CN101687247B - Coil component manufacturing method and coil component - Google Patents

Abstract

The present invention provides a method for manufacturing a coil component formed from tungsten wire, characterized by comprising the following steps: a winding step of winding the tungsten wire around a core rod; a first cutting step of cutting the tungsten wire after the winding step; an annealing step of heat-treating the coil in a reducing atmosphere while it is wound around the core rod; and a removal step of removing the core rod from the coil after the heat treatment. Furthermore, the second cutting step of cutting the coil component is preferably performed after the core rod removal step. With this configuration, a coil component for use in a directly heated cathode, for example, for a magnetron can be obtained with high dimensional accuracy.

Description

Coil component manufacturing method and coil component

technical field

The present invention relates to a coil component used in a direct-heating cathode (filament cathode) component for a magnetron, and a manufacturing method thereof, and particularly relates to a coil component capable of preventing disconnection of the coil component, having high shape precision, and greatly improving manufacturing yield Coil component and manufacturing method thereof.

Background technique

Conventionally, high-melting-point metal wires (wires) such as tungsten have been used as direct-heating cathode members for magnetrons. Magnetrons have been used in microwave ovens and the like, and have, for example, the structure described in JP-A-6-5197 (Patent Document 1). As described in Patent Document 1, the direct-heating cathode member for a magnetron is a coil member in which a refractory metal wire or the like is formed into a coil shape.

The tungsten wire before manufacturing the coil component is formed into a thin wire having a diameter of 1 mm or less, further 0.7 mm or less, by drawing a tungsten rod. In order not to break the wire during wire drawing, for example, in JP-A-11-86800 (Patent Document 2), a lubricant is applied to the wire to reduce the frictional force with the wire-drawing die. In this way, the current situation is that the tungsten wire is easily disconnected due to stress, so some kind of countermeasure must be taken.

In addition, to form a tungsten wire into a coil shape, as described in Patent Document 2, a winding method in which the wire is wound around a mandrel and formed into a helical shape is generally employed. In Patent Document 2, mass productivity of coil components is improved by mechanizing the above-mentioned winding process. As an example of the winding device used in the said winding process, the winding device described in Unexamined-Japanese-Patent No. 7-14558 (patent document 3) can be illustrated. That is, in Patent Document 3, a tungsten wire is supplied from a wire reel, wound around a mandrel, and wound, and the obtained coil is cut into a desired length to manufacture a coil component. It is reported that mass productivity can be greatly improved by adopting a winding device such as Patent Document 3.

However, in the coil components manufactured by the above-mentioned conventional manufacturing apparatus, the outer diameter of the manufactured coil components varies greatly, and there are defects such as large variation in characteristics for each product or batch, and unstable product quality. Furthermore, since the rigidity (elasticity) of the tungsten wire itself is strong, if the wire is simply wound around the mandrel, there is also a problem that the target shape cannot be obtained stably.

In addition, in order to improve this inconvenience, an experiment was conducted while applying a strong stress to the tungsten wire, but there was a problem that the tungsten wire was easily disconnected and the manufacturing yield of the coil component was likely to decrease.

Patent Document 1: Japanese Patent Application Laid-Open No. 6-5197

Patent Document 2: Japanese Patent Application Laid-Open No. 11-86800

Patent Document 3: Japanese Patent Application Laid-Open No. 7-14558

Contents of the invention

The present invention was made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a coil component and a manufacturing method thereof, which can suppress deviations in the shape of the coil and breakage of the tungsten wire in the manufacturing method of the coil component using a tungsten wire, The yield rate of the coil component can be greatly improved, and the deviation of the outer diameter of the coil component is reduced, and the characteristics are uniform.

In order to achieve the above object, the method for manufacturing a coil component of the present invention is a method for manufacturing a coil component formed of a tungsten wire, and is characterized in that it includes the following steps: a winding step of winding the tungsten wire around the mandrel; The first cutting process of cutting the tungsten wire after the process, the annealing process of heat-treating in a reducing atmosphere with the coil wound on the mandrel, and the extraction process of pulling out the mandrel from the coil after the heat treatment.

According to the above manufacturing method, since the tungsten wire is cut while being wound around the mandrel, and heat-treated in a reducing atmosphere while the coil is wound around the mandrel, the shape of the coil component can be maintained by the mandrel. , so that coil components with small deformation and high dimensional accuracy can be obtained.

