RU198087U1 - Mobile construction surface of a layer synthesis device - Google Patents

Abstract

The utility model relates to units of a layered synthesis device. A feature of the mobile building surface of the layer-by-layer synthesis device is that it is made of a material having a coefficient of linear thermal expansion less than 1.0 μm / m-° K (less than 10.0 x 101 / ° K) in the temperature range from 290 ° K to 770 ° K, which can be removed and installed in a layered synthesis device without additional adjustment at any time during operation of the layered synthesis device, for which it is mounted in a housing made of magnetic material, which allows it to be mounted on magnetic or electromagnetic supports. The technical result of the utility model is to reduce the technological time for removal and installation of the building surface on the layered synthesis device, to reduce the downtime of the layered synthesis device due to heating and cooling of the building surface and the possibility of using the building surface in other technological processes outside the layered synthesis device.

Description

The utility model relates to nodes of a layer synthesis device. A feature of the mobile building surface of the layer-by-layer synthesis device is that it is made of a material having a coefficient of linear thermal expansion less than 1.0 μm / m-° K (less than 10.0 × 10 ^-7 1 / ° K) in the temperature range from 290 ° K up to 770 ° K, which can be removed and installed in the layered synthesis device without additional adjustment at any time during operation of the layered synthesis device, for which it is mounted in a housing made of magnetic material and mounted on magnetic or electromagnetic supports.

The technical result of the utility model is to reduce the technological time for removal and installation of the building surface on the layered synthesis device, to reduce the downtime of the layered synthesis device due to heating and cooling of the building surface and the possibility of using the building surface in other technological processes outside the layered synthesis device.

FIELD OF TECHNOLOGY TO WHICH A USEFUL MODEL IS

Mobile construction surface of a layer-by-layer synthesis device (object table, table) - the surface on which the device builds (manufactures, prints, etc.) in one way or another product in additive manufacturing. In particular, it can be used in the technology of layer-by-layer deposition of a thermoplastic material, also known as FDM (Fusing Deposition Modeling), or in the technology of manufacturing by melting a filament, also known as FFF (Fused Filament Fabrication).

BACKGROUND

Layered synthesis can be carried out in different ways and using different materials, which are based on the principle of layer-by-layer synthesis (creation, growing) of the product. One of the methods is, in particular, FDM (Fused Deposition Modeling) technology - layer-by-layer printing with molten polymer filament, as a result of which the product is formed by sequentially laying on a building surface (object table, work surface, etc.) layers, each of which it is formed by molten thread from a fusible building material (consumable or modeling material), for example, plastic. The FDM printing process includes at least:

heating to a fluid state of a thread from a source material, in particular, a thermoplastic;

feeding the molten material with a high accuracy by a thin layer onto the working surface of the 3D printer;

after the formation of the first layer on the building surface, the layers are applied to each other, connected to each other and harden, gradually forming the finished product.

Thus, the construction surface is an important part of the device for the layer-by-layer synthesis of additive production, which determines the productivity of the device and the quality of the resulting product. Its important feature is the flatness and parallelism of one of the coordinate planes of the reference coordinate system of the product.

The flatness of the building surface is initially provided by the process of its manufacture. Additive technologies exert minor power loads on the building surface. However, some materials from which the products are made require a heated building surface. Maintaining the temperature of the product is also important because the temperature expansion and contraction of the source material distort the proportions of the created product. With technologies that require the use of heating a building surface above ambient temperature, uneven thermal expansion violates flatness. This is caused, in particular, by the fact that not the entire building surface is occupied by the product, and by the not ideal heating elements, which cannot ensure uniform heating due to non-ideal thermal conductivity of the structure.

All this leads to a change in the position of the construction plane relative to the extruder, which distorts the product itself and can lead to the dumping of the unfinished product.

