Parallel multi-head three-dimensional printer tool head lifting structure and height difference measuring method

Abstract

The invention discloses a parallel multi-head three-dimensional printer tool head lifting structure and a height difference measuring method, and relates to the technical field of three-dimensional printing, the parallel multi-head three-dimensional printer tool head lifting structure comprises a tool head, a back plate and a lifting assembly, the side face of the tool head is slidably assembled on the back plate, the lifting assembly comprises a driving piece and a connecting piece, and the driving piece is used for driving the connecting piece to retract and release; the connector is used for driving the tool head to lift; and a photoelectric switch is arranged on the back plate. A traditional short-range rigid driving scheme is replaced on the premise that the precision is guaranteed, the motion quality of the tool head is reduced, and help is provided for improving the motion speed and the printing quality. In addition, the height difference measuring method based on the scheme is simplified, the measuring precision and the repeated positioning precision are improved, and the reliability is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of three-dimensional printers, and in particular to a tool head lifting structure of a parallel multi-head three-dimensional printer and a height difference measuring method. Background Art

[0002] At present, multi-head 3D printers can be divided into independent multi-head and parallel multi-head according to the tool head movement mode. When independent multi-head printers are running, the heads do not move synchronously: for example, when one head is working, the other heads usually wait in the tool magazine or on both sides of the X-axis and other non-working areas; while when parallel multi-head printers are running, the heads move synchronously. Different from independent multi-head, parallel multi-head 3D printers have a simple movement structure and high repeatability positioning accuracy, but because each head moves in the working area, the interference between the nozzle and the workpiece must be considered.

[0003] For parallel multi-heads, there are currently design solutions such as equal height type and lifting type on the market. The equal height type relies on complex manual zeroing and other methods to constrain each head to the same height to avoid interference. However, due to assembly and zeroing errors, it is impossible to ensure that each head is absolutely flush, so interference cannot be completely avoided under actual working conditions.

[0004] The lifting type avoids interference by raising or lowering the tool head to increase the distance between the nozzle and the top surface of the part. The mainstream liftable tool head designs on the market are mostly electrically driven by short-range push rods, servos, etc., and rely on rigid transmission structures to act on the heads to achieve high-precision lifting. First of all, the introduction of short-range drive motors and rigid transmission mechanisms undoubtedly increases the moving mass of the tool head. On the one hand, the greater movement inertia causes a greater load on the moving motor and reduces the upper limit of the movement speed. On the other hand, it significantly amplifies the vibration of the tool head during printing and reduces the printing quality. Secondly, for this type of rigid transmission lifting solution, a more complex tool head zero point calibration and height difference measurement method is required. For example, for a dual-head rigid lift printer, you need to first lower the A head and raise the B head, and continuously move the A4 paper (or a feeler gauge with a thickness of about 0.1mm) between the hot bed and the nozzle. During this process, lift the hot bed (or lower the gantry) in a jog manner to gradually bring the hot bed closer to the nozzle until the moving resistance of the A4 paper (or feeler gauge) reaches a more appropriate empirical value, and record this position as the zero position of the A head; then lower the B head and raise the A head, repeat the above operation and record the zero position of the B head. The difference between the zero positions of the two heads is the height difference. This method is extremely dependent on the personal experience of the measurer, and not only has low accuracy, but also has high requirements for the operator. In addition, every time the nozzle or the hot bed panel is replaced, it is necessary to repeatedly measure the zero position and height difference of the two heads. The operation is cumbersome and complicated, and the repetition accuracy is poor. Summary of the invention

[0005] The purpose of the present invention is to provide a parallel multi-head 3D printer tool head lifting structure and height difference measurement method to solve the problems existing in the above-mentioned prior art, replace the traditional short-range rigid drive solution under the premise of ensuring accuracy, reduce the tool head movement mass, and help improve the movement speed and printing quality. In addition, the height difference measurement method based on this solution is also simplified, the measurement accuracy and repeated positioning accuracy are improved, and the reliability is greatly increased.