Moreover, in the manufacturing method of the said coil component, it is preferable to perform the 2nd cutting process of cutting a coil component after the said extraction process. By continuously winding one tungsten wire to form a long coil component and then cutting it to a desired length (product length L), it is possible to efficiently manufacture a plurality of coil components with uniform dimensional accuracy.

Moreover, in the manufacturing method of the said coil component, it is preferable to set the wire diameter of the said tungsten wire to 1 mm or less. By setting the wire diameter of the wire to 1 mm or less, the rigidity of the wire is lowered, and processing into a coil is facilitated. In addition, the stress generated inside the wire can be reduced, and a coil component with less disconnection in the manufacturing process can be obtained.

Moreover, in the manufacturing method of the said coil component, it is preferable that the said tungsten wire contains 0.4-3 mass % of thorium in conversion of oxide (thorium oxide). By containing 0.4 to 3% by mass of thorium in terms of oxides, it is possible to obtain a tungsten wire that has high high-temperature strength due to ThO ₂ dispersion, is excellent in vibration resistance and electron emission, and is hardly deformed at high temperatures. When the content of the above-mentioned thorium oxide is less than 0.4% by mass, the improvement effect of the above-mentioned high-temperature strength is insufficient. On the other hand, if the content exceeds 3% by mass and becomes excessive, not only the effect of adding 3% by mass or more of Th cannot be obtained, In addition, Th is a cost-increasing factor because Th is a more expensive metal than W. Therefore, the content of thorium is set in the range of 0.4 to 3% by mass in terms of oxide. In particular, in order to achieve high high temperature deformation resistance and electron emission properties, it is preferable to set the content of ThO ₂ within the range of 0.8 to 1.8% by mass. In addition, in order to realize high vibration resistance, it is preferable to set the content of thorium oxide (ThO ₂ ) in the range of 0.6 to 0.8% by mass.

In addition, in the above method of manufacturing a coil component, it is preferable that the winding step includes a step of supplying the tungsten wire while applying a back tension (tension) of 3 kg/cm or more to the tungsten wire. By supplying the tungsten wire while applying a predetermined back tension to the tungsten wire, slack in the wire on the supply line can be eliminated, and the accuracy of the winding shape can be improved. When the above-mentioned back tension is less than 3 kg/cm, the effect of eliminating the slack of the above-mentioned yarn is not sufficient.

Moreover, in the manufacturing method of the said coil component, it is preferable that the said winding process includes the process of winding a tungsten wire around a mandrel at the rotational speed of 300-1000 rpm. If the above-mentioned rotation speed corresponding to the winding speed of the wire is lower than 300 rpm, the manufacturing efficiency of the coil component is low. On the other hand, if the above-mentioned rotation speed exceeds 1000 rpm, the stress acting on the tungsten wire is sometimes too large, and the wire is likely to be broken. Wire. Therefore, it is preferable to set the above-mentioned rotational speed in the range of 300 to 1000 rpm.

Moreover, in the manufacturing method of the said coil component, it is preferable that the ratio (D1/D2) of the outer diameter D1 of the said coil component and the outer diameter D2 of the said mandrel exists in the range of 1.2-1.5. When the outer diameter ratio ( D1 / D2 ) is less than 1.2, the wire diameter relative to the outer diameter D1 of the coil component is too small, and the wire is easily broken, and the shape retention of the coil component as a product is also reduced. On the other hand, if the outer diameter ratio ( D1 / D2 ) exceeds 1.5 and becomes too large, the variation in the finished dimension of the coil component increases although the disconnection decreases. In addition, the bending radius of the wire rod with respect to the mandrel is reduced, and cracks and the like are likely to occur in the wire rod due to bending.

Moreover, in the manufacturing method of the said coil component, it is preferable to include the process of heating the said tungsten wire before the said winding process.

The heating step is, for example, a step of heating the tungsten wire at a temperature of 800 to 1000° C. for about 1 to 10 minutes. By including this heating step, the ductility of the tungsten wire can be improved, and disconnection of the wire can be effectively prevented.

Moreover, in the manufacturing method of the said coil component, it is preferable to perform the process of heating the said tungsten wire with a combustion flame. Combustion flames can be easily formed by equipping a small burner, thereby preventing enlargement of the heating device.

