GB2107614A

GB2107614A - Coating bottles

Info

Publication number: GB2107614A
Application number: GB08228873A
Authority: GB
Inventors: Ewald Georg Welp
Original assignee: Jagenberg Werke AG
Current assignee: Jagenberg Werke AG
Priority date: 1981-10-12
Filing date: 1982-10-08
Publication date: 1983-05-05
Also published as: ES8307128A1; JPS5895627A; BR8204273A; IT1152887B; DD204082A5; CA1194290A; FR2514267A1; DE3140486A1; DE3140486C2; IT8223664A0; ES516427A0

Abstract

Glass bottles (2) are coated with a synthetic material using a nozzle head (3) with a plurality of spaced nozzles (11-13) adapted to eject the synthetic material with successive droplets. Relative movement is effected between the surface of the bottle and the nozzle head and the nozzles are so arranged with respect to the direction of the relative movement that the traces of the synthetic material emerging from adjacent nozzles overlap on the container. The relative movement is coordinated with the ejection rate of the droplets so that the surface areas of the bottle coated with successive droplets from the same nozzle overlap. <IMAGE>

Description

SPECIFICATION Apparatus for coating objects, such as glass bottles, with synthetic material The invention relates to an apparatus for coating objects, such as glass bottles, with a synthetic material, consisting of a nozzle head for the synthetic material.

It is known to cover glass bottles with a layer of synthetic material, in order to conceal surface defects, such as scratches (German OS 2 941 105). The layer of synthetic material can be applied in various ways, for example by the spraying method. Thus, insofar that the synthetic material is applied in the form of a spray mist, it is hardly possible to apply a uniform coating providing surface cover with the least possible thickness.

It is the object of the invention to provide an apparatus with which it is possible to provide an uninterrupted coating of any thickness, in particular of very slight thickness and which is uniform over the entire surface.

This object is achieved according to the invention with an apparatus of the aforementioned type, which is characterised by the following features: 1) The nozzle head consists of several nozzles distributed in a geometrically uniform manner, from which the synthetic material is ejected in the form of successive droplets.

2) Driving means are provided, which bring about a relative movement between the surface of the object to be coated and the spray head.

3) The nozzles are arranged with respect to the direction of relative movement so that the traces of the synthetic material emerging from adjacent nozzles overlap on the container.

4) The relative movement is coordinated with the repetition frequency of the droplets ejected so that the areas on the surface of the object to be coated covered by the droplets emerging in succession from the same nozzle overlap.

The invention utilized the properties of the recorder head known per se from the ink jet printing method (Simen's Journal 51st year, volume 4, April 1977, pages 219-221; Spektrum der Wissenschraft (Spectrum of Science), that each droplet has a certain volume and that the repetition frequency of the droplets can be adjusted exactly. Taking the properties of the synthetic material into consideration, which is to run on the surface to be coated and/or flow one into the other, by way of the geometry and relative movement, a closed layer can be achieved on the object with the exact thickness. Naturally, in this case, the distance of the nozzles from the surface to be coated as well as the kinetic energy of the impact of the droplets must be taken into consideration, since this is critical for the punctiform surface, which the droplets cover.Overlapping of the droplet jets on the bottle solely on account of the geometric arrangement of the nozzles can be achieved for example due to the fact that the nozzles are arranged in several rows lying side by side and are staggered with respect to each other.

Even in the case of a large mutual spacing of the nozzles, an overlap can be achieved in this way.

However it is also possible that deflecting means for the droplet jet are associated with the nozzles. Like a cathode ray, in this case the droplet jet sweeps over a larger surface, which adjoins the surface of the adjacent droplet jet.

There are various possibilities for the construction of the nozzle head. In a first embodiment the nozzle head may be constructed as a bar extending over the entire height of the surface of the object to be coated, opposite which bar the container rotates about its own axis. In a case of this type, the entire surface is coated due to a rotation of a bottle of circular cross-section through 360 . However, the nozzle head may also be constructed as a bar extending solely over part of the height of the surface to be coated. In this case, not only does a rotation of the container about its own axis with respect to the bar take place, but at the same time also an axial displacement. The nozzle head thus produces a spiral path on the surface of a cylindrical bottle.

Finally it is possible for the nozzle head to be constructed as a ring, which is moved axially with respect to the object to be coated, for example a bottle.

