JPH11104739A - Manufacture of frame for flat shadow mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of parts and welding points by form processing a pipe stile from a plate material to make a rectangular frame. SOLUTION: A stainless hoop member of 2.2 mm sheet thickness is used, and a blanking, and a hole punching processings are carried out to a long stile member 1, a short stile member 2 and a notching processing is given to an acute bending portion B2. At this time, a central portion of a base face forming part of the bending die is made to be convexed in a longitudinal direction, and, a U shape formed member is convexed and curved like an arrow. In succession, the U shape formed member is made into a right-angled triangle shape pipe and its tip end of a bended portion is welded to become the stile. At this time, a curvature arising from a contraction of the welded metal is negated by a curve formed at the time of U shape bending and the stile become straight, thereby an omission of a curvature correction is made possible. At the last step, one each pair of the long stile 1, and the short stile 2 are assembled into a rectangular frame, and both ends of each stile, namely four frame corners are welded together so as to become a finished product.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a frame of a shadow mask used for a color cathode ray tube, and more particularly to a method of manufacturing a frame of a flat type shadow mask used for a flat type color cathode ray tube which requires rigidity. The present invention relates to a method of manufacturing a frame related to the processing method of (1).

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing a frame of a flat type shadow mask, a stainless steel plate having a thickness of 2.5 mm is used, and as shown in FIG. The two frame parts A having the corner portions W2 and W2 welded are connected to the end faces W1 of the short-side bars A2 and A2, respectively.
・ W1 is abutted face-to-face and welded to form a rectangular frame. Next, a long side reinforcing plate B shown in FIG. 8A using a stainless steel plate having a thickness of 2 mm and FIG.
The short side reinforcing plate C shown in (b) is a welding surface, and the width direction both end surfaces W3 and W4 of the long side bars A1 and A1 and the short side bars A2 and A2 of the frame F in FIG. The width-direction end surfaces W3 and W4 of the long side reinforcing plate B and the short side reinforcing plate C are respectively connected to a frame F (7) XX shown in FIG.
'The hypotenuses of the right-angled triangle in the sectional view (the four sides are joined) are brought into contact with each other, and W3 and W4, which are the welding locations, are welded all around the four sides. Further, four welding portions W5, which are the corner portions of the frame F in FIG. 9 and in which the respective longitudinal end faces W5 of the long side reinforcing plate B and the short side reinforcing plate C abut against each other, are welded. There is a method of manufacturing the frame F shown.

[0003]

However, in the above-mentioned method, the number of parts is as large as two points of the frame part A, two points of the long side reinforcing plate B and two points of the short side reinforcing plate C, and a total of six points. The number of welds is also as large as 18 in total. There are many parts,
The large number of welding points complicates the assembling work, and it is difficult to increase the number of assembling steps and maintain dimensional accuracy. In particular, in welding the two reinforcing plates B and C, FIG.
Since the welding spots W3 and W4 shown in FIG. 4A cover the entire periphery of the four sides of the frame F, distortion of the bars on each side due to welding, twisting of the frame, and the like are required, and correction work is required. Further, since the number of parts is large, the press working is inefficient and the method is not suitable for mass production, including inefficiency, and there is a problem that it is extremely difficult to increase the manufacturing cost and maintain quality such as dimensional accuracy.

Further, since the flat type shadow mask is to be welded and attached to the upper surface of the frame while being tensioned at a high tension of 10 kg per 1 mm ² , a strong tensile load is applied to each bar toward the inside of the frame. Requires high rigidity. Therefore, since the material used for the frame is a relatively thick stainless steel plate having a thickness of 2.5 mm, it is difficult to perform an acute-angle bending process in which a bending angle is particularly emphasized. Also, XX ′ of frame F in FIG. 9 shown in FIG.
In the enlarged sectional view, the reinforcing plates B and C which are the oblique sides thereof are shown.
Surface, that is, the inner surface of the frame F hits the electron beam, so that the flatness in the oblique line direction is ± 0.2 mm due to the characteristics.
Similarly, the long side bar A1 · A1 and the short side bar A2 in FIG.
・ The flatness in the longitudinal direction of the reinforcing plate surface of each bar of A2 is ± 0.
Since it is restricted to 7 mm, distortion due to welding is a problem. Further, the outer shape R of the acute angle portion having the welding portion W4 shown in FIG. 10 is also restricted to a radius R3 mm due to the above-mentioned characteristics, and a stainless steel plate having a thickness of 2.5 mm is used.
Since it is impossible to make the outer shape R within R3 mm by bending the acute angle portion, there is a problem that the reinforcing plate has to be joined by welding.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of manufacturing a frame of a flat type shadow mask which is effective in reducing the number of parts and welding spots in order to solve the above problems.

