JP7204245B2 - 3D printer, hot end module for 3D printer, ejection head, and filament feeding method - Google Patents

Description

The present invention relates to a filament feeding method in a fused deposition layer (FFF (FDM)) three-dimensional printer, a hot-end module for the three-dimensional printer, an ejection head, and a three-dimensional printer equipped with these.

2. Description of the Related Art In recent years, it has become popular to manufacture three-dimensional objects using computers and three-dimensional printers. As a modeling apparatus that manufactures such three-dimensional objects, a filament (filament-shaped modeling material) is fed into a head equipped with a heater for melting the filament, and the molten (dissolved) modeling material is layered. 2. Description of the Related Art FFF (FDM) three-dimensional printers that form objects are known (see, for example, Japanese Unexamined Patent Application Publication No. 2002-200013).

In the modeling apparatus disclosed in Patent Document 1, a motor (extruder) having a gear (rotating member) that contacts the filament is arranged between the filament reel and the head, and the filament drawn out from the filament reel is driven by the motor. is sent out toward the head by the rotation of the The filament sent into the head is melted by the heat given by the heater that heats the filament, which is the modeling material, and the melted filament is extruded from the outlet of the nozzle provided at the tip of the head toward the modeling stage. The head discharges while moving in two directions relative to the modeling stage, depositing the melted filament on the modeling stage.

In such a three-dimensional printer, the ejection speed of the molten modeling material in the modeling operation is controlled by the speed at which the filament is fed into the head, that is, by the rotational speed of the motor. The rotation speed of the motor is controlled to a desired rotation speed by a rotation drive signal given from the control section.

JP 2018-89923 A

However, since the feeding direction (moving direction) of the filament in the conventional three-dimensional printer is perpendicular to the rotation axis of the motor (the rotation axis of the feed gear (feed roller)), the feed mechanism is moved horizontally. Moreover, the rotation speed of the motor directly becomes the moving speed (feeding speed) of the filament, so that it cannot be said that it is suitable for fine and precise control of the feeding speed of the filament. For example, if the diameter of the feed gear is set to 5 mm, 15.7 mm of filament is fed in one rotation. , it is not suitable for high-resolution feeding, and requires a reduction gearbox with a reduction ratio of 1/22.4, resulting in a large filament feeding mechanism.

In a three-dimensional printer such as the one disclosed in Patent Document 1, an extruder (a feeding mechanism such as a gear that feeds filament to the head, a motor that rotates the gear, and a shaft member that transmits the drive of the motor to the gear) is used. is located at a distance from the head on the upstream side of the filament. As the head moves, the filament between the extruder and the head is flexed and twisted, and the filament is accurately conveyed to the head. It is thought that a situation in which it is difficult to feed at high speed may occur. Such a situation can be a factor that hinders precise adjustment of the discharge amount of the modeling material, and hinders accurate modeling operations. Furthermore, since the extruder is relatively large, if the head is assembled with the extruder to form a module, the size of the hot end module will increase.

The present invention has been made in view of such circumstances. It is an object of the present invention to provide a three-dimensional printer and an ejection head provided in a hot-end module.

As a result of intensive research to achieve the above object, the present inventors have found that by feeding the filament while the worm of the worm gear is in contact with the filament, in addition to the rotation speed of the worm, the screw thread of the worm threaded portion It was found that the feeding speed of the filament can be controlled also by the interval (pitch) of , and that the filament can be fed more finely and precisely. In addition, the worm (drive shaft) can be arranged (for example, substantially parallel) along the feeding direction of the filament, that is, along the (passage of) the discharge head (for example, substantially parallel), the reduction gearbox can be eliminated, the number of parts can be reduced, and the filament feeding mechanism can be used. It was found that the size and weight of the hot end module can be reduced, and the rotation can be controlled with a small torque.

Furthermore, by using the worm, it is possible to place the force transmitting portion that pushes the filament closer to the melting portion of the ejection head or in the passage of the ejection head, so that the filament is sent out more accurately and minutely by the melting portion of the ejection head. (Pushing) can be performed, and a modeled article can be manufactured with high accuracy. In other words, the inventors have found that by feeding (pushing) the filament at a position relatively close to the melting portion and the ejection port of the ejection head, the ejection amount of the molten modeling material can be controlled more accurately and precisely.

That is, the present invention is a method for feeding a filament in a three-dimensional printer, wherein the threaded portion of a worm having a threaded portion is brought into contact with the filament, and the worm is rotated to feed the filament. characterized by

In the present invention, the temperature of the contact portion of the filament with which the threaded portion contacts is preferably about 40% or less, more preferably about 30% or less of the melting temperature of the filament. For example, when PEEK (polyetheretherketone) is used as the filament and the melting temperature is 500°C, the temperature of the contact portion is preferably 140°C. This is because if the filament is softened at the abutting portion, it is possible to reduce the accumulation of filament waste in the thread groove of the worm.

In the filament feeding method of the present invention, the filament may be fed by bringing the screw portion into contact with the filament inside the ejection head (inside the supply portion (inside the barrel portion)). Further, the worm may be rotated by a drive shaft along the feeding direction of the filament.

