KR19990020606A - Grid and Grid Holder Bonding Method for Microwave Oscillation Tube - Google Patents

Abstract

The present invention relates to a method for joining a grid and a grid holder of a microwave oven tube for microwave oven, and includes a joining step of the first grid 134 and the grid holder 138 and a cooling step after joining. The first grid 134 uses a sheet of 53 wt% molybdenum and 47 wt% rhenium alloy, its coefficient of linear expansion is 64 × 10 ⁻⁷ at 600 ° C., and the grid holder 138 is 100 wt% molybdenum Since the linear expansion coefficient is 52 × 10 ⁻⁷ at 600 ° C., it is preferable that the first grid 134 has a larger coefficient of linear expansion than the grid holder 138. The grid 134 and the grid holder 138 are bonded by holding the bonding agent 200 of molybdenum and nickel alloy powder for about 1-2 minutes at about 1370 ℃ under hydrogen atmosphere. Subsequently, if the junction of the grid 134 and the grid holder 138 is cooled to room temperature, the grid 134 is further contracted because the coefficient of linear expansion is larger than that of the grid holder 138, so that the grid 134 and the grid holder 138 ) Maintains a tight relationship.

According to the present invention, since the assembly is completed in a state where the tension force is applied between the grid and the grid holder, the assembly temperature is always maintained at room temperature, and even though the ultra-high frequency oscillation tube operates, the operating temperature of the grid portion is about 1000 ° C. or less. Therefore, the thermal deformation of the grid does not occur.

Description

Joining method of grid and grid holder of microwave oven for microwave oven

The present invention relates to an ultra-high frequency oscillation tube for a microwave oven, and more particularly, to a method of joining a grid and a grid holder capable of maintaining flatness of the grid when the grid and a grid holder are joined.

As is well known, magnetron is employed as a microwave oven for microwaves. However, such a conventional magnetron for a microwave oven requires a high voltage transformer and a high pressure diode according to a high pressure driving, and thus, there is a problem in safety, and a magnet is needed because it adopts a resonance method by electromagnetic movement in an electromagnetic field. There was a problem that the weight is heavy and the manufacturing cost is high.

To solve this problem, Klystron disclosed in U.S. Patent No. 5,541,391 is used as an ultra-high frequency oscillation tube, but the microwave oven employing such Klystron still applies high voltage of DC 4KV, so the input terminal is a separate insulation member. Since the product must be insulated from the main body, the product is heavy and the manner of movement of electrons is complicated, the cooling structure must be complicated, the structure having a large number of cavities, the electron beam focusing structure is required, and a magnet is required. Since it was necessary, the structure had a complicated disadvantage.

Accordingly, the present applicant proposed in Korean Patent Application No. 97-36327, a microwave microwave oscillation tube with a simple structure, which can eliminate the risk of high voltage and achieve light weight. As shown in FIG. 1, the microwave oscillation tube has a power input 110, a heater 120, an input cavity 130, and an output in a filter box 105 having a cover 104 covered therein. The cavity 140 and the feedback rod 160 are provided, and the antenna 150 in the anode 146 is installed in the bracket 102. The interior of the filter box 105 and the antenna 150 portion of the anode 146 maintain a vacuum. This bracket 102 is the same as that used for a conventional microwave magnetron.

In addition, the ultra-high frequency oscillation tube 100 emits hot electrons in such a manner that the cathode 132, which is an electron radiator, is indirectly heated by the heat of the heater 120 composed of an annular filament as a heat generating means. That is, when the cathode 132 mounted on the upper surface of the heater 120 is heated to about 600-1200 ° C. by the heat of the heater 120, the electrons are emitted.