[0006] To achieve the above-mentioned purpose, the present invention provides the following solution: The present invention provides a parallel multi-head 3D printer tool head lifting structure, including a tool head, a back plate and a lifting assembly, the side of the tool head is slidably mounted on the back plate, the lifting assembly includes a driving member and a connecting member, the driving member is used to drive the connecting member to retract and extend, and the connecting member is used to drive the tool head to rise and fall; a photoelectric switch is arranged on the back plate.

[0007] In one embodiment, the lifting assembly includes a winding drum, a servo and a wire core, one end of the wire core is fixedly connected to the tool head, and the other end of the wire core is wound around the winding drum, and the servo is used to drive the winding drum to rotate forward or reverse.

[0008] In one embodiment, a hose is provided on the outside of the wire core, one end of the hose is fixed on the top of the back plate, the other end of the hose is assembled on the fixed plate, the winding reel is installed on the bottom of the fixed plate, and the wire core passes through the fixed plate and the top of the back plate in sequence and is connected to the tool head.

[0009] In one embodiment, the printing consumables are arranged in a material tube, one end of which is connected to the top of the tool head, and the other end of which is mounted on a fixed plate. The printing consumables pass through the fixed plate and the material tube and enter the tool head and are discharged through the nozzle.

[0010] In one embodiment, the lifting assembly includes a short-range extruder and a long-range extruder, the short-range extruder is installed in the tool head, one end of the printing consumables passes through the short-range extruder and is transported to the nozzle, and the other end of the printing consumables passes through the long-range extruder and is connected to the consumable supply end.

[0011] In one embodiment, a hose is provided on the outside of the printing consumables, one end of the hose is fixed on the top of the back plate, and the other end of the hose is assembled on the fixed plate. The remote extruder is arranged at the bottom of the fixed plate, and the printing consumables pass through the remote extruder, the hose and the short-range extruder in sequence and then discharge to the nozzle.

[0012] In one embodiment, a slider is fixed to the side of the tool head, a linear guide rail is provided on the back plate, and the slider is slidably assembled in the linear guide rail; a magnetic buckle is provided at the bottom of one side of the back plate located at the tool head.

[0013] The present invention also provides a method for measuring the height difference of tool heads of a parallel multi-head 3D printer, which is applied to the above-mentioned parallel multi-head 3D printer tool head lifting structure, and comprises the following steps:

[0014] Step 1: When measuring the height difference between tool heads, any tool head can be used as the main head. First lower the main head and raise the other tool heads. Gradually bring the printing platform and the nozzle of the main head closer until the main head is lifted and the photoelectric switch is triggered. Record the position of the printing platform at this time and calculate the working zero height of the main head.

[0015] Step 2: In the same way as step 2, lower each head in turn and lift the non-measuring end tool head to obtain the height of the working zero point of each tool head, and subtract it from the working zero point height of the main head to obtain the height difference of each head.

[0016] Compared with the prior art, the present invention has achieved the following beneficial technical effects:

[0017] The parallel multi-head three-dimensional printer tool head lifting structure and height difference measurement method of the present invention include a tool head, a back plate and a lifting assembly. The side of the tool head is slidably assembled on the back plate. The lifting assembly includes a driving member and a connecting member. The driving member is used to drive the connecting member to retract and extend, and the connecting member is used to drive the tool head to rise and fall. A photoelectric switch is arranged on the back plate. Under the premise of ensuring accuracy, it replaces the traditional short-range rigid drive scheme, reduces the movement mass of the tool head, and helps to improve the movement speed and printing quality. In addition, the height difference measurement method based on this scheme is also simplified, the measurement accuracy and repeated positioning accuracy are improved, and the reliability is greatly increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 This is a schematic diagram of the lifting structure before lifting in Example 1;

[0020] Figure 2 This is a schematic diagram of the lifting structure after lifting in Example 1;

[0021] Figure 3 This is a schematic diagram of the lifting structure before lifting in the second embodiment;