In addition, the present invention has an inlet for introducing a filament as a modeling material, a supply section (barrel section) for supplying the filament introduced from the inlet to the downstream side, and a supply section for supplying the filament. a melting section for heating and melting the filament on the downstream side, a discharge section having a discharge port for discharging the filament melted by the melting section, and a passage communicating from the introduction port to the discharge port. A hot end module for a three-dimensional printer comprising an ejection head and a filament feeding mechanism for feeding the filament to the downstream side, wherein the supply portion of the ejection head is an opening exposing the passage. and the filament feed mechanism includes a worm having a threaded portion facing the passage from the opening, and driving means for driving the worm, wherein the threaded portion of the worm is The filament is sent out to the downstream side by rotating the worm while it is in contact with the filament in the passage.

In the present invention, the ejection head may be one in which the supply section, the melting section, and the ejection section are integrally formed, or the supply section (barrel section), the melting section, and the ejection section (nozzle section) may be separately formed. Alternatively, the supply section, the melting section, and the discharge section may be separate bodies. For the supply unit, metals with low thermal conductivity, such as metal materials such as iron alloys (stainless steel), nickel alloys, titanium, and titanium alloys, and inorganic materials such as ceramics, can be preferably used. In addition, when the melting part and the discharge part, or the discharge part, are separate from the supply part, they are not necessarily made of the same material as the supply part. In addition, conventionally known metal materials such as brass can be widely used. At this time, it is preferable to form the melting section and the discharge section, or the discharge section, from a material having a higher thermal conductivity than the supply section. A preferred example is to use 64 titanium for the feed section and SUS304 or brass for the discharge section.

In the hot end module of the present invention, it is preferable that a convex portion facing the worm is formed on the inner wall of the passage exposed from the opening of the supply portion of the ejection head. Further, the supply portion of the ejection head has a facing opening facing the opening through the passage, and the filament feeding mechanism faces the passage from the facing opening. and a backup member disposed at a position facing the worm, and rotating the worm while the filament is sandwiched between the worm and the backup member so that the filament is transferred to the downstream You may make it send out to the side. In the present invention, the backup member and/or the worm are preferably biased toward the other party by a spring or the like.

Also, the three-dimensional printer of the present invention is equipped with the hot end module described above.

Further, the ejection head of the present invention has an introduction port for introducing a filament as a modeling material, a supply unit for supplying the filament introduced from the introduction port to the downstream side, and Discharge comprising the downstream melting section that heats and melts the filament, a discharge section having a discharge port that discharges the filament melted in the melting section, and a passage that communicates from the introduction port to the discharge port. In the head, the supply section has an opening that exposes the passage, and a protrusion is provided on the inner wall of the passage facing the opening.

In the ejection head of the present invention, the convex portion can be provided by forming concave portions on the inner wall above and below the position where the convex portion is to be formed. Moreover, it is preferable that the supply section, the melting section, and the discharge section are integrally formed.

According to the present invention, the threaded portion of the worm is brought into contact with the filament, which is the modeling material, and the filament is sent out by the rotation of the worm. For example, when the maximum diameter of the worm (screw part) is about 3 to 5 mm and the pitch between screw threads is about 0.5 to 1.0 mm, the pitch A filament feed of about 0.5 to 1.0 mm per minute is possible, and fine feed is possible in a small diameter worm. In addition, by using a worm, the torque of the motor to rotate it can be reduced, and the number of parts can be reduced by eliminating the need for a reduction gearbox, making the filament feeding mechanism smaller, lighter, and more energy efficient. can be achieved, and can contribute to speeding up the modeling speed. Further, since the worm of the filament feed mechanism is arranged in the opening formed in the supply portion of the discharge head, the size of the device can be reduced. In addition, since the filament can be fed (pushed) at a position relatively close to the melting section and the discharge port, the feeding speed of the filament (i.e., the discharge amount of the molten modeling material) can be controlled more accurately. As a result, it is possible to provide a filament feeding method, a hot-end module, a three-dimensional printer, and an ejection head capable of forming a more dense and highly accurate model.

1 is an explanatory diagram showing an example of a three-dimensional printer provided with a hotend module according to one embodiment of the invention; FIG. 1 is a partial cross-sectional view of an example of a hot end module according to one embodiment of the invention; FIG. 1A and 1B are a front view and a bottom view of an ejection head used in a hot-end module according to an embodiment of the present invention; FIG. FIG. 4 is a partial cross-sectional view of another example hot end module in accordance with one embodiment of the present invention; FIG. 4 is a partial cross-sectional view of yet another example of a hot end module in accordance with one embodiment of the present invention; FIG. 4 is a partial cross-sectional view of yet another example of a hot end module in accordance with one embodiment of the present invention;

First, a three-dimensional modeling apparatus (3D printer) having a hotend module according to one embodiment will be described with reference to the drawings. FIG. 1 schematically shows an example of a fused lamination type 3D printer including a hot-end module according to an embodiment. In the illustrated 3D printer P, a three-dimensional modeled object is formed by layering molten modeling material ejected from a nozzle (ejection head) 100 on a modeling stage S movable in the Y-axis direction.