In addition, in the above method of manufacturing a coil component, it is preferable that the combustion flame is a flame formed by burning a combustible gas. In addition, it is preferable that the combustible gas is a mixed gas mixed with the air. By changing the mixing ratio of combustible gas and air, the combustion temperature and combustion speed can be adjusted.

Moreover, in the manufacturing method of the said coil component, it is preferable that the reducing atmosphere for implementing the said annealing process is a hydrogen gas atmosphere. By adjusting to the hydrogen atmosphere, the oxidation of the coil components can be prevented, and the effect of eliminating deformation of the structure can be obtained. Furthermore, impurities such as carbon remaining on the surface can be reduced, and deterioration of the coil component due to impurities can be prevented.

In addition, in the above-mentioned manufacturing method of a coil component, it is preferable that the supply amount of the hydrogen gas into the atmosphere is 700 standard liters/hour or more. If the above-mentioned supply amount is less than 700 standard liters/hour, the above-mentioned anti-oxidation effect and the effect of eliminating deformation will be insufficient.

Moreover, in the manufacturing method of the said coil component, it is preferable that the heat treatment temperature in the said annealing process is 1000-1500 degreeC. The annealing step is a heat treatment for removing residual stress generated in the wound coil component, removing deformation of the structure, and stabilizing the shape of the coil component. When the heat treatment temperature is lower than 1000° C., the effects of removing residual stress, eliminating deformation, and stabilizing shape are insufficient. On the other hand, when the above heat treatment temperature exceeds 1500°C, the tungsten structure will recrystallize.

Moreover, in the manufacturing method of the said coil component, it is preferable that the heat treatment time in the said annealing process is 5 to 30 minutes. Within the range of the above heat treatment time, the above residual stress removing effect, deformation eliminating effect and shape stabilizing effect are sufficient.

In addition, in the above coil component manufacturing method, it is preferable that the second cutting step is a step of inserting a fixing jig into a hollow portion of the coil component, and cutting the coil component by moving a cutter in a direction perpendicular to the fixing jig. By inserting the fixing jig into the hollow portion of the coil component, the cutting portion can be effectively fixed, and by moving the cutter in a direction perpendicular to the fixing jig in this state, the coil component can be accurately cut. Since the cutting direction of the cutter is fixed, the cuts are the same, and the directionality at the time of installation will not be a problem.

Moreover, in the manufacturing method of the said coil component, it is preferable that the said coil component is a direct heating type cathode component for magnetrons. When the above-mentioned coil component is used for a direct-heating cathode component for a magnetron, excellent durability and shape stability can be exhibited.

The coil component of the present invention is a coil component manufactured by each of the above-mentioned manufacturing methods, and is a coil component formed of a tungsten wire having a wire diameter of 1 mm or less, and is characterized in that when the average outer diameter is defined as D1 (mm), the outer The diameter deviation is within the range of D1±0.1mm. That is, a coil component with high dimensional accuracy of the outer diameter can be obtained.

In addition, in the above-mentioned coil component, it is preferable that the wire diameter of the tungsten wire is 0.7 mm or less. In the present invention, the wire diameter of the tungsten wire constituting the coil component is set to be 1 mm or less. When the wire diameter exceeds 1 mm, the rigidity of the wire increases, making it difficult to form a coil shape. By making the wire diameter 0.7 mm or less, the rigidity of the material can be reduced, and it can be processed into a coil shape more easily.

In addition, in the above-mentioned coil component, it is more preferable that the deviation of the outer diameter is within the range of D1±0.05 mm from the viewpoint of improving shape accuracy.

Moreover, in the said coil component, it is preferable that the said tungsten wire contains 0.4-3 mass % of thorium in conversion of an oxide. By containing 0.4 to 3% by mass of thorium in terms of oxides, it is possible to obtain a tungsten wire having high high-temperature strength due to _ThO2 dispersion, excellent vibration resistance and electron emission, and hardly deformed at high temperature.

Moreover, in the said coil component, it is preferable that the length of the said coil component is 10 mm or more. As long as the length L of the coil component is 10 mm or more, the number of times of continuous winding can be increased, and the mass productivity of the coil component can be improved.

In addition, in the above-mentioned coil component, it is preferable that the coil component is a direct-heating cathode component for a magnetron. When the above-mentioned coil component is used for a direct-heating cathode component for a magnetron, excellent durability and shape stability can be exhibited.

In addition, in the above-mentioned coil component, it is preferable that the average aspect ratio of crystal grains in the surface portion of the tungsten wire is less than 3, and that the average aspect ratio of crystal grains in the center portion is 3 or more.