The input cavity 130 is a space surrounded by the cathode 132, the first grid 134, and the choke structure 136, and the cathode 132 is a ring-shaped disk having a hole formed in the center thereof. The first grid 134 arranged at a predetermined interval on the upper side of the N th) is applied with a bias voltage to control and focus electrons emitted from the cathode 132 to the input cavity 130. At this time, the first grid 134 and the cathode 132 is electrically insulated, that is, the direct current must be shielded, the surface current forming the microwave inside the input cavity 130 must be energized, so choke for this purpose The structure 136 is arranged between the cathode 132 and the first grid 134.

The output cavity 140 arranged on the upper portion of the input cavity 130 is installed to face the upper portion of the first grid 134 of the input cavity 130 so that surface current is increased while electrons passing through the first grid 134 pass. A space surrounded by the induced second grid 142 and the anode 146 having protrusions 144 protruding downward from the bottom surface, in which the electrons focused on the input cavity 130 are densely modulated and thus, the first grid. Accelerated by the potential difference between 134 and the second grid 142, the microwave is formed by the surface current induced in the second grid 142. The anode 146 that dissipates the slowed-down electron beam is also stacked with a plurality of cooling fins 148 to radiate heat.

The first and second grids 134 and 142 are made of metal and are identical to each other in the shape corresponding to the cathode 132, and slot-shaped rectangular openings 170 are formed along the circumferential direction with respect to the holes therein. The predetermined gap is maintained by the ceramic pins 172 provided between the choke structure 136 and the output cavity 140.

The electrons focused on the input cavity 130 are densely modulated by the automatic shielding function of the bias power of the first grid 134 to pass through the first grid 134, and at this time, the input / output cavities 130 and 140 insulated from each other. When the operating voltage is applied, the potential difference is generated therebetween, and electrons passing through the first grid 134 are accelerated to pass through the second grid 142, so that surface current is generated in the output cavity 140. Induced. As a result, microwaves are formed in the output cavity 140, and the formed microwaves penetrate through the center of the anode 146 and are radiated through the antenna 150 formed in the output cavity 140. For this purpose, the coupling end 152 of the antenna 150 is located in the output cavity 140. The antenna ceramic 154 and the antenna cap 156 connected to the upper portion of the antenna 150 have the same structure as a conventional marknetron.

In addition, the ultra-high frequency oscillation tube 100 is provided with a feedback rod 160 to feed back a portion of the microwave formed in the output cavity 140 to the input cavity 140 in the center between the input and output cavities (130, 140) Amplifies and resonates microwave power.

In the conventional microwave microwave tube for the microwave, the grid serves to focus the electron cloud, and also to generate a high frequency current when passing through the electron, and eventually to generate a high frequency output. Since it is essential to maintain the gap between the grids, between the first grid and the second grid, between the second grid and the anode, and to prevent deformation during operation, the holder is used to fix and maintain the gap. Typically, the grid is made of 1mm Mo: Molybdenum Re: Rhenium alloy sheet or other materials with high thermal strain and low thermal expansion coefficient, while the holder material has a grid and thermal expansion coefficient Since it is used as another material, it is difficult to maintain the flatness of the grid when joining the grid and the holder, there is a problem that the thermal deformation occurs in the grid portion during high temperature operation.

Therefore, the present invention has been devised accordingly, and its object is to make the coefficient of linear expansion of the grid larger than the coefficient of linear expansion of the holder, but the tension between the holder and the grid is improved by using the point that the operating temperature of the grid portion is 1000 ° C or less. The present invention provides a method for joining a grid and a grid holder of a microwave oven tube for microwave oven that can be bonded in a working state and maintain the flatness of the grid during a high temperature operation.

The grid and grid holder joining method of the present invention for achieving this purpose is that the grid uses a sheet of molybdenum and rhenium alloy so that the coefficient of linear expansion of the grid is greater than the coefficient of linear expansion of the grid holder, the grid holder uses molybdenum Bonding the grid to the grid holder by holding a bonding agent of molybdenum and nickel alloy powder at about 1370 ° C. under a hydrogen atmosphere for about 1-2 minutes between the grid and the grid holder. And cooling the junction of the grid and the grid holder to shrink the grid.

