TECHNICAL FIELD

The invention relates to methods and systems for coating a surface in general and cleaning the surface, coating and melting and bonding different types of material on the surface in particular.

BACKGROUND

Laser cladding is bonding together of, for example, dissimilar metals, minerals, ceramics, polymers, biological materials, etc. using laser. Laser cladding can be performed to improve the surface properties of parts locally. A cladding material with the desired properties is fused onto a substrate by means of a laser beam. Laser cladding is considered as a strategic technique, since it can yield surface layers that, compared to other hard facing techniques, have superior properties in terms of pureness, homogeneity, hardness, bonding and microstructure.

Cladding may also be used for coating, in which powdered metal or similar is deposition material, in which the powder is injected into the path of a beam. The powder may be carried through a tubing using an inert gas that allows the coating material to be blown into the path of a laser beam. The blown powdered metal particles are partially melted by the beam. The laser creates a small melt pool on the surface of the substrate that fully melts the powdered metal.

The melt pool that is created corresponds to a single level of clad.

In additive manufacturing, i.e. solid freeform fabrication or 3D printing, three-dimensional objects are built-up from raw material, such as powders in a series of two-dimensional layers or cross- sections.

According to some methods layers are produced by melting or softening material, for example, selective laser melting (SLM) or direct metal laser sintering (DMLS), selective laser sintering (SLS), fused deposition modeling (FDM), while others cure liquid materials using different technologies, e.g., stereolithography (SLA). SUMMARY

It is important that the deposition surface, i.e. where the powder material is deposited on, is clean of impurities, which may affect the bonded layer(s).

The invention also allows for preparing the deposition surface by preheating the surface providing better bonding between the substrate or previous layer and deposited layer.

For these reasons a system for coating a substrate with a coating material. The system comprises: a deposition feeder, at least one laser source, and a controller. The deposition feeder comprises an adjustable feeder opening. The at least one laser source is arranged to generate a first laser beam to pre-heat and/or clean a surface of the substrate where the coating material is to be deposit. The at least one laser source is configured to generate a second laser beam to melt the coating material in a melt point. A speed detector is arranged to detect the speed of movement of the substrate relative the system and the controller is configured to control power of the at least one laser source and/or opening of the feeder with respect to a measured speed value. At least one temperature detector is arranged to detect the temperature of an area where the laser beam is applied to control power of the at least one laser source. In another embodiment two separate laser sources may be used. The feeder may comprise an opening covering the width of the substrate. In one embodiment the feeder may comprise one or several nozzles. The feeder may comprise a chamber. According to one embodiment the feeder may also comprise adjustable feed flaps to adjust feeding of material. The system may also comprise at least one controllable reflective arrangement for controlling laser beam.

The invention also relates to a method of coating and bonding layers of a material on a moving substrate. The method comprises the steps of: measuring the speed of the moving substrate; cleaning and/or pre-heating at least a part of a substrate surface on which said material will be deposited by means of a first laser beam; depositing said material on said substrate surface; heating and melting said material deposited on said surface by means of second laser beam; and with respect to measured speed adjusting feeding rate of said material and/or power of said second laser beam.

The invention also relates to a computer-readable storage medium storing instructions that when executed by a computer cause the computer to perform a method for using a computer system for coating and bonding layers of a material on a moving substrate. The method comprises: measuring the speed of the moving substrate; cleaning and/or pre-heating at least a part of the moving substrate surface on which said material will be deposited by means of a first laser beam; depositing said material on said substrate surface; heating and melting said material deposited on said surface by means of a second laser beam; and with respect to measured speed adjusting feeding rate of said material and/or power of said second laser beam.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference is made to the attached drawings, wherein elements having the same reference number designation may represent like elements throughout.

Fig. 1 illustrates the general principles of the present invention according to one exemplary embodiment;

Figs. 2a and 2b illustrate the general principles of a feeding arrangement according to one exemplary embodiment;

Fig. 3 is a diagram of an exemplary system in which methods and arrangements described herein may be implemented; and

Fig. 4 is a flow diagram illustrating exemplary processing by the system of Fig. 3.

DETAILED DESCRIPTION

The following detailed description refers to the accompanying drawings. The same reference numbers in different drawings may identify the same or similar elements.

The term“printing” as used herein, may refer to transfer or depositions of material onto a carrier and bonding the material together or a previous layer. The term“substrate” as used herein, may refer to any type of material on which a suitable powder material can be distributed and bonded. The term“feeder” as used herein may refer to a device designed to control the direction or characteristics of a material flow as it exits a connected chamber or pipe. Fig. 1 is a schematic view of the general construction of a plant 10 showing a first embodiment of a method and arrangement of depositing and producing a composite material layer in accordance with teachings of the present invention. In Fig. 1 , reference numeral 1 1 refers to a powder feeding arrangement comprising a feeder 1 1 1 , 12 to a first laser source, 121 to a first reflective arrangement, 122 to a first laser beam, 13 to a second laser source, 131 to a second reflective arrangement, 132 to a second laser beam, 15 to a speed detector and 101 to a housing. A backing material or substrate is referred to as 14, which may be a strip of a suitable material arranged to travel under the plant 10 (e.g. in the direction of arrow 141 ).

