RU2142436C1 - Method of manufacture of glass rectangular frame for shell of vacuum luminescent instrument and device for its embodiment - Google Patents

Abstract

FIELD: manufacture of vacuum electronic devices, particularly, of vacuum luminescent indicators applicable in devices of data indication. SUBSTANCE: method includes application to four canes forming frame of low-melting solder glass layer with melting point of 370-390 C; fusing of solder glass; assembling of frame in assembling device - mandrel; soldering of canes into frame in conveyor furnace at temperature of 450-470 C and holding at this temperature for 20-25 min. Applied to canes is layer of solder glass after fusing 0.3-0.4 mm thick and with length exceeding thickness of contact of soldering by 30-50%. They are pressed in point of soldering with pressure of 0.20-0.25 kgf/sq. mm. Device for method embodiment has four canes, flat inclined base with two lateral and one longitudinal stops and spring-loaded stop. Device is provided with three removable plates and removable spring-loaded clamps. Flat external plates are made of glass with coefficient of thermal expansion close to that of cane glass. Internal plate is made of glass whose coefficient of thermal expansion exceeds that of canes and have depression or chamfers in their corners. EFFECT: reduced cost of frames. 2 cl, 3 dwg

Description

 The invention relates to the production of vacuum electronic devices, in particular to the production of vacuum fluorescent indicators used in information display devices.

 One of the main elements of a vacuum flat luminescent device is a glass shell, which is formed by fusing a glass anode plate with a flat glass cylinder (see the book by B.I. Gorfinkel and others. Low-voltage cathodoluminescent indicators. M., Radio and communication, 1983, p. 33, 34). Instead of a monolithic flat cylinder made by the method of molding due to a number of its ergonomic flaws (glare due to residual sphericity, distortion of information of signs, etc.), a shell consisting of two flat glasses - an anode plate and a cover sheet has found widespread use glass - and an intermediate glass rectangular frame. Almost all developments of new types of devices (domestic and foreign) use a prefabricated shell design using the specified intermediate frame (devices P-730, P-652, VI-3, P-782, P-806, etc.). The main technical requirements for the frame are: tightness around the perimeter, flatness, the presence of right angles from the outside and optimal radii inside, the absence of stresses in the glass. Right angles of the frame without radii from the outside provide greater strength of the device, since there are no cantilever ends at the corners of the joints of the frame with flat glasses, in addition, the appearance of the device improves.

 The inner radii in the corners reduce the internal stresses in the glass at the places of soldering, increase the strength of the frame and the cylinder during subsequent thermal operations and influences. The flatness of the frame is necessary for a sealed joint with both the anode plate and the cover glass with a minimum voltage difference at the junction points.

Several methods are known for forming glass frames and devices for their manufacture. So according to the Japanese application (see Japanese application N 3-75495, MKI ⁵ : C 03 B 23/06, 23/207, publ. 02.12.92) a method for manufacturing a glass gasket for a fluorescent indicator lamp, characterized in that the sheet glass cut into blanks with a thickness of 2.3 mm, a width of 4 mm and a length of 210 mm The sections of the workpiece - the staff to be bent, are softened by heating with the help of a heater and bent, giving it a closed shape - the shape of a frame, after which the ends of the workpiece are fused using a forming tool.

The method and device for its implementation have the disadvantage that accurate local heating of the bending points is required: with a simple single-seat heater, the bending places are heated sequentially. With simultaneous heating, the design of the heater is greatly complicated. A special soldering tool is required. Besides. the frame when bending the workpiece has large external radii (R _nar = r _in +, where R _nar is the outer radius of the frame, r _in is the inner radius of the frame, δ is the thickness of the workpiece). In places where the glass preform is bent, the preform material bulges, i.e. the flatness of the frame is violated, which is a source of internal stresses in the manufacture of the shell. This method also requires operations and a mechanism for bending the workpiece.

A similar method of manufacturing a glass frame according to Japanese application N 63-11287, MKI ⁵ : C 03 B 23/06 // C 03 B 23/207, publ. 03/14/88, in which the glass cylindrical rod in the areas of inflection is heated from the inside to a softening state and bent at an appropriate angle with external force.