A heating means 60 is attached to the ejection head 100 to heat and melt the modeling material inside the ejection head 100 . The upper portion of the ejection head 100 is attached to the head portion H. As shown in FIG. The head portion H can be moved to any position in the X-axis direction together with the ejection head 100 by an X-axis belt Bx movable in the X-axis direction. The X-axis frame Fx on which the X-axis belt Bx is installed is movable in the Z-axis direction by two Z-axis movement mechanisms Bz. A Y-axis belt By is attached to the modeling stage S so that it can move in the Y-axis direction, and the modeling stage S can move to any position in the Y-axis direction. Thereby, the relative positional relationship between the ejection head 100 and the modeling stage S can be adjusted three-dimensionally.

A hot end module integrally including a filament feeding mechanism together with the ejection head 100 and the heating means 60, which will be described later in detail, is attached to the head portion H via a holder portion. A filament-shaped modeling material (filament) 3a is supplied from a filament reel FT to the ejection head 100 provided in the hot end module. A filament feeding mechanism included in the hot end module feeds the filament 3 a to the tip side of the ejection head 100 . The sent filament 3a is melted by the heat applied from the heating means 60, then ejected from the ejection port provided at the lower end of the ejection head 100, and stacked on the modeling stage.

Next, referring to FIG. 2, a hot-end module for a three-dimensional printer of one embodiment, which can be installed in the 3D printer P described above, will be described. FIG. 2 is a partial cross-sectional view of a hot-end module 1, which is an example of a hot-end module according to one embodiment. The hotend module 1 has a discharge head 100 with a supply section 10 , a melting section 20 and a discharge section 30 . The supply unit 10 has an inlet 11 for introducing solid filaments 3a, which are filament-shaped modeling materials, into the ejection head 100 . The melting section 20 provided on the filament downstream side of the supply section 10 (the side opposite to the introduction port 11) heats the filament 3a in a solid state to change it into a filament 3b in a molten state. A discharge port 31 for discharging the filament 3b in a melted state is provided at the lower end of the discharge section 30 provided downstream of the melting section 20 . A passage 12 is formed inside the ejection head 100 to communicate from the introduction port 11 to the ejection port 31 .

At the upper end of the ejection head 100 where the introduction port 11 is provided, a holder portion A is attached that supports the ejection head 100 and can also serve as a connecting portion (adapter) with a three-dimensional printer to which the hot end module 1 is attached. It is When the hotend module 1 is attached to the 3D printer P described above, it can be attached to the head portion H via the holder portion A. The holder portion A can also function as a heat sink portion that dissipates heat from the inlet 11 side of the ejection head 100 to the outside. In the illustrated example, the holder part A has a cylindrical shape and is connected to the ejection head 100 by covering and fitting a part of the outer periphery of the supply part 10 . In the illustrated example, the pulse motor (driving means (driving unit)) 44 of the cylindrical filament feeding mechanism 40 is fixed and supported to the holder A together with the ejection head 100, as will be described later in detail. It is

An opening 10a is formed in the peripheral wall defining the passage 12 of the supply portion 10, and the passage 12 is exposed from the opening 10a. A part of a rotating member (worm) 41 that constitutes a filament feeding mechanism 40, which will be described later in detail, enters an opening 10a formed in the supply section 10 and contacts the filament 3a. In the illustrated example, a part of a backup roller 42 as a backup member facing the worm 41 enters into the facing opening 10b provided facing the opening 10a across the passage 12 and contacts the filament 3a. in contact with The worm 41 and the backup roller 42 constitute a filament feeding mechanism 40 together with a driving means (driving section) 44 and a driving shaft (driving shaft) 43 which will be described later. The backup roller 42 is appropriately biased in the direction of the worm 41 by pressing the shaft of the rotating shaft with biasing means such as a spring such as a leaf spring or an elastic body such as rubber. preferable.

The opening 10a can be formed by cutting the pipe-shaped discharge head 100 from the outside in the longitudinal direction until the passage 12 appears.

The filament feeding mechanism 40 in the hot end module of the embodiment includes a worm (screw portion) 41 as a rotating member that feeds the filament downstream (melting section 20 side) by rotating in contact with the filament 3a. The worm 41 has a continuous helical thread groove (thread), and the threaded portion (worm 41) contacts the filament 3a. A drive shaft 43 to which the worm 41 is attached extends in the longitudinal direction of the passage 12 (the feeding direction of the filament 3a). The worm 41 rotates around the drive shaft 43 to feed the filament 3a from the supply section 10 to the downstream side (melting section 20 side). It is preferable that the threaded portion (worm 41) is appropriately pressed against the filament 3a by the backup roller 42. As shown in FIG.

The drive shaft 43 is rotated by the rotational force generated by the drive section 44 . The direction of rotation generated by the driving portion 44 and the direction of rotation of the worm 41 match. On the other hand, a backup member (backup roller) 42 that sandwiches the filament 3a at a position facing the worm 41 in the passage 12 does not have an independent drive source. passively rotates in response to movement The drive shaft 43 is arranged slightly inclined with respect to the discharge head 100 (passage 12). In this case, the worm 41 (screw portion) preferably has a substantially conical shape so as to contact or press contact with the filament 3a in parallel so that the contact area (contact distance) with the filament 3a becomes large. . The driving shaft 43 can be arranged parallel to the ejection head 100 (passage 12) depending on the parts of the filament feeding mechanism 40, the size of the ejection head 100, the size of the opening 10a, and the like. In this case, it is preferable that the worm 41 (screw portion) has a substantially cylindrical shape.