In addition, due to the characteristics of the printing itself, when the temperature of the lower layer is much lower than the temperature of the applied layer, stresses arise that can lead to warpage of the product and even its destruction in the process of the product. To relieve these stresses, the product is subjected to heat treatment. According to the authors of the book "STRUCTURAL PLASTICS AND POLYMERIC COMPOSITE MATERIALS" (Omsk 2002 UDC 621.891.669 Yu.K. Mashkov, M.Yu. Baibaratskaya, B.V. Grigorevsky) "Heat treatment of polymeric materials is one of the important technological processes of the whole complex processing of polymers Even if the plastic product does not have high strength or wear resistance requirements, it is necessary to carry out heat treatment to relieve internal stresses generated during the manufacture of any part. By rational heat treatment of thermoplastic crystallizing polymeric materials it is possible to increase the density, hardness, molecular mass, tensile and compressive strength, impact strength, wear resistance and stability of the geometric dimensions of the parts during their operation.

The effectiveness of heat treatment depends on the entire cycle of temperature conditions in the process of manufacturing a product from polymers. For polymers, as well as for metals, four types of heat treatment are used: quenching, annealing, normalization, and tempering. In the narrow sense of the word, heat treatment of polymers means heating a part to a certain temperature, holding and cooling in order to change the desired properties. "

The best option is heat treatment directly on the building surface. However, this leads to prolonged downtime of the synthesis device. So, for annealing the product from ABC thermoplastic, it is placed on a building surface in a heating cabinet heated to a temperature of 135 ° C for a time depending on the geometric dimensions of the product. Then the product is cooled together with a heating cabinet or at a speed of not more than 1 ° C per minute. The whole process takes from an hour and a half. As can be seen from figure 1, the upper product 1, removed from the building surface of the additive device, is curved in relation to the product 2, which has undergone heat treatment.

US Pat. No. 7,939,003 B2 (p. 8, pp. 24-37) discloses a construction structure of a layered synthesis device consisting of a surface onto which material is deposited from a material deposition tool. The surface is preferably made of precision aluminum plate, but can be made of any material capable of providing flatness. The surface is supported by a support structure that holds the surface horizontal or, alternatively, can be adjusted to change the orientation (i.e., angle) of the surface plane relative to the positioning system. The supporting structure preferably has a rigid structure. This design requires the operator to perform manual calibration through visual alignment, and labor and time are required for each tool change (1-5 minutes for each calibration, possibly hundreds of tool changes during a relatively simple assembly operation). To reduce calibration costs, the patent proposes a method (k.22 p. 4-30) that automates this calibration process. For this, a calibration device is installed on the base. The calibration device eliminates the need for a reference mark and the use of the operator in the measurement process, but does not exclude the need for the operator to adjust the horizontal position of the base. The patent does not offer a method for ensuring horizontal foundation, removal and installation of a building surface without operator intervention.

From the patent RU 2567318 C1 known system for ensuring the horizontal desktop. One of the options for the calibration of the desktop includes at least two racks with springs and clamps, which are installed on the base of the desktop at two points on the sides of the desktop closer to its front edge, and providing mobility of the table at the above points, with this table at a point located near the lead screw (closer to the rear edge of the table) is fixed motionless. In this embodiment, one end of the rack of the desktop calibration mechanism is rigidly attached to the table from the side of its lower surface, the other end is mounted on the base through the spring (Fig. 17), the clamp is placed on the base, which in the free (unlocked) position provides the spring position ( effortlessly), in which part of the table at a given point is higher than the level of the table fixed at the "fixed" point, and when the print head moves from the "fixed" point to the "moving" one, as a result of which the stand moves vertically downward, compressing the spring, the clamp provides a fixation of the position of the rack in the "moving" point at a fixed level. As a result, the calibration process requires operator intervention. In addition, to remove the desktop, you need to dismantle it, with subsequent installation and adjustment.

In the prior art, removable surfaces are known that are quite easily removed together with the finished product. This is implemented, in particular, in 3DWOX printers from Sindoh, Prusa i3 MK3 from Jose Prusa. However, only the upper part of the building surface is removed, the heating element remains in the device. Moreover, they are flexible, deform the product when shooting.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 presents for comparison two products. The first product is removed from the building surface after cooling in an additive device. The second product was removed along with the building surface and subjected to heat treatment to relieve internal stresses.