Here, the average aspect ratio of the crystal grains in the surface portion and the central portion of the tungsten wire was measured as follows. That is to say, as shown in Figure 8, from the tissue of the surface part and the central part of the tungsten wire, the enlarged photographs of the area with a unit area of 50 μm × 50 μm are taken respectively, and the length of the longest axis of each tungsten particle reflected here is defined as The major axis length (L1) is drawn vertically from the center point of the longest axis, and the length of the part where the vertical line is included in the particle is regarded as the minor axis length (S1), and is obtained by calculating the major axis length/minor axis length The aspect ratio of each particle. The average aspect ratio is the average value of the aspect ratios of all the particles contained in the above region.

As long as the average aspect ratio of the crystal grains in the surface portion of the tungsten wire is lower than 3, and the average aspect ratio of the crystal grains in the central portion is 3 or more, the occurrence of deformation of the tungsten wire accompanying bending can be effectively prevented and can be achieved. Reduce the outer diameter deviation of coil components.

Preferably, heat treatment is performed so that the average aspect ratio of crystal grains in the surface portion of the tungsten wire is less than 2 and the aspect ratio in the central portion is 5 or more, thereby reducing the variation in the outer diameter of the coil component.

In order to make the average aspect ratio of crystal grains in the surface portion of the tungsten wire less than 3 and the average aspect ratio of crystal grains in the center portion to be 3 or more, the following processes are required. That is, as the heat treatment conditions in the annealing step, the temperature may be set to 1000 to 1500° C. and the time may be set to 5 to 30 minutes. The aspect ratio between the surface portion and the central portion can be changed by performing short-time heat treatment for 30 minutes or less at a temperature at which effects such as residual stress removal, deformation elimination, and shape stabilization can be obtained. In other words, it is preferable to perform annealing treatment so that the average aspect ratio of the crystal grains in the surface portion and the central portion becomes a predetermined size.

In addition, in the above-mentioned coil component, it is preferable that the average grain size of the tungsten constituting the tungsten wire is 6 μm or less. By setting the average crystal grain size of the above-mentioned tungsten to 6 μm or less, the structural strength of the coil component can be improved and disconnection can be prevented.

Furthermore, regarding the above-mentioned average crystal grain size, as shown in the above-mentioned FIG. 8, enlarged photographs of regions with a unit area of 50 μm×50 μm were taken from the surface and central structures of the tungsten wire, and each of the areas shown here was The average value of the long axis length (L1) and the short axis length (S1) of the tungsten grain is calculated as the grain size ((long axis length + short axis length) ÷ 2 = grain size)). For tungsten wire This crystal grain size was obtained for one part of the surface part and one part of the center part, and was set as the average value of both.

According to the present invention, it is possible to greatly reduce the variation in the outer diameter of the coil component formed of the tungsten wire and the disconnection of the tungsten wire. Therefore, the manufacturing yield of coil components with high dimensional accuracy can be greatly improved. In addition, it is possible to provide a high-quality coil component with low variation in the outer diameter of the coil component and stable characteristics.

Description of drawings

FIG. 1 is a flow chart showing an example of the process sequence of the method for manufacturing a coil component of the present invention.

Fig. 2 is a front view showing a winding step of the method of manufacturing the coil component of the present invention.

Fig. 3 is a front view showing a specific example of a first cutting step in the method of manufacturing a coil component of the present invention.

Fig. 4 is a front view showing a state in which a long coil component is manufactured.

5 is a cross-sectional view showing a state in which a plurality of mandrels around which a coil component is wound are annealed at a time in a heat treatment furnace.

Fig. 6 is a front view showing the outer diameter of the coil component of the present invention with the mandrel removed.

Fig. 7 is a partial sectional view showing a second cutting step in the method of manufacturing the coil component of the present invention.

Fig. 8 is a structure diagram schematically showing the crystal structure of the tungsten wire used in the present invention.

Detailed ways

The method for manufacturing a coil component of the present invention is a method for manufacturing a coil component formed of a tungsten wire, and is characterized in that it includes the following steps: a winding step of winding the tungsten wire around the mandrel; cutting the tungsten wire after the winding step The first cutting process, the annealing process of heat-treating in a reducing atmosphere with the coil wound on the mandrel, and the extraction process of pulling out the mandrel from the coil after heat treatment.