 The disadvantages of this method are similar to the above.

To eliminate the disadvantage of buckling of material in places of bending in Japanese application N 3-66260, MKI ⁵ : C 03 B 23/06, publ. 10.16.91, on the method of forming a glass frame for a double-glazed window, pressing a curved section before curing with tools moving up and down perpendicular to the horizontal plane of the curved section is used to smooth the protrusion formed on the bending section.

 Obviously, all the other disadvantages listed above are not eliminated by this method. The device for making the frame is complicated by the introduction of a bonding mechanism.

There is also a method of joining glass parts by brazing at a temperature of about 500 ^o C using glass cement (see "Production of color picture tubes", under the editorship of VI Baranovsky, M., "Energy", 1978, p. 209 - 220). This method is used to obtain the tube shell by soldering a glass screen with a glass cone.

When implementing this method, a layer of glass cement - a slip of a thickness of about 1 mm, which is then dried for 0.4-1.0 hours, depending on the drying temperature, is applied to the end surface of the cone by extruding through the nozzle. After that, the cone and the screen are combined in a container, which is then placed in the furnace. The soldering cycle is carried out at a temperature of 500 ^o C. The duration of the cycle is up to 7.5 hours, depending on the dimensions of the devices and furnaces. Upon melting, the layer thickness decreases to 0.1 - 0.3 mm at a specific pressure on the slip (5 - 8 kPa).

 This method also has several disadvantages. It is very long and therefore energy intensive. The accuracy of applying ceramic cement by extruding through the nozzle by weight of the sealant is low, especially if it is necessary to apply small doses of material on small parts, which can lead to a large number of rejects when soldering, for example, an indicator frame consisting of 4 frames.

 A well-known more accurate method of applying layers of soldering sealing compounds to glass parts is the method of screen printing, which is widely used in the production of liquid crystal and vacuum fluorescent indicators in the operations of forming shells, cases.

An analogue of the claimed invention is a method and apparatus for manufacturing a rectangular frame of a vacuum luminescent indicator used in the production of technological documentation 486.004 MK. The method and device provide for the assembly of a frame of 4 workpieces-racks in the fixture, all of whose parts are made of graphite. In this device, the piles, laid in the form of a frame, are placed in a conveyor furnace, where at a temperature of 960 ^o C ± 10 ^o and an atmosphere of formgas (nitrogen + hydrogen), under the influence of the load, the piles are fused and a frame is formed. The flatness of the frame is provided by the plane of the graphite base on which the racks are placed, and the plane of the graphite cargo placed on the racks. The process in the furnace lasts 110 - 120 minutes.

 This method and device for its implementation have a number of significant drawbacks, first of all, this method is very energy intensive, since a high temperature is required for glass fusion, a reducing atmosphere in the furnace is required so that graphite devices are not destroyed. Since the heating and cooling process is carried out smoothly to eliminate the occurrence of stresses in the glass, it is very long. Despite this, the yield of the framework is low and amounts to no more than 5%. In addition, the cost of the graphite parts of the device is high, since the material is expensive and its processing is difficult. The method requires special safety measures, since hydrogen is present in the furnace. All this leads to high costs in the manufacture and high cost of the frame. After fusion of the staff, the frame, in case of detection of fusion defects, can not be disassembled and everything goes into marriage.

 The invention is as follows. The tasks to which the claimed invention is directed are to reduce the cost of the framework by reducing the cost of the process (reducing the temperature and duration of the heat process), eliminating the cost of a special gas environment in the furnace (eliminating forming gas), and saving costs on the manufacture of devices for assembly and fusion, increase the yield of the framework by improving the accuracy of the operation of joining the staffs into the frame and the regeneration of the rejected frames.

The specified technical result in the implementation of the invention is achieved by the fact that in the known method of manufacturing a rectangular glass frame for the shell of a vacuum luminescent device, consisting of four separate elements - racks, including applying to the racks by meshing a layer of fusible solder glass having a melting point of 370-390 ^o C , reflow solder glass frame assembly in the assembly apparatus - the mandrel of bars in the welding of the container frame in an oven at a temperature of 450 - 470 ^o C with resists at a temperature of 20–25 minutes, layers of solder glass are applied onto the racks, having a thickness of 0.3–0.4 mm after melting and a length greater than 30–50% of the width of the contact point of the razed joints, the brazed racks are pressed with force creating a pressure of 0.20 - 0.25 kgf / mm ² at the place of soldering.