The hot-end module of the embodiment has a configuration in which the filament 3a is fed by the rotation of the worm 41, thereby realizing feeding of the filament 3a with relatively high accuracy. Specifically, the worm 41 feeds out the filament 3a by rotating the worm 41 while making the screw thread bite into the filament 3a along the direction in which the screw thread extends. there is At this time, the filament 3a and the worm 41 are formed by forming the worm 41 (screw portion) with a material that does not easily wear out, such as by making the thread portion of the thread portion sharpened so as to easily bite into the filament 3a. It is possible to reduce the occurrence of slippage over a long period of time, and more reliable delivery of the filament 3a can be realized. The bottom (valley) of the groove of the threaded portion of the worm 41 can be formed to have an acute angle or a flat shape.

In addition, since the worm 41 is inserted into the opening 10a of the ejection head 100 and the feed mechanism 40 and the ejection head 100 are integrated, the size of the hot end module can be reduced. Therefore, the distance from the worm 41 to the melting section 20 where the filament 3a is melted is relatively short, and the possibility that the filament 3a is bent by the sending force applied from the worm 41 to the filament 3a is small. Therefore, the feeding speed of the filament can be adjusted with high precision, and the amount of the modeling material discharged from the discharge port 31 can be controlled accurately. Even when a flexible filament is used for modeling, it is thought that bending and twisting of the filament can be suppressed, and a modeled object can be produced satisfactorily.

In other words, in the filament feeding method according to one embodiment of the present invention, by rotating the worm 41 with the threaded portion of the worm 41 constituting the filament feeding mechanism 40 in contact with the filament 3a, Filament 3a is delivered. The threaded portion of the worm 41 contacts the filament 3a in the passage 12 exposed from the opening 10a of the supply section 10 of the ejection head 100, and the rotation of the worm 41 sends the filament 3a downstream. By rotating the driving shaft 43 extending along the filament feeding direction (extending direction of the filament 3a) by the driving section 44, the filament 3a is fed downstream. By controlling the rotation speed of the drive unit 44 , the speed at which the filament 3 a is sent to the melting unit 20 can be controlled, and the discharge speed of the modeling material discharged from the discharge port 31 can be controlled.

Worm 41 may be removably attached to drive shaft 43 . The worm 41 (screw portion) having different screw thread dimensions (height, pitch, lead angle, etc.) can be replaced according to the resolution and the dimensions, shape, material, etc. of the filament 3a used in modeling. . The dimensions of the filament 3a, the worm 41, and the screw thread can be appropriately selected according to the size of the model to be manufactured using the hot end module 1 and the required accuracy. Also, the worm 41 may be formed by processing the tip of the drive shaft 43 into a worm shape. In this case, the drive shaft 43 may have a configuration in which it is replaceably attached to the drive portion 44 .

The worm 41 and the backup roller 42 may also have the function of cooling the filament 3a by coming into contact with the filament 3a. The softening (melting) of the filament 3a due to the heat transmitted from the melting section 20 is prevented, so that clogging of the filament within the passage 12 can be prevented. Therefore, the worm 41 and the backup roller 42 are preferably formed using a material with high thermal conductivity, and metal materials such as copper, aluminum, and stainless steel can be used, for example. Ceramics with high thermal conductivity, such as aluminum nitride and aluminum oxide, may be used, and resin materials with high thermal conductivity may be used.

The drive shaft 43 of the filament feeding mechanism 40 extends along the length direction of the filament 3a (the length direction of the passage 12) and can be attached to a drive portion 44 integrally fixed to the holder portion A. A configuration in which the drive shaft 43 extends in a lateral direction perpendicular to the extending direction of the ejection head 100 (for example, a configuration in which a rotating member rotating along the extending direction of the filament 3a feeds the filament 3a within the opening 10a); By comparison, the lateral dimensions of the hotend module 1 can be relatively small. An increase in the lateral dimensions of the hotend module 1 may be undesirable. This leads to an increase in the lateral dimension of the head portion H of the 3D printer P, which limits the area in which the modeling material can be discharged on the shaping stage in the modeling operation, which may hinder the modeling. From the viewpoint of avoiding such troubles, it may be preferable for the lateral dimension to be relatively small.

The drive shaft 43 can be configured to have a predetermined angle with respect to the extending direction of the filament 3a, as shown. As a result, the worm 41 located at the tip of the drive shaft 43 can be brought into contact with the filament 3a with a relatively strong force. With this configuration, the feeding of the filament 3a by the rotation of the worm 41 can be carried out more reliably.

The drive unit 44 is, for example, a stepping motor (pulse motor) that can control its rotation by a pulse signal. When the drive unit 44 is a stepping motor, a drive pulse signal for controlling the ejection of the modeling material is generated by a drive pulse generation circuit (not shown) according to a predetermined modeling program, and the motor coil current is supplied. Input to a driver (not shown). The stepping motor rotates due to current supplied from the driver based on the drive pulse signal, and the rotational force is transmitted to the worm 41 via the drive shaft 43 to send the filament 3 a to the melting section 20 .

In the illustrated example, the drive part 44 is fixed to the holder part A. As shown in FIG. Specifically, for example, a substantially cylindrical driving portion 44 is fitted into an opening of the holder portion A and assembled, and the holder portion A supports the driving portion 44 . However, the configuration of the drive unit 44 is not limited to this. The drive part 44 can also be arranged above the holder part A and spaced therefrom.

