WO2007026204A1

WO2007026204A1 - Device for flock application and procedure thereof

Info

Publication number: WO2007026204A1
Application number: PCT/IB2006/002321
Authority: WO
Inventors: Manuel Silva Correia De Sa
Original assignee: S. Roque - Maquinas E Tecnologia Laser, Lda.
Priority date: 2005-08-30
Filing date: 2006-08-25
Publication date: 2007-03-08
Also published as: EP1931481A1; PT103340A; BRPI0617090A2

Abstract

The invention relates to a device and a method for electrostatic flocking that resort to a grid (2) and to brushes (4) and that are characterised in that the grid is provided with alternated movement (Q), rough and automatic, in a plane essentially parallel to the zone to be coated in the target piece (9), and in that, at the side of the grid opposite to the piece, there is a set of brushes (4) with movement (P) in relation to the grid (2) provided with automatic movement. An involving box (1); with skirts (6) that are supported in a serigraphic screen (8), encloses the structure (3) of brushes (4) that is operated by an actuator (12) and whose movement is transmitted, inverted, to the grid by a mechanical system (13, 14, 15). Outside the screen, the piece placed on a platform (11), connected to the generator (5), is coated with flock (10).

Description

DESCRIPTION

^vDevice for flock application and method thereof"

Field of the invention

The present invention regards a device and a method for application of fibres⁷- hereinafter named flock (s) - in pieces with adhesive, that is, a device belonging to a category of equipments usually named flocking devices. In particular the device according to the invention is a flocking device by electrostatic process. -

State of the art

Among the flocking devices by electrostatic process, that is, devices that allow the application of flocks on a surface by action of the electrostatic force, are known in particular, the ones provided with a perforated plate and with brushes, these ones promoting the brushing of the flock in order to direct it to the said holes existing on the plate, from where the flocks are projected into the adhesive, by action of the magnetic field to which they are subjected. Such type of devices is represented in Figure 1.

The mentioned perforated plate (2) , also named grid, is set in parallel to the surface of the piece (9) where the flock (10) is to be applied, the grid remaining immobile during the mentioned process and being swept by a set of brushes

(4) located over it, brushes that are animated of a seesaw movement parallel to the grid. Since the mentioned perforated plate consists in an electrode generator of a magnetic field, the flocks that cross it are projected against the piece to coat, which, to that effect, is previously covered, in the zones to coat with flock, with an adhesive matter (not represented in the Figures) where the projected flocks (10) get fixed (vide Figure 1, detail A) .

The flocking (i.e. the process of applying flock on a surface) is a very complex process, since it depends on a high number of variables, which provokes problems at the level of reliability and of the mechanisation and makes difficult the repeating and mechanical processes.

The reliability of a system of application of flock may be analysed during a production of pieces, depending on the ratio between the number of defected pieces and the total number of pieces.

Thus, a low reliability of the system represents a high number of defected pieces, which forces the frequent stop of the production to try to apply corrective measures, resulting in an insufficient cadence of production.

The value of the reliability depends directly from the linearity and proportionality of the placement of the flock, that is, of the existence or not of lack of flock in certain parts of the area to coat and of excess of flock in other parts of that area.

Besides the problem of the reliability, it must also be borne in mind the problem resulting from the risk of contamination of the area surrounding the device of application of flock.

In Figure 1, may be seen examples of these problems (details B, C and D) .

The lack of flock (detail C) , is due to the obstruction of the holes of the perforated plate (2) during the process of application of the fibre or flock. It is a problem that appears in diverse shapes: Sometimes it happens always in the same point of the piece to coat and provokes a lack of flock underneath that point; other times it is a defect that is provoked by a flock that is in bad condition (lumpy) and that moves accordingly to the structure (3) of brushes (4), over the plate (2), provoking a defect of lack of flock (detail C) less emphasized but with bigger area.

Lumping of the flock (detail D) , consists in the appearance of small quantities of flock that is stuck to each other, forming in this way small lumps that originate the obstruction of the holes and the consequent failure (C) in the application of flock to the piece.

This problem derives often from the quality of the flock.

The excess of flock (detail B) , results from the excessive placement of flock in the area to coat. This defect happens due to the fact that the operator tries to correct areas with lack of flock (detail C) , increasing the quantity of flock that applies in the piece. In fact, to increasing the quantity of flock applied in the piece does not correct properly the problem of the localised lack of flock (detail C) . It only allows a small attenuation of the lack of flock, but provokes the problem of excess of flock in other areas of the piece where the quantity of flock applied was already enough.

