GB2227193A

GB2227193A - Manufacturing method for electrode of electron gun of cathode ray tube

Info

Publication number: GB2227193A
Application number: GB9001301A
Authority: GB
Inventors: Tae-Geun Ha
Original assignee: Samsung Electron Devices Co Ltd
Current assignee: Samsung SDI Co Ltd
Priority date: 1989-01-20
Filing date: 1990-01-19
Publication date: 1990-07-25
Anticipated expiration: 2010-01-19
Also published as: GB9001301D0; MY104888A; CN1023851C; CN1044363A; KR910004753B1; KR900012313A; GB2227193B

Abstract

A manufacturing method for an electrode for an electron gun of a cathode ray tube comprises: a step of pressing conical projections C to be provided with beam passing holes, pressing reinforcing beads B for preventing the deformations of the body of the electrode, and pressing annular grooves E having wrinkles around the conical projections; a first piercing step of punch-forming the beam passing holes H through the top planes of the conical projections; a step of pressing annular slopes around the beam passing holes; a step of pressing the top planes of the conical projections to reduce the thickness of them; a trimming step of removing the remaining portions other than the body portion of the electrode; a second piercing step of punching through the beam passing holes; and a step of cutting out the completed electrodes from the continuous line. The number of the steps of the prior art process is reduced, and a heat treating step is omitted. <IMAGE>

Description

MANUFACTURING METHOD FOR ELECTRODE OF ELECTRON GUN OF CATHODE RAY TUBE The present invention relates to a manufacturing method for an electrode of an electron gun for use in cathode ray tubes, and particularly to a manufacturing method of an electrode, by which a high quality electrode can be produced with a shortened manufacturing process.

The first electrode of an electron gun for a usual type of cathode ray tube consists of two types, namely a cup type and a plate type, and of them, the plate type first electrode is literally of a plate type as shown in Figure 1.

In this type, beam passing holes H which are adequate for controlling the electron beams are provided, and beside the beam passing holes H, beads B having wrinkles are provided for preventing the deformation due to external forces, the beam passing holes being positioned on the top planes of conical projections C, and annular grooves E being formed around the beam passing holes H.

Such an electrode has been most extensively used recently, and due to the complexity of its structure, it is fabricated by progressive pressing processes through many processes such as pressing, piercing, and trimming.

The conventional manufacturing method for this electrode will be described referring to the drawings for each of its processing steps.

First step: As shown in Figures 2A,2B, if a roll type stock having a certain thickness (about 0.30 + O.Olmm) advances through a progressive die, three conical projections C are formed at the positions where the beam passing holes are to be formed, and beads B having wrinkles are formed near the opposite edges of the body of the electrode in order to prevent the deformation of the body.

Second step: As shown in Figures 3A, 3B, beam passing holes H are punched through the top planes of the conical projections.

Third step: As shown in Figures 4A, 4B, annular ridgesD are press-formed around the conical projections, and at the same time, annular slopes R are formed along the circumferences of the beam passing holes H.

Fourth step: As shown in Figures 5A; 5B, the whole of the planes where the beam passing holes H are formed are pressed so as for them to have a thickness less than a certain size (usually 0.17mm).

Fifth step: As shown in Figures 6A,6B, the remaining portions other than the body of the electrode are removed for all the incoming parts.

Sixth step: As shown in Figures 7A,7B, the opposite edge portions 0 of the body of the electrode are bent into Z shape.

Seventh step: As shown in Figures 8A,8B, the individual bodies of the electrode are cut out from the continuously progressing stock.

Eighth step: The individual electrodes cut out in the preceding step are subjected to heat treatment in order to facilitate the machining processings to be performed later.

Ninth step: As shown in Figures 9A,9B, dish-shaped recesses R' are formed around the beam passing holes H which are formed at the centres of the planes within the annular grooves.

Tenth step: As shown in Figures 10A,10B, the dishshaped recess R' is pressed again to form a cylindrical recess R', and a punching is performed through the beam passing holes H in order to expand the size of the holes which have been narrowed through the pressing processes performed before.

The conventional manufacturing method for the electrode as described above will now be examined as to its contradictory features. The annular slope R which is formed at the third step disappears during the pressing process which is the next step, and therefore, it has to be reformed at the ninth step which is the final step, as well as requiring a heat treating process in order to facilitate the workability at the finishing steps to be performed later.

Such a conventional manufacturing method for the electrode is irrational and contradictory in view of the productivity, with the result that the competitiveness of the product is impaired.

Therefore, it is the object of the present invention to provide a manufacturing method for an electrode of an electron gun of a cathode ray tube, in which the fastidious and dangerous heat treatment process requiring a large scale facility and a large amount of labor is omitted, as well as decreasing the number of the steps of the manufacturing process to a great extent.

