WO2004087335A1

WO2004087335A1 - Method, apparatus and software for coating.

Info

Publication number: WO2004087335A1
Application number: PCT/SE2004/000510
Authority: WO
Inventors: Mikael Håkansson
Original assignee: Mevein Holding Ag
Priority date: 2003-04-04
Filing date: 2004-04-02
Publication date: 2004-10-14
Also published as: EP1610908A1; SE0300983D0

Abstract

The present invention relates to a method of removing coating from a part comprising a programmable work device, which method comprises the steps of, in a pre-programmed work cycle, transfer the work device to pre-chosen defined part of the part, initiate the work device and work the pre-chosen defined part, and transfer the work device, and repeat the steps until the part is finished. The invention also relates to an information carrier for initiation of the method.

Description

Method and apparatus for coating .

TECHNICAL AREA

The present invention relates to a method and device for in particular surface treatment of a part Using a programmable work device.

BACKGROUND OF THE INVENTION

A large number of parts, components and devices are surface treated for different purposes such as protection, durability, appearance and esthetical impression. The surface treatment comprises in many cases painting with or without colour pigmentation. Common methods in particular during series production is paint spraying with powder, so called powder coating, or with liquid, so called wet coating.

For many types of coating work it is desirable that not all surfaces obtain a coating layer. For this often masking is used where the areas that are not to be coated, are protected from being coated. The protection comprises often some form of template that is arranged to the part to be coated or masking tape that is fastened to the part.

During series production or if a larger number of parts are to be coated means that the masking entails a labour intensive and often a personnel intensive work in that the masking has to be attached before the coating and removed after the coating. For certain parts the masking can be performed automatically if the part to be masked is planar.

The masking tape can then be "rolled on" while the part is passed by. The de-masking however still has to be performed manually. In all the masking and de-masking gives a rather large production cost, in particular for large series where this work will constitute an disproportionally large part of the production of the part. Manual masking and de-masking often causes quality problems due to that the masking material comes loose during the process or is forgotten.

Another labour intensive moment during coating work is the inspection of the parts that are to be coated before the coating. Conventionally this is performed by manual inspection of the parts, which requires a rather large input of manpower.

Robots, such as one type of programmable devices, are used to a certain extent in coating work but this is the case during application of the coating material and not as a remover. During coating work the robot is programmed to follow the contours of the part to be coated and the coating movement is performed continuously in order to obtain an even coating layer. If automatic inspection of parts before and or after the treatment is used it might be valuable if these inspections are controlled or performed based on the specific part to be treated. It may for example be so that only certain areas of the part are important and that the rest of the areas do not need to be inspected or that the inspection can be performed with a reduced accuracy or resolution.

BRIEF DESCRIPTION OF THE INVENTION

The aim of the present invention is to remedy the above mentioned problems in connection with coating work of parts by rational and appropriate use of programmable devices such as robots.

This aim is achieved according to the invention with a method characterised by the characterising part of patent claim 1. Preferable embodiments of the invention are characterised by the dependent claims.

According to one aspect of the invention this is constituted by a method for removing coating from a part comprising a programmable work device, which method comprises the steps of, in a preprogrammed work cycle, move the work device to a pre-selected defined part of the part, work the pre-selected defined part, and then move the work device and repeat the steps until the part is finished. According to another aspect of the invention the work cycle is adapted to the current part to be worked.

Preferably the removal comprises blowing away with a gaseous medium, suction, mechanical working or wiping of the coating material.

According to a preferred embodiment the method comprises the arrangement of information carriers in connection to the part, characterised in that it comprises the steps of moving the coated part within the working range of a robot, to initiate a control program arranged to the robot adapted for the current part and to perform the removal of the coating material on pre-selected, defined surface areas. According to another aspect of the invention it is characterised in that the information carrier is arranged to the first part in a series of the similar parts. The information in the information carrier may also be used in order to automatically initiate inspection devices that are programmed for the current part for inspection before and/ or after the treatment of the part. The advantages with the present invention are several. By controlling the work cycle of the programmable work device according to the invention, very well defined and delimited sections, areas and points may be worked, and in particular for specific parts. Thereby is obtained a repetitive and easily adaptable method of removing sections that are coated without affecting sections and areas that are to be coated. If a robot is used, thanks to its manoeuvrability the work cycle may include the working of protruding parts, holes and complexly curved parts. By using a suitable removal method a plurality of different types of coating material may be removed such as for example blowing or sucking off powder coating material, wiping of wet paint, mechanical work of hard coatings, etc. If information carriers are arranged to the current parts that are to be treated the robot and eventual inspection devices, as well as the transport of the parts, may be re-programmed automatically in that the information is transmitted to the robot and possibly other devices, which initiates a change of control program, which control program is adapted to the current part. It is thereby also conceivable that the information carrier is arranged to the first part in a series of parts of the same type, which enables a reduction of the number of information carriers. The great advantage in this context is that the conversion of the treatment line for the part and in particular the robot that is to remove coating material from pre-defined parts is done completely automatically without the involvement of an operator. When each control program for specific parts is stored in the robot, these only need to be collected and activated when the information carrier is at such a distance that the information can be transmitted to the robot.

