CN1271236C - Built-in type jet nozzle for laser melting and coating - Google Patents

Abstract

The present invention discloses a built-in laser smelting spray nozzle. A powder channel, a cooling water channel and a shielding gas channel are arranged in a cylinder wall of a conical cylinder body. Outlets of the powder channel is uniformly arranged on the circumference of the lower end of the conical cylinder body, and other outlets and inlets are arranged on the circumference of the upper end of the conical cylinder body. An included angle alpha between an axial line of the powder channel and an axial line of the center of the spray nozzle is from 30 to 70 degrees. The bottom wall of the conical cylinder body is inlaid with a cooling water ring which is communicated with the cooling water channel. A transverse shielding gas curtain is composed of a gas inlet, a connecting channel, a gas box, a group of gas discharging holes and a gas outlet. The present invention has the characteristics of compact structure and no exposed water pipe, gas pipe or powder pipe. The transverse gas curtain can effectively protect a focusing mirror system; the anti-laser capacity of the conical surface of the bottom of the spray nozzle and the heat radiation capacity of the melting metal is strong. The built-in laser smelting spray nozzle can be used as a paraxonic powder feeding spray nozzle or a coaxial powder feeding nozzle; the built-in laser smelting spray nozzle is suitable for laser alloying, laser welding, laser smelting, laser 3d free drawing manufacture of a metal piece, etc.

Description

A built-in laser cladding nozzle

technical field

The invention belongs to the application field of laser processing, and in particular relates to a laser cladding nozzle.

Background technique

As an advanced manufacturing technology, laser processing is being used more and more widely in industrial production. Laser processing technology involves a wide range of fields, including laser quenching, laser cladding and laser welding. The most commonly used method in laser cladding technology is the automatic powder feeding method, that is, according to the required thickness of the cladding layer, an automatic powder feeder is used to transport a certain weight of alloy powder to the laser action area on the surface of the workpiece. Among them, the shape and size of the nozzle in the automatic powder feeder are the key factors that determine the uniformity and continuity of the cladding layer, the utilization rate of alloy powder and other parameters in the laser cladding process. Laser cladding automatic powder feeding mainly includes side-axis powder feeding mode and coaxial powder feeding mode.

When side-axis powder feeding (the corresponding nozzle is referred to as side-axis nozzle), the alloy powder is sent from the side to the front of the laser melting pool, and the powder is melted and combined with the base material to form a cladding layer. The advantage is that the utilization rate of the alloy powder is high, and the surface of the cladding layer is smooth and the quality is stable. As long as you choose the appropriate laser process parameters, accurately adjust the position of the powder on the surface of the part and the position of the laser spot during automatic powder feeding, and pay attention to controlling the speed of the powder ejected from the nozzle to a lower range, it is easy to get Uniform and continuous laser cladding layer, and the utilization rate of alloy powder can easily reach more than 90%.

However, the existing side-axis nozzles have two disadvantages: first, the position of the nozzle must be adjusted manually, which is very inconvenient in many cases. For example, when performing laser cladding on large mechanical parts, the surface of the workpiece often needs Preheat to reduce cracking or increase cladding speed. However, the high temperature of the surface of the part, or its large size, made it difficult for the operator to get close to the nozzle for manual operation. Second, the volume occupied by the powder feeding pipe and the nozzle is too large, which not only brings inconvenience to the addition of a water cooling system, but also when laser cladding is performed on the surface of parts with complex shapes, the powder feeding pipe often becomes an obstacle to the movement of the laser processing head. Bring inconvenience to the processing process.

Coaxial powder feeding (corresponding nozzles are referred to as coaxial nozzles for short) can solve the above problems. Because, during coaxial powder feeding, the alloy powder and the laser processing head are integrated into one body, no external powder feeding tube is required, and the space occupied is small. For complex-shaped processing parts, when adjusting the drop point position of the alloy powder, it will not be in the space. Difficulties arise. As long as the height and position of the laser head are adjusted through the numerical control system, so that the falling point of the powder, the irradiated part of the spot and the position of the workpiece are controlled at the preset coordinates, the laser cladding process can be realized conveniently, regardless of the size of the part and whether to preheat to a higher temperature. In particular, the coaxial powder feeding nozzle has no directionality, and laser cladding can be realized in both positive and negative directions, so it is especially suitable for the requirements of rapid laser manufacturing of metal parts.