Preferably, the nozzles can be turned on individually or in groups. The nozzles can be controlled according to a pre-set programme.

It is then possible to apply coatings not only over a large surface area, but also coatings over a small surface area, for example labels or other information. In this case also, exact metering of the thickness occurs with a closed layer.

The invention is described in detail hereafter with reference to a drawing illustrating one embodiment. The apparatus illustrated diagrammatically in the drawing consists of a plate 1 driven in the machine frame by which the bottle 2 located thereon can be set in rotation about its own axis and of a nozzle head 3, which is supported by way of a holder 4 by a spindle 5, which can be rotated by way of a gear 6. The gear meshes with teeth 7 on the outer periphery of the driven rotary plate 1, so that during the rotation of the rotary plate 1, the spindle 5 is driven in synchronism and an axial displacement of the holder 4 with the nozzle head 3 arranged on the spindle 5 and guided in a sliding guide 1 4 takes place. The nozzle head 3 then describes a spiral path on the surface of the bottle 2.

The nozzle head 3 is constructed as a multi sectional bar 8, 9, 10. Located in each bar 8, 9, 10 is a row of uniformly distributed nozzles 11, 12, 13, which are staggered from one row to another and are at the same distance from the surface of the object. Nozzle heads 3 with nozzles 11, 12, 1 3 of this type are known in various forms (Siemens Journal, 51st year, volume 4, April 1977, pages 219-221; Spektrum der Wissenschaft (Spectrum of Science) 1 979 volume 6, page 90.99 "Ink Jet Printing Method"). In any case, the nozzles 11, 12, 1 3 can be controlled individually and droplets of a predetermined volume are ejected from the latter in a certain repetition frequency.With an 80-90 lim nozzle, the droplet has a diameter of 60 jum and depending on the coating medium, the wetted area will have an approximate size of 300-500 item.

Provided that the rotary plate 1 is driven, but the spindle 5 is disconnected from the rotary plate, 1 the nozzles 11, 12, 1 3 produce a trace of overlapping points on the surface of the object 2. On account of the staggered arrangement of the nozzles 11, 12, 13, with respect to the direction of movement between the nozzle head 3 and the surface, it is also ensured that the traces of droplets from adjacent nozzles likewise overlap. The degree of the overlap is determined on the one hand by the stagger of the nozzles, with respect to the direction of movement and on the other hand by the ratio of the pulse repetition frequency to the relative movement. Since the volume droplet for a certain synthetic material is always the same size, the thickness of the coating can be adjusted exactly in this way.

One can manage with fewer nozzles 11, 12, 1 3 and a greater mutual spacing, if the droplet jets are not directed in a straight line, but are deflected, so that in the case of relative movement between the nozzle head 3 and object 2, they described zig-zagged traces. In this case, the tips of adjacent zig-zag traces overlap.

Claims

1. Apparatus for coating objects, e.g.

glass bottles with a synthetic material, the apparatus comprising a nozzle head with a plurality of spaced nozzles adapted to eject the synthetic material as successive droplets and driving means for effecting relative movement between the surface of the object and the nozzle head, the nozzles being so arranged with respect to the direction of said relative movement that the traces of the synthetic material emerging from adjacent nozzles overlap on the container and said relative movement being coordinated with the ejection rate of the droplets so that the surface areas of the object coated with successive droplets from the same nozzle overlap.

2. Apparatus as claimed in claim 1, wherein the nozzles are arranged in staggered parallel rows.

3. Apparatus as claimed in claim 1 or 2, wherein deflection means for the droplet jets are associated with each nozzle.

4. Apparatus according to any one of claims 1 to 3 wherein the nozzle head is constructed as a bar which is preferably multo-sectional and extends over the entire height of the surface of the object to be coated, opposite which bar the object rotates about its own axis.

5. Apparatus according to any one of claims 1 to 3, wherein the nozzle head is constructed as a bar which in particular is multi-sectional and extends over part of the height of the surface of the object to be coated, opposite which bar the object rotates about its own axis with a superimposed axial displacement.

6. Apparatus according to any one of claims 1 to 3 wherein the nozzle head is constructed as a ring which in particular is multi-sectional, which can be adjusted axially with respect to the surface of the object to be coated.

7. Apparatus according to one of claims 1 to 4, wherein the nozzles can be turned on individually or in groups.

8. Coating apparatus substantially as herein described with reference to and as illustrated in the accompanying drawing.