RU88592U1 - POWDER POWDER LEVELING DEVICE FOR SINTERING PARTS BY LAYERED SYNTHESIS TECHNOLOGY - Google Patents

Abstract

1. A device for leveling layers of powders for sintering parts by layer-by-layer synthesis technology, comprising a leveling mechanism made in the form of a cylinder pivotally mounted on a carriage driven by a drive, a mechanism for storing and supplying powder to the working table, characterized in that the knife is made with adjustable the height of the installation relative to the plane of the desktop and mounted on the carriage, while the knife is equipped with a control mechanism made in the form of a differential screw with a stepper servo. ! 2. The device for leveling the layers of powders for sintering parts by the technology of layer-by-layer synthesis according to claim 1, characterized in that the mechanism for storing and feeding the powder is made in the form of a glass to accommodate a portion of the powder for one layer connected to the hopper through a dosed type powder feed mechanism. ! 3. The device for leveling layers of powders for sintering parts by the technology of layer-by-layer synthesis according to claim 1, characterized in that the working table is equipped with a hopper for collecting excess powder.

Description

Technical field

The utility model relates to the field of powder metallurgy, the production of metal, ceramic powders with the process of sintering, and in particular to devices for the manufacture of complex parts from fine powder using the technology of laser layer synthesis. The device can find application in various branches of machine and aircraft industry.

State of the art

A known method of manufacturing bulk products from bimetallic powder compositions (RF patent No. 2217266 C2 class B22F 3/105, D22F 7/100, 08/11/2000) comprising the operation of forming an even powder layer using a device such as a cylinder to level the powder layer and its subsequent layer-by-layer laser sintering.

Pnenix installations are known, for example, the Pnenix-250 machine (according to wwwl.pomori.ru, 2009), consisting of a laser-optical system and a working chamber. The working chamber is made with a vertically movable working table equipped with a dosed powder supply mechanism and a leveling mechanism made in the form of a cylinder. The working chamber is also equipped with systems for evacuating, cleaning and protecting the gaseous medium, as well as systems for controlling the temperature of the sintered layer, cooling the part, a control system and software.

Known devices for leveling powder layers, made in the form of knives, for example in a machine Conzept M2 (Germany) (source of information http://www.mcp.by/equipment?id=49, 2009). The knives are installed with constant gaps relative to the plane of the table of the sintering chamber.

The closest in technical solution is the device according to the patent of the Russian Federation 2021881 C1, class B22F 3/22 01/20/1994, "Method of manufacturing parts and device for its implementation." According to the patent, the device is equipped with a laser, a laser beam control system, a hopper with a mechanism for dosing powder to the work table, and also a leveling mechanism made in the form of a cylinder with knurling on the outer surface, installed with the possibility of plane-parallel movement and with the formation of a gap of constant thickness between the cylinder and desktop surface.

The disadvantages of all of the above devices is that the leveling of the powder layer using knives or cylinders occurs with constant gaps between them, on the one hand, and the working planes of the chamber tables, on the other, while the powder has a bulk density and the presence of pores in the layer is possible powder, which leads to a decrease in product quality.

Utility Model Essence

The objective of this utility model is to create such a device for leveling the powder layers, which would improve the quality of sintering of the part by achieving an optimum density for each powder layer that provides sufficient surface activity of the microparticles during sintering.

The problem is solved due to the fact that the device for leveling the layers of powders for sintering parts by the technology of layer-by-layer synthesis, containing a leveling mechanism made in the form of a cylinder pivotally mounted on a carriage, driven by a drive, as well as a mechanism for storing and feeding powder to the desktop. The knife is made with an adjustable installation height relative to the plane of the desktop and mounted on a movable carriage, while the knife is equipped with a control mechanism made in the form of a differential screw with a stepper servo drive. The mechanism for storing and feeding the powder is made in the form of a glass, to accommodate a portion of the powder of one layer connected to the hopper through a dosed type powder feed mechanism.

In addition, the desktop is equipped with a hopper for collecting excess powder.