One of the factors that originates this problem is the lumping of the flock (detail D), mentioned before.

Another source of problems that affect the reliability of the device is the breakdowns of the actuator

(12) . If the latter is in direct contact with the flock particles it deteriorates very rapidly, since the flock sticks on the mobile pieces of the actuator creating very accentuated plays with time and provoking a precocious malfunction in the actuator at the end of a short time of use.

Besides the problem of the reliability one must also have in mind the problem of the security, namely deriving from the risk of contamination in the surrounding area of the device of application of flock.

Due to its magnetic properties, the flock fibres tend to be attracted by metallic surfaces and by the electrostatic energy of the operators, so it becomes necessary to protect these and the very equipment against the flock fibres, avoiding that these get out of the area

(7) where they circulate.

Although there is a multiplicity of flocking devices by electrostatic process, essentially all obeying to the same general principle of operation, the above mentioned problems of reliability of the flocking and/or the equipment, as well as the problem of security continue to demand perfecting.

In particular, as variables to the system described above we may cite, for example:

- A device whose dosing means are provided with rotating brushes combined with grids substantially cylindrical, such as described in US 1 430 346;

- A- device where, on one hand, the piece to coat is displaced continuously under the perforated plate

^• and, on the other hand, there is a hopper of flock that discharge the flock, by gravity, into a perforated plate (that functions as electrode) , hopper that may be adapted to oscillate longitudinally to ease the discharge of the flock, and may additionally be combined with brushes in its interior that operate in order to promote a bigger exit of flock and to break up clumps of material that are formed within that hopper, as is described in US 3 798 048;

- A device where at least an electrode of perforated plate is made to vibrate, accordingly to a direction substantially parallel to the force lines of the magnetic field, with a very „high frequency, preferably between 1 000 and 10 000 cycles per second, and with a small amplitude of about 0,1mm or less, device that is devoid of any sweeping brushes of the electrode of perforated plate, such as described in US 3 211 129; - A device provided with a vibrating hopper full with tubes disposed in the vertical and destined to be loaded with flock, hopper provided with, at the bottom, an electrifiable grid, that device being devoid of brushes, such as described in EP 0 030 203;

- A device provided with an electrifiable grid constituted by cylindrical individual elements disposed in parallel, that are placed in rotation motion around the respective axes, device that is devoid of brushes, such as described in FR 1 496 958;

- A manual device and therefore more subject to the problem of contamination of the involving surroundings/means, provided with a mobile car whose bottom is an electrode of perforated plate, car that is made to translate, by hand, in parallel to the plane of support of the piece to coat with flock, according to movements of small amplitude, device that is devoid of brushes, such as described in FR 2 615 416.

Aims of the invention

The present invention aims a device and a method that allow, inter alia:

- To increase the reliability of the coating by the flock, strongly decreasing the occurrence of defects;

- To increase the reliability of the device;

- To obtain a constructively simple device; and

- To obtain a high production cadence of pieces coated by flock .

Other objectives of the invention will be apparent from the reading of this description.

Description of the invention

According to the invention, the indicated objectives are reached through a device comprising a grid and brushes, characterised in that the said grid is provided with alternating movement, rough and automatic, in a plane essentially parallel to the zone to be coated of the target piece, and in that, at the side of the grid opposite to said piece, there is a set of sweeping means with relative movement in relation to the said grid provided with automatic movement .

The correspondent flocking method consists in a method for application of flock by electrostatic action characterised in that the flock is submitted, during the crossing of the electrostatic grid, to a double mechanical action resulting from the simultaneous combination of two effects :

- the one of the sweeping of the said flock in the electrified grid, said sweeping being promoted by the action of brushes provided with relative movement in relation to said grid, with

- the one of mechanical choc deriving from the fact that the crossing of that electrified grid, by said flock, is made with the grid in alternating rough movement in a plane essentially parallel to the zone to be coated in the target piece. The results obtained with the mentioned device are surprisingly good in comparison with the ones of the devices of the state of the art, namely the device of the type represented in Figure 1 and also, for example, with the results of the device described in the cited document FR 2 615 416.