However, the obvious disadvantage of the coaxial powder feeding method is that the appearance quality of the laser cladding layer is poor. Because the process of laser cladding is that the front end of the laser spot along the scanning direction is in the process of continuous melting, while the rear end of the molten pool is in the process of continuous solidification. On the other hand, when the powder is fed coaxially, the alloy powder is sprayed from the periphery of the nozzle to the center of the molten pool. In this way, the alloy powder falling on the front of the molten pool can absorb sufficient laser energy to form a cladding layer, and part of the alloy powder falling on the rear end of the molten pool adheres to the surface of the solidifying molten pool because of insufficient laser energy, making The alloy powder utilization rate and surface quality of the laser cladding layer are reduced.

It must be pointed out that although the existing coaxial powder feeding nozzles are being continuously improved and perfected, there has not been a substantial improvement in the situation where the alloy powder is easily adhered to the outer surface of the laser cladding layer. Moreover, in the existing coaxial nozzles at home and abroad, the protective gas is blown down along the optical axis, which will cause great interference to the powder beams sent by the coaxial nozzles to gather at the laser spot, which is not conducive to laser cladding process. Sometimes, in order to ensure the stability of the sprayed powder, it is often necessary to adjust the flow rate of the protective gas to a small value, so that the protection of the focusing lens is not sufficient. Another Achilles heel of the existing coaxial nozzles is that the integration of water, air and powder in the nozzle system is not high, and the cooling water mechanism is exposed to the position that is easily irradiated by the reflected laser, and there are hidden dangers in the long-term production process. It is difficult to fundamentally meet the stability and reliability requirements of industrial applications. In view of this, designing a built-in laser cladding nozzle has great practical application value.

Contents of the invention

The purpose of the present invention is to overcome the shortcomings of existing nozzles and provide a built-in laser cladding nozzle, which has the advantages of both coaxial powder feeding and side-axis powder feeding. The utilization rate of the alloy powder is high, and the quality of the cladding layer is uniform and stable.

A built-in laser cladding nozzle provided by the present invention is characterized in that: powder passages, cooling water passages and protective gas passages are arranged in the cylinder wall of the conical cylinder; the entrances of the powder passages are distributed on the upper circumference of the conical cylinder , the outlet of the powder channel is evenly distributed on the lower circumference of the conical cylinder; the angle α between the axis of the part connecting the powder channel and its inlet and the central axis of the nozzle is between 30-70°; built in the bottom wall of the conical simplified body There is a cooling water ring, and the cooling water ring communicates with the cooling water channel; the outlet and inlet of the cooling water channel are distributed on the upper circumference of the tapered cylinder; the protective gas channel is formed by the air inlet located on the upper circumference of the The connection channel in the upper wall of the cylinder, the air box, a group of exhaust holes and the air outlet are composed. The air box communicates with the air inlet through the connection channel, and the position of the air outlet is opposite to the exhaust hole. Inverted trapezoid.

The above-mentioned conical cylinder body is composed of an upper cone cylinder and a lower cone cylinder, and the lower cone cylinder is composed of a lower inner cone cylinder and a lower cone sleeve covering it, and the upper cone cylinder and the lower cone sleeve are connected.

Function and characteristics of the present invention are as follows:

(1) Its multiple powder feeding channels are built inside the nozzle, and the outlet size can be designed and processed according to needs. Side-axis nozzles with the same outlet size can be used as co-axial nozzles or side-axis nozzles. Side-axis nozzles with different outlet sizes can meet laser cladding applications with different powder feeding requirements.

(2) The horizontal protective air curtain can fully protect the focusing system and prevent the materials splashed from the molten pool from contaminating the focusing lens during laser cladding.

(3) The entrance of the powder channel, the cooling water channel and the lateral protection air curtain channel are all located on the upper circumference of the conical cylinder, which fundamentally solves the external softness of the laser and heat flow reflected by the molten pool during laser cladding. Tube burns and damage.

(4) The water path, gas path and powder path are all built inside the nozzle, which makes the nozzle have the characteristics of high temperature resistance and anti-burning loss, which is conducive to the industrial application of laser cladding technology.

(5) The nozzle is suitable for reflective focusing system, which is beneficial to reduce the cost of the focusing system and improve the service life of the focusing system, and can be used for high-power laser cladding of 5kW or above 10kW. This nozzle system is also suitable for transmissive focusing systems.

In short, the applicable fields of the present invention include automatic powder feeding laser cladding, automatic powder feeding laser alloying, automatic powder feeding laser welding, laser three-dimensional free forming of metal parts, etc.

Description of drawings

Fig. 1 is a schematic structural view of a specific embodiment of the built-in laser cladding nozzle of the present invention.