This embodiment of the device allows to improve the quality of sintering of the part due to the achievement of the optimum density for each layer of powder, to reduce energy consumption for production and to improve the quality of sintered parts.

The list of figures in the drawings.

The device is illustrated by drawings, in which:

Figure 1 shows the mechanism of the device for leveling and compaction of the powder layer;

Figure 2 shows the node And figure 2, which shows a diagram of a differential screw.

Implementation of a utility model.

The stand for the manufacture of parts by the technology of layer-by-layer synthesis consists of a frame on which a container made of steel sheet material with powder placed in it is rigidly fixed, a slide-type powder dosed feed mechanism, a leveling and compaction mechanism for the powder layer. In addition, the device is equipped with a mechanism for vertical movement of the laser optical head, consisting of a laser optical head rigidly fixed (with the exception of a possible shift) on the linear servo rod, the linear servo rod moves along the guide, rigidly fixed (with the exception of the possibility of shear) fasteners on the experimental bracket stand. The device is equipped with a carriage, a fiber optic ytterbium laser, a control cabinet, and a working chamber (with systems for evacuating, pressurizing a protective gas, cleaning, cooling the chamber, and monitoring the actual temperature of the sintered powder). The device is also equipped with a desktop made with the possibility of its vertical movement using a high-precision step-by-step screw drive with CNC, a control panel with manual and automatic control modes, a stand with software, a protective casing. The protective casing is made of metal sheet with minimal reflectivity. The stand is equipped with a hopper for collecting excess powder located in the stand plate and made in the form of an opening with a depth of at least 200 mm, equipped with a receiving device with the possibility of its extraction from the hopper.

In figure 1. the leveling and sealing mechanism of the powder layer is shown, made with a carriage 2, a cup 4, a sealing roller 5 intended for sealing the powder layer, a knife 9. The carriage is made in the form of a rigid bracket with two positional electric drives 6 horizontally moving it along the guides 10, made in the form parallel plates rigidly connected to the frame of the experimental stand 1. The carriage 2 is rigidly mounted on the plate of the experimental stand 1. The sealing roller 5 and the housing 7 are vertically fixed to the carriage 2 disposed differential screw 8 stepper actuator 11 and equalizing powder knife 9.

The cup 4 is made in the form of a pipe with inlet and outlet openings of steel sheet material and is rigidly fixed to the movable carriage 2. A portion of powder 13 is placed in the cup 4.

The sealing roller 5 is made in the form of a massive steel (cast) cylinder pivotally mounted on the carriage 2. The cylinder of the sealing roller 5 can operate in free rolling mode

The knife 9 is rigidly mounted on a differential screw 8, made with the housing 7. The housing 7 of the vertical screw 8 is rigidly mounted on the carriage 2, with a stepper servo drive 11, which ensures vertical movement of the knife with high accuracy.

The operation of the device for leveling the powder layers is as follows.

A dose of powder sufficient for one layer is poured into a glass 4 from the hopper using a metered-feed slide mechanism. After that, the desktop 3 is lowered to a height equal to the height of one layer of powder.

The next step is the alignment of the poured powder layer. Preliminary determine the required thickness of the layer of powdered powder. The height of the aligned powder layer depends on the set height of the knife 9 relative to the plane of the working table 3. In this case, the estimated thickness of the powder layer is determined by the formula with the condition of ensuring a relative increase in the given bulk density.

After that, the knife 9 is set relative to the plane of the working table, taking into account the calculated relative increase in bulk density. In this case, the gap of the sealing roller to the working plane of the table is less than the similar gap of the knife 9, which ensures an increase in the bulk density of the powder during horizontal movement of the carriage 2.