In fact, from the aforesaid, it is verified that, in what concerns the device of the document FR 2 615 416, the type of defects provoked by the lumping of the flock tend to assume a linear configuration in the ~ coated piece. In fact, if a hole gets clogged due to a lump, the linear translation movement of the grid in parallel to the plane of the piece to be coated will make the hole not staying permanently over the same point of the piece, but rather to go through a straight line segment correspondent to the amplitude of the seesaw movement of the carriage. Consequently, the defect is less intense but encompasses a bigger area correspondent to the lane around the mentioned segment of straight line.

As is evident, when putting in perspective the eventual mechanisation of the mentioned movement, a person skilled in the art although could expect an eventual increase of the production cadence, would not have any reason to expect an increase in quality. The obstructed hole would circulate more rapidly and the piece would also be finished more quickly, but the defect would remain. The simple automatisation of the mentioned movement would not reveal attractive, since the defect would endure and, while in the manual operation the operator surveys the quality of the coating, and may intervene manually in case he verifies that it is being created a defect motivated by a lump that obstructs a hole, in the case of the mechanical operation that surveillance is non-existent, or more sporadic, since normally there is only one operator for several machines in simultaneous functioning.

In the case of the devices represented in Figure 1, the effect of a lump is similar. In fact, if the brushes manage to dislocate the lump from the correspondent hole to the neighbouring holes, the lump will go through a substantially straight line (considering the most common case when the movement of the brushes in a linear seesaw movement) . If, on the contrary, the lump is jammed in the hole in such a way that it does not come out with the repeated passage of the brushes, the defect in the piece will be more evident, although encompassing a smaller area, substantially circular, around the zone of the mentioned point .

Well, accordingly to the above indicated, the method and the device according to the invention originate a rate surprisingly low of defects, since even the defects of the linear type, characteristic of the two previous systems just analysed, are very decreased in the pieces produced accordingly to the invention.

This is indicative that the combined effect of the brushing with the alternating rough movement of the grid allows destroying the agglomerations of ^"flock responsible by the lumping.

Although it is not known concretely if that is what goes on, nor how that is processed, it is admitted that, without intending any binding to that thesis, the rough acceleration and deceleration of the grid have for first effect to avoid the formation of big lumps and, for second effect, to favour the brushing action that, before minor lumps, manages to push them through the grid eliminating the obstruction of the holes.

On the other hand, the device according to the invention is of rather simple construction and much more simple than, for example, the device described in the also cited document US 3 211 129.

Accordingly to a preferential embodiment of the invention, the movement of the grid and the movement of the brushes are of the same amplitude and of opposite directions .

Accordingly to another preferential embodiment of the invention, the movement of those components is linear (i.e. in a straight line) .

Brief description of the drawings

In Figure 1, as previously indicated, is schematically represented a device of the state of the art, provided with fixed grid, representing the detail A a correct distribution of flock in the piece and the details

B, C, and D situations of defect.

In Figure 2 is schematically represented a device according to the invention, representing the detail A a situation of correct distribution of the flock in the piece. In Figure 3 is represented the same machine, in a perspective view.

Detailed description of a preferred embodiment

The description, more in detail, that follows, of a preferred embodiment of the device according to the invention, is made based on the enclosed Figures, where, independently of each particular embodiment, are used the following references:

1 - Involving box; 2 - Perforated plate or grid;

3 - Structure where are coupled the brushes (4);

4 - Brushes coupled to the structure (3);

5 - Apparatus generator of the electric or electrostatic field; 6 - Protective skirts;

7 - Area where oscillates the orierϊted flock;

8 - Serigraphic board;

9 - Target piece or piece where is going to be applied the flock; 10 - Flock already applied;

11 - Support platform of the piece, on the side opposite to the perforated plate;

12 - Actuator of the seesaw movement;

13 - Oscillating arm; 14 - Fixing means of the oscillating arm;

15 - Coupling structure of brushes/oscillating arm;

P - Seesaw movement of the structure of brushes;

Q - Movement inverse to P, of the perforated plate ( 2 ) ;

A - Flock applied in the right quantity; B - Defect, provoked by excess of flock; C - Defect, provoked by lack of flock;

D - Obstruction of the holes of the perforated plate.