The holder part A is fixed to the head part H of the 3D printer P, is in thermal contact with the guide shaft, moves around along the X-axis frame Fx by the X-axis belt Bx, and dissipates heat together with the head part H. For this reason, in order to improve the heat dissipation of the holder part A, the head part H, and/or the guide shaft, the shape, color, etc. are changed, for example, by forming fins on the outer surface or making them black. or may be added.

The openings 10 a and 10 b formed in the supply section 10 can reduce the cross-sectional area of the supply section 10 and increase the thermal resistance of the supply section 10 . The openings 10 a and 10 b can have the effect of suppressing heat transfer from the melting section 20 to the inlet 11 in the supply section 10 . That is, the supply section 10 having the openings 10 a and 10 b can function as a heat insulating section that suppresses heat transfer from the melting section 20 to the inlet 11 .

A heating means (heating head) 60 is attached to the melting section 20 . The filament in the passage 12 in the melting section 20 is melted by the heat given from the heating means 60, and melted through the filament 3c in the mixed state of solid and liquid on the downstream side of the boundary between the barrel section 10 and the melting section 20. It changes to the filament 3b in the folded state. In the example shown in FIG. 1, two heating means 60 are provided so as to sandwich the melting portion 20 of the ejection head 100 .

As the heating means 60, for example, a heating head having a thick-film resistor layer formed on an insulating substrate, a heat block, or other known means can be widely used. is preferred. A heating head 60 in the illustrated example has a ceramic substrate (insulating substrate) 61 made of, for example, rectangular plate-shaped alumina or zirconia, and strip-shaped heating resistors 62 formed on the surface of the insulating substrate 61 . In the example of FIG. 1, a cover substrate 63 which is another insulating substrate is provided on the opposite side of the heating resistor 62 from the insulating substrate 61 .

In a state where the heating head 60 is attached to the ejection head 100, the heating head 60 is applied with its insulating substrate 61 side to the flat portion of the melting portion 20 of the ejection head 100, for example, by applying a silver-based thick film paste as a bonding material. Fired and joined. In the example shown in FIG. 2, two heating heads 60 are attached with the ejection head 100 interposed therebetween. , the heating heads 60 may be provided on all planes thereof, and the hot end 1 may have four heating heads 60 . If the heating head 60 is of a small size, it is possible to provide a plurality of heating heads 60 in the lengthwise direction of one flat portion.

The heating head 60 heats the melting portion 20 to a desired temperature by controlling the voltage applied to the heating resistor 62 . The temperature of the melting portion 20 can be detected, for example, based on the resistance value change of the heating resistor 62 . A temperature monitoring means such as a sensor may be separately provided to detect the temperature of the melting section 20 . The voltage applied to the heat generating resistor 62 is adjusted according to the detected temperature of the melting portion 20, and during the molding operation for forming the modeled object, the temperature distribution in the passage 12 in the melting portion 20 changes to the shape of the model. The temperature is controlled so that the material remains molten and stable. Depending on the configuration of the heating head 60, the melting portion 20 may be heated so as to have a temperature gradient. For example, by configuring the heating resistor 62 so that the heating temperature on the filament upstream side of the melting section 20 is lower than the heating temperature on the filament downstream side of the melting section 20, the amount of heat transferred to the supply section 10 is suppressed. It is possible to suppress the softening or melting of the filaments 3 a within the passage 12 in the supply section 10 , which can cause clogging of the passage 12 with the building material.

At the lower end of the supply section 10 in the passage 12, there is a backflow prevention member 50 that prevents the molding material melted in the melting section 20 by the heating means 60 from flowing back to the supply section 10 side (introduction port 11 side). It can be arranged as needed. In the example shown in FIG. 2, the backflow prevention member 50 is a stepped portion 21 provided at the inlet (boundary portion between the supply portion 10 and the melting portion 20) to which the molding material of the melting portion 20 inside the passage 12 is supplied. It is provided in contact with the upper surface. The backflow prevention member 50 can be fixed so as to be sandwiched between an annular fixing member (retaining member 51 ) having an inner diameter larger than that of the backflow prevention member 50 and the stepped portion 21 .

In the example shown in FIG. 2, the backflow prevention member 50 is formed in a ring shape that can surround and hold a portion of the filament in the longitudinal direction. The backflow prevention member 50 is preferably made of an elastic material whose inner diameter can follow fluctuations in the diameter of the filament within the tolerance and can maintain a tightly held state. The material used for the backflow prevention member 50 preferably has heat resistance against the temperature at which the filament melts, and for example, a Ni—Ti alloy, which is a superelastic alloy, can be used. Since the melting portion 20 and the feeding portion 10 are separated in the passage 12 by the backflow prevention member 50, the filaments 3c and 3b in the melted state flow backward and then solidify in the feeding portion 10 to clog the passage 12, thereby clogging the filament 3a. can be prevented from occurring.