In operation, a first laser source 12 is arranged to generate a laser beam 122, which by using an adjustable reflective arrangement, such as a mirror 121 sweeps and illuminates the surface of the substrate 14. This results in cleaning the surface of the substrate by heating the surface and removing impurities where the laser beam hits the surface and may also preheat the surface on which the powder material will be deposit. In another embodiment, the laser source may be arranged moveable or optical devices may be used to cover the area to be illuminated.

Additional cleaning solutions such as blow or suction nozzles (not shown) may also be used. Other optical elements such as focusing elements are not shown. In one embodiment the mirror 121 may be cancelled and the laser may be directed directly onto the surface.

The powder feeding arrangement 1 1 deposits powder material 161 through the adjustable feeder 1 1 1 onto the substrate 14. The powder feeding arrangement 1 1 according to one exemplary embodiment is detailed below:

Fig. 2a illustrates a schematic exemplary embodiment of the powder feeding arrangement 1 1 in a cross-sectional view. Fig. 2b is a perspective view of the powder feeding arrangement 1 1 in accordance with Fig. 2a.

The powder feeding arrangement 1 1 according to this embodiment is an oblong arrangement, substantially covering the width of the substrate, comprising a chamber 1 13 for receiving and containing the powder material 16 and a feeder portion 1 1 1 having an adjustable opening 1 12. The arrangement may comprise channel(s) 1 14 for, e.g. an inert gas. The powder coating material may be carried by the inert gas through the powder feeder into the melt point. The feeder 1 1 1 itself is adjustable, i.e. the opening 1 12 can be increased or decreased to feed more or less powder material. The opening may be adjusted e.g. by opening or closing hinged flaps, mechanical shutter system, various small holes or other mechanically, pneumatically or electrically controlled designs. The feeder may also comprise one or several nozzles, one or several with adjustable openings.

Back to Fig. 1 , the laser source 13 illuminates the deposited powder material 161 , which melts and bonds, together and/or with the previous layer (not shown) at a melt pol building composite material 162. The laser beam 132 may be adjusted and aimed using an adjustable mirror 131 .

In one embodiment, the laser sources 12 and 13 may be the same source and refractive and reflective devices may be used to illuminate different positions and act as both preheating source and bonding source.

Speed detector 15 may comprise an optical speed detector, which detects the relative speed between the plant 10 and the substrate 14. The result of measurement of the speed allows control of power of laser source(s) (at least laser source 13) and also adjusting amount of deposit powder material by adjusting the feeder 1 1 1 , i.e. controlling the deposition rate of the coating material, which can be varied to ensure a constant coating thickness and smooth surface.

The plant 10 and substrate 14 are movable with respect to each other. In one embodiment, the substrates can be a band shaped carrier moving in direction of the arrow 141.

The powder feeder 1 1 1 with variable (programmable) opening and with controllable laser beam from the second laser source 13, it is possible to control both width and thickness of the applied layer 162.

Using the first laser source 12, the surface of the substrate 14 can first be cleaned and surface temperature can be increased to achieve a significantly better bonding between the substrate and the coating.

Fig. 3 is a schematic illustration of an exemplary system 100 according to the present invention. The system 100 comprises a controller 1 10, laser controllers 120 and 130, powder feed and feeder controller 130, and a speed measuring controller 150. Other measuring devices such as distance measuring (between the pant and the substrate) and temperature measuring units may also be employed.

The controller 101 may comprise a processor 102, memory 103, interface portion 104 and communication interface 105.

Processor 102 may include any type of processor or microprocessor that interprets and executes instructions. Memory 103 may include a random access memory (RAM) or another dynamic storage device that stores information and instructions for execution by processor 1 02. Memory 103 may also be used to store temporary variables or other intermediate information during execution of instructions by processor 102.

The controller 102 or the memory may also comprise ROM (not shown) which may include a conventional ROM device and/or another static storage device that stores static information and instructions for processor 102. Additionally, a storage device (not shown) may be provided, including a magnetic disk, optical disk, solid state drive and its corresponding drive and/or some other type of magnetic or optical recording medium and its corresponding drive for storing information and instructions. Storage device may also include a flash memory (e.g., an electrically erasable programmable read only memory (EEPROM)) device for storing information and instructions.

The interface portion 104 may comprise an input device (not shown) including one or more conventional mechanisms that permit a user to input information to the system 100, such as a keyboard, a keypad, a directional pad, a mouse, a pen, voice recognition, a touch-screen and/or biometric mechanisms, etc. The interface portion 104 may also comprise an output device (not shown), which may include one or more conventional mechanisms that output information to the user, including a display, a printer, one or more speakers, etc.

