Method for machining a surface of a component

Abstract

A method for machining at least one portion of a surface of a component for a vehicle, which is painted with a layer of clear coat of a given first layer thickness. The component is situated in an inner space of a blasting chamber. An opening of at least one conveying device for a blasting material emerges into the inner space. The inner space of the blasting chamber and the component are placed entirely under a partial vacuum. Blasting material in a carrier air flow generated by the partial vacuum is supplied through the opening of the conveying device to the inner space. The portion of the surface being machined and the opening of the conveying device are moved relative to each other. The blasting material is shot from the opening of the conveying device onto the portion of the surface being machined.

Claims

1. A method for machining at least one portion of a surface of a component for a vehicle, which is painted with a layer of clear coat of a given first layer thickness, wherein the method comprises: situating the component in an inner space of a blasting chamber, wherein an opening of at least one conveying device for a blasting material emerges into the inner space of the blasting chamber, placing the inner space of the blasting chamber and the component arranged therein entirely under a partial vacuum, generating, by a partial vacuum source, a carrier air flow for blasting material to be provided into the blasting chamber, wherein said partial vacuum source is provided opposite the opening of the at least one conveying device and downstream of said opening, supplying blasting material in the carrier air flow generated by the partial vacuum through the opening of the at least one conveying device to the inner space, wherein the portion of the surface being machined and the opening of the at least one conveying device are moved relative to each other, machining the surface by shooting the blasting material from the opening of the at least one conveying device onto the portion of the surface being machined, wherein the blasting material is accelerated, by suction action provided on the carrier air flow by the partial vacuum source, onto the portion of the surface being machined.

2. The method according to claim 1, wherein the blasting material is accelerated by combination with at least one additional gas flow suctioned by the partial vacuum source from the inner space, said at least one additional gas flow being under at least under atmospheric pressure, before impinging onto the surface being machined, wherein a terminal velocity of the impinging blasting material is greater than the flow velocity of the carrier air flow.

3. The method according to claim 2, in which the terminal velocity is adjusted, by operation of the partial vacuum source, as a function of the type and shape of the surface being machined, the type of blasting material, the degree of loading of the carrier air flow with blasting material, the value of the partial vacuum in the carrier air flow, the blasting time and/or the blasting temperature.

4. The method according to claim 1, in which at least 1% and at most 50% of the given first layer thickness of the layer of clear coat is removed from the surface of the component by machining the surface, whereby the surface of the component being machined becomes matte and a reduced second layer thickness of the layer of clear coat is formed.

5. The method according to claim 4, in which the resulting matte surface of the component is then polished to a glossy finish.

6. The method according to claim 1, in which the partial vacuum is adjusted to a value of at most 950 mbar.

7. The method according to claim 1, in which free-flowing particles are used as the blasting material for the removal of a portion of the layer of clear coat, these particles having a size of at least 15 m and at most 350 m, the particles comprising at least one of: sand, plastic, glass beads, crushed glass, dry ice and/or soda.

8. The method according to claim 1, in which the surface of the component is covered by a stencil except for the at least one portion being machined.

9. The method according to claim 6, wherein the partial vacuum is adjusted to 200 mbar.

10. The method according to claim 7, wherein a liquid, said liquid comprising at least one of: water or another liquid, is added to the blasting material.

11. The method according to claim 7, wherein the particles have a size of 150 m.

12. The method according to claim 7, wherein the free-flowing particles are provided as at least one of a granulate and a powder.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The invention is represented schematically on the basis of embodiments in the drawings, and will be described schematically and in detail, making reference to the drawings.

(2) FIG. 1 shows in schematic representation a first example of a device for carrying out a first embodiment of the method according to the invention.

(3) FIG. 2 shows in schematic representation a second example of a device for carrying out a second embodiment of the method according to the invention from different perspectives.

(4) The figures shall be described coherently and comprehensively. The same reference numbers are used for the same components.

DETAILED DESCRIPTION OF THE DRAWING

(5) The example of the device 2 represented schematically in FIG. 1 comprises a blasting chamber 4, a conveyor device 6, a hopper 8, a transport mechanism 10, and a container 12 for a blasting material 14, composed here of free-flowing particles.

(6) The hopper 8 is connected by a line 36, deigned here as a hose, to a pump 15. If the pump 15 is turned on, a partial vacuum is created in the inner space 18 by an opening 16 of the line 36, this opening 16 also being designed at the same time as an opening of the inner space 18 of the blasting chamber 4. As long as the partial vacuum prevails in the inner space 18 of the blasting chamber 4, blasting material is suctioned from the container 12, here via another line 20 of the conveying device 6 designed as a hose, to a blasting lance 22 of the conveying device 6 and further shot through an opening 24 of the blasting lance 22 and thus of the conveying device 6 into the inner space 18 of the blasting chamber 4, thus being delivered into this inner space 18.

(7) With this device 2 carrying out the first embodiment of the method of the invention, it is possible to machine a surface 26 of a component 28, usually a component 28 for a vehicle or a motor vehicle, the surface 26 having a layer of clear coat painted on the component 28.

(8) At first, it is provided that the conveying device 6 and the pump 15 are deactivated and a normal atmospheric pressure prevails in the inner space 18. Furthermore, the component 28, as indicated by a first curved arrow 30, is arranged through an opening of the blasting chamber 4, not shown further here, in the inner space 18 and arranged at a first end of the transport mechanism 10 inside the inner space 18. After this, the opening to the inner space 18 of the blasting chamber 4 is closed.