As shown in FIG. 2, the hot end module 1 is provided so as to surround the outer circumference of the ejection head 100 at the portion where the backflow prevention member 50 is arranged (the boundary portion between the supply section 10 and the melting section 20). It may have a temperature control section 70 . The temperature control part 70 can be a means for increasing the heat capacity near the boundary between the supply part 10 and the melting part 20, such as a metal block having a predetermined thickness, such as aluminum or stainless steel. That is, the temperature control section 70 is provided so as to surround the vicinity of the boundary between the supply section 10 and the melting section 20 so as to increase the heat capacity of the boundary portion between the supply section 10 and the melting section 20 . Therefore, the vicinity of the boundary between the supply section 10 and the melting section 20 can be stably maintained at a desired temperature. The size, shape, dimensions, and the like of the temperature control unit 70 can be appropriately determined according to the type of modeling material, the delivery speed of the modeling material during the modeling operation, and the like. For example, specific examples of the shape include a ring shape, a cylindrical shape, and a polygonal prism shape.

The temperature of the melting portion 20 heated by the heating portion 60 described above is It can be about 400° C. to 450° C. higher than its melting point. In addition, the vicinity of the boundary between the supply section 10 and the melting section 20, where the backflow prevention member 50 is arranged, has a temperature lower than the melting point of the filament, and can be maintained at about 300.degree. C. to 330.degree. The vicinity of the boundary between the supply section 10 and the melting section 20 can be relatively stably maintained below the melting temperature of the filament by attaching the temperature control section 70 .

In the illustrated example, the temperature control section 70 includes a cover member that covers a part of the melting section 20 and the discharging section 30 to retain the heat generated from the heating means 60 in the vicinity of the melting section 20 and the discharging section 30. 80 is installed. The cover member 80 can be formed using metal materials with high thermal conductivity, such as aluminum and stainless steel. Since the cover member 80 is provided, the temperature distribution (temperature gradient) in the region of a predetermined width from the vicinity of the inlet of the melting section 20 to the discharge section 30 can be adjusted according to the type of filament to prevent clogging of the passage 12. In some cases, a stable temperature distribution can be achieved. The space between the case member 80 and the ejection head 100 covered by the case member 80 may be filled with a heat-resistant insulating material such as glass fiber. The temperature adjustment section 70 and the cover member 80 are made of a material with a higher thermal conductivity than the supply section 10 (ejection head 100), and suppress the transfer of the heat heated in the melting section 20 to the supply section 10 side.

In the supply section 10 which can suppress the heat transfer from the melting section 20 to the introduction port 11 by forming the openings 10a and 10b, the temperature at the introduction port 11 is relatively low and maintained at about 60°C. obtain. The holder part A attached to the outer periphery of the inlet 11 also has a function of radiating heat in the vicinity of the inlet 11 to the outside, and the inlet 11 side of the supply part 10 is maintained at a relatively low temperature. obtain. Further, at the contact portion between the worm 41 entering the opening 10a and the filament 3a, the temperature is preferably lower than the glass transition point of the filament 3a, for example, 140° C. or lower.

FIG. 3A shows a front view of the ejection head 100 used in the hot end 1 shown in FIG. 2, viewed from the side where the opening 10a is formed, and a bottom view of the ejection port 31 side. is shown in FIG. 3(B). In the ejection head 100, the supply section 10, the melting section 20, and the ejection section 30 may be integrally formed using, for example, stainless steel, nickel alloy, titanium, titanium alloy, or ceramics. . The ejection head 100 may be formed by combining independent members, or another member may be interposed between each member. In this case, for example, the ejection head 100 can be configured by combining the supply section 10, the melting section 20, and the ejection section 30 as separate members.

When the ejection head 100 is formed by combining independent members, the thermal conductivity of the material of the member used for the melting section 20 and the ejection section 30 is higher than the thermal conductivity of the material for the member used for the supply section 10. A high value is preferable from the viewpoint of effectively utilizing the heat of the heating means 60 for melting the modeling material while suppressing heat transfer to the introduction port 11 side. In addition, when the supply section 10 and the melting section 20 are formed as separate members, the backflow prevention member 50 should be sandwiched between the supply section 10 and the melting section 20 when connecting the supply section 10 and the melting section 20 . Can be configured.

The ejection head 100 shown in FIG. 3 is formed by cutting a cylindrical metal rod, for example. The total length of the ejection head 100 illustrated in FIG. 3A is, for example, 33 mm. The ejection head 100 is made of, for example, 64 titanium (an alloy of titanium mixed with 6% by mass of aluminum and 4% by mass of vanadium). In the illustrated example, the supply unit 10 has a columnar shape (cylindrical shape) with a diameter of, for example, 3 mm and a length of, for example, 17.5 mm. A passage 12 having a diameter of, for example, 2.3 mm is formed in the central portion of the supply portion 10 .

For example, an opening 10a with a length of 9 mm and a width of 2.1 mm and an opening 10b with a length of 9 mm and a width of 2 mm are provided in the peripheral wall of the supply part 10 so as to reduce the cross-sectional area of the supply part 10 and increase its thermal resistance. are formed in pairs so as to face the passage 12 . The width and length of the openings 10a and 10b are determined so that the diameter of the passageway 12 of the supply unit 10, or the width and length of the openings 10a can be adjusted while maintaining the rigidity of the supply unit 10 and increasing the heat resistance. The arrangement and size of the worm 41 of the filament feeding mechanism 40 that contacts the filament 3a exposed from the opening 10a, and the backup roller 42 that enters the opposing opening 10b or contacts the filament 3a exposed from the opening 10a are taken into account. It can be determined as appropriate. For example, the opening 10a is formed by cutting a pipe-shaped supply portion 10 having a diameter of 3 mm by about 1 mm so as to expose the filament 3a. pressure contact. Further, for example, the opening 10b is opened by plane cutting to an opening width of about 2 mm, and the filament 3a exposed from the opening is pressed against the backup roller 42 having a width of less than 2 mm.

