DD292766A5 - METHOD AND DEVICE FOR FORMING A LAYER CUTTING TO MAKE A MASK FOR A CATHODE RAY TUBE AND MASK PRODUCED BY THIS METHOD FOR A CATHODE RAY TUBE - Google Patents

Abstract

The present invention includes a method for forming a sheet metal blank, in particular for producing a mask for a cathode ray tube on a press, after the edge portion of a sheet metal blank is held over a small width in a peripheral member, the central part of the sheet metal blank formed according to a certain rounding is, by the punch and the die are deformed under the action of an upper pressure plate on locally delimited zones of the tightening member is a mechanical action by the opposite elements of said tightening member are approached each other and the edge region of the sheet metal blank along the side walls of the punch or the die is simultaneously pressed and unrolled by relative movement of the tightening member with respect to the punch or the die to obtain the final fringe strip. The invention also includes a mask for a cathode ray tube manufactured by this method. Fig. 3 {method; Device; molding; Sheet metal blank; manufacture; Mask; Cathode ray tube; Press; Die; Tightening member; Stamp; Side walls; hems}

Description

For this 10 pages drawings

Application area for invention

This invention relates to a method and apparatus for forming a sheet metal blank, in particular for making a mask for a cathode ray tube.

The invention also relates to a mask produced by this method for a cathode ray tube.

Characteristic of the known state of the art

In a conventional method for forming a sheet metal blank, the sheet metal blank is held in its edge region and acted on its central part of the downward or upward movement of a punch, which gradually forms the sheet metal blank by folding over the edge region. In this method, the edge portion is drawn in from the outer edge in consideration of the reduction of the circumference while the central part expands. Consequently, in order to avoid wrinkling, it is necessary to increase the pressure under the blank holder, which results in an increase in the tensile force which must be exerted on the central part depending on the peripheral stresses and, consequently, the elongation of the metal in that part leads.

This is unacceptable for certain applications in which deformation by stretching can not be tolerated, especially in the case of extra-thin and / or perforated sheets, especially for masks of cathode ray tubes.

Namely, it is known that the masks for cathode ray tubes are made of an extra-thin sheet metal blank containing a grid of microholes in its central area.

To date, the masks for cathode ray tubes are made by a classical deep drawing operation of the central part with punch and die by the edge portion of the sheet metal blank is heated to an appropriate temperature to make the latter malleable and thus to favor its degree of deformation, the tensile stress in the central part is limited.

Disadvantage of the heating is, however, that while oxides are formed and that removal of the oxide layer and cooling in the central region of the sheet metal blank is required.

Incidentally, in order to take into account the elongation of the metal under the action of the punch during the deep drawing operation, it was necessary to give the microholes produced by a chemical attack method on the sheet blank a specific starting shape, so that the latter had the desired shape after the deep-drawing operation.

Object of the invention

The invention eliminates the disadvantages of the prior art.

Explanation of the essence of the invention

The object of the invention is to provide a cold running method for forming a sheet metal blank, which performs in a single operation, the rounding of the central region and the turning or pulling up the edge region of the sheet metal blank, without deforming the grid of perforations of the sheet metal blank.

The energy for the deformation of the edge region is therefore no longer of thermo-mechanical origin, but of mechanical origin.

The invention relates to a method for forming a Blechzsuchnittes, in particular for producing a mask for a cathode ray tube on a press, characterized in that:

is placed in a sheet metal blank between a deformable punch and a deformable die,

- The edge region of the sheet metal blank is held over a small width in a peripheral clamping device,

the central area of the sheet metal blank is clamped between the deformable punch and the deformable die,

- The central portion of the sheet metal blank is formed after a certain rounding by the punch and the die are deformed under the action of an upper pressure plate so that the center line of the sheet metal blank with respect to the neutral fiber of the unit punch and die brought into a specific position is, so that at least in limited areas of said sheet metal blank an adjustable, internal stress can be generated,

a mechanical action is exerted on limited areas of the tensioning element by bringing the opposing elements of said tensioning element closer to each other in order, on the free part of the sheet metal blank located between the plunger and the clamping device, to be controlled and applied to the peripheral area of the said machine Perform sheet metal blanks directional buckling, wherein thickness and circumference of said sheet metal blank are kept approximately constant,

- And that at the same time the edge portion of the sheet metal blank along the walls of the punch or the die is pressed and unrolled by relative movement of the clamping member with respect to the punch or on the die to obtain the final hem strip.