[0022] Figure 4 This is a schematic diagram of the lifting structure after lifting in the second embodiment;

[0023] Figure 5It is a schematic diagram of a parallel multi-head remote flexible control lifting structure;

[0024] Figure 6 It is a schematic diagram of the "1" head in the parallel multi-head lifting structure in working state;

[0025] Figure 7 It is a schematic diagram of the "0" head in the parallel multi-head lifting structure in working state;

[0026] Figure 8 This is a state change diagram of the lifting structure in Example 1 when measuring the height difference;

[0027] Fig. 9 This is a state change diagram of the lifting structure in Example 2 when measuring the height difference;

[0028] Among them, 1. Printing consumables; 2. Wire core; 3. Material tube; 4. Hose; 5. Fixed plate; 6. Winding reel; 7. Slider; 8. Back plate; 9. Magnetic buckle; 10. Tool head; 11. Nozzle; 12. Short-range extruder; 13. Long-range extruder. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] The purpose of the present invention is to provide a parallel multi-head 3D printer tool head lifting structure and height difference measurement method to solve the problems existing in the above-mentioned prior art, replace the traditional short-range rigid drive solution under the premise of ensuring accuracy, reduce the tool head movement mass, and help improve the movement speed and printing quality. In addition, the height difference measurement method based on this solution is also simplified, the measurement accuracy and repeated positioning accuracy are improved, and the reliability is greatly increased.

[0031] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Embodiment 1

[0033] like Figure 1-Figure 2 As shown, this embodiment provides a parallel multi-head 3D printer tool head lifting structure, including a tool head 10, a back plate 8 and a lifting assembly. The side of the tool head 10 is slidably assembled on the back plate 8. The lifting assembly includes a driving member and a connecting member. The driving member is used to drive the connecting member to retract and extend, and the connecting member is used to drive the tool head 10 to rise and fall; a photoelectric switch is provided on the back plate 8.

[0034] In one embodiment, the lifting assembly includes a winding drum 6, a servo and a wire core 2, one end of the wire core 2 is fixedly connected to the tool head 10, and the other end of the wire core 2 is wound on the winding drum 6, and the servo is used to drive the winding drum 6 to rotate forward or reverse.

[0035] In one embodiment, a hose 4 is provided on the outside of the wire core 2, one end of the hose 4 is fixed to the top of the back plate 8, the other end of the hose 4 is assembled on the fixed plate 5, the winding reel 6 is installed at the bottom of the fixed plate 5, and the wire core 2 passes through the fixed plate 5 and the top of the back plate 8 in sequence and is connected to the tool head 10.

[0036] In one embodiment, the printing consumables 1 are disposed in a material tube 3, one end of the material tube 3 is connected to the top of a tool head 10, and the other end of the material tube 3 is mounted on a fixed plate 5. The printing consumables 1 pass through the fixed plate 5 and the material tube 3 and enter the tool head 10 and are discharged through a nozzle 11.

[0037] Taking the lifting of a single tool head as an example, its structural diagram is as follows: Figure 1-2 As shown. The tool head 10 is required to be connected to the back plate 8 through a linear guide and a slider 7, and can slide up and down relative to it; the hose 4 is a Teflon hose, one end of the hose 4 is connected to the back plate 8, and the other end is fixed to the fixed plate 5 at the far end, and a winding servo is fixed below the outlet of the hose 4; the wire core 2 (made of flexible high modulus fiber, such as Kevlar fiber) passes through the hose 4, one end of which is fixed on the tool head 10, and the other end passes through the hose 4 and is wound around the winding reel 6. In the low position, the servo rotates the winding reel 6 to relax the wire core 2, and the tool head 10 falls under its own weight and is attracted by the magnetic buckle 9 on the back plate 8. In the high position, the servo rotates the winding reel 6 in the opposite direction to tighten the wire core 2. The tension of the wire core 2 overcomes the deadweight of the tool head 10 and the suction force of the magnetic buckle 9 to pull up the tool head 10, and the lifting distance of the tool head 10 is adjusted by controlling the rotation angle of the servo. The structural comparison before and after the tool head 10 is lifted is as follows Figure 1-2 shown.