(9) Once the component 28 whose surface 26 is to be machined has been arranged in the inner space 18, the conveying device 6 and the pump 15 are activated, whereby blasting material 14 is suctioned into the inner space 18. In addition, the component 28 is transported by the transport mechanism 10 relative to the opening 24 of the conveying device 6. Blasting material 14 impinges onto the surface 26, removing a portion of the layer of clear coat and giving the surface 26 a matte finish. The blasting material 14, as indicated by arrows 32, is at first shot onto the component 28 and then removed from the inner space 18 by way of the suction effect of the pump 15.

(10) In the embodiment here it is proposed that the transport mechanism 10 is configured as a running belt or conveyor belt, on which the component 28 is to be placed. Furthermore, it is possible for the transport mechanism 10 to have only a carrier body on which the component 28 is placed, this carrier body being moved back and forth in the inner space 18, for example, on rails with the component 28 arranged thereon.

(11) Regardless of the specific configuration of the transport mechanism 10, it is provided here that it has a plurality of openings through which the blasting material 14 can be transported to the opening 16 of the hopper 8 or the line 36. In this case, the running belt or the carrier body is fashioned as a lattice or a netting, for example.

(12) Once the surface 26 of the component 28 has been sufficiently machined by removal of clear coat, and generally been rendered matte, the conveying device 6 and the pump 15 are shut off. Thus, once again the normal atmospheric pressure prevails in the inner space 18. After this, it is possible to remove the component 28 with the machined surface 26 from the inner space 18 through an opening of the blasting chamber 4, not shown further here, as indicated by the arrow 34.

(13) Since the pump 15 is connected here by another line 37, which is designed as a hose, to the container 12, it is possible for the blasting material 14 to provide a closed circuit, wherein at least when the pump 15 is switched on, the blasting material 14 is delivered from the container 12 via the line 20 to the opening 24 of the conveying device 6 into the inner space 18 standing under partial vacuum, machining the surface 26 of the component 28. Furthermore, the blasting material 14 is transported by the pump 15 via the line 36 out from the inner space 18 and via the additional line 37 to the container 12, from which the blasting material 14 is to be transported once more to the opening 24 of the conveying device 6. It is possible to integrate a cleaning mechanism 38 in the container 12, which is designed to separate clear coat, usually residues or particles of the clear coat removed from the surface 26 of the component 28 by the blasting material 14, from the blasting material 14 delivered to the container 12. This cleaning mechanism 38 is designed as a sieve, for example.

(14) The second device 52 is represented schematically in FIG. 2a from the front, in FIG. 2b along a cross section A-A of FIG. 2a and in FIG. 2c from above. The device 52 comprises a blasting chamber 54, having a wall 56 which encloses an inner space 58 of the blasting chamber 54. On one surface of the blasting chamber 54 are arranged a first hatch 60, which is open here, and a second, closed hatch 62. Furthermore, on the top side there is arranged a conveying device 64, configured here as a blasting lance. A bottom side of the blasting chamber 54 is bounded here by a hopper 66, which comprises a pump, not shown further here. Moreover, the device 52 comprises a transport mechanism, which in turn comprises a conveyor belt 70, which is arranged in the inner space 58 of the blasting chamber 54. A component arranged on the conveyor belt 70 is to be moved in the inner space 58 of the blasting chamber 54 relative to the conveying device 64.

(15) The second embodiment of the method according to the invention is designed for the machining of a surface of the component. The component has been painted with a layer of clear coat, forming the surface to be machined. In order to carry out the method, it is proposed at first that the component is arranged on the conveyor belt 70. After this, the inner space 58 is closed by shutting both hatches 60, 62. The conveying device 64, which here comprises a blasting lance whose opening emerges into the inner space, is connected by lines, not shown further here, to a container for blasting material. By activating the pump, a partial vacuum is created in the inner space 58 of the blasting chamber 54, by which the blasting material is suctioned from the openings of the conveying device 64 into the inner space 58. At the same time, after the transport mechanism is activated, the component arranged on the conveyor belt 70 is transported relative to the opening of the conveying device 64. The blasting material then strikes the surface of the component, partly removing the clear coat painted on it. Residues of the removed clear coat and blasting material are suctioned out from the inner space 58 by the pump. Moreover, it is possible to clean the blasting material of residues of clear coat and again provide it to the container for the conveying device 64.

(16) The proposed method is suitable for the machining of a surface 26 of a component 28, designed as a body component or also as an interior component of a vehicle. With the method, a layer of clear coat can be machined, the clear coat not having any matting agents. As a result, the surface 26 of the component 28 becomes matted and a surface 26 with a matte appearance is formed. Existing layers of clear coat of high technical quality can be used when performing the method. Since only a fraction of the layer of clear coat is removed, a protective action of the layer of clear coat with respect to climate factors is preserved. By polishing the now matte surface 26, a matte effect can be polished out, so that the surface 26 once more appears glossy. In this way, it is possible to perform local repairs on painted surfaces. Likewise, matte decorations on a finish-coated body or interior component, such as trims and covers, can be applied to glossy surfaces 26 painted with clear coat. Moreover, a matte surface 26 can be polished once again, so that a glossy surface 26 is produced, which can then be matted once more with the proposed method. In this way, for example, flaws in matte surfaces 26 can be repaired. The protective action of the layer of clear coat remains preserved.