RU209858U1 - 3D PRINTING TABLE DEVICE WITH AUTOMATIC PART REMOVAL CONVEYOR SYSTEM - Google Patents

Abstract

The utility model belongs to the field of additive technologies and can be used for the manufacture of three-dimensional (3D) parts by the method of layer-by-layer deposition (FDM/FFF) in automatic mode. A table for 3D printing with an automatic conveyor system for removing parts, containing a support frame, a film feed unit with a reel, a vacuum table, a film heating system and telemetry sensors, characterized in that it includes a cooling unit installed in series, made with the possibility of sharp cooling of the heated film, a parts removal unit with a knife for separating the finished part from the film, and a film winding unit containing a reel with a spindle driven by a stepper motor with a gearbox and a lever for adjusting the diameter of the rotating shaft of the reel. The technical result is the exclusion of manual removal of parts and the possibility of reusing the film. 7 w.p. f-ly, 3 ill.

Description

The utility model belongs to the field of additive technologies and can be used for the manufacture of three-dimensional (3D) parts by the method of layer-by-layer deposition (FDM/FFF) in automatic mode.

A table of a device for three-dimensional printing is known (application for invention US No. 20200047411, IPC B29C 64/245, B29C 64/25, publ. 02/13/2020), containing a support platform, two conveyor rollers inside the support platform, vacuum means, cooling fans, heating means. The first and second conveyor rollers are configured to accommodate an endless conveyor belt. The invention provides layer-by-layer printing of three-dimensional parts with more complex or detailed features.

However, in this solution, the parts are printed directly onto the belt, and unlike film, an adhesive is applied to the belt to adhere the parts to the conveyor belt. Since the parts often come off right with the adhesive on them, it is necessary to apply the adhesive again the next time the tape is pulled. Thus, an operator is required to apply the adhesive after one or two full passes of the tape. Moreover, not all thermoplastics adhere to the tape, even with the use of an adhesive, which limits the list of possible materials. It should also be noted that the use of cooling fans alone is not sufficient for accurate and complete removal of details from the film.

Known table devices for three-dimensional printing (US invention No. 8994592, IPC B29C 67/00, B22F 3/105, publ. base. The advantages of this technical solution include faster removal of the base layer from the build chamber of the additive manufacturing apparatus, minimization of damage to the finished object during its removal. However, the invention involves the manual removal of the finished product from the film; printing autonomy is not ensured. In addition, the fasteners of the rollers make it difficult to remove them.

As the closest analogue, a device was chosen (European patent No. 2934859B1, IPC B29C 67/00, published on October 28, 2015), used in an automated additive manufacturing system for printing and removing three-dimensional parts, and including a table made with the possibility of holding and pulling film, and a head support frame configured to hold a print head for printing three-dimensional details on the held film. The table assembly includes a platform part holding a bracket configured to engage with the surface of the platform part to hold the film therebetween and detach from the surface to release the film. Also, the device is equipped with a removal unit, configured to draw a film with a printed three-dimensional detail from the table assembly and cut off the stretched film.

Significant disadvantages of this invention are the uneconomical consumption of the film, since the used film is not reused, it is wound over the entire length of the working area, regardless of the size of the part and cut off, and the time spent on removing the used film from the finished parts manually by the operator.

The objective of the claimed utility model is to provide a table for 3D printing of serial products using FDM/FFF technology around the clock without the participation of an operator in the removal of parts.

The technical result is the exclusion of manual removal of parts and the possibility of reusing the film.

The technical result is achieved by the fact that the table for 3D printing with an automatic conveyor system for removing parts contains a support frame, a film supply unit with a reel, a vacuum table, a heating system, telemetry sensors, a cooling unit installed in series, a part removal unit with a knife for separating the finished part from the film, and a film winding unit containing a reel with a spindle driven by a stepper motor with a gearbox and a lever for adjusting the diameter of the rotating shaft of the reel.

The utility model is further illustrated by the following drawings:

Fig. 1. Top view of a 3D printing table.

Fig. 2. Side view of the 3D printing table.

Fig. 3. View of the bobbin in section.

The 3D printing table device contains:

support frame;

film feed unit;

film winder;

vacuum table;

heating unit;

cooling unit;

removal unit;

telemetry sensors.

The support frame is formed by a platform (1) and four brackets (2)-(5) holding the platform (1) and reels (6, 7). The brackets (2)-(5) are made with a horizontal platform for placing the platform (1) and channels for placing the reels (6, 7) below the surface of the platform (1). Under the platform (1) there is a bracket (8) with a pressure plate (9) for installing the end sensor.