The invention also includes a device for forming a sheet metal blank, in particular to produce a mask for a cathode ray tube on a press containing a punch and a die, characterized in that the die and the punch are made of a deformable material and that they Clamping member for the edge of the sheet metal blank, means for mechanically acting on the clamping member in limited areas by the opposite elements of the clamping member are approached, means for relative movement of the clamping member with respect to the punch or the die, and additional means to the To control buckling and to roll off the edge portion of the sheet blank along the sidewalls of the punch or die to obtain the final hem strip.

The invention also includes a mask for a cathode ray tube made by the aforementioned method.

A preferred embodiment of the method according to the invention is characterized in that

- That the deformation of said free part is aligned during the buckling of the free part of the sheet metal blank.

Preferred embodiments of the device according to the invention are characterized in that

- That the Umfangseinspanneinrichtung the sheet metal blank has the shape of a frame,

in that the circumferential tensioning device consists of an upper clamping device, which is seated on the intermediate pressure plate, and a lower clamping device,

- That the lower clamping device at the level of its upper edge has an inclined surface,

the means for exerting a mechanical action on the tightening device are formed in limited areas of cams which are seated on the upper base plate,

- That the cams include a beveled bottom and a shoulder which is provided with a tapered surface which cooperates with the inclined surface of the clamping device,

- that the means for vertical movement of the tensioning device consist of guide cams which cooperate with cams and a frame which is arranged between said guide cams and said clamping device,

- That the guide cams are movable in a direction perpendicular to the direction of movement of the cam,

- That the guide cam on its upper wall have a sequence of several inclined surfaces of different orientation and inclination,

- That the frame is provided at the level of its outer peripheral edge with an inclined surface which has the same inclination as the inclined surface of the guide cam,

- That the additional means for controlling the buckling of the peripheral portion of the sheet metal blank consist of a deformable, running along the circumference profile,

- That the deformable circumferential profile consists of a resilient element, of which a first part presses against the unit punch-die and of which a second part presses against the clamping device,

- That the first part of the profile rests on a frame-shaped base,

- That the pad includes a vertical wall plate and a horizontal base plate, which is adjacent to an edge of said wall plate and forms a right angle with this,

- That the base plate has a bottom which is approximately as beveled as the inclined surface of the guide cam,

that the second part of the peripheral profile is supported on a printing device formed by a vertical plate whose lower end rests on the base plate of the base,

that springs are arranged between the wall plate of the base and the printing device,

- That it contains means to block the die at bottom dead center.

embodiment

The invention will be explained in more detail with reference to drawings, in which

FIG. 1 is a perspective view of a sheet metal blank from which a mask for a cathode ray tube is made,

FIG. 2 is a perspective view of a molded mask;

FIG. 3 is a sectional view of the device according to the invention,

FIG. 4 is a schematic perspective view of the clamping device of the edge region of the sheet metal blank and the means for aligning the buckling of the free part of said sheet metal blank;

Figures 5 to 11 are sectional views showing the successive stages of forming a mask.

FIG. 1 shows a sheet metal cut 1 of very small thickness, from which a mask for a cathode ray tube is produced. This sheet metal blank contains a central region 1 a, which is provided with a grid of micro-perforations, and an edge region 1 b, which is not perforated.

The mask produced after deformation consequently has its central region 1 a, which corresponds to the curved grid of microholes and their raised edge 1 b, as can be seen from FIG.

The device for forming shown in FIG. 3 for the production of a mask for a cathode ray tube comprises a lower support 10 on which a matrix base 11 rests. This Matrizenboden 11 is provided in its central region with a training 12.

About the die bottom 11, the device for forming a deformable die 13, which rests with ihi em edge region 14 on the die base.

The die 13 is connected by a rod 15 with a locking system 16, which consists for example of a cylinder.

The forming apparatus also includes a deformable punch 17 held by an intermediate plate 18, which in turn is supported by spacer posts 20 from an upper plate 19 which are slidably mounted in said upper plate. Compression springs 21 are arranged between the two pressure plates 18 and 19.

The die 13 and the punch 17 are made of deformable material, and the underside of the punch 17 may include at the edge a bead 22 intended to prevent slippage of the sheet metal blank na .Ji outside at the moment of forming.