In the illustrated example, the melting portion 20 is formed in the shape of a quadrangular prism having a rectangular cross-sectional shape of, for example, 3.2 mm on each side, with C-plane corners, and a length of, for example, 12.5 mm. Heating means 60 can be attached to each of the four side surfaces (flat portions) of the melting portion 20 in the shape of a quadrangular prism. Depending on the size, number, position, etc. of the heating means 60 attached to the melting section 20, the melting section 20 may be formed in a prismatic shape other than a square prism (for example, a triangular prism shape or a pentagonal prism shape). A passage 12 having a diameter of, for example, 1.8 mm is formed in the center of the melting section 20 in communication with the passage 12 of the supply section 10 .

The diameter of the passage 12 in the melting section 20 is formed smaller than the diameter of the passage 12 in the feeding section 10, and a backflow prevention member 50 can be fixed at the boundary between the melting section 20 and the feeding section 10 where the passage diameter changes. A portion 21 may be formed. That is, the thickness of the peripheral wall of the passage 12 in the supply section 10 can be formed thinner than the thickness of the peripheral wall of the passage 12 in the melting section 20 . In addition, openings exposing the passages 12 may be formed on the four side surfaces of the melting section 20 in order to more efficiently heat and melt the molding material therein. By attaching the heating means 60 so as to close the opening, the modeling material is directly heated by the heating means 60, and the modeling material can be melted more efficiently.

The discharge part 30 has a substantially conical shape with a length of 3 mm, for example, and has a tapered shape from the melting part 20 toward the tip part (discharge port 31 ) of the discharge part 30 . The discharge part 30 is formed to have a diameter of, for example, 3 mm at the boundary with the melting part 20, and is formed to have a diameter of, for example, 1.5 mm at the tip where the discharge port 31 is formed, and the discharge port 31 has a diameter of, for example, 0.4 mm. It is formed. Note that the size of each part of the ejection head 100 and the passage 12 described above can be appropriately changed according to the size of the filament.

In the hot end module of this embodiment, a member different from the backup roller 42 can be used as a backup member that faces the worm 41 via the filament 3a. In the hot end module 1a of the example shown in FIG. 4, a pressing member 42a is employed as a backup member. A portion of the pressing member 42a enters the opposing opening 10b and contacts the filament 3a at a position corresponding to the portion where the worm 41 contacts the filament 3a.

The pressing member 42a has a plate-like member PL and a protrusion PR formed at the tip of the member PL. The end of the member PL opposite to the projection PR is attached to the holder portion A. As shown in FIG. That is, the pressing member 42a is a cantilever-type member having one end attached to the holder portion A. As shown in FIG. The protrusion PR enters the opposing opening 10b and contacts the filament 3a. As the worm 41 rotates and the filament 3a is sent out toward the melting section 20, the filament 3a slides against the protrusion PR. The plate-shaped member PL has a restoring force against deformation caused by an external force, and can be formed using, for example, a stainless steel plate having spring properties. The member PL can elastically urge the projection PR arranged at its tip against the filament 3a by its springiness.

The surface of the protrusion PR can be made of a material with high slidability and wear resistance. For example, the surface of the protrusion PR may be coated with a resin having high slidability, such as polyphenylene sulfide (PPS) resin, acetal resin, polyester resin, or polyetheretherketone (PEEK) resin. The pressing member 42a can be formed by joining these members made of resin to the tip of the member PL as the protrusion PR. The pressing member 42a can also be formed by using a plate-like member PL having a bump-shaped protrusion on one end thereof and coating the protrusion with the resin material described above. By using the pressing member 42 a instead of the backup roller 42 as a backup member, it is not necessary to dispose a member that serves as a bearing for the backup roller 42 . Therefore, the lateral dimensions of the hotend module can be further miniaturized.

Further, as a configuration for sandwiching the filament 3a facing the worm 41, instead of the backup member (backup roller 42, pressing member 42a), a protrusion provided on the inner wall of the passage 12 may be employed. A hot end module 1b is shown in FIG. 5 as an example of adopting a configuration in which a protrusion is provided on the inner wall of the passage 12. As shown in FIG. In this case, no opening is provided in the peripheral wall at a position facing the opening 10a into which the worm 41 enters, and a protrusion 42b projecting toward the center of the passage 12 is formed on a part of the peripheral wall. The convex portion 42b is formed so as to face the portion of the worm 41 that contacts the filament 3a so as to contact the filament 3a.