The film feeding unit includes a reel (6), a stepper motor with a gearbox (10), which controls the reel braking (6), and a pressure roller (11) for clamping the reel (6) during rotation. Stepper motor with gearbox (10) and pressure roller (11) are mounted on brackets (2, 3) of the support frame at the rear of the device.

The film winding unit includes a reel (7), a stepper motor with a gearbox (12) that controls the rotation of the reel (7), and a pressure roller (13) for clamping the reel (7) during rotation. The stepper motor with gearbox (12) and the pressure roller (13) are mounted on the brackets (4, 5) of the support frame in the front of the device.

The reels of the feeding unit (6) and the winding unit (7) have the same design and are interchangeable and quick-detachable.

The reel is a shaft (14) with side walls (15), one of which is removable. The side walls of the reels (15) provide additional fixation of the film on the table. On the one hand, the bobbin contains a spindle (16), which perceives rotational movement from a stepper motor with a gearbox, and on the other hand, a lever (17) for increasing or decreasing the diameter of the shaft (14) of the bobbin. The shaft (14) consists of two semi-cylinders, one of which is made to move up and down to increase or decrease the diameter of the shaft (14). A platform (18) is rigidly attached to the inner surface of the movable half-cylinder, which receives reciprocating movements from the pusher (19). The pusher (19) is an elongated element on legs with bevelled edges. The beveled edge of the left leg is in mate with the stop (20), and the beveled edge of the right leg is in contact with the plunger (21). The stop (20) is fixed. The pusher (19) is configured to move up and down in response to the reciprocating movement of the plunger (21) communicated by the lever (17). On the sides of the reel there are two pressure elements (22) for pressing the film. In the clamping position and during winding, the shaft (14) has a larger diameter. In the film removal position, the shaft (14) has a reduced diameter.

The vacuum table (23) is a slotted worktable mounted on four brass legs, which are in turn screwed to the base frame platform (1). Brass supports and slots on the platform perform the function of thermal decoupling of the structure in order to avoid curvature of the surface of the vacuum table (23) during thermal expansion. Brass supports reduce heat loss by reducing the area of the contact surface. Special slots on the vacuum table (23) allow the table to expand when heated, preventing warping.

On the lower surface of the vacuum table (23) there is a slot with through holes to create a vacuum in the channels on the upper surface of the vacuum table (23) and press the film against the vacuum table (23). The slot is covered with a part on which a vacuum system fitting is installed to distribute the vacuum and ensure good pressing of the film against the vacuum table (23). A vacuum hose is attached to the fitting, which communicates with the vacuum system. The vacuum system is located in the housing of the entire installation and consists of a vacuum pump, a receiver, a vacuum level sensor and a solenoid valve for air evacuation (not shown in the drawing).

For additional fixation of the film on the surface of the vacuum table, there are four film stops (24). The outer corners formed between the brackets (2)-(5) and the vacuum table (23) ensure that the film adheres to the table without evacuation.

On the lower surface of the vacuum table (23) there is a heating unit, consisting of two quick-release flexible heating silicone plates, insulating material and a grid (not shown in the drawing). PTC thermistors are built into each heating plate to control the heating of the vacuum table (23). On the lower surface of the vacuum table (23) there is a recess for laying heating plates, insulating material and a grid. The grid is attached to the inside of the vacuum table (23) with bolts to provide quick access to the heating plates for easy replacement in case of failure.

The cooling unit includes a flow straightening channel (25) mounted on the brackets (4, 5) of the support frame, and an axial fan with a tachometer line (not shown in the drawing) installed at the inlet of the flow straightening channel (25) for sharp local cooling of the film and the lower detail layer. The fan tachometer controls the rotation of the fan. Instead of one fan with a staggered flow straightening system, it is possible to use several fans without using a staggered flow straightening system. Apart from the air type of cooling, the cooling unit can be realized with a compressor type of cooling with a compressed air or water cooled tube, by placing a coolant supply tube under the film instead of a straightening channel.

The parts removal unit includes a roller shaft (26) with bearings and a knife (27) installed in series. The roller shaft (26) ensures that the film with the finished parts is evenly guided towards the cutter (27). The knife (27) is an elongated plate installed across the entire width of the vacuum table (23) at an angle with respect to the flow straightening channel (25) of the cooling unit, so as to pry the part and completely separate it from the film. The removal unit is installed on the brackets (4, 5) of the support frame, while the knife (27) is attached to the brackets (4, 5) with winglets (28).

In addition to PTC thermistors and fan tachometers, the table telemetry collection includes a limit sensor and flatness sensors (not shown in the drawing). A limit switch is provided to determine the zero position of the table. Four flatness sensors are used to check the flatness of the table at four points and provide a higher quality of the first layer and the entire print.

Turning on and off stepper motors, opening and closing valves of the vacuum system, control of heaters and fan is carried out by the control system on the signal of the corresponding sensors.

