with the FDM-3D printer mainly comprises a structural shell of the 3D printer, an electronic control system supporting the movement of a mechanical system, a mechanical carrying platform and a printing workbench under the constrained drive of X, Y, a Z-axis guide rail and a motor, wherein the carrying extruder moves in a plane, the extruder, a pushing mechanism or a storage box is fixed on the mechanical carrying platform for carrying the extruding machine, and the extruding machine (the pushing mechanism of the micro screw gear pushing mechanism and an extrusion nozzle can be assembled in a short distance or in a long distance) and the printing workbench need 3-dimensional relative movement, namely: the extruder remains stationary and the printing table performs a 3-dimensional motion; or the extruder keeps 1-dimensional motion and the printing workbench keeps the motion in 2-dimensional motion; or the extruder keeps 2-dimensional motion and the printing workbench keeps the motion in 1-dimensional motion; or the extruder is kept in 3-dimensional motion while the printing table is not moved; and the whole work is completed cooperatively.

Micro screw gear pushing equipment suitable for FDM-3D prints, and the structure includes: the device comprises a pushing gear, a transmission gear, a swing arm, a pushing motor, a motor shaft end screw rod and a motor shaft middle hole; specific mounting relation:

a motor shaft of the pushing motor is provided with a middle hole, and an external thread (a shaft end screw rod) is arranged at the extending part of the motor shaft; the external thread of the screw rod part at the end of the motor shaft (extending out) is meshed with 2 transmission gears on a fixed shaft which is arranged on a supporting component and is perpendicular to the motor shaft, the 2 transmission gears are arranged on the 2 side of the motor shaft and are oppositely arranged, the 2 gear disc surfaces (the gear center surface is a plane which is perpendicular to the axis of the gear and has equal distance from the upper end surface and the lower end surface of the gear, and the section of the middle part of the gear) are respectively meshed with 2 pushing gears (the center surface of each pushing gear is also in a plane with the axis of the motor and the center surface of each transmission gear), at least 1 pushing gear is arranged on a moving shaft on a swinging arm, and the moving shaft on the swinging arm and the rotating shaft on the swinging arm which is perpendicular to the motor shaft are fixed shafts which are perpendicular to the motor shaft; the spring piece pushes on the swing arm, the elastic direction of the spring piece enables the pushing gears to be close to each other, the swing arm is forced to rotate, the pushing gears are driven to be close to the pushing gears on the other non-swing arm, the outer edges of the 2 pushing gears are close to the central axis of the motor, the distance from the central axis is between 0 mm and 5mm, at least 1 protrusion with slightly larger diameter of the outer edge of the pushing gears exists, namely the tooth tops of the pushing gears are provided with recesses, the diameter of the recesses is reduced, and the purpose is that the material wires clamped between the tooth tops of the 2 gears are not easy to break away;

the basic working mode is as follows: the external thread of the screw rod part of the motor shaft of the pushing motor drives 2 pushing gears through 2 transmission gears on the driving fixed shaft, and when a material wire passes through a rotating shaft passing hole of the pushing motor, the material wire is clamped by the 2 pushing gears to push out the material wire; when the rotary shaft of the tubular motor rotates clockwise or anticlockwise, the pushing gear is driven to push the material forwards or backwards, so that feeding or back suction is obtained; after the heating rod is powered, the metal (heating aluminum block or copper block) structure body is heated, so that a melting cylinder (a space where wires are gathered) in the heating aluminum block generates high temperature; in a remote wire feeding mode, the pushed wire can be conveyed to the extrusion nozzle through the material guide hose and then sprayed out from a heated nozzle of the extrusion nozzle; under the short-range pushing mode, the pushed material wire can directly enter the extrusion nozzle through a short pipeline (throat pipe) with poor heat conduction capability and is sprayed out from a heated extrusion nozzle of the extrusion nozzle;

the invention has the beneficial effects that:

the defects of low efficiency and the like caused by large volume of an extruder and low rotation speed of an applied motor of a traditional 3D printing extruder are overcome, and the whole volume of the extruder can be reduced by more than 50%.

Drawings

FIG. 1 is a schematic diagram of a remote mating of a micro screw gear pushing mechanism with an extrusion nozzle.

Fig. 2 is a schematic diagram of the basic configuration of a micro screw gear pushing mechanism.

FIG. 3 is a schematic cross-sectional view of a micro-screw gear pushing mechanism.

Description of the reference numerals:

(1) Miniature screw gear pushing mechanism

(1-1) Transmission Gear

(1-2) Pushing Gear 1

(1-3) Pushing gear 2

(1-4) fixed shaft 1

(1-5) fixed shaft 2

(1-6) fixed shaft 3

(1-7) moving shaft

(1-8) swing arm

(1-9) spring piece

(1-10) Material pushing motor

(1-11) Motor shaft Medium hole

(1-12) Motor shaft end screw (thread)

(1-13) support Member

(1-14) catheter locking nozzle

(1-15) passing holes

(1-16) shaft hole

(2) Extrusion nozzle

(2-1) extrusion nozzle

(2-2) extruding filaments

(2-3) heating aluminum Block

(3) Material guiding hose

(4)