Figure 2 presents a variant of the practical implementation of the utility model in the context.

Figure 3 presents a variant of the practical implementation of the utility model general plan.

The positions in the figures indicated:

1. the product after cooling in a layer synthesis device,

2. product after heat treatment together with the building surface,

3. building surface

4. electric heating element with temperature sensor,

5. housing

6. floating supports,

7. elastomer,

8. ventilation holes.

DISCLOSURE OF A USEFUL MODEL

The utility model provides removal and installation of the building surface of the layer-by-layer synthesis device, which can be removed and installed in the layer-by-layer synthesis device without additional adjustment at any time during operation of the layer-by-layer synthesis device, including with the finished product, for which it is integrated into the body of magnetic material , which is installed on the magnetic or electromagnetic supports of the layer-by-layer synthesis device.

The technical result is to reduce the technological time for removal and installation of the building surface on the layered synthesis device, reducing downtime due to heating and cooling of the building surface, and the possibility of using the building surface in other technological processes outside the layered synthesis device.

IMPLEMENTATION OF A USEFUL MODEL

From the patent RU 183167 U1 it is known that the dimensional stability of the building surface of the layer-by-layer synthesis device in the operating temperature range is ensured by using a material with an extremely low coefficient of linear thermal expansion (CTE). As a result, when the temperature fluctuates, the building surface will minimally change its geometric dimensions, which ensures flatness and stable adhesion.

However, there are no available structural materials with a low coefficient of thermal expansion for attaching the building surface to the layer-by-layer synthesis device, which complicates the task. The proposed utility model solves this problem.

The design of the utility model is based on the free position of the building surface, with the possibility of its thermal movement relative to the structural elements only in planes parallel to the building surface. In the perpendicular direction, the building surface is overwhelmed by the supports with which it is attached to the body. And already the case is installed on the supports of the layer-by-layer synthesis device. Since the body has a KLTR much higher than the building surface, it changes its size when the building surface is heated. However, in the perpendicular direction it moves at least N-times less (N = V / D, where B is the height of the body, D is its length). Therefore, in the parallel direction, the supports float, and in the perpendicular direction they are fixed.

For this, the housing is made of sheet magnetic material. Floating supports of porcelain-type thermal insulation material are installed in it. Due to the low thermal conductivity, the elongation of the supports is minimal. So a support, 20 mm high made of technical porcelain, at a building surface temperature of 120 ° C and an ambient temperature of 20 ° C is extended by 4.5 microns. The floating support is a layer of elastomer (silicone rubber) as an option.

A practical implementation of the utility model is shown in FIG. 3. It is a building surface 3 (Fig. 2) made of glass ceramics with an applied electric heating element 4, with a temperature sensor, which is fixed in the case 5 of aisi 430 steel through porcelain bearings 6 and is limited from elastomer 7 being moved in a parallel direction poured between the hull and the building surface. A housing with a building surface is mounted on magnetic or electromagnetic supports, allowing it to move in a parallel direction to compensate for thermal expansion. To reduce thermal deformation in the housing there are ventilation holes 8, which reduces the temperature of the supports due to convection heat transfer. The presented design allows you to install and remove the building surface from the layer-by-layer synthesis device together with the finished product. At the same time, the temperature of the building surface can remain stable for as long as required when connected to an external power source. It can also be placed in a heating cabinet up to 200 ° C for subsequent heat treatment.

Claims (1)

A mobile building surface of a layered synthesis device made of a material having a linear thermal expansion coefficient of less than 1.0 μm / m ° K (less than 10.0 × 10 ^-7 1 / ° K) in the temperature range from 290 ° K to 770 ° K , characterized in that it is integrated into the casing of magnetic material, which allows you to install it on the magnetic or electromagnetic supports of the layered synthesis device without additional adjustment, as well as remove from these supports at any time during operation of the layered synthesis device.

Images