On the other hand sit on the upper pressure plate 19 cams 23 which pass through the pressure plate 18 through the openings 24.

Each cam 23 has on its inside specific profiles 23a, 23b and 23c.

The vertical stroke of the intermediate pressure plate 18 and consequently of the punch 17 is limited by columns 25 which are arranged on the lower pressure plate 10.

The device for forming contains around the die 13 and around the punch 17 at the level of the parting plane of these two elements, a frame-like clamping device 30, which is intended to clamp the edge portion 1 b of the sheet metal blank 1 to a small width. This composite-material-made clamping device is formed by an upper clamping device 31 and by a lower clamping device 32 and has the shape of a frame, as shown in FIG.

The upper clamping device 31 is held by a plate 33 by means of the screws 34 which are arranged inside the elongated holes 35 which are provided in the upper clamping device 31, to allow a lateral displacement of said clamping device with respect to the plate 33. This plate 33 is from the intermediate pressure plate over

Distance columns 36 held, which were slidably mounted in this pressure plate. Compression springs 37 are arranged between the plate 33 and the intermediate pressure plate 18.

The upper clamping device 31 finally has a beveled side surface 31 a, which is intended to cooperate with the inclined surface 23 c of the cam 23 to a limited lateral areas, a mechanical side effect on the

Exercise clamping device 30. The lower clamping device 32 includes on the one hand guide rods 38, which are intended to penetrate into holes 39, the

are provided inside the upper clamping device 32, and on the other hand evenly on the outer periphery of

Clamping device 32 distributed metal pieces 40, which are intended to center the sheet metal blank 1 and openings 41 disappear in the upper clamping device 31 when the clamping device 30 is closed.

The lower clamping device 32 is supported by a frame 42 which rests on guide cam 43, which in turn are supported on the lower pressure plate 10. The frame 42 has a beveled outside 42 a.

Each guide cam 43 has at its top a first inclined surface 43 a, which is intended to cooperate with the inclined surface 23 a of the cam 23, a second inclined surface 43 b, which is intended with the chamfered surface 42 a of the frame 42nd and a third bevelled side 43c intended to cooperate with additional means 50 to control buckling, as will be seen later.

Springs 44 are disposed between the die bottom 11 and each Fünrungsnocke 43.

The complementary means for aligning the kink may be of a deformable, circumferential circumference

Metal blue 50 are formed, which is inserted between the die 13 and the lower clamping device 32 to align the buckling of the free portion 1 b of the sheet metal blank 1 uniformly and in one direction.

The metal blade 50 consists of a resilient rod, which is made of composite material, for example.

According to an embodiment illustrated in this application, a first portion 50a of the sheet 50 is supported on a frame-shaped holder 51 which surrounds the die bottom. The holder 51 includes a vertical wall plate 51 a, which contacts the outer wall of the Matrizenbodens 11, and a horizontal base plate 51 b, which borders on an edge of the wall plate, wherein it forms a right angle with this. The bottom 51 c is chamfered to the same slope as the inclined surface 43 c of the guide cam 43.

A second part 50 b of the metal strip 50 is supported on a pressure piece 52 which is formed by a vertical plate whose lower end rests on the base plate 51 b of the holder 51. Springs 53 are mounted between the wall plate 51 a and the plate 52 so that the genannton plates are held at a desired distance from each other and are based on the outer wall of the die bottom 11 and on the inner side wall of the lower clamping device 32.

In the illustrated embodiment, the metal strip 50 has been shown under the sheet metal blank 1, resulting in a lifting of the edge, but it is obvious that a symmetrical variant is conceivable in which the edge is bent by means of a metal strip, which is arranged above the sheet metal blank is and is making a downward movement.

The shaping of the cut-out sheet 1 takes place in the following manner.

First, the sheet metal blank 1 is placed on the die 13, that a small width of its edge region also on the

lower clamping device 32 rests within the bounded by the metal pieces 40 area.

Under the action of a plunger of the press, not shown, which acts on the upper pressure plate 19, the upper part of the device is lowered so far that the punch 17 is pressed against the sheet metal blank and closes the clamping device to the edge region of said sheet metal blank over a small Width between the clamping devices 31 and 32 (Figure 5) to hold. The guide rods 38 and the metal pieces 40 respectively penetrate into the holes 39 and 41 of the upper clamping devices 31.