Tungsten wire is a wire (wire) mainly composed of tungsten, and pure tungsten or tungsten alloy can also be used. Examples of tungsten alloys include W alloys containing thorium, W alloys containing rhenium, W alloys containing dopants such as Al, Si, and K, and the like. Among them, tungsten alloys containing thorium, because thorium oxide is a high melting point substance, can improve the mechanical properties at high temperature through its dispersion strengthening effect, strong resistance to high temperature deformation, and excellent electron emission, so it is suitable for use as a magnetron Directly heated cathode components.

In addition, it is preferable to add the above-mentioned thorium in the form of thorium oxide (ThO ₂ ), and it is preferable to contain 0.4 to 3% by mass of thorium in terms of oxide. If it is less than 0.4% by mass, the addition effect is low, and even if it is added in excess of 3% by mass, better effects cannot be obtained.

In addition, the wire diameter of the tungsten wire is not particularly limited, but is preferably 1 mm or less. If the wire diameter of the wire exceeds 1 mm, the rigidity is too strong, and it is difficult to process it into a coil shape. Considering the ease of processing the wire into a coil shape, the wire diameter is preferably 0.2 to 0.7 mm. It can also be less than 0.2mm, but if it is too thin, accidents of disconnection will increase.

FIG. 1 shows an example of the steps of the production method of the present invention. The steps are described below in order.

First, the winding process will be described. As shown in FIG. 2 , the winding step is a step of spirally winding the tungsten wire 1 around a mandrel 2 having an outer diameter D2 to form a long coil component 3 . The mandrel 2 is preferably made of a refractory metal such as tungsten or molybdenum.

For example, when manufacturing a coil part 3 for a direct-heating cathode part for a magnetron, if there is a deviation in the coil outer diameter D1 or the coil pitch (the gap between adjacent coils) P, the performance as a cathode may be produce deviations. If the performance of the cathode varies, the performance of the magnetron using it, and further, the performance of equipment such as a microwave oven will vary, and the specified performance may not be ensured. Therefore, in order to ensure stable performance, it is necessary to reduce dimensional variations such as the outer diameter of the coil and the winding width of the coil as much as possible.

On the other hand, the tungsten wire 1 is highly likely to be disconnected due to the method of operation. If the production process is interrupted many times, not only the production efficiency is likely to decrease, but also materials are wasted. Therefore, in order to improve the product yield and manufacturing efficiency of the coil component 3 , it is necessary to take dual measures of reducing the dimensional variation of the coil component 3 and reducing the disconnection of the tungsten wire 1 .

First, in the winding step, it is preferable to include a step of supplying the tungsten wire 1 while applying a back tension of 3 kg/cm or more when feeding the tungsten wire 1 around the mandrel 2 . The tungsten wire 1 is supplied in a state of being wound up on a reel portion such as a wire reel. If the tungsten wire 1 is loose at this time, the tungsten wire 1 cannot be stably supplied when it is wound spirally around the mandrel 2, and the winding state may not be constant.

Therefore, it is preferable to add back tension (tension) to the supplied tungsten wire 1 . The upper limit of the back tension depends on the wire diameter of the tungsten wire 1, but is preferably 7 kg/cm or less when the wire diameter is 1 mm or less. If the back tension is too large, the possibility of yarn breakage increases. A more preferable range of the back tension is 4 to 6 kg/cm.

In addition, when supplying the wire 1 and winding it around the mandrel 2, it is preferable to include a step of holding the front end of the wire 1 and rotating the rotating reel that winds the wire around the mandrel at a speed of 300°C. The tungsten wire 1 is wound around the mandrel 2 in a range of ~1000 rpm. If the above-mentioned rotation speed exceeds 1000 rpm, the load acting on the tungsten wire 1 increases, and the possibility of wire breakage increases. In addition, the pitch (winding pitch) P of the coil components 3 tends to vary. On the other hand, in the part where the rotation speed is slow, the possibility of thread breakage is low, but if it is too slow, the productivity will be poor. In particular, the tungsten wire 1 containing thorium has high strength and is not easy to break, so it can be wound relatively quickly at a relatively fast rotation speed of 700 to 900 rpm.

In addition, it is preferable that the ratio (D1/D2) of the outer diameter D1 of the coil component 3 to the outer diameter D2 of the mandrel 2 is in the range of 1.2 to 1.5.

