WO1998035782A1

WO1998035782A1 - Device and method for reproducible surface finishing of a test surface

Info

Publication number: WO1998035782A1
Application number: PCT/SE1998/000227
Authority: WO
Inventors: Peter Larsson; Anders Larsson; Erland Max
Original assignee: Ab Volvo
Priority date: 1997-02-17
Filing date: 1998-02-10
Publication date: 1998-08-20
Also published as: SE9700538L; SE510932C2; DE19882111B4; SE9700538D0; AU6233598A; DE19882111T1

Abstract

The invention relates to a device and a method for reproducible surface finishing, such as polishing, rubbing or grinding of a test surface, thereby imitating conventional, manual surface finishing. The invention may be applied, for example, in connection with development of painted sheet metal details, paints, enamels and polishing equipment within the motor car industry, or for other similar applications. The device (1) comprises at least one finishing apparatus (2) with finishing member (3), movement means (4), recording device and control device. The device is characterized in that the finishing member (3) is arranged to be able to be brought into contact with said test surface (6) with a chosen pressure application, and that at least one sensor (5, 5', 5''), for recording significant parameters for reproducible surface finishing, is connected to said recording device. The test surface (6) and the finishing member (3) are thereby arranged in order to describe a movement pattern, controlled by said control device, in x, y and/or z-directions in relation to each other, with the aid of the movement means (4). The finishing device (3) may be arranged to rotate, oscillate or vibrate in contact with said test surface (6).

Description

TITLE:

Device and method for reproducible surface finishing of a test surface.

TECHNICAL FIELD:

The present invention relates to a device and a method for surface finishing of a test surface in a reproducible way, imitating conventional, manual surface finishing.

The device and the method according to the invention are primarily applicable for polishing of test surfaces in connection with development of paints, painted sheet metal details or polishing equipment within the motor car industry, but may also be used for other similar applications where a standardised surface finishing method is required. Other applications for the invention occur in connection with rubbing (coarse polishing), and in connection with different grinding methods.

BACKGROUND OF THE INVENTION:

Within the vehicle manufacturing industry today, increasingly higher demands are made on the quality of the final product, something which has resulted in increasingly more advanced systems for quality testing and quality control being brought into use. Also the requirements on efficiency and speed have increased heavily, where, for example, product development is concerned. As is well-known to the skilled person within the field, a modern passenger car or truck consists of a plurality of different components which originate from different production lines or from different manufacturers, and which step by step are assembled into a vehicle.

A number of these components are constituted of painted sheet metal components which, in the case of visual car body components are concerned, generally are polished in order to achieve an attractive uniform and glossy surface finish. In certain cases it may also occur that components of polymeric materials are polished for the same reason. Examples of such materials are different plastics and composites which may have different properties, e.g. with respect to the degree of hardness.

Components which are intended to be polished before, during, or after assembly, are subjected to intensive product development, for example concerning the type of paint to be used.

In such product development of paints, or when developing the equipment which is to be used for polishing or other similar surface finishing, a possibility to perform a standardized, reproducible polishing of different test surfaces is desired. Thereby, it is desirable to be able to obtain a polishing result which as far as possible imitates the polishing result which conventional, manual polishing achieves. The polishing result for different test surfaces is usually evaluated by means of manual, visual assessment, and the evaluation may thereby serve as a guide for the choice of, for example, paint type, painting method, polishing equipment or polishing method. Hitherto, such polishing of test surfaces, which are to be evaluated, has primarily been performed by means of manual polishing with the use of some kind of polishing device.

A great disadvantage with such manual polishing in connection with, for example, product development is that the polishing is strongly dependent on the individual, and that the polishing is not reproducible, i.e. the polishing result when polishing two identical test surfaces will not be identical. This is of course a great disadvantage in product development where it is of the utmost importance that even small changes in polishing result can be registered and be used as a guide for the development work.

A common defect, which may arise when polishing different components, is so-called polishing roses. In this context, the term "polishing roses" refers to a certain type of surface defects which have arisen during polishing. The polishing roses may adopt a number of different forms, depending on which conditions they have arisen under.

Accordingly, a typical form of polishing roses appears as a so-called holographic image. With a holographic image it is to be understood that the image or pattern appears to be situated below the plane of the polished surface when it is observed from one direction, whereas the same image appears to be situated above the plane of the polished surface, when the surface is observed from the opposite direction.

Another commonly occurring form of polishing roses appears as a blurred polishing pattern in the surface, when this is observed from above. Such a blurred polishing pattern usually appears together with polishing roses of the above- mentioned type, i.e. holographic images. A third form in which polishing roses occur is sharp, thin scratches, which are clearly visible when the angle of observation is perpendicular to the scratches. This form of polishing rose may appear alone or together with polishing roses of the two above-mentioned types .