FIG. 2 is a longitudinal sectional view of FIG. 1. FIG.

Figure 3 is a top view of Figure 2

FIG. 4 is a transverse sectional view of FIG. 2 .

Detailed ways

Below in conjunction with example and accompanying drawing, the present invention is described in further detail.

As shown in the drawings, powder passage 4, cooling water passage 10 and shielding gas passage are arranged in the cylinder wall of the conical cylinder. The cone body is made of upper and lower parts, namely the upper cone 1 and the lower cone made of the lower inner cone 5 and the lower cone sleeve 6 . The upper cone 1 and the lower cone sleeve 6 are threadedly connected and positioned with positioning pins. The powder passage inlets 3 are distributed on the upper circumference of the upper cone 1, and the powder passage outlets 7 are evenly distributed on the lower circumference of the lower cone. The included angle between the axis of the part where the powder channel 4 is connected to the inlet 3 and the central axis of the nozzle is between 30° and 70°. A cooling water ring 12 is built in the bottom of the lower inner cone 5, and the cooling water ring 12 is connected to the cooling water circuit. The cooling water path is sealed with a sealing ring 11 at the junction of the upper and lower cones. Cooling water outlet, inlet 9,9 ' are distributed on the upper end circumference of upper cone 1. The protective gas channel is composed of an air inlet 13 located on the upper circumference of the upper cone 1, a connecting channel 14 located in the upper cone, an air box 15, a set of exhaust holes 16 and an air outlet 17. The air box 15 is connected by The channel 14 communicates with the air inlet 13 , and the air outlet 17 is an inverted trapezoid, and its position is opposite to the exhaust hole 16 . The gas enters the air box 15 from the air inlet 13, passes through the conical cylinder body through the exhaust hole 16, and is discharged through the air outlet 17 to form a horizontal protective air curtain 8, which can fully protect the focusing system and prevent laser cladding. Material spattered from the molten pool contaminates the focusing lens.

The upper cone 1 of the nozzle is provided with a connecting thread 2, and the connecting thread 2 can be externally connected with a special telescopic connecting shaft.

The calibers of the powder channel outlets 7 can be the same or different. Side-axis nozzles with the same outlet diameter can be used as co-axial nozzles or side-axis nozzles. Side-axis nozzles with different outlet diameters can meet laser cladding applications with different powder feeding volumes and cladding layer widths.

In the actual production process, the upper cone 1 of the nozzle can be made of aluminum alloy, and the lower inner cone 5 and lower cone sleeve 6 of the nozzle are made of red copper, which can not only make the nozzle high temperature resistant, but also reduce the weight of the nozzle. It is beneficial to the industrial application of laser cladding.

The key of the present invention lies in the nozzle. The water, air and powder passages are built inside the nozzle. The inlets of these water, air and powder passages are all located on the top of the nozzle, and there are no water, air or powder pipes outside the nozzle. . This design is characterized by compact structure, high temperature resistance and anti-burnout.

The present invention is not limited to the above implementation manners, and those skilled in the art can implement the technical solutions in various ways according to the above ideas.

Claims (3)

1, a kind of built-in laser melting-painting nozzle is characterized in that: be provided with powder channel (4), cooling water channel (10) and protection gas passage in the barrel of conical shell; Powder channel inlet (3) is distributed on the upper end circumference of conical shell, and powder channel outlet (7) is evenly distributed on the lower end circumference of conical shell; Powder channel (4) link to each other with its inlet (3) part axis and the angle α between the nozzle centre axis between 30-70 °; Base wall at conical shell is built-in with cooling water ring (12), and cooling water ring (12) communicates with cooling water channel (10); Cooling water channel entry and exit (9,9 ') are distributed on the upper end circumference of conical shell; The protection feed channel is by being positioned at the inlet mouth (13) on the circumference of conical shell upper end and being positioned at connecting passage (14), gas tank (15), one group of venting hole (16) and air outlet (17) formation of conical shell top wall; gas tank (15) communicates with inlet mouth (13) by connecting passage (14), and air outlet (17) are relative with the position of venting hole (16).

2, nozzle according to claim 1 is characterized in that: conical shell is made of upper conical-tube (1) and slower conical tube, and wherein slower conical tube is made of the following tapered sleeve tube (6) of following inner conical-tube (5) and its overcoat, and upper conical-tube (1) is connected with following tapered sleeve tube (6).

3, nozzle according to claim 1 and 2 is characterized in that: the air outlet (17) of protection gas passage is for trapezoidal.

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