The communication interface 105 may include any transceiver-like mechanism that enables system 100 to communicate with other devices and/or systems. For example, communication interface 105 may include a modem or an Ethernet interface to a LAN. Alternatively, or additionally, communication interface 105 may include other mechanisms for communicating via a network, such as a wireless network. For example, communication interface may include a radio frequency (RF) transmitter and receiver and one or more antennas for transmitting and receiving RF data.

The laser controller 120 communicates with the controller 101 and may obtain instructions from the controller 101 to control laser 12 and the mirror 121. Parameters such as power, pulse intensity, mirror rotation etc. may be controlled. In one embodiment additional mirror controller may be used.

The laser controller 130 communicates with the controller 101 and may obtain instructions from the controller 101 to control laser 13 and the mirror 131. Parameters such as power, pulse intensity, power distribution in the melt, mirror rotation, powder flow and density, gas protection flow and pressure, melt or surface temperature, etc. may be controlled by controller 130. In one embodiment additional mirror controller may be used.

The feeder controller 1 10 communicates with the controller 101 and may obtain instructions from the controller 101 to control the feeder opening width and in some embodiments move the feeder horizontality and/or vertically. The feeder controller may thus control the feed of powder material into the feeder (or a feeder chamber) and provide the controller 101 with information about speed, direction, opening width, etc. and possible errors.

The speed measuring controller 150 is connected to the measuring apparatus 15. The measuring apparatus may be a camera, a laser, an ultrasound unit, a mechanical unit or the like.

System 100, consistent with the invention, provides a platform through which laser cladding, SLM, DMLS, SLS, FDM, SLA for achieving 3d-printing, or any similar constructions may be achieved.

According to an exemplary implementation, system 100 may perform various processes in response to processor 101 executing sequences of instructions contained in memory 102. Such instructions may be read into memory 102 from another computer-readable medium, such as storage device, or from a separate device via communication interface. It should be understood that a computer-readable medium may include one or more memory devices or carrier waves. Execution of the sequences of instructions contained in memory 102 causes processor 101 to perform the acts that will be described hereafter. In alternative embodiments, hard-wired circuitry may be used in place of or in combination with software instructions to implement aspects consistent with the invention. Thus, the invention is not limited to any specific combination of hardware circuitry and software.

In one embodiment, the controller 101 , laser controllers 120 and 130, feeder controller 1 10 and measuring controller 150 may be combined in one computer unit.

Flow diagram of Fig. 4 illustrates some exemplary method steps according to the invention.

The process starts at step 400 by receiving instructions for building a layer. The instructions may be stored in an internal memory or received from a computer, running a construction program, CAD or similar. In the embodiment using speed detection the speed of the substrate (relative speed of substrate and plant), the speed is detected 401 . Based on the detected speed, parameters such as power of lasers, nuzzle opening for controlling amount of deposited powder may be adjusted 402. Laser 12 illuminates 403 the surface of the substrate. The temperature of the surface may be measured 404, which can be used for adjusting laser power or speed of substrates. The powder is distributed 405 by means of the feeder 1 1 1. Laser 13 illuminates 406 the position powder reaches the surface of the substrate, i.e. at the melting point under the feeder. The temperature of the surface may be measured 407, which can be used for adjusting laser power, speed of substrate and/or material feed rate. Depending on the temperature required, either laser parameters are adjusted, based on temperature and speed data from detectors, and the process continues, or the process continues until the process is finished 408, 409.

The various embodiments of the present invention described herein is described in the general context of method steps or processes, which may be implemented in one embodiment by a computer program product, embodied in a computer-readable medium, including computer- executable instructions, such as program code, executed by computers in networked

environments. A computer-readable medium may include removable and non-removable storage devices including, but not limited to, Read Only Memory (ROM), Random Access Memory (RAM), compact discs (CDs), digital versatile discs (DVD), etc. Generally, program modules may include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Computer-executable instructions, associated data structures, and program modules represent examples of program code for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps or processes. Software and web implementations of various embodiments of the present invention can be accomplished with standard programming techniques with rule-based logic and other logic to accomplish various database searching steps or processes, correlation steps or processes, comparison steps or processes and decision steps or processes. It should be noted that the words "component" and "module," as used herein and in the following claims, is intended to encompass implementations using one or more lines of software code, and/or hardware implementations, and/or equipment for receiving manual inputs.

The foregoing description of embodiments of the present invention, have been presented for purposes of illustration and description. The foregoing description is not intended to be exhaustive or to limit embodiments of the present invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of various embodiments of the present invention. The embodiments discussed herein were chosen and described in order to explain the principles and the nature of various embodiments of the present invention and its practical application to enable one skilled in the art to utilize the present invention in various embodiments and with various modifications as are suited to the particular use contemplated. The features of the embodiments described herein may be combined in all possible combinations of methods, apparatus, modules, systems, and computer program products.