WO2005008712A2

WO2005008712A2 - A process for the production of anti-implosion bands for television tubes

Info

Publication number: WO2005008712A2
Application number: PCT/IT2004/000206
Authority: WO
Inventors: Gianfranco Natali
Original assignee: Cervino Technologies S.R.L
Priority date: 2003-07-17
Filing date: 2004-04-13
Publication date: 2005-01-27
Also published as: ITVR20030088A1; WO2005008712A3

Abstract

A process for the production of anti-implosion bands for television tubes comprises the operating steps of preparing a strip (2) of material extending between two ends (3), with predetermined thickness, width and length, bending the strip (2) into a ring, bringing together the fronts of the ends (3) of the strip (2), thus obtaining a band (1) with the desired shape, and connecting the two ends (3) of the strip (2) to one another by laser welding. The process may also comprise a step of shaping the ends (3) during which a connecting profile (4) is created on each end (3).

Description

A process for the production of anti -implosion bands for television tubes

Technical Field The present invention relates to a process for the production of anti-implosion bands for television tubes, of the type described in the preamble to claim 1.

Background Art Anti-implosion bands are metal bands shaped to fit the side profile of the television tube, which are mounted on the television tube close to the screen after being suitably expanded by heating. Their subsequent cooling clamps them to the television tube. According to the technology used today, all procedures for the formation of anti-implosion bands involve firstly a first step in which a strip of material extending between two ends is prepared,, with predetermined thickness, width and length. Then the strip of material is bent into a band in a shape corresponding to that of the television tube to which it must be applied, making the ends of the strip overlap one another. The two ends of the strip are then joined together. According to a first known technique (illustrated in Figures 1 to 3) the connection between the two ends is made with projection welding at a plurality of points (in Figure 3 a wider strip of material is also represented with a dashed line) . A second known technique (illustrated in Figures 4 to 6) , normally known as T0X joining, involves pressing the two ends at several points between the two parts of a special tool, with one part male-shaped and the other female. This causes localised deformation of the strip of material with interpenetration of the two ends (in Figure 6 a wider strip of material is also represented with a dashed line) . A third type of connection (Figures 7 - 9) involves resistance welding of the two ends at various points (in Figure 9 a wider strip of material is also represented with a dashed line) . However, all of the known processes described have some disadvantages. Firstly, the thickness of the resulting band at the joint is at least doubled (this thickness is even greater in the case of TOX connections) . As a result, when a television model is designed it is always necessary to take into account the position of the joint, a position often determined, based on the dimensions of the other parts of the television, by the television or television tube manufacturer which first introduces a certain type of television tube on the market . Consequently, television tube manufacturers must adapt to the requirements of television manufacturers and provide them with precise joint positioning for each new television tube format. Since allowing the possibility of changing the position of the joint would be too costly (production uses moulds and other equipment which cannot be used very flexibly) , other television manufacturers which also want to produce televisions with television tubes in the new format remain constrained in their design choices by the position of the joint previously established by the competitor who first produced the new model . A second disadvantage of the processes known today is linked to the use of a greater quantity of material than that theoretically necessary. This problem is accentuated by the fact that in order to guarantee improved band reliability, a large number of connecting points is required (welds or TOX connections) , therefore, a relatively large area for overlapping of the ends of the strip. Another disadvantage, linked to welding, is the fact that an effective connection between the two ends of the strip cannot be created at all points where welding is carried out. For this reason, a higher number of weld points than those theoretically necessary are required, increasing production times and costs. Moreover, when the connection is made by welding there is a further cost due to energy consumption by the electrode used. This is without considering that the temperature reached at the weld points is so high that the protective metal (Zn and/or Al) vaporises, releasing toxic oxides into the environment. Moreover, at the weld points exposed in this way, the band is subject to unwanted oxidation. Finally, further problems arise in the case of bands with ribs (either longitudinal or transversal) , since such ribs made correct adherence between the two overlapping ends practically impossible.