The accuracy of the installation of the knife 9 is ensured by the operation of the differential screw 8 (Figure 2):

The rotor of the stepper servo drive 11 of the differential screw is rigidly connected to the knife 9 using a screw 15, on which the external and internal threads of one direction are made, and the pitch of the external thread K ₂ differs from the pitch of the internal thread K ₁ by a small amount (100-250 μm). When the screw 15 is rotated, the internal screw 16 translationally moves vertically by a distance depending both on the difference between the pitch K _{1 of the} internal thread and the pitch K _{2 of the} external thread of the screw 15, and the value of the angle G of rotation of the rotor with discreteness g. In this case, the key 17 (in the gapless design) prevents the rotation of the screw 16.

The estimated movement L of the knife 9 and its estimated height S _{1 are} determined by the formulas:

Where:

S ₁ - Estimated installation height of the knife, [μm].

L - Estimated movement of the knife, [μm].

G - The angle of rotation of the rotor of the servo, [deg],

g is the angle of rotation of the rotor (discrete value), [deg],

To ₁ - The pitch of the internal thread of the screw 15, [μm].

K ₂ - Pitch of the external thread of the screw 15, [μm].

The alignment of the poured powder layer is carried out by moving at a speed of 70 mm / s, from the extreme right position to the left, the movable carriage 2 (figure 3). At the same time, the knife 9 rigidly fixed on the carriage rakes and evens out a portion of the powder with the set thickness of the powder layer. The accuracy of the vertical movement of the knife is provided by the differential screw. The thickness of the poured layer of powder on the working plane of the table 3, compacted by the value of h ₂ , while increasing the bulk density of the powder. The seal is performed by horizontal movement of the carriage 2 to the left and the roller 5 fixed on it, in the free rolling mode. Moreover, the roller gap to the working plane of the table is set smaller than the clearance of the knife 9 to the working plane of the table by h ₂ (Fig. 3).

After the compaction process, excess powder is removed as follows: the carriage 2 is stopped, the knife 9 is lowered relative to the plane of the working table with a guaranteed clearance between it and the plane of the working table of at least 10 microns. After that, the carriage is moved to the leftmost position to the hopper 12 for collecting excess powder 13, while the knife rakes the entire volume of excess powder into the hopper 12. Next, the knife 9 is raised to a height of h ₂ + h ₁ and the carriage 2 is moved to the extreme right position.

The next step is the shielding gas (nitrogen or argon) P = 1.3 × 105 MPa.

The prepared densified powder layer is sintered by a laser beam in accordance with the sintering mode software.

When forming the following layers, the cycle of operations is repeated until the entire part is manufactured. Then the finished part is subjected to cooling, cleaning and removal from the working chamber of the stand.

An experiment was conducted to confirm the improvement of the quality of sintering of the powder by the proposed method (by pore formation factor).

Experimental results: The absence of pore formation of a sintered powder layer with an increased bulk density at a reduced laser radiation power indicates an increase in the quality of sintering of the compacted powder by increasing the surface activity of sintered microparticles.

Thus, the use of the proposed device due to the vertical movement of the leveling knife with high accuracy, as well as the functioning of the roller in free rolling mode allows you to:

1. To improve the quality of sintering of the powder (with an increase in its bulk density) by increasing the surface activity of the sintered microparticles of the powder.

2. Reduce the laser beam power necessary for sintering the powder.

Claims (3)

1. A device for leveling layers of powders for sintering parts by layer-by-layer synthesis technology, comprising a leveling mechanism made in the form of a cylinder pivotally mounted on a carriage driven by a drive, a mechanism for storing and supplying powder to the working table, characterized in that the knife is made with adjustable the height of the installation relative to the plane of the desktop and mounted on the carriage, while the knife is equipped with a control mechanism made in the form of a differential screw with a stepper servo. 2. The device for leveling the layers of powders for sintering parts by the technology of layer-by-layer synthesis according to claim 1, characterized in that the mechanism for storing and feeding the powder is made in the form of a glass to accommodate a portion of the powder for one layer connected to the hopper through a dosed type powder feed mechanism. 3. The device for leveling the layers of powders for sintering parts by the technology of layer-by-layer synthesis according to claim 1, characterized in that the working table is equipped with a hopper for collecting excess powder.