In achieving the above object, the manufacturing method according to the present invention comprises: a pressing step of press-forming conical projections to be provided with beam passing holes, press-forming reinforcing beads for preventing the deformations of the body of the electrode, and press-forming annular grooves having wrinkles around the conical projections; a piercing step of punch-forming the beam passing holes through the top planes of the conical projections; a pressing step of press-forming annular slopes along the circumferences of the beam passing holes; a pressing step of pressing the top planes of the conical projections to reduce the thicknesses of them to below a certain size (usually 0.17mm); a trimming step of removing the remaining portions other than the body portion of the electrode;; a bending step of parallelly bending the opposite edges of the body of the electrode; a second piercing step of performing a punching through the beam passing holes to expand the diameters of them as the final finishing step; and a cutting step of cutting out the completed individual electrodes from the continuous line, the above steps being performed in the cited order.

The above object and other advantages of the present invention will become more apparent by describing in detail by way of example a preferred aixdiment of the present invention with reference to the attached drawings in which: Figure 1 is perspective view of the usual type electrode; Figures 2A,2B to 1OA,1OB illustrates the steps of the conventional manufacturing method for the electrode in the cited order; and Figures llA,llB to 19A,19B illustrate the steps of a manufacturing method for the electrode according to the present invention in the cited order.

Before describing the preferred embodiment of the present invention it should be mentioned that a continuous stock passes through progressive dies, although the drawings illustrate individual electrodes in all of them.

First step: As shown in Figures 11A,11B, a roll type sheet stock having a thickness of 0.3 + O.Olmm is caused to advance through a progressive die.

Second step: As shown in Figures 12Al12B, conical projections C to be provided with beam passing holes, annular grooves E around the projections C, and reinforcing beads B at the opposite sides of the projections C are press-formed, and the thickness of the plate at the bottom of the annular groove E is made to be 0.25mm.

Third step: As shown in Figures 13A,13B, beam passing holes H are formed through the top planes of the conical projections C.

Fourth step: As shown in Figures 14A,14B, annular slopes R are press-formed along the circumferences of the lens forming holes H formed through the top planes of the conical projections C, and at the same time, the thicknesses of the whole areas of the top planes are caused to have a certain value (usually 0.21mm).

Fifth step: As shown in Figures 15A,15B, the diameter of the annular slope is expanded so as for an annular step to be formed between the beam passing hole H and the annular slope R. By this means the top planes of the conical projections are reduced in thickness to below a certain size (usually 0.17mum).

The top plane thickness may for example be O.imm.

Sixth step: As shown in Figures 16A,16B, the remaining portions other than the body of the electrode are cut of.

Seventh step: As shown in Figures 17A,17B, the opposite edges of the body of the electrode are bent into a Z shape.

Eighth step: As shown in Figures 18A,18B, a punching is performed through the beam passing holes H in order to expand the holes H which have been narrowed through the two rounds of the press-forming steps.

Ninth step: As shown in Figures 19A,19B, the individual electrodes are cut out from the continuous stock.

The manufacturing method for the electrode according to the present invention is completed through the above described nine steps, and the completed products as shown in Figures 19A,19B are obtained at the ninth step.

According to the present invention as described above, the number of the steps of the manufacturing process is significantly reduced compared with the conventional manufacturing method, and particularly, the heat treating step is eliminated.

That is, in the conventional method, the beam passing holes are formed through the top planes of the conical projections, and then, the top planes of the conical projections are further pressed after forming annular grooves around the conical projections. Therefore, the annular grooves disappear due to the plastic deformations, and therefore, it becomes difficult to re-process them in restoring the annular grooves and the beam passing holes by means of ordinary machine tools, thereby bringing the necessity that a heat treatment has to be carried out.

According to the present invention, however, the press- forming of the conical projections is carried out in such a manner that it should not give any impediment to forming the beam passing holes and the annular grooves as can be seen in the above described steps of the manufacturing process.

Thus, according to the manufacturing method of the present invention, several steps are omitted, and particularly, the heat treatment which is a troublesome task and requires a large amount of investment in the facility becomes needless. Accordingly, the expense for the facility of the heat treatment is saved with the consequent saving of the manufacturing cost, and the manufacturing time is saved to a great degree, thereby improving the productivity.

Claims

1. A manufacturing method for an electrode of an electron gun of a cathode ray tube, comprising: a pressing step of press-forming conical projections to be provided with beam passing holes, press-forming reinforcing beads for preventing the deformations of the body of the electrode, and press-forming annular grooves having wrinkles around said conical projections; a first piercing step of punch-forming said beam passing holes through the top planes of said conical projections; a pressing step of press-forming annular slopes around said beam passing holes; a pressing step of pressing the top planes of said conical projections to reduce the thickness of them to below a certain size, a trimming step of removing the remaining portions other than the body portion of the electrode; ; a second piercing step of performing a punching through said beam passing holes to expand the diameters of them as the finishing step; and a cutting step of cutting out the completed electrodes from the continuous line, the above steps being performed in the cited order.

2. A manufacturing method for an electrode of an electron gun of a cathode ray tube, substantially as hereinbefore described with reference to Figures 11A to 19B of the accompanying drawings.