The specified technical result in the implementation of the invention is achieved by the fact that the known device for the manufacture of a rectangular glass frame for the shell of a vacuum fluorescent device, consisting of four posts, containing a flat inclined base with two transverse and one longitudinal stops, as well as a spring-loaded clip, is additionally equipped with three removable flat spring loaded plates and removable clamps for receiving and compressing of bars in places soldering with a pressure of 0.20 - 0.25 kgf / mm ^2, wherein the melting point The outer outer plates are made of sheet glass with a temperature coefficient of linear expansion (TEC) close to that of the glass beads, and the inner plate is made of glass with TEC greater than the TECs of the bead glass and are provided with recesses or chamfers in the corners to avoid contact with soldering staffs.

As shown by experiments and the manufacture of pilot batches of frames from racks with sizes of 28.0 • 3.8 ^+0.1 • 2.3 mm and 142.0 • 3.8 ^+0.1 • 2.3 mm for the P-782 device when applying a layer of paste of solder glass having, after melting, the maximum thickness of the fused layer is 0.3 - 0.4 mm and when squeezing the racks with a force of 1.8 - 2.2 kgf, which corresponds to a joint area f _sp. = 3.9 • 2.3 = 9 mm ^{2, the} pressure in the seam is 0.2 - 0.246 kgf / mm ² , a durable tight joint of the posts without voids, bubbles, etc. defects is ensured.

 The length of the solder glass layer was 3 - 3.5 mm, which corresponds to a joint thickness of 2.3 mm 1.3: 1.5 of the width of the joint, i.e. large widths of the soldering place by 30 - 50%.

Soldering was carried out in the air of a conveyor furnace at a temperature of 460 ^o C ± 10 ^o , exposure at this temperature ranged for different parties from 20 to 25 minutes with a total cycle time of 70 - 75 minutes. Due to wetting and surface tension of the glass melt forces formed inside radius r in the compound _in = 0.7 - 1.0 mm.

 The manufacture and use of flat plates, upper and lower, made of glass with a thermal expansion coefficient close to the thermal expansion coefficient of the glass of the racks, reduces the likelihood of the racks being displaced, violating their initial position relative to each other during heating and cooling of the bag. The use of an inner plate, the glass of which has an expansion coefficient of thermal expansion more than the expansion coefficient of glass of glass, eliminates frame breaking during cooling, because in this case, the inner plate is compressed by a larger amount than the frame, a gap is formed between the frame and the inner plate and force interaction between the frame and the inner plate does not occur.

 The essence of the technical solution is illustrated by graphic materials and description.

 In FIG. 1 shows a General view of the frame, consisting of 4 racks - flat bars.

In FIG. 2 shows the racks, on the sides of the long racks - the place of application of enamel. Here in _w is the width of the staff; in _c - the length of the glass enamel layer, in _c = (1.3 - 1.5) b _w ; δ _c is the width of the glass enamel layer after reflow, δ _c = 0.3 - 0.4 mm.

 In FIG. 3 shows a schematic diagram of a device in plan without an upper plate and a removable clip compressing the upper and lower plates into a packet. The neckline shows the bottom plate with chamfers.

 In FIG. 4 is a side view of the device with fixed and compressed racks.

The frame (Fig. 1) consists of two longitudinal glass racks 1 and two transverse glass racks 2 of the same cross section, welded in four places with solder glass with an inner radius at the place of gluing "r _in ".

Longitudinal racks 1 (Fig. 2) are fed to the assembly with deposited and fused layers of solder glass 3. Glass is applied to the ends of the sides of the racks. The thickness of the layer after melting δ _c = 0.3 - 0.4 mm, the length of the layer in _c = (1.3 - 1.5) in _w , where in _w is the thickness of the staff.