Common to all different forms of polishing roses is that they are nearly invisible during normal lighting conditions, something which renders detection difficult.

One reason for the appearance of polishing roses is the uneven pressure application which arises in different motion moments, when a rotating polishing drum or polishing cloth is moved across the surface which is polished with a rotating movement. Also grinding and rubbing, or other rotating, oscillating or vibrating surface finishing, may cause polishing roses.

The product development work, with regard to, for example, painted details for the motor car industry, therefore often aims at reducing the sensitivity to polishing and thereby the risk for the appearance of polishing roses.

Previously known devices for polishing test surfaces have comprised test surfaces being polished with some kind of simple motion pattern in the x,y.-plane, and with a constant pressure application in the z-direction.

The disadvantage with such previously used devices is that they cannot simulate the varying pressure application which the polishing drum or polishing cloth apply onto the test surface in the z-direction, when manual polishing is performed.

It is therefore obvious that there has long existed a need to be able to polish test surfaces, which are to be evaluated with regard to polishing result, in a reproducible, standardized way, which is not dependent on a person, and which can simulate the polishing result obtained by manual polishing.

SUMMARY OF THE INVENTION:

Accordingly, the object of the present invention is to provide a device and a method for reproducible surface finishing, such as polishing, rubbing or grinding of a test surface in a way which imitates conventional, manual surface finishing.

This object is achieved by means of the device, according to the invention, comprising at least one finishing apparatus having a finishing member, movement means, recording device and control device. Thereby, the finishing member is arranged to be brought into contact with the test surface with a chosen pressure application. At least one sensor for recording parameters which are important for reproducible surface finishing is connected to the recording device, whereby preferably the test surface or the finishing members are fixed to the above-mentioned movement means. Thereby, the test surface and the finishing member are arranged to describe a movement pattern in the x, y and/or z-directions in relation to each other, with the aid of the movement means .

The finishing device with its finishing member is preferably constituted of a conventional polishing or grinding apparatus, having a rotatable, oscillatable or vibratable polishing member. The polishing member may be constituted of a polishing drum or the like of a previously known type. Embodiments of the invention wherein the finishing apparatus does not set the finishing members into any movement are also conceivable. In such cases, the grinding effect is obtained by means of the relative movement between finishing member and test surface which the movement means provides.

According to one preferred embodiment of the invention, the movement means is constituted of a table, movable in x,y- plane and/or z-direction. The movement means may, however, be constituted of any suitable means, which can provide the test surface and the finishing member with a desired movement pattern in x, y and/or z-direction in relation to each other.

The above-mentioned control device may be constituted of different previously known means for controlling movements and functions of the different parts of the device, such as the finishing apparatus, the finishing member and the movement means. Thereby, the control device may comprise electrical motors, servo-power transmission systems, hydraulics or pneumatics, and different components which are necessary for signal transmission, regulation, control, etc.

According to one preferred embodiment of the invention, the earlier-mentioned sensor or sensors are arranged for recording parameters which are important for reproducible surface finishing for example momentum, pressure, number of revolutions, or temperature, at positions adjacent to the test surface, the movement means or the finishing member. Thereby, the recording device is arranged to collect parameters from the sensors, and to present these to a user in a suitable way. The collection of the parameters takes place in a previously known way, by means of analogue or digital, preferably electronic, signals which are transferred from the sensors to the recording device. The presentation to the user may take place in any previously known way, for example by means of an analogue or digital display unit, on a computer screen, or in the form of a paper printout. The presentation may also be done by means of a separate display unit, to which the signals collected by the recording device are transferred according to previously known techniques. If desired, further processing of the signals may take place in this separate unit before presentation.

According to another preferred embodiment of the invention, the device comprises at least one central unit, which is connected to the recording device and/or the control device. Thereby, the central unit is arranged for controlling said movement pattern and pressure application, and/or other significant parameters for reproducible surface finishing, with the aid of the control unit. The control may take place according to the instructions from a user and/or based on the parameters collected by the recording device.

The control device and the recording device may at least partially be integrated in the central unit. Accordingly, the central unit may, for example by means of a microprocessor integrated in the central unit, process measurement signals from the sensors which have been collected and presented to a user, by means of the recording device, which is also integrated in the central unit, and thereafter transmit control signals to the external movement means of the control device.

The central unit is preferably constituted of a computer device according to previously known technique, by means of which a user may feed in his instructions with a keyboard or other suitable controls. The device according to the invention may, however, also be controlled via other previously known types of controls, which act directly on the earlier-mentioned control device. The central unit may also process the collected parameters in different ways before they are presented to the user.