Still under the action of the plunger of the press, the deformable punch 17 and the deformable die 13 are bent by means of the pressure plate 19 and 18, so as to form a desired rounding of the central part of the sheet metal blank 1.

This position is held by the cylinder 16 at the bottom dead center (Figure 6). The bead 22 prevents any slippage of the sheet metal blank.

Under the action of the compression spring 37 and the plate 33, the upper clamping device 31 to the lower clamping device

32, which is held by the frame 42 and the guide cam 43 in the desired position. Thus, the edge region of the sheet metal blank 1 is clamped.

During this stage of deformation of the central part, the mean real fiber of the sheet metal blank 1 is placed in such a position with respect to the neutral fiber of the whole, consisting of the punch 17 and the drawing ring 13, that at least in limited areas of said sheet metal blank, an inner, adjustable voltage can be generated, which serves to eliminate the possible stresses that can be caused by external phenomena, such as the thermal expansion and the vibrations, which can be caused by acoustic, magnetic and other phenomena.

Thus, by changing the position of the sheet metal blank with respect to the neutral fiber of the complex punch 17 die 13 can be generated at least in the limited areas of the sheet blank internal compressive or tensile stresses depending on the further intended use of the molded part.

Furthermore, the deformation with respect to the central fiber of the metal of which the sheet metal blank is made in order to achieve a homogeneous deformation and not to affect the accuracy of the microholes of the central portion of the sheet metal blank.

During this shaping step of the rounding, the upper part of the encircling metal strip 50 presses from below against the edge region 1b of the sheet metal blank 1b (FIG. 6).

At the end of this rounding stage, the controlled buckling of the free part 1 b of the sheet metal blank, which is located between the punch 17 of the clamping device 30 takes place.

While the intermediate pressure plate 18 is in abutment against the columns 25 and thereby the edge portion 1 b of the sheet metal blank 1 is held by the clamping device 30 under the action of the springs 37, a mechanical action is exerted on limited areas of the clamping devices 31 and 32 of the clamping member 30, which is illustrated by the arrows F1 (Figures 7 to 9).

This mechanical action is carried out by lowering the cam 23 by means of the upper pressure plate 19, so that the beveled surface 23 c mentioned cam contacts the inclined surface 31 a of the upper clamping device 31, whereby the opposite legs of the clamping device 30 are approximated (Figures 7 to 9 ).

In addition, this mechanical action on each opposite leg of the clamping device 30 with the result that with the help of the small pieces of metal 40, a thrust action on the edge region of the sheet metal blank is caused, which took place in comparison to the classical deep drawing process, which is due to the pulling action of the sheet metal blank located under the punch , is completely new.

Thus, the approach of the opposite legs of the clamping device 30 on the free part 1 b of the sheet metal blank 1 produces a controlled buckling. This directed buckling, which arises around the central fiber of the sheet metal blank, is effected in such a way that the deformation of the edge region of the sheet metal blank corresponds to a flow of the material, so that the thickness of the sheet blank and the circumference of the latter are kept approximately constant. In the course of this mechanical action on the clamping element 30, the opposite legs of the clamping devices 31 and 32 deform, as can be seen from FIG. The wheels of the sheet metal blank 1 are pressed by the metal pieces 40.

This mechanical action also causes a concurrent approach movement of the two parts 50a and 50b of the metal profile 50, which is illustrated by the arrows F2, and an upward movement of the tip of the metal profile 50, which is illustrated by the arrow F3 (FIGS. 7 and 8) ).

This combined upward and closing movement of the metal profile 50 has the alignment of the kink of the free part 1 b of the sheet metal blank 1 to the target, which is located between the die stamping die assembly and the clamping device 30. With the help of the plunger of the press, the downward movement of the upper pressure plate 19 and the cam 23 is continued, whereby the chamfered underside 23a of the cam contacts the inclined surface 43a of the guide cam. The tensioning device and the metal profile 50 are held by the side wall of the cam 23 in an approximate position, as shown in Figures 9 and 10.

The following phase of the method (Figures 10 and 11) consists in a rolling of the edge 1 b of the sheet metal blank 1 by translation in a simultaneous upward movement of the clamping device 30 and the metal profile 50 according to the arrows F4 and F5.

For this purpose, the downward movement of the upper pressure plate 19 and the cam 23 is continued.