(5) Material wire

(6) An axis line

(7) Direction of spring force

(8) FIG. 1 explosion

(9) Explosion figure 2

Detailed Description

The invention is further described with reference to the preferred embodiments in the following with reference to the accompanying drawings:

as shown in fig. 1, 2 and 3:

construction of a micro screw gear pushing mechanism (1): the supporting component (1-13) is connected with the pushing motor (1-10), and a motor shaft middle hole (1-11) of the pushing motor (1-10) is used for passing through a material wire; a fixed shaft 2 (1-5) and a fixed shaft 3 (1-6) which can enable the pushing gear 2 (1-3) and the transmission gear (1-1) to freely rotate are respectively arranged on the shaft hole of the supporting member (1-13); a movable shaft (1-7) and a fixed shaft (1-4) which can enable the pushing gear (1-2) and the transmission gear (1-1) to freely rotate are respectively arranged on the swing arm (1-8); the elastic displacement end of the spring piece (1-9) pushes the swing arm (1-8) along the elastic direction (7), so that the pushing gear (1-2) fixed by the moving shaft (1-7) is close to the pushing gear (1-3) of the fixed shaft, and the material wire (5) passing through the material passing hole (1-15) is pressed; the guide pipe locking nozzle (1-14) is connected with a guide hose (3); the elastic force direction (7) is the direction in which the spring piece (1-9) pushes the swing arm (1-8) to displace, and when feeding the wire, the swing arm (1-8) is pushed reversely by hands, so that gaps between 2 pushing gears are obtained, and the feeding wire passes through the feeding hole (1-15).

From the exploded view 1 (8) and exploded view 2 (9) of fig. 2, the assembly relationship between the respective parts, in particular, the connection relationship between the fixed shaft 1 (1-4) of the swing arm (1-8) and the fixed shaft hole (1-16) on the support member (1-13), the fixed shaft 1 (1-4) being actually the rotation shaft of the swing arm (1-8), can be seen.

As shown in fig. 3:

the cross-section view of the motor axis (6) of the micro screw gear pushing mechanism (1) shows: the screw rod (1-12) at the shaft end of the motor drives 2 pushing gears through meshing transmission with the transmission gear (1-1) at the side 2; the 2 pushing gears clamp and push the material wires (5) to pass through the material guiding hose (3) and then push the material wires to the heating aluminum block (2-3) of the extrusion nozzle (2), and after the melting cavity in the material wires is melted, the extrusion nozzle nozzles (2-1) spray out the extruded material wires (2-2).

Claims (1)

1. The special miniature screw gear pushing equipment of three-dimensional printer, its structure includes: the device comprises a pushing gear, a supporting member, a transmission gear, a swing arm, a pushing motor with a motor shaft middle hole and a motor shaft end screw rod; specific mounting relation: the external thread of the part of the motor shaft extending out of the screw rod is meshed with 2 transmission gears arranged on a fixed shaft vertical to the motor shaft, the 2 transmission gears are positioned at the 2 side of the motor shaft, the surfaces of the gears are oppositely arranged and are respectively meshed with 2 pushing gears in a plane, at least 1 pushing gear is arranged on a moving shaft on a swinging arm, and the moving shaft on the swinging arm and the rotating shaft on the swinging arm vertical to the motor shaft are fixed shafts vertical to the motor shaft; the spring piece pushes on the swing arm, the elastic direction of the spring piece enables the pushing gears to be close to each other, the swing arm is forced to rotate, the pushing gears are driven to be close to the pushing gears on the other non-swing arm, the outer edges of the 2 pushing gears are close to the central axis of the motor, the distance from the central axis is between 0 mm and 5mm, at least 1 protrusion with slightly larger diameter of the outer edge of the pushing gears exists, namely the tooth tops of the pushing gears are provided with recesses, the diameter of the recesses is reduced, and the purpose is that the material wires clamped between the tooth tops of the 2 gears are not easy to break away; the basic working mode is as follows: the external thread of the screw rod part of the motor shaft of the pushing motor drives 2 pushing gears through 2 transmission gears on the driving fixed shaft, and when a material wire passes through a rotating shaft passing hole of the pushing motor, the material wire is clamped by the 2 pushing gears to push out the material wire; when the rotary shaft of the tubular motor rotates clockwise or anticlockwise, the pushing gear is driven to push the material forwards or backwards, so that feeding or back suction is obtained; after the heating rod is powered, the metal (heating aluminum block or copper block) structure body is heated, so that a melting cylinder (a space where wires are gathered) in the heating aluminum block generates high temperature; in a remote wire feeding mode, the pushed wire can be conveyed to the extrusion nozzle through the material guide hose and then sprayed out from a heated nozzle of the extrusion nozzle; under the short-range pushing mode, the pushed material wire can directly enter the extrusion nozzle after passing through the throat pipe with poor heat conduction capability, and is sprayed out from the heated extrusion nozzle of the extrusion nozzle;

the method is characterized in that: a screw-shaped external thread is processed at the extending part of the pushing motor shaft, the thread drives 2 transmission gears arranged on the supporting member to rotate, and the 2 transmission gears indirectly drive the pushing gear on the swing arm moving shaft and the fixed shaft pushing gear on the supporting member to synchronously rotate in opposite directions; the mounting position relationship is as follows: the axis of the motor is in the same plane with the central planes of the 2 pushing gears and the 2 transmission gears respectively.