These and other aspects of and advantages with the present invention will become apparent from the following detailed description and from the appended drawings. BRIEF DESCRIPTION OF THE DRAWINGS

In the following detailed description of the invention, reference will be made to the appended drawing that schematically shows a coating line for parts where the present invention can be used.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is intended to be used during coating work on articles, for example painting, such as powder coating, wet coating and the like.

In the drawing a treatment line 10 is schematically shown for articles to be coated. Conventionally a conveyor 12 is used in the form of a chain of a band, onto which holders 14 are hung with a certain distance between each other. On the holders are arranged the parts 16 that are to be coated.

Parts that are to be treated are first fed into a coating station 24, usually a spray booth where the surfaces of the part are coated. As an example, only one side of the part is coated, which for example can be an apparatus housing or a backplane to an electrical device. In order to obtain a good metallic contact for e.g. earthing it is desirable that the back side is not coated. Due to the spraying in the spray booth, coating particles will however stick also to the back side, in particular around holes and lead-through as well as around edges, and in particular during powder coating where the particles are charged and drawn to the article.

The coated article is then fed to a removal station 26, a removal step. In this case a removal means 28 is arranged to a programmable device, in the shown case the end of a robot arm 30, which robot arm is arranged with a control system 32 capable of controlling the removal means to the desired position. The control system contains a control program comprising a work cycle designed for the specific article used, which during control of the removal means during a work cycle permits it to follow very complex surfaces, such as for example double-curved surfaces, which are very difficult to mask with conventional technology. The removal means can also be arranged to treat certain components such as for example protruding parts like screws, pins and the like as well as holes and recesses. The control of the removal means with the help of the robot arm then permits a very exact positioning of the removal means in relation to the article.

In this context it is also possible to introduce some form of guiding of the holder of the article as well as sensors for sensing the position of the holder, in order to facilitate the control of the removal means in relation to the article.

A work cycle preferably comprises transfer of the removal means to one or more pre-programmed areas or points of the article, stopping the transfer, positioning and activation of the removal means at the pre-programmed area/ point until the work is performed, and transfer to the next area/ point, possible stop of the transfer, working etc. until the article is treated. The work cycle for each specific product is pre-programmed and is preferably stored in an internal memory or the like in connection to a computer or the like executing the program.

Activation of the specific work cycle can be performed either by choice and activation by an operator but may also be done automatically.

According to one embodiment of the present invention, an information carrier 18 is used for transmitting information to the control system via the receiver 20 so that it is controlled in the right manner and performs the removal operations that are to be performed. The information carriers can be of many different types capable of transmitting information of different kind. As a non- limiting example it may be bar-codes or other types of optically readable marking, transmitters capable of transmitting information, for example IR, Bluetooth®, radio waves, magnetically stored data or the like. The information that can be transmitted by the information carriers is specific for the article that is placed in the holders. The programmable device is thereby arranged with appropriate receiver 20 such as a bar-code reader, IR-receiver, receiver of radio waves and the like in order to obtain the information regarding the article.

Suitably the information carriers 18 are arranged at the holders of the articles.

A large number of designs of the removal means are used for specific parts and removals that are to be done, ranging from point-to-point to whole surfaces. The use of a programmable device also implies that a large number of different parts can be treated without major adaptation work in that the control system can contain a large number of programs adapted to specific parts and that the removal means during use of a robot arm for example are arranged on tool changers, which facilitates the change of removal means. The change of removal means can also be solved by other members available on the market and adapted to e.g. an industrial robot. For the case where the information carriers are used in connection to specific parts the specific work cycle intended for the specific part is loaded automatically after obtaining information. This simplifies the change of parts in the coating line whereby the information carriers provides an automatic adaptation to the current parts. In this context the information carriers can be present at each part or more simplified at the first part in a series of similar parts. The robot thus does not need to be re-programmed for each change of type of part.

The removal means may for example be a nozzle that via a conduit is connected to a source of pressurized air and a valve for control of the pressurised air to the nozzle. The nozzle is moved over the part to the surface part where the coating material is to be removed. The pressurised air is then released to the nozzle that blows away the coating material. The strength of the pressurised air that is released can be varied in a suitable way depending on the type of part and the size of the area that is to be treated. In connection to the blowing of coating material, suction may be arranged that takes care of surplus coating material, whereby this material can be brought back to the coating station. It is also conceivable that the removal device is arranged in a sealed off compartment, for example a spray booth, whereby the removed material is allowed to fall onto the bottom of the booth, where it is taken care of for re-cycling. This method is particularly suitable for powder material.

As an alternative to pressurised air and blowing of coating material it is also conceivable to suck away the coating material. The nozzle is then connected to an air source capable of providing an underpressure to the nozzle. The advantage with this is that the removed coating material is transferred in a very controlled way. In this context it is possible to re-introduce the removed coating material to the coating station for re-use of it. Preferably the removal means is also here arranged in a sealed off space, corresponding to a spray booth, in order that foreign particles do not mix with the removed coating material.