The cams 23 transferred by means of the inclined surfaces 23a and 43a, a transverse movement on the guide cam 43 in contact with the springs 44. The transverse movement F6 of the guide cam 43 in turn causes an upward displacement F4 of the tensioning device 30 by means of the inclined surface 43 b of said guide cam and the tapered surface 42 a of the frame 42 and an upward movement F5 of the metal profile 50 on the inclined surface 43 c of the guide cam and the inclined surface 51 c of the holder 51st

The inclination of the inclined surface 43 b is larger than that of the inclined surface 43 c, to achieve a faster vertical displacement of the clamping device 30 than that of the metal profile 50.

During the last manufacturing phase of the edges, the end of the free edge 1 b of the cut-out plate 1 is brought against the side wall of the punch 17 by the upward movement of the metal profile 50.

For this purpose, the decline of the upper pressure plate 19 and the cam 23 is continued to the transverse movement of the

Continue guiding cam. The frame 42 slides over the inclined surface 43 b of the guide cam 43 away and reaches the top 43 d, which has the interruption of the upward movement of the clamping device result. In contrast, the metal profile 50 moves upward, so that the end of the free edge 1 b of the sheet metal blank 1 is pressed against the side wall of the punch 17 (Figure 11).

Thereafter, the upper pressure plate goes back up, which the opening of the device by the upward movement of the

Cam 23, the intermediate pressure plate 18, the punch 17 and the upper clamping device 31 result.

Under the action of the springs 44 and 53, the guide cam 43, the lower clamping device 32 and the metal profile 50 resume their initial position.

The cylinder 16 is further held at bottom dead center to prevent the re-rising of the die 13, which would result in a deformation of the shaped sheet metal blank 1.

Finally, the end of the edge of the sheet metal blank can be cut by a suitable device.

Claims (6)

-292 763 claims: A method for forming a sheet metal blank, in particular for the production of a mask for a cathode ray tube on a press, characterized in that: a sheet metal blank (1) is arranged between a deformable punch (17) and a deformable die (13), - The edge region of the sheet metal blank (1) over a small width in a Umfangsspanneinrichtung (30) was had, - The central portion of the sheet metal blank (1) between the deformable punch (17) and the deformable die (13) is clamped, - The central portion of the sheet metal blank (1) is formed after a certain rounding, wherein the punch (17) and the die (13) are deformed under the action of an upper pressure plate (19) so that the central fiber of the sheet blank (1) in a relative to the neutral fiber of the assembly punch (17) and die ( 13) is brought into a certain position, so that in limited areas of said sheet metal blank (1) an adjustable, internal tension can be generated, a mechanical effect is exerted on limited areas of the clamping device (30) by approximating the opposing elements of said clamping device to each other on the free part (1b) of the sheet metal blank (1) extending between the module die (17 ) -Matrize (13) and the tensioning device (30) is to perform a controlled buckling, which is directed by engine action on the edge region of the sheet metal blank (1), - The edge portion 1 b of the sheet metal blank (1) along the side walls of the punch (17) or the die (13) by a relative movement of the clamping device (30) relative to the punch (17) or on the die (13) pressed simultaneously and unrolled to get the final hemline. 2. The method according to claim 1, characterized in that the deformation of said free part during the buckling of the free part (1 b) of the sheet metal blank (1) is aligned. A device for forming a blank Blecnzuschnittes, in particular for the production of a mask for cathode ray tubes on a press containing a die and a punch, which is held by an upper pressure plate via an intermediate pressure plate, characterized in that the die (13) and the punch (17) is made of a deformable material and that it has a clamping device (30) for the edge of the sheet metal blank (1), means (23) for exerting a mechanical effect on the clamping device (30) in limited areas the opposite elements of the clamping device (30) are approximated to each other, means (23, 42,43) for the vertical movement of the clamping device (30) with respect to the assembly die (17) -Matrize (13) and additional means (50) for the Control the buckling and unroll the edge portion of the blank along the sidewalls of the punch (17) or die (13) to obtain the final sow to get striped. 4. Apparatus according to claim 3, characterized in that the Umfangseinspanneinrichtung (30) of the sheet metal blank (1) has the shape of a frame. 5. Device according to claims 3 and 4, characterized in that the Umfangsspanneinrichtung (30) consists of an upper clamping device (31) which sits on the intermediate pressure plate (18), and a lower clamping device (32). 6. Apparatus according to claim 5, characterized in that the lower clamping device (32) at the level of its upper edge has an inclined surface (31 c).