According to the particular embodiment represented in the Figures 2 and 3, the functions, characteristics and functioning of the main elements of the device are the following:

- The box (1) , involving the perforated plate (2) and the set (3) of brushes (4), allows making the lateral and superior isolation;

- Isolates totally the area where are the fibres of flock;

- It is composed by an insolating material, preferentially acrylic, of appropriate thickness, so that there is electric isolation between the electrode of perforated plate (2) - preferentially with the function of positive electrode - and the surrounding environment; - Has an opening in the zone where is placed the perforated plate (2), proportional to this one's size.

The perforated plate (2) is formed by a plate of perforated metal of standard model, with holes of diameter of 0,2 to 8 mm, the spacing between the holes being proportional to the diameter of the hole. It is a plate that is always in contact with the brushes (4) of the structure (3) and that is laying on the hedge of the opening at the bottom of the involving box (1) .

The movement of the plate (2) is ensured by an oscillating arm that is indirectly coupled to the structure (3) of brushes (4) . By moving the structure (3) of brushes

(4), these provoke a friction movement over the plate (2), which moves in direction opposite to the one of the structure (3) of brushes (4). The movement is repeating and automatic. The number of cycles is approximately between 10 to 60 cycles/minute, this cadence being adjustable by the operator. Values typical for the displacement of the grid are, for example, around 5cm although they may be others.

The structure (3) of brushes (4) is a structure that integrates a set of brushes (4) of propylene (or other adequate material) . These brushes are installed with their hair disposed orthogonally in relation to the inferior plane of the structure (3) and saliently in relation to that plane, allowing, in this way, this same structure (3) to stay apart from the contact with the plate (2) . However, the hair of the brushes (4) stays in contact with the plate (2) . The movement of the structure (3) of brushes (4) is exactly the same as the one of the plate (2) but in the opposite direction.

The inverted movement between the structure (3) of brushes (4) and the plate (2) is put in motion by an actuator (12), of pneumatic, electric or hydraulic type. The actuator put in motion the structure (3) of brushes (4) and this, in turn, drives the perforated plate (2), by means of an arrangement defined by the coupling (15) and by the oscillating arm (13), the latter being articulated in the fixing means (14), thus allowing that the movement of the structure (3) of brushes (4) drives the plate (2) . So, it is used one single actuator (12) to generate the movement the movement of both the elements: plate (2) and structure (3) of brushes (4) .

The actuator (12) is placed outside of the involving box (1) , to be protected from the particles of flock that are inside the box, thus allowing to prolong much more the lifetime of the actuator.

The protective skirts (6) are formed by some bars of adequate thickness, made either in the same material that composes the box, or in another adequate insulating material. They may be fixed or mobile and allow isolating, from the exterior, the area (7) of oscillation of the flock. They are adjusted until they are next to the serigraphic screen (8) and next to the involving box (1) of system. Thus, is formed a closed box, wit-h the elements 1, 6 and 8, that does not let the flock escape to the exterior. The serigraphic board (8) only allows the passage of fibres in the zone with adhesive. All the fibres of flock that come out of the area (7) through the serigraphic screen (8), are glued in the piece, in the area to coat with flock (10) .

The metallic platform (11) allows supporting the piece to be coated with flock and may be fix or mobile, and may also belong to a carousel. It is the opposed terminal of the magnetic field generated by the system, which may or may not be connected to the land terminal, for the operation of coating pieces with flock.

The functioning of the device is as described hereinafter starting from a situation in which said device is inactive.

First of all, it is necessary to place the flock over the perforated plate (2), making it enter inside the structure (3) and between the brushes (4) . The quantity of flock to place depends on the area to coat with flock (10) .

The bigger the area, the higher the quantity of flock and, consequently, the bigger the number of brushes that are used.

The high voltage apparatus (5) has the high voltage terminal, preferably positive, connected to the perforated plate (2), the land terminal being placed on the metallic platform (11) that supports the piece to be coated with flock.

As soon as the system is connected, the plate (2) and the structure (3) of brushes (4) start to move in opposite directions - put in motion by the actuator (12) - and the high voltage apparatus (5) is turned on., The flock starts to go between the holes of the plate (2) and as soon as it crosses it is magnetised at the area (7) and, due to the magnetic field created by the high voltage generator, is projected with high velocity against the piece (9) that contains adhesive.

In the device according to the invention the use of the inverse movement between the structure (3) of brushes (4) and the plate (2), inside the insolating box (1), allows eliminating or at least reducing very significantly the problem of lack of linearity and proportionality when applying flock - problems (B) and (C) - allowing a very high repeatability. Such device has also the capability of isolating effectively the flock, from the involving area.