[0038] In this structure, the wall thickness of the hose 4 is required to be greater than 1mm to ensure that it can provide sufficient support when the core 2 is tightened. There should be an appropriate gap between the inner wall of the hose 4 and the outer wall of the core 2 (about 0.2mm is appropriate), which should ensure the smooth movement of the core 2 and avoid the movement idle distance caused by too large a gap. The length of the hose 4 should not be too short to hinder the normal movement of the tool head 10. The suction force of the magnetic buckle 9 should be moderate. Excessive magnetic force will bring too much burden to the core 2 and over-squeeze the printing platform during leveling and measuring the height difference (see the height difference measurement section for the specific principle); too small magnetic force will affect the positioning accuracy and cause the tool head 10 to be lifted during printing. Use F Print Indicates the required pressure between the tool head 10 and the workpiece during normal printing; F m Indicates the suction force of the magnetic buckle 9 on the tool head 10; GTool represents the weight of the tool head 10 itself; T represents the tension of the wire core 2 when the tool head 10 is lifted; F Level Indicates the minimum pressure that the printing platform is allowed to withstand when leveling and measuring height difference. The structure must meet

[0039] F Print <F m +G Tool =T<<F Level .

[0040] Embodiment 2

[0041] like Figure 3-Figure 4 As shown, this embodiment provides a parallel multi-head three-dimensional printer tool head lifting structure. For tool heads that print consumables of specific properties, this embodiment proposes a derivative form based on the structure of embodiment one, which further simplifies the structure, reduces the quality of the tool head, and reduces the difficulty of assembly and control. This structure uses the consumable itself instead of the wire core 2 to play a traction role, so the consumable is required to have a higher strength and modulus, and elastic materials such as TPU are not applicable. Different from the basic structural form of embodiment one, this derivative form requires that one end of the consumable material tube 3 is fixed to the back plate 8 instead of the tool head 10, and an extruder is required in the tool head 10 and on the distal fixed plate 5, wherein the short-range extruder 12 is responsible for the precise feeding of the consumables, and the long-range extruder 13 is its auxiliary feeding, and the long-range extruder 13 is required to have an active bite loosening function (the specific reason is detailed in the height difference measurement part).

[0042] Define the short-range extruder feed speed as v Direct , the remote extruder feed speed is v Broden , the extrusion direction is positive. During normal printing, the two extruders always keep the same feed speed to stabilize the material supply, that is,

[0043] v Direct =v Broden

[0044] When the tool head 10 is raised and lowered, the long-distance and short-distance extruders need to have a certain speed difference in a short time and then restore the same speed. Let the time be t, the lifting distance be h, and downward is positive, then it satisfies

[0045]

[0046] The above contents are all based on a single tool head 10 as an example. For a parallel multi-head printer, each head needs to share a back plate 8, and a suitable flexible lifting structure can be selected according to the type of printing consumables 1 used, such as Figure 5 As shown. The tool head 10 in working state is in the low position, and all other heads are in the high position. The parallel multi-head remote lifting system using the flexible lifting scheme and its derivative schemes conforming to the above structure and principle are all within the protection scope of the present invention.

[0047] In particular, for a parallel dual-head printer, its structure can be further optimized: it is not necessary for both heads to be actively lifted, and one of the heads can be fixed or passively lifted (i.e., there is no lifting and traction structure, only the guide rail slider 7 and the magnetic buckle 9 are retained for height difference measurement, and the specific principle is described later). The appropriate active lifting head lifting distance and the height difference of the dual heads can also achieve the same effect of active lifting of the dual heads. Figure 6-Figure 7 The figure shows the schematic diagram of the optimized double-head structure, where the "0" head is a traditional tool head, connected to the back plate 8 through a guide rail and a slider 7, with a small sliding space (preferably about 3mm). Under normal conditions, it is in a low position due to gravity and attracted by the magnetic buckle 9, that is, the working height of the "0" head; the "1" head is lifted and lowered by the flexible wire core 2. When the "1" head is in working condition, the "1" head is lowered so that its nozzle 11 is lower than the "0" head h1, that is, the designed height difference; when the "0" head is in working condition, the "1" head is lifted and its nozzle 11 is higher than the "0" head h2, so the total lifting distance of the "1" head is