According to the joining method of the grid and the grid holder of the present invention, since the coefficient of linear expansion of the grid is larger than the coefficient of linear expansion of the holder, the grid is joined in a slightly stretched state, and then the grid is further contracted by cooling. As a result, the assembly is completed in a state where the tension force is applied between the grid and the grid holder. Therefore, the assembly is maintained at room temperature at all times. Even though the ultra-high frequency oscillation tube operates, the operating temperature of the grid portion is about 1000 ° C. or lower, Heat deformation has the effect of not occurring.

1 is a schematic diagram showing a conventional ultra-high frequency oscillation tube for a microwave oven,

Figure 2 is a schematic diagram for explaining the bonding method of the grid and the grid holder of the microwave oven for microwave oven according to the present invention.

Explanation of symbols for main parts of the drawings

120: heater 130: input cavity

132: cathode 134: first grid

140: output cavity 142: second grid

146: anode 150: antenna

152: coupling end 160: feedback rod

Hereinafter, a method of joining a grid and a grid holder of a microwave microwave tube for a microwave oven according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings. For convenience of description, the same reference numerals are given to the same components as those in FIG. 1.

As shown in FIG. 2, the joining method of the grid and the grid holder of the present invention includes a joining step of the first grid 134 and the grid holder 138 and a cooling step after joining.

The first grid 134 uses a sheet of 53 wt% molybdenum and 47 wt% rhenium alloy, its coefficient of linear expansion is 64 × 10 ⁻⁷ at 600 ° C., and the grid holder 138 is 100 wt% molybdenum Since the linear expansion coefficient is 52 × 10 ⁻⁷ at 600 ° C., it is preferable that the first grid 134 has a larger coefficient of linear expansion than the grid holder 138.

The grid 134 and the grid holder 138 are bonded by holding the bonding agent 200 of molybdenum and nickel alloy powder for about 1-2 minutes at about 1370 ℃ under hydrogen atmosphere.

Subsequently, if the junction of the grid 134 and the grid holder 138 is cooled to room temperature, the grid 134 is further contracted because the coefficient of linear expansion is larger than that of the grid holder 138, so that the grid 134 and the grid holder 138 ) Maintain a tight relationship.

While maintaining this state at room temperature, when the ultra-high frequency oscillation tube operates, that is, the heater 120 is heated to 1200 ° C, the cathode 132 emits hot electrons at approximately 1050 ° C. In this case, since the temperature of the first grid 134 is 900 to 950 ° C., and the grid holder 138 is 700 to 750 ° C., the first grid 134 does not generate heat deformation, and between the cathode and the first grid. The gap between the first and second grids and between the second grid and the anode can be maintained normally.

As described above, the grid and the grid joining method of the microwave microwave oscillation tube of the present invention is completed in a state in which the tension force is applied between the grid and the grid holder, so that the state is always maintained at room temperature, and then the microwave oscillation Even if the tube is operated, the operating temperature of the grid portion is approximately 1000 ° C. or less, so that the thermal deformation of the grid does not occur.

Claims (4)

In the method of joining the grid and the grid holder of the microwave oven tube for microwave, The grid and the coefficient of linear expansion of the grid holder is larger than the coefficient of linear expansion of the grid holder, and between the grid and the grid holder is maintained for about 1 to 2 minutes at a high temperature in a hydrogen atmosphere by using a binder, the grid and the Joining the grid holders, Cooling the bonding of the grid and the grid holder shrinking the grid, characterized in that the grid and the grid holder bonding method of the microwave oven. The grid of claim 1, wherein the grid uses 53% by weight of molybdenum and 47% by weight of rhenium alloy, and the grid holder uses 100% by weight of molybdenum. How to join the grid holder. The method of claim 1, wherein the bonding agent comprises molybdenum and nickel alloy powders. The method of claim 1, wherein the joining temperature is about 1370 ° C.