Disclosure of the Invention In this situation the technical need of the present invention is the preparation of a process for the production of anti-implosion bands for television tubes which overcomes the above-mentioned disadvantages . The specific technical need and the aforesaid aims are substantially achieved by a process for the production of anti- implosion bands for television tubes as described in the claims herein.

Brief Description of the Drawings Further characteristics and advantages of the present invention are more apparent in the detailed description below, with reference to the accompanying drawings, which illustrates some preferred embodiments of the process for the production of anti -implosion bands for television tubes, without limiting the scope of its application and in which: Figure 1 is a schematic side view of a portion of band before closure according to a first known method for the production of anti -implosion bands; Figure 2 is a schematic side view of the portion of band illustrated in Figure 1 after closure; Figure 3 is a schematic front view of the portion of band illustrated in Figure 2; Figure 4 is a schematic side view of a portion of band before closure according to a second known method for the production of anti-implosion bands; Figure 5 is a schematic side section according to line V - V in Figure 6 of the portion of band illustrated in Figure 4 after closure; Figure 6 is a schematic front view of the portion of band illustrated in Figure 5; Figure 7 is a schematic side view of a portion of band before closure according to a third known method for the production of anti -implosion bands; Figure 8 is a schematic side view of the portion of band illustrated in Figure 7 after closure; Figure 9 is a schematic front view of the portion of band illustrated in Figure 8; Figure 10 is a front view of a first type of anti-implosion band made using a process in accordance with the present invention; Figure 11 is a view from below of the band illustrated in Figure 10; Figure 12 is a side view of the band illustrated in Figure 10; Figure 13 is a front view of a second type of anti-implosion band made using a process in accordance with the present invention; Figure 14 is a cross-section according to line XIV - XIV of the band illustrated in Figure 13; Figure 15 is an enlarged view of the upper corner illustrated in Figure 14; Figure 16 is a side view of the band illustrated in Figure 13; Figure 17 is a schematic cross-section of the closing point of a band made using the process in accordance with the present invention; Figure 18 is a top view of the band closing point in a first embodiment of the process in accordance with the present invention; Figure 19 is a top view of the band closing point in a second embodiment of the process in accordance with the present invention; and Figure 20 is a top view of the band closing point in a third embodiment of the process in accordance with the present invention.

Detailed Description of the Preferred Embodiments of the Invention The process for the production of anti-implosion bands 1 for television tubes disclosed begins with a step of preparing a strip

2 of material extending between two ends 3. According to requirements, the preparation step may also comprise an initial step for formation of the strip 2, preferably using a metal material such as aluminised steel, although the material may be selected according to requirements on each occasion. Alternatively, the strip 2 of material may already have been formed, in which case the preparation step will be limited, if necessary, to cutting the strip 2 of material to size. The thickness, width and length of the strip 2 are determined according to the television tube model to which the band 1 must be applied. Since, under certain circumstances, the anti-implosion band 1 may require ribs (not illustrated) , if these are not already present they must also be made during the preparation step. The strip 2 of material is then bent into a ring in such a way as to create the closed band 1, with the desired shape. In particular, the fronts of the ends 3 of the strip 2 are brought together and aligned with one another (Figures 17 - 20) . At this point the two ends 3 are connected together by laser welding which joins the fronts of the two ends 3. According to requirements, welding may be performed either with or without the addition of weld material. During the previous preparation step (therefore, either in conjunction with the strip 2 forming step or after it) there may also be a step of shaping the ends 3 of the strip 2 of material, during which a connecting profile 4 is created on each end 3, the profile preferably shaped to fit the connecting profile 4 created on the other end 3. Examples of possible connecting profiles 4 are illustrated in Figures 17 to 20. As illustrated in Figure 18, the connecting profile 4 may, therefore, be linear with a length corresponding to the width of the strip 2 of material. In contrast, according to the embodiments illustrated in Figures 19 and 20, the length of the connecting profile 4 is greater than the width of the strip 2 of material, thus guaranteeing a greater seal surface. In the cases illustrated this is achieved by giving the profile