Since the device, according to a preferred embodiment of the invention, is provided with suitable cooling means for cooling the test surface and/or the finishing members, a possibility to control the temperature during the finishing operation is obtained. Thereby, the reproducibility is increased.

The device and the method according to the invention make it possible to record, present and document significant parameters for reproducibility in connection with surface finishing. Parameters which have been recorded at one surface finishing occasion may thereby be used as a basis for both manual and automatic control at a later occasion. As a whole, this provides a possibility to obtain reproducible results which imitate the results which are obtained with conventional surface finishing.

BRIEF DESCRIPTION OF THE DRAWINGS:

In the following, the invention will be described with reference to the attached drawing, in which

Fig. 1 schematically illustrates a preferred embodiment of a device according to the invention, which primarily is intended for reproducible polishing of a test surface.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS:

The device 1 according to the invention, shown in Fig. 1, comprises a finishing apparatus in the form of a polishing apparatus 2 having a finishing or polishing member 3, rotatable in the direction of the arrow ω. The polishing apparatus 2 is mounted on an arm (not shown) or the like, movable in the z-direction, above a movement means in the form of a table 4, movable in the x- and y-directions. Thereby, the arm (not shown) is manoeuvred by means of hydraulic or pneumatic movement means (not shown), or by means of other previously known techniques. The polishing apparatus 2 is advantageously of the same type which is used for manual polishing, whereas the polishing member 3 advantageously is a polishing drum of a conventional type, suitable for the purpose.

The table 4 is provided with force sensors 5, 5', 5', which are able to record the forces which are received by a test surface 6, which is to be polished, applied onto the table 4. In the described embodiment, the force sensors are sensors of a conventional type and can record forces both in x-, y- and z-directions. The sensors may, however, also be of a type which records different momentums, pressures, numbers of revolutions, or other parameters which are regarded as being significant for the reproducibility of the surface finishing operation.

The table 4 is further provided with two electrical motors (not shown), and a servo-power transmission system (not shown), which is able to displace the table in the x,y- plane, and with clamping means (not shown) for fixing the test surface 6 to the table 4.

Finally, the device 1 is provided with a central unit 7, which is connected to said polishing apparatus 2, movement member and electrical motor, wherein the central unit 7 comprises control functions for controlling said connected units. Furthermore, the central unit 7 comprises functions for recording signals from the force sensors 5, 5', 5'', functions for feeding in desired polishing settings or parameters, functions for presentation of the polishing settings which have been used during a polishing operation, and functions for presentation of the forces which have been registered by the force sensors 5, 5', 5''. The central unit 7, according to the described embodiment, is preferably constituted of a computer device according to currently well-known technique, and comprises both a recording device and control functions for controlling the earlier-mentioned control device (comprising pneumatics and/or hydraulics, electrical motors and servo-power transmission systems).

When a polishing operation is to be performed, by means of the method according to the invention, the test surface 6 is placed onto the table 4, movable in the x,y-plane, whereafter the test surface 6 is fixed to said table by means of the earlier-mentioned clamping means (not shown).

Thereafter, the desired polishing settings are fed into the central unit 7. The polishing settings may for example be constituted of total polishing time, the number of revolutions and the pressure application in the z-direction of the polishing member 3, and the movement pattern in the x,y-plane of the test surface 6 mounted on the table 4.

The polishing operation is started by means of providing an instruction intended for that purpose via the central unit 7, wherein the polishing member 3, controlled by the central unit 7, starts to rotate and is applied onto the test surface 6 with a desired pressure application in the z-direction at the same time as the test surface 6, due to the movement of the underlying table 4, is displaced in the x,y-plane in a desired movement pattern, and with a desired speed in relation to the rotating polishing member 3. During polishing, the force sensors 5, 5', 5' continuously record the forces which are applied by the polishing member 3 on the test surface 6, both in the x-, y- and z- directions.

When the total polishing time has been achieved, and the test surface 6 has been polished by the polishing member 3 within an area, defined by the movement of the test surface 6 in the x,y-plane in relation to the polishing member 3, the polishing operation stops.

The polishing settings, which have been used for the polishing operation, are preferably recorded in the central unit 7, together with the forces in the x-, y, and z- directions which have been recorded by the force sensors 5, 5', 5''. The information registered in the central unit 7 can, for example, be presented on a computer screen, or be printed out on paper by means of a printing device and thereby provide a reliable documentation of the polishing operation the test surface 6 has been subjected to.