[0006]

In order to achieve the above-mentioned object, the invention of claim 1 is directed to a long-sided and a short-sided bar, each having a right-angled triangular cross-section having the same shape but different length. Each of the bars is formed into a right-angled triangle by bending from a plate material, and a bent-end joint to be the top of the right-angled triangle is welded. The two long-side bars and the two short-side bars are formed into a rectangular frame with four sides. This is a method of manufacturing a frame of the flat type shadow mask by framing and welding and joining each end face of each of the four sides.

In this method, first, the members of the long side bar and the short side bar are formed by blanking a plate from a plate material, and after drilling, a right angle bending for forming each member into a right triangle is performed. An inverted trapezoidal recessed part having a half depth of the member thickness over the entire length on the bending line parallel to the longitudinal direction is formed by embossing at the acute bending part of the two acute bending parts. Next, so-called U-shaped bending is performed as a primary bending in which the above-mentioned two bending portions are bent at a right angle.
Simultaneously with this U-shaped bending, the welded joint at the top of the right triangle is contracted longitudinally by so-called shrinkage by welding,
Since both ends of the bar are bowed in the direction of the top in the shape of a bow, only the amount of warping is applied to the bottom of the U-shaped bend,
The crosspiece is formed into a bow shape with the center in the longitudinal direction at a middle height. Each of the above processes is performed by pressing the long side bar and the short side bar in a progressive feed method. Next, as a secondary bending, an acute angle bending of a bending portion provided with the concave portion in the plate material is performed by a single process. The acute angle bending can be easily performed because of the inverted trapezoidal concave portion, and the outer shape of the acute angle bending portion is also within the radius R3 mm. Next, the top of the right-angled triangle, which is the joint at the bending tip, is welded over the entire length of the crosspiece. The above-described processing method is the same for the long side bar and the short side bar, whereby the long side bar and the short side bar are completed as bars. Finally, the completed two long and two short sides are framed into a rectangular frame with four sides, and the four corners of the frame, which is the joint of the four sides, are welded to form a flat shadow mask frame. Is manufactured.

According to this method, an inverted trapezoidal concave portion is formed at the acute-angled bent portion, that is, the so-called notching process is performed, so that the acute-angled bending process with the minimum radius becomes possible. In addition, the total length of the welded portion can be reduced by about 36%, and the number of parts can be reduced from the conventional 6 points to 4 points.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

In this embodiment, a hoop material having a thickness of 2.2 m is used.
m stainless steel plate, and the above-mentioned long side bar and short side bar are processed in the following process order by press working. First, the long side bar shown in FIG. 1 and the short side bar 2 shown in FIG. 1- (b) are subjected to blanking processing and punching processing of holes as shown in the developed views of the short side bars 2 and then to acute angles shown in FIGS. 1- (a) and (b). Bending point B
FIG. 2 shows an inverted trapezoidal recess V having an opening width of 5 mm and a bottom width of 3.5 mm as shown in the enlarged cross-sectional view of FIG. Is subjected to notching to form a half depth of the sheet thickness by embossing. Next, as the primary bending, FIG. 2 shows two places of a right-angle bending point B1 and an acute-angle bending point B2 shown in FIGS. 1- (a), (b), and (c). A so-called U-shaped bending process is performed in which the steel sheet is bent at a right angle as shown in the A-A 'enlarged sectional view of b). In addition, the bottom forming part of this U-shaped bending mold is made into a drum shape with the middle part in the longitudinal direction at a middle height,
As shown in FIGS. 3- (a) and (b), the crosspiece is formed into a shape in which the center portion is curved in a middle-high bow shape. This is because the upper side of the bar, which will be described later, that is, the top of the right triangle is welded, so that the welded portion is contracted longitudinally by so-called shrinkage due to the welding, and both ends of the bar are bowed toward the top in an arc shape. The long side bar 1 shown in FIGS. 3- (a) and (b) corresponding to the warpage.
Of the short side bar 2 is 1 mm
However, in each case, the bar is curved in advance, and after welding, the bar is returned to a straight line by the longitudinal contraction. Finally, after the U-shaped bending process, the product bar is cut off from the connecting bar of the hoop material. Up to the above-described processing steps, the same processing is performed on each of the long side bar 1 and the short side bar 2 on a progressive pressing system.