4 a herringbone shape (Figure 19) or a saw-toothed shape (Figure 20) . However, the same result may be achieved even with a linear profile 4 set at an angle of less than 90° to the strip 2 of material . Alternatively, although not illustrated, there are also embodiments in which the connecting profile 4 is at least partly curved, and others in which on at least one of the ends 3 a connecting profile 4 is created which is designed to hook onto the connecting profile 4 made on the other end 3. In the latter case, one profile 4 has undercut seats, whilst the other has projections shaped to match the undercut seats . Advantageously, the welding step takes place by making the laser beam follow the connecting profile, either manually, or preferably automatically, using special electronic-control welding heads . In the embodiment illustrated in Figure 10 there is also a step of mounting on the band 1 a plurality of connecting elements 5 for subsequent connection of the band 1 to the casing of a television. In the embodiment illustrated in Figure 10 the connecting elements 5 are fixed to the four corners of the band 1, and have connecting through-holes 6. The welding zone is labelled 7 in the accompanying drawings. The present invention has important advantages. Firstly, the process disclosed can be used to obtain anti- implosion bands 1 with a constant thickness even at the joint zone, thus freeing television tube and television manufacturers from the design constraint which was the joint with increased thickness in conventional bands 1. Secondly, the process disclosed allows savings in material compared with the conventional processes, since the ends 3 of the strip 2 of material which forms the anti-implosion band 1 do not overlap. Moreover, the process according to the present invention can be used to create joints between the two ends 3 which are much stronger than conventional joints and minimal zones without protective metal (Al, Zn or other metals) . It should also be noticed that the present invention is relatively easy to produce and even the cost linked with implementation of the invention is very low. The invention described can be subject to modifications and variations without thereby departing from the scope of the inventive concept . Moreover, all the details of the invention may be substituted by technically equivalent elements and in practice all of the materials used, as well as the shapes and dimensions of the various components, may take any form according to requirements.

Claims

1. A process for the production of anti-implosion bands for television tubes, comprising the operating steps of:

- preparing a strip (2) of material extending between two ends (3) , with predetermined thickness, width and length; - bending the strip (2) into a ring, bringing the ends (3) of the strip (2) together to obtain a band (1) with the desired shape; and connecting the two ends (3) of the strip (2) to one another; the process being characterised in that during the strip (2) bending step the fronts of the two ends (3) of the strip are brought together, and also characterised in that the connecting step is performed by laser welding the fronts of the two ends (3) brought together.

2. The process according to claim 1, characterised in that it also comprises a step of mounting on the band (1) a plurality of connecting elements (5) for subsequent band (1) connection to the casing of a television.

3. The process according to claim 1 or 2 , characterised in that the preparation step also comprises a step of forming at least one rib on the strip (2) .

4. The process according to any of the foregoing claims, characterised in that the preparation step also comprises a step of shaping the ends (3) during which a connecting profile (4) is created on each end (3) .

5. The process according to claim 1, characterised in that during the step of shaping the connecting profiles (4) on the two ends (3) they are shaped to fit one another.

6. The process according to claim 4 or 5, characterised in that a linear connecting profile (4) is created on each end (3) .

7. The process according to claim 4 or 5, characterised in that a connecting profile (4) whose length is greater than the width of the strip (2) of material is created on each end (3) .

8. The process according to claim 7, characterised in that a connecting profile (4) with at least a partly saw-toothed shape is created on each end (3) .

9. The process according to claim 7, characterised in that a connecting profile (4) at least partly curved is created on each end (3) .

10. The process according to claim 7, characterised in that on at least one end (3) a connecting profile (4) designed to hook onto the connecting profile (4) on the other end (3) is created.

11. The process according to any of the claims from 4 to 11, characterised in that the welding step takes place by making the laser beam follow the connecting profile.

12. The process according to claim 11, characterised in that the laser beam automatically follows the connecting profile (4) .

13. The process according to any of the foregoing claims, characterised in that the laser welding step takes place without the addition of material.

14. The process according to any of the foregoing claims, characterised in that the laser welding step takes place with the addition of material in the welding zone.

15. The process according to any of the foregoing claims, characterised in that the preparation step involves the creation of the strip (2) of aluminised steel.