The defect (C) of lack of flock provoked by the obstruction (D) of the holes is eliminated by means of the action of the movement of the plate (2) and of the structure (3) of brushes (4) that, before anything else, displaces the defect continuously to another position, allowing the lack of flock in that point to be not significant. To point out that the relative movement between the plate (2) and the brushes (4) - with increased effect due to their opposite movements - originates a rough movement, subject to rough inversions of direction, that allows the cleaning of the holes initially obstructed (D) . In this way, when a hole is obstructed, is made possible its release and cleaning, through that movement. Thus, is produced an effect of self—cleaning of the holes of the perforated plate (2) during the application of flock.

To point out that, in this way, the obstructions of the holes of the plate (2) will be only momentary, given that the rough movement, inverse and continuous, will release the holes of the plate automatically.

So, it is eliminated the defect provoked by excess (B) of flock that happened in the previous systems whenever the operator selects an excessive time of application of flock, in an attempt to compensate defects (C) of localised lack of flock, due to the obstruction of the holes of the plate (2) . In this way, the operator, by attempting to correct the lacks of flock in certain areas of the piece, provokes an excess of flock in other areas of the piece. The device according to the invention eliminates or strongly reduces the lumping of the flock, problem that consists in the appearance of small quantities of flock that get stuck to each other, process that ends up leading to the formation of small lumps that originate the obstruction of the holes and the consequent failure (C) in the application of flock.

This problem originates in the quality of the flock, but may be minimised with the method according to the invention and the correspondent device, since the rough movement, inverse and continuous, between the structure (3) of brushes (4) and the plate (2), allows to get the flock that is lumped loose in order so that it is possible to make a bigger use of flock.

On the other hand, it is eliminated the contamination of the involving area bearing in mind that a closed box is formed with the elements 1, 6 and 8 that does not let the flock escape to the exterior, only allowing the passage of flock into the zone where the flock must adhere. The fact that the reliability of the application of the flock determines a lesser need to stop and open the machine for manual corrections is itself an additional factor of making less severe the contamination, since the access to the zone of the flock by the operator is smaller.

Claims

1. Device for application of flock comprising a grid (2) and brushes (4), characterised in that the said grid (2) is provided with alternating movement, rough and automatic, in a plane essentially parallel to the zone to be coted of the target piece (9), and in that, at the side of the grid opposite to said piece, there is a set of sweeping means (4) with relative movement in relation to the said grid (2) provided with automatic movement .

2. Device according to claim 1, characterised in that the movement of the grid (2) and the movement of the brushes (4) is linear.

3. Device according to one of the claims 1 or 2, characterised in that the movement of- the grid (2) and the movement of the brushes (4) are of the same amplitude and of opposite directions.

4. Device according to claim 3, characterised in that the inverted movement between the structure (3) of brushes

(4) and the plate (2) is obtained by the insertion among them of an oscillating arm (13), articulated in a fixing means (14) , arm that connects to the said structure and plate by one or more couplings (15) .

5. Device according to the claim 4, characterised in that the actuator (12), that is at the origin of the driving of the structure (3) of brushes (4) _^and of the plate (2), is placed outside of the involving box (1).

6. Device according to claim 4, characterised in that the movement (P and Q) is about 10 to 60 cycles per minute.

7. Device according to claim 4, characterised in that the movement (P and Q) has an amplitude comprised between about 1 and 10 cm.

8. Device according to claim 1, characterised in that the skirts (6) are adjusted to the box (1) and the serigraphic screen (8) those three elements defining a restricted zone of access or exit.

9. Method for application of flock by electrostatic action characterised in that the flock is submitted, during the crossing of the electrostatic grid (2), to a double mechanical action resulting from the simultaneous combination of two effects, i) the one of the sweeping of the said flock in the electrified grid (2) , said sweeping being promoted by the action of brushes (4) provided with relative movement in relation to that grid, with ii) the effect of mechanical choc deriving from the fact that the crossing of that electrified grid (2) , by said flock, is made with the grid in alternating rough movement in a plane essentially parallel to the zone to be coated in the target piece

(9) .

10. Method according to claim 9, characterised in that the movement of the grid (2) and the movement of the brushes (4) are of the same amplitude and of opposite directions .

11. Method according to one of the claims 9 or 10, characterised in that the movement of the grid (2) and the movement of the brushes (4) is linear.