[0048] h=h1+h2

[0049] Among them, h1 and h2 are preferably 1-3mm. If the value is too large, the lifting distance will be too large, and the too long linear guide will cause mass redundancy and extend the time of switching the tool head 10, reducing the printing quality and efficiency; if the value is too small, it will be difficult to suppress the interference: considering the existence of assembly errors and the non-smooth printing surface of the workpiece, too small a value may still cause interference between the non-working nozzle 11 and the workpiece.

[0050] Method for measuring the height difference of tool heads of parallel multi-head 3D printers:

[0051] The difference in the working height of each tool head nozzle is the height difference. When different tool heads are working, the printer can compensate the height according to the height difference, so as to ensure smooth switching between different tool heads during printing. The measurement accuracy of the height difference determines the printing quality to a certain extent. Although the above structure gives a suitable design height difference, errors are inevitably introduced in the actual assembly, so the design height difference cannot represent the actual height difference.

[0052] For traditional printers with a single tool head, the Voron team proposed a high-precision automatic zeroing solution - VoronTap, but it is only used for zero-point calibration of single-head printers and automatic leveling of their printing platforms. When the hot bed is close to the nozzle 11, the tool head 10 is lifted up a certain distance and the microswitch or photoelectric switch with a Schmidt trigger is triggered to determine the contact position between the platform and the nozzle 11, that is, the working zero point of the tool head. Because the triggering distance of the microswitch and photoelectric switch is constant, and the trigger is the direct contact between the nozzle and the panel, the calibration process is not affected regardless of the size of the nozzle and panel, and high-precision measurement without human intervention is achieved. For dual-tool head and multi-tool head printers, this structure can provide effective assistance for high-precision measurement of height differences. Based on the zeroing principle of Voron TAP, this patent proposes a fully automatic high-precision height difference measurement method for parallel multi-head flexible remote lifting printers.

[0053] This method requires that each tool head is equipped with a photoelectric switch with a Schmitt trigger. The specific structure can be referred to as voron tap, which is not the focus of this invention. Take tool head i as an example, when it is lifted to a height z i When the photoelectric switch is triggered, it will send a signal to the printer. The trigger distance of each head is z i After the assembly is completed, it remains unchanged. After the photoelectric switch is triggered, it should be ensured that each print head still has space to move upward to ensure the normal function of active traction and lifting. If the maximum movement distance of each head is h imax , the active lifting distance is h ilift , it should be ensured

[0054] z i <h ilift <h imax

[0055] Since each head is only lifted up at a low position, and the flexible active traction of each head is not activated in the low position state, it is necessary to consider the active traction state of each head when it is forced to be lifted up. For the wire core 2 traction structure, when the tool head 10 is lifted up at a low position, the winding servo remains stationary, and the wire core 2 will bend and relax adaptively due to its flexibility until the tool head 10 is put down and the wire core 2 recovers. Figure 8-Figure 9 As for the consumable traction structure, when the tool head 10 is lifted up in a low position, the remote extruder 13 should be actively loosened, while the short-range extruder 12 remains engaged, and the consumable is pushed out of the remote extruder 13 for a distance as the tool head 10 is lifted up, until the tool head 10 is lowered, and the consumable retracts and engages the remote extruder 13.