A 3D printing table with an automatic parts removal conveyor system works as follows. Before starting work, the table plane is calibrated with four-point table flatness sensors. If there are deviations, the necessary adjustments can be made to the control program.

The zero position of the table is determined using the end sensor.

The reel (6) with a new film is installed in the feed unit. The film is pulled through the vacuum table (23) to the reel (7) of the winding unit. The film is passed between the clamps (22) and the shaft (14) of the reel (7) of the winding unit. To clamp the film, increase the diameter of the shaft (14) by moving the lever (17) back. The lever (17) acts on the plunger (21). The pusher (19) in response to the linear movement of the plunger (21) raises the platform (18) together with one of the semi-cylinders. Thus, the semi-cylinders open and clamp the film.

Next, a vacuum pressing the film is created by pumping air between the vacuum table (23) and the film through a vacuum hose that goes from the vacuum table (23) to the vacuum system. The sensor transmits information about the vacuum level to the control system and, depending on the set value, the control system regulates the opening or closing of the solenoid valve. After the film is pressed and all systems are ready to start the process, the printing of products begins according to a predetermined program. Products are printed on film. At the command of the control system, the heaters heat the table to a predetermined temperature. PTC thermistors with an operating temperature of up to 250°C transmit data to the control board to control the heating of the table. When the parts are printed, the vacuum is released at the command of the control system to the solenoid valve. Even when the vacuum supply is interrupted, the film does not come off the table due to the external angles formed between the brackets (2)-(5) and the vacuum table (23).

Next, the film winding unit is launched along with the parts on it to the cooling unit. In the cooling unit with a stepped flow straightening system, the film and the bottom layer of the part are rapidly cooled. Due to the direct flow and powerful air fan, a sharp temperature difference is ensured. Due to a sharp temperature drop, the part comes off the film. This phenomenon is based on the physical properties of films of some polymers - they work with increased adhesion to thermoplastics with increasing temperature, and when cooled - lose adhesion. Thus, printing is done on hot film, which is quenched before dropping the finished product from the printer table into a container. After the cooling unit, before winding the film onto the spool (7), the knife (27) pry the part so that the part is precisely and completely separated from the film. Thus, manual post-processing in the form of separation of the part from the film is excluded.

Next, the film is wound onto a reel (7), the finished parts fall into a container for collecting parts, and the process is repeated. Thus, the film being printed on is rewound from one reel to another in the process. When one roll of film has been completely wound, the waste film is reused, the reel is placed at the beginning and rewound again. If necessary, the used film can be easily removed from the reel (7). To do this, reduce the diameter of the shaft (14) of the bobbin (7) using the lever (17). The plunger (21), free from the action of the lever (17), moves back, the pusher (19) is lowered, the semi-cylinders are closed. Next, the side wall (15) of the shaft (14) is removed and then the film itself.

Claims (8)

1. A table for 3D printing with an automatic conveyor system for removing parts, containing a support frame, a film feed unit with a reel, a vacuum table, a film heating system and telemetry sensors, characterized in that it includes a cooling unit installed in series, configured to quench the heated film, a part removal unit with a knife for separating the finished part from the film, and a film winder unit containing a reel with a spindle driven by a stepper motor with a gearbox and a lever for adjusting the diameter of the rotating reel shaft. 2. Table for 3D printing according to claim 1, characterized in that the cooling unit and the removal unit are installed on the support frame bracket. 3. Table for 3D printing according to claim 1, characterized in that the cooling unit includes a flow straightening channel and an axial fan with a tachometer installed at the inlet of the flow straightening channel. 4. Table for 3D printing according to claim 1, characterized in that the part removal unit includes a roller shaft with bearings. 5. Table for 3D printing according to claim 1, characterized in that the knife is made in the form of an elongated plate installed across the entire width of the table at an angle with respect to the cooling unit. 6. Table for 3D printing according to claim 1, characterized in that the reels of the feed unit and the take-up unit are interchangeable. 7. Table for 3D printing according to claim 1, characterized in that the reels consist of a shaft assembled from two half-cylinders and side walls, while one of the half-cylinders is made with the possibility of transverse movement to increase or decrease the diameter of the shaft, while to the platform is rigidly attached to the inner surface of the movable semi-cylinder, which perceives reciprocating movements from the pusher, which has the form of an elongated element on legs with beveled edges, while the beveled edge of the left leg is mated with the stop, the beveled edge of the right leg is mated with the plunger, while the stop is stationary, and the pusher is configured to move up and down in response to the reciprocating movement of the plunger reported by the lever. 8. Table for 3D printing according to claim 1, characterized in that the reels are made with clamps for pressing the film.

Images