The convex portion 42b is formed by partially cutting or polishing the upper side (introduction port 11 side) and lower side (melting portion 20 side) of the convex portion 42b formation position on the inner wall of the passage 12 from the opening 10a of the discharge head 100, for example. Therefore, it can be formed by forming a concave portion (a portion of the passage 12 having a larger diameter than the portion where the convex portion 42b is formed). Further, in this embodiment, a hard member (for example, metal or ceramic) is bonded or vapor-deposited at the position where the projection 42b is to be formed (the position facing the worm 41 with the filament 3a interposed therebetween). Yes, but not necessarily. That is, the width of the worm (screw portion) 41 is urged by the spring so that the screw portion 41 is pressed against the convex portion 42b (a convex portion on which no hard member is formed), so that the screw portion 41 is attached to the filament 3a. Good pressure contact is possible. In this embodiment, for example, in the portion where the convex portion 42b is formed, the inner diameter of the passage 12 is about 2.3 mm, and the portion corresponding to the concave portion on the introduction port 11 side and the melting portion 20 side of the convex portion 42b. The inner diameter of the passageway 12 may be 2.5 mm. The convex portion 42b can be formed by inserting a suitable tool from the opening 10a, polishing the inner wall of the passage 12, and applying a hard member. The surface of the projection 42b may be coated with a slidable and wear-resistant resin material or metal material, similar to the protrusion PR of the backup member (pressing member) 42a.

By adopting the convex portion 42b instead of the backup members (pressing members) 42 and 42a as the member that sandwiches the filament 3a facing the worm 41, the hot end module provided with the filament feeding mechanism 40 can be further miniaturized. . In particular, the lateral dimensions in the vicinity of the feed section 10 can be kept relatively small. The formation of the convex portion 42b is realized by forming a metal bump at a position facing the worm 41 after the passage 12 having the same diameter (for example, 2.3 mm diameter) is formed in the supply portion 10, or by spot-welding a resin material. may be

Embodiment hot-end modules are not limited to those comprising the structures illustrated in the drawings, and the structures, shapes, and materials illustrated herein. The configuration of the holder section A and the filament feeding mechanism 40 can be modified according to the configuration of the head section H of the 3D printer to which the hot end module of the embodiment can be attached. The hot end module of the embodiment can have a configuration in which the drive section 44 is separated from the holder section A, as shown as a hot end module 1c in FIG. In the illustrated example, the drive shaft 43 extends to the drive section 44 which is arranged further above the holder section A (upstream of the filament 3a) as a separate body from the holder section A. As shown in FIG. The holder portion A is attached to the ejection head 100 while partially covering the vicinity of the inlet 11, and the holder portion A is not provided in the portion where the drive shaft 43 extends. Therefore, in the hot end module 1c, an increase in lateral dimension in the vicinity of the inlet 11 can be suppressed.

Reference Signs List 1, 1a, 1b, 1c hot end module 3a, 3b, 3c filament 10 supply section 10a opening 10b facing opening 11 introduction port 12 passage 20 melting section 21 step section 30 discharge section 31 discharge port 40 filament feeding mechanism 41 worm 42 Backup roller 42a Pressing member 42b Convex portion 43 Drive shaft 44 Drive unit 50 Backflow prevention member 51 Retaining member 60 Heating means (heating head)
61 Insulating substrate 62 Heating resistor 70 Temperature control unit 100 Ejection head PL Member PR Projection P 3D printer H Head unit A Holder unit S Modeling stage

Claims (7)

a supply unit having an inlet for introducing a filament as a modeling material, supplying the filament introduced from the inlet to a downstream side; and the downstream side heating and melting the filament supplied from the supply unit. a melting part, a discharge part having a discharge port for discharging the filament melted in the melting part, and a passage communicating from the introduction port to the discharge port;
a filament feeding mechanism for feeding the filament to the downstream side;
A hot-end module for a three-dimensional printer , comprising a holder unit that couples the ejection head and the filament feeding mechanism ,
the supply portion of the ejection head has an opening that exposes the passage,
The filament feeding mechanism has a worm having a threaded portion facing the passage from the opening, and a driving means for driving the worm,
A hot end for a three-dimensional printer, characterized in that the filament is sent out to the downstream side by rotating the worm while the screw portion of the worm is in contact with the filament in the passage. module. The passage communicates linearly from the introduction port to the discharge port, and a convex portion facing the worm is formed on the inner wall of the passage exposed from the opening of the supply portion of the discharge head. The hot-end module for a three-dimensional printer according to claim 1 , characterized by: the supply portion of the ejection head has a facing opening provided to face the opening through the passage;
The filament feed mechanism has a backup member arranged facing the passage from the opposed opening and arranged at a position facing the worm,
2. The three-dimensional device according to claim 1 , wherein the filament is sent out to the downstream side by rotating the worm while the filament is sandwiched between the worm and the backup member. Hotend module for printers. A three-dimensional printer comprising the hot end module according to any one of claims 1 to 3 . a supply unit having an inlet for introducing a filament as a modeling material, supplying the filament introduced from the inlet to a downstream side; and the downstream side heating and melting the filament supplied from the supply unit. a melting part, a discharge part having a discharge port for discharging the filament melted in the melting part, and a passage communicating from the introduction port to the discharge port,
The ejection head, wherein the supply part has a vertically long opening that exposes the passage, and a protrusion is provided on an inner wall of the passage that faces a position of the opening that is closer to the introduction port side. . 6. The ejection head according to claim 5 , wherein the protrusion is provided by forming recesses in portions of the inner wall above and below a position where the protrusion is to be formed. 7. The ejection head according to claim 5 , wherein said supply section, said melting section, and said ejection section are integrally formed.

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