After the U-shaped bending process is completed, the bar separated from the progressive feeding process, the long side bar 1 and the short side bar 2 are respectively
As secondary bending, the acute angle bending portion B2 shown in FIG. 2 is sharply bent by a single press working as shown in FIG. 4, and the bent end is brought into contact with the other end at the position of We1 in FIG. Then, it is formed into a right-angled triangular tubular crosspiece shown in FIGS. This acute angle bending can be easily bent because the inverted trapezoidal concave portion V is machined, and the outer radius Ro of the acute angle bent portion shown in FIG. be able to. Next, each of the long-side bar 1 and the short-side bar 2 that has been subjected to the acute angle bending process is welded to the welding point We1 shown in FIGS. 4 and 5A and 5B over the entire length of the bar. The side bar 1 and the short side bar 2 are completed at the stage of the bar. The welded bar is the top of a right-angled triangle and the welded portion We1, which is the upper side of the bar, contracts longitudinally due to so-called shrinkage due to welding. For each of the crossings 2,
Since the bending process with the curvature degrees α and β shown in FIGS. 3- (a) and (b) is performed, the bending is caused by the above-mentioned longitudinal shrinkage, so that the long side beam is the α and the short side beam is the β. Pulled back,
Each becomes straight, and the work of correcting warpage after welding can be omitted.

Lastly, after the welding process is completed, the four long-sided bars and two short-sided bars which are completed as the bars are assembled into a rectangular frame F shown in FIG. The frame FL is completed by welding four welding locations We2 on the entire circumference of the end face of the crosspiece, which are joints between both ends of the crosspiece and the corners of the frame FL.

[0013]

According to the first aspect of the present invention, the cross section of the right-angled triangular tubular frame is formed by bending from a plate material. The number of welding points can be reduced from four to eight, and the number of welding points can be reduced from eighteen to eight, and the length of the welding surface can be reduced by about 36% from about 2.500 mm to about 1.600 mm. This means that in terms of part processing, the number of molds is reduced because the number of types of parts is reduced, and it is possible to press the two types of parts up to the U-shape bending process in a progressive feed method, increasing efficiency. I can do it. In addition, in terms of assembling work, the number of assembly steps can be reduced by about 30% by reducing the length of the welding location and the welding surface and reducing the distortion correction work after welding.
In terms of quality control as well, by reducing the number of parts and the number of welded parts, automation of component processing and simplification of assembly work can be achieved, and quality uniformity and quality control costs can be reduced.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention.
(B) is an exploded view of each of the short sides, and (c) is
It is an AA 'expanded sectional view of (a) and (b).

FIG. 2 is a cross-sectional view of the embodiment, taken along line A- in FIGS. 3 (a) and 3 (b).
It is an A 'expanded sectional view and shows the state of U-shaped bending.

FIGS. 3A and 3B are front views of the embodiment after a U-shaped bend, showing a state in which the crosspiece is curved, where FIG. 3A is a long-side crosspiece and FIG. 3B is a short-side crosspiece.

FIG. 4 is an enlarged cross-sectional view of the same example taken along the line AA ′ in FIG. 5, showing a state of acute angle bending and a welding position.

FIG. 5 is a front view of the embodiment after an acute angle bending,
(A) is a long side bar, (b) is a short side bar.

FIG. 6 is a completed perspective view of the frame of the flat type shadow mask of the embodiment.

FIG. 7 is a perspective view of a frame component of a conventional example.

8A and 8B are perspective views of a reinforcing plate of a conventional example, in which FIG. 8A is a long-side reinforcing plate and FIG. 8B is a short-side reinforcing plate.

FIG. 9 is a completed perspective view of a frame of a conventional flat type shadow mask.

FIG. 10 is an enlarged cross-sectional view of the conventional example taken along line XX ′ of FIG. 9, showing a state in which a reinforcing plate is welded and joined.

[Explanation of symbols]

 1 Long-side bar 2 Short-side bar α Curvature of U-shaped bend of long-side bar β Curvature of U-shaped bend of short-side bar B1 Right-angled bending point B2 Acute-angled bending point FL frame Ro Bending outer radius of acute-angled part V Inverted trapezoidal recess Welding point at Welding end of Welding bar Welding point at Welding bar

Claims (1)

[Claims] 1. A method of manufacturing a flat type shadow mask frame for use in a flat type color cathode ray tube, wherein the cross section of a rectangular frame having four side cross sections is formed from a plate material into a tubular shape. A method for manufacturing a flat shadow mask frame.