 The device (Fig. 3, 4) for implementing the proposed method consists of the following elements: an inclined base 4, a transverse stop 5, two longitudinal stops 6 of a spring-loaded clip 7, a removable clip 8, removable flat plates 9, 10, 11, a removable clip 12.

 The method is carried out, and the device operates as follows.

With the clips 8 and 12 removed and with the clamp 7 removed, the lower plate 10 is placed on the inclined base, which is pressed against the stops 5 and 6 under its own weight, because the angle of inclination is greater than the angle of friction. Then on this plate is placed: the first longitudinal staff 1 with the applied layers inward until it contacts the stops 5 and 6; the first transverse head 2 before contact with the transverse stop 5 and the longitudinal head; place the inner plate 9 before contact with the placed transverse and longitudinal stakes; then - the second transverse strut 2 against the stop in the plate 9. After that, include a clamp 7, which compresses the transverse racks and the inner plate 9 to the abutment 5. Next, a second longitudinal rake with layers of solder glass inward to the stop in the transverse racks is installed. The top plate 11 is placed on top of the racks 11. A packet of glasses forms. After that, with the help of a spring-loaded clamp 12, one of the levers of which enters the slot of the base, the lower and upper plates are compressed, that is, the packet fixing the racks between these plates is compressed. Next, the racks using one or two clamps 8 are compressed with a given force. The package, including the racks placed and sandwiched between the plates together with the clamps, is removed and placed in a conveyor oven where, at a temperature of 460 ^° C ± 10 ^° , the racks are soldered into a frame. The total time of the heating process to 460 ^o C exposure at this temperature for 20 to 25 minutes and cooling to room temperature is 70 to 75 minutes.

The use of this method of manufacturing frames and a device for its implementation, as shown by the manufacture of pilot batches of frames for the device P-782, allows you to drastically - 2.5 - 3 times reduce the cost of the frames compared to the reflow method at a temperature of 960 ^o C ± 10 ^o per due to a significant reduction in energy costs, the manufacture of assembly and gluing devices described above, increasing the yield of up to 80% (depending on the batch) regeneration of frames in case of gluing defects. During regeneration, the frames are glued in nitric acid and, after washing the staffs, are again put into production. The strength of the frames increased due to a decrease in internal stresses in the corners of the frame, as when soldering, the length of the applied enamel layer ensures the formation of an inner radius of "r _in ".

 The base of the device, stops and clamps are made of ordinary structural steel, circuit clamps are made of heat-resistant steel type 12X18H9T or X25. Removable flat plates made of cheap flat glass. The heated mass of the bag (plates and racks) and clamps is much less than in the case of fusion racks in graphite mandrels. The spring-loaded removable clamps are made in the form of clips with flat springs, i.e. have a simple design and inexpensive to manufacture.

Claims (2)

1. A method of manufacturing a rectangular glass frame for the shell of a vacuum fluorescent device, consisting of four separate staff members, including applying to the staff method of meshing a layer of fusible solder glass having a melting point of 370 - 390 ^o C, melting the solder glass, assembling the frame in the assembly device -adjustment, soldering the beads in a frame in a conveyor oven at 450 - 470 ^o С with holding at this temperature for 20 - 25 minutes, characterized in that a layer of solder glass is applied to the beads after reflow with a thickness equal to 0.3 - 0.4 mm, and a length greater than 30 - 50% of the width of the contact point of the soldering beads, the brazed beads are compressed with a force that creates a pressure of 0.20 - 0.25 kgf / mm at the place of brazing ² . 2. A device for the manufacture of a rectangular glass frame for the shell of a vacuum luminescent device, consisting of four frames, containing a flat inclined base with two transverse and one longitudinal stops, as well as a spring-loaded clip, characterized in that it is additionally equipped with three removable flat plates and removable spring-loaded clamps for placement and compression of the racks in the places of brazing with a pressure of 0.20 - 0.25 kgf / mm ² , while the flat outer plates are made of sheet glass with a temperature with a linear expansion coefficient (TEC) close to the TEC of the glass of the piles, and the inner plate is made of TEC glass, exceeding the TEC of the glass of the piles, and are provided with recesses or chamfers in the corners.

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