The recorded information, together with the obtained polishing result, can also be used for adapting the polishing settings in such a way that the polishing result obtained by means of the method according to the invention corresponds to the polishing results obtained by means of manual polishing in the best possible way.

According to one preferred embodiment, the device according to the invention is provided with suitable cooling means (not shown) according to previously known technique, which are arranged for cooling the test surface and/or the polishing members during the polishing operation. This may be necessary in order to save time, in cases where very rapid polishing operation is desired. Since such forced polishing creates a lot of heat, cooling of the test surface is required in order to prevent the paint from melting or degrading. By means of the cooling means, the possibility to control the temperature during the polishing operation is also obtained, something which increases the reproducibility.

Accordingly, by means of the device and the method according to the invention, the possibility to obtain surface finished test surfaces in a reliable, reproducible and non-person dependent way, with a surface finishing result which correlates well with the results which are obtained with manual surface finishing, is obtained.

The components which are included in the device according to the invention should be well-known to the person skilled in the art, and each sub-component in itself is commercially available, without implying that the inventive thought which is the basis of the present invention should be previously known.

The present invention should not be regarded as being limited to practising according to the above-mentioned embodiments, or to what is shown the attached figure, but may be varied within the scope of the attached claims.

Claims

CLAIMS :

1. Device for reproducible surface finishing, such as polishing, rubbing or grinding of a test surface (6), said device (1) comprising at least one finishing apparatus (2) with finishing member (3), movement means (4), recording device and control device, c h a r a c t e r i z e d i n that said finishing member (3) is arranged to be able to be brought into contact with said test surface (6) with a predetermined pressure application, and that at least one sensor (5, 5', 5''), for recording significant parameters for reproducible surface finishing, is connected to said recording device, wherein the test surface (6) and said finishing member (3) are arranged to, with the aid of said movement means (4), describe a movement pattern controlled by said control device in x, y and or z-directions in relation to each other.

2. Device according to claim 1, c h a r a c t e r i z e d i n that said finishing member (3) is arranged to rotate, oscillate or vibrate when standing in contact with said test surface (6).

3. Device according to claim 1 or 2, c h a r a c t e r i z e d i n that said sensors (5, 5', 5' ' ) are arranged for recording said significant parameters for reproducible surface finishing, such as momentum, pressure, number of revolutions or temperature, at positions adjacent to said test surface (6), movement means (4) or finishing member (3), and that said recording device (7) is arranged for collecting and presenting said parameters to a user.

4. Device according to any one of the preceding claims, c h a r a c t e r i z e d i n that said device ( 1 ) comprises at least one central unit (7), connected to said recording device and/or said control device, and that said central unit (7) is arranged for controlling said movement pattern and pressure application, with the aid of said control device, and/or other significant parameters for reproducible surface finishing, according to instructions from said user and/or based on the parameters collected by said recording device.

5. Device according to any one of the preceding claims, c h a r a c t e r i z e d i n that said movement means (4) are constituted of a table, movable in x,y-plane or in z-direction.

6. Device according to any one of the preceding claims, c h a r a c t e r i z e d i n that said device (1) is provided with cooling means for cooling said test surface (6) and/or said finishing member (3).

7. Method for reproducible surface finishing, such as polishing, rubbing or grinding of a test surface (6), with the use of a device (1) comprising finishing member (3), movement means (4), recording device and control device, c h a r a c t e r i z e d i n that said finishing member (3) with a predetermined pressure application is brought into contact with said test surface (6), and that at least one sensor (5, 5', 5''), which is connected to said recording device, records significant parameters for reproducible surface finishing, wherein the test surface (6) and said finishing member (3), by means of said movement means (4), describe a movement pattern in x, y and/or z-directions in relation to each other, controlled by said control device.

8. Method according to claim 7, c h a r a c t e r i z e d i n that said finishing member (3) rotates, oscillates or vibrates when standing in contact with said test surface (6).

9. Method according to claim 7 or 8, c h a r a c t e r i z e d i n that said sensor (5, 5', 5'') records said significant parameters for reproducible surface finishing, comprising momentum, pressure, number of revolutions or temperature, at positions adjacent to said test surface (6), movement means (4) or finishing member (3), and that said recording device (7) collects and presents said parameters to a user.

10. Method according to any one of claims 7 - 9, c h a r a c t e r i z e d i n that a central unit (7), with the aid of said control device, controls said movement pattern and pressure application, and/or other significant parameters for reproducible surface finishing, according to instructions from said user and/or according to the parameters collected by said recording device.

11. Method according to any one of claims 7 - 10, c h a r a c t e r i z e d i n that said test surface (6) and/or said finishing member (3) is cooled down by means of cooling means.