[0056] When it is necessary to measure the height difference between the tool heads 10, one head can be made the main head, the main head is lowered first, and the other heads are raised, so that the printing platform and the nozzle 11 are gradually approached until the main head is lifted and the photoelectric switch is triggered, and the platform position at this time is recorded and the working zero point height of the main head can be calculated. The same is true for the other heads. Each head is lowered in turn and the other tool heads 10 are raised. The height of each working zero point is obtained respectively, and it is subtracted from the working zero point height of the main head to obtain the height difference of each head. In particular, for a parallel double-head printer, since only one head is actively raised and lowered, this head can be made the main head, and it is first lowered and its working zero point height is measured. Then it is raised and the platform is slowly approached to the nozzle of the other tool head until its photoelectric switch is triggered and its working zero point height is measured. The height difference of the two heads can be obtained by subtracting the working zero point heights of the two heads.

[0057] It should be noted that it is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention, and any figure mark in the claims should not be regarded as limiting the claims involved.

[0058] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A tool head lifting structure for a parallel multi-head 3D printer, characterized in that: It includes a tool head, a back plate and a lifting assembly. The side of the tool head is slidably mounted on the back plate. The lifting assembly includes a driving member and a connecting member. The driving member is used to drive the connecting member to retract and extend, and the connecting member is used to drive the tool head to rise and fall. A photoelectric switch is arranged on the back plate.

2. The tool head lifting structure of a parallel multi-head 3D printer according to claim 1, characterized in that: The lifting assembly includes a winding drum, a steering gear and a wire core, one end of the wire core is fixedly connected to the tool head, and the other end of the wire core is wound on the winding drum, and the steering gear is used to drive the winding drum to rotate forward or reverse.

3. The tool head lifting structure of a parallel multi-head 3D printer according to claim 2, characterized in that: A hose is arranged on the outside of the wire core, one end of the hose is fixed on the top of the back plate, the other end of the hose is assembled on the fixed plate, the winding drum is installed on the bottom of the fixed plate, and the wire core passes through the fixed plate and the top of the back plate in sequence and is connected to the tool head.

4. The tool head lifting structure of a parallel multi-head 3D printer according to claim 3, characterized in that: The printing consumables are arranged in a material tube, one end of which is connected to the top of the tool head, and the other end of which is mounted on a fixed plate. The printing consumables pass through the fixed plate and the material tube, enter the tool head, and are discharged through a nozzle.

5. The tool head lifting structure of a parallel multi-head 3D printer according to claim 1, characterized in that: The lifting assembly includes a short-range extruder and a long-range extruder. The short-range extruder is installed in the tool head. One end of the printing consumables passes through the short-range extruder and is transported to the nozzle. The other end of the printing consumables passes through the long-range extruder and is connected to the consumable supply end.

6. The tool head lifting structure of a parallel multi-head 3D printer according to claim 5, characterized in that: A hose is arranged on the outside of the printing consumables, one end of the hose is fixed on the top of the back plate, and the other end of the hose is assembled on the fixed plate. The remote extruder is arranged at the bottom of the fixed plate, and the printing consumables pass through the remote extruder, the hose and the short-range extruder in sequence and then discharge to the nozzle.

7. The tool head lifting structure of a parallel multi-head 3D printer according to claim 1, characterized in that: A slider is fixed on the side of the tool head, a linear guide rail is provided on the back plate, and the slider is slidably assembled in the linear guide rail; a magnetic buckle is provided on the bottom of one side of the tool head on the back plate.

8. A method for measuring the height difference of tool heads of parallel multi-head 3D printers, applied to the tool head lifting structure of parallel multi-head 3D printers as claimed in claim 4 or 6, characterized in that: The following steps are involved: Step 1: When measuring the height difference between tool heads, make any tool head the main head, lower the main head first and raise the other tool heads, gradually bring the printing platform and the nozzle of the main head closer until the main head is lifted and the photoelectric switch is triggered, record the position of the printing platform at this time and calculate the working zero height of the main head; Step 2: In the same way as step 2, lower each head in turn and lift the non-measuring end tool head to obtain the height of the working zero point of each tool head, and subtract it from the working zero point height of the main head to obtain the height difference of each head.

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