It is possible to design the nozzle in a plurality of ways in order to function for the specific demands regarding removal that are put on the various parts. For example a nozzle may be designed with a gap, which is narrower than the part if only a band is to be removed. It is also conceivable to provide an air or suction thrust when the part has come to a certain position in relation to the nozzle in order to remove material at a certain place on the part. Suction or blowing of coating material works very well with powder coating material, but may also be applied to wet coating material. In these cases, a higher over or under-pressure may respectively be required in order to remove the coating material. A specific part may also require different types of nozzles and/ or both blowing and suction in order to remove the coating material in the most suitable way. The control program initiated via the information carriers may then control the robot to change nozzle and control the airflow through the nozzle. Conceivable are also nozzles for blasting as work means capable of blasting abrasive sand on specific areas.

For certain coating work other removal means are conceivable than nozzles. A wiping means may for example be used for wet coating material.

The thus treated and "de-masked" part is then transferred further to a finishing station 34, for example a heating furnace during powder coating, whereby the powder is heated and treated. After the treatment the holders with the parts suitably pass a control station 38 for controlling that the parts are free from defects. Conventionally this is often done by a manual inspection of one or more workers. It is however possible to use an inspection device in the form of for example an imaging camera connected to an imaging system capable of detecting defects on the part and when so alert. A large number of cameras are available on the market as well as software suitable for this purpose, whereby these are not going to be described in detail here. For this purpose the information carrier 18 may be used for providing information to the receiver 20 regarding the appearance, size, specific areas that require a more thorough inspection and areas that require lesser, or no, inspection of the part. This information is used for controlling the camera and its speed over the part, resolution (i.e. accuracy) and the like in order to obtain an optimal inspection regarding quality and processing time.

As a further development of the present invention, the part that has areas with removed coating material may be re-introduced to the coating station, in particular during powder coating, in order to coat these areas with for example another colour. The re-introduction can be controlled by the information carriers that affect for example a branch switch 36 of the conveyor, which branch switch is arranged with a receiver 20 for obtaining information from the information carriers 18. The re-introduction of the part with removed areas may be performed either directly after the removal step of after a treating step, by for example a hardening furnace.

The use of automatic inspection and control of parts with for example imaging systems can be used for further control of the coating work. For example an automatic control of the parts may be done after the removal step in order to control that the areas that are to be removed have been performed properly; this in order to avoid that parts are transferred to finishing treatment if areas are not properly removed from coating material, which reduces the rejection rate. Inspection may also be done of the untreated parts before coating.

It is to be understood that the invention described above and shown in the drawing is not limited to this but may be modified in a number of ways within the scope of the patent claims.

Claims

PATENT CLAIMS

1. Method of removing coating from a part comprising a programmable work device, which method comprises the steps of, in a pre-programmed work cycle,

- transfer the work device to pre-chosen defined part of the part,

- initiate the work device and work the pre-chosen defined part,

- and transfer the work device, and repeat the steps until the part is finished.

2. Method according to claim 1, characterised in that the work cycle is adapted to the current part to be treated.

3. Method according to claim 1 or 2, characterised in that the removal comprises blowing with a gaseous medium.

4. Method according to claim 1 or 2, characterised in that the removal comprises suction.

5. Method according to claim 1 or 2, characterised in that the removal comprises mechanical working.

6. Method according to claim 5, characterised in that the removal comprises wiping of the coating material.

7. Method according to claim 1, further comprising the arrangement of information carriers in connection to the part, characterised in that it comprises the steps of transferring the coated part within the working range of the programmable work device, to transfer part specific information from the information carrier to the work device, to initiate a control program arranged to the work device adapted to the current part and to perform the removal of coating material on pre- chosen, defined surface areas.

8. Method according to claim 7, characterised in that the information carrier is arranged to the first part in a series of similar parts.

9. Method according to any of the preceding claims 7-8, characterised in that it comprises the steps of, with information from the information carrier, initiate an inspection program adapted to the current part as well as automatically inspect the part with removed parts.

10. Method according to any of the preceding claims 7-9, characterised in that it comprises the step of, with information from the information carrier, initiate an inspection program adapted to the current part as well as automatically inspect the part before coating.

11. Method according to any of the claims 7-10, characterised in that it comprises the step of, with information from the information carrier, initiate an inspection program adapted to the current part as well as automatically inspect the finished part.

12. Information carrier comprising storage means and transfer means of information specific for a certain product to be treated and capable of initiating a control program arranged to a robot adapted to the current part as well as to perform the removal of coating material on pre-chosen, defined surface areas.

13. Information carrier according to claim 12, characterised in that it also comprises information capable of initiating an inspection program adapted to the current part as well as automatically inspect the part with removed areas.

14. Information carrier according to claim 12 or 13, characterised in that it further comprises information capable of initiating an inspection program adapted to the current part as well as automatically inspecting the part before coating.

15. Software capable of, when run on a computer, performing the method according to any of the claims 1-11.