Here, the outer diameter D1 of the coil component can be calculated by measuring the outer diameter of the coil component at arbitrary five places in the axial direction, and calculating it as an average value.

Since the tungsten wire 1 has strong rigidity as described above, it tends to return after the mandrel 2 is removed, so that the outer diameter of the coil tends to increase outward. Therefore, it is difficult to roughly match the outer diameter D1 of the final coil component with the outer diameter D2 of the mandrel 2 only by the difference in wire diameter. If the value is large, the possibility of disconnection increases.

However, by adjusting the ratio of the outer diameter D1 of the coil component 3 to the outer diameter D2 of the mandrel 2 (D1/D2) in the range of 1.2 to 1.5, wire breakage can be effectively prevented, and the return of the shape is also small. Therefore, the dimensional variation of the coil component 3 can be reduced. If the above (D1/D2) ratio is less than 1.2, the stress load on the tungsten wire 1 increases when it is wound on the mandrel 2, so the possibility of wire breakage increases. On the other hand, if the (D1/D2) ratio exceeds 1.5, although the possibility of disconnection decreases, the dimensional deviation of the formed coil component 3 increases. A more preferable range of (D1/D2) ratio is 1.3-1.4.

In addition, in order to effectively prevent a disconnection accident of the wire 1 in the winding step, it is preferable to include a step of preheating the tungsten wire. It is preferable to include a step of heating the tungsten wire 1 in the process of supplying the tungsten wire 1 to be wound around the mandrel 2 , that is, during feeding the wire from the wire reel to the vicinity of the mandrel 2 .

Various stresses act on the tungsten wire 1, such as the above-mentioned back tension (tension), the weight of the wire itself, and the stress at the time of winding. In order to prevent disconnection due to these stresses, it is preferable to heat the tungsten wire 1 in advance. The stress generated in the tungsten wire 1 can be relieved by heating and the ductility can be improved, making it difficult to break the wire.

In addition, it is preferable to perform the step of heating the tungsten wire 1 with a combustion flame. In addition, the combustion flame is preferably a flame formed by burning a hydrogen-containing gas or a combustible gas. In addition, it is preferable that the hydrogen-containing gas is a mixed gas of hydrogen gas and the air.

The ductility of the tungsten wire 1 can be improved by heating, so that disconnection can be prevented. In addition, by employing a combustion flame, it is possible to prevent an increase in the size of the heating device. In addition, by using a reducing gas such as hydrogen, the effect of removing impurities or eliminating deformation can also be obtained. In addition, since the purpose of this heating step is to prevent yarn breakage, a mixed gas in which hydrogen gas is mixed with air can also be used. Moreover, as a combustible gas, methane gas, ethane gas, and propane gas used for city gas, or these mixed gases, etc. are mentioned. In addition, if it is to prevent disconnection, even combustible gas can obtain sufficient effect.

As shown in FIG. 2 , after the tungsten wire 1 is wound around the mandrel 2 with a predetermined axial length (2L), a first cutting step of cutting the tungsten wire 1 is performed. The first cutting step is usually a step of cutting the tungsten wire 1 at the end point of the winding operation, but as shown in FIG. The fixing jigs 4 are attached to the cutting position of the coil component 3 , and cutting is performed by the cutter 5 reciprocating between the fixing jigs 4 . When the coil component 3 is a product, the cutting position is determined according to the required length L.

The length (winding length) of the coil component 3 formed by one winding operation depends on the length of the mandrel 2, but is preferably 300 mm or more, more preferably 400 mm or more. That is, as shown in FIG. 4 , it is preferable to form the long coil component 3 a by winding a tungsten wire around the outer periphery of the long mandrel 2 a. As long as the winding length obtained by one winding operation is long, productivity can be improved in proportion to the length.

In addition, the winding length in embodiment shown in FIG. 2 shows the example formed by length 2L which is twice the coil component length L required as a product.

After the above-mentioned first cutting step is performed, an annealing step is then performed in a state where the coil component 3 is wound around the mandrel 2 . That is, the annealing step of heat-treating in a reducing atmosphere is performed with the coil wound around the mandrel.

The specific process is: a tungsten wire is wound around the long mandrel 2a shown in FIG. The plates 6 are stacked on both ends of the mandrel 2a, and the obtained stack is put into a heat treatment furnace adjusted to a predetermined reducing atmosphere, and heat treated under predetermined conditions.

The reducing atmosphere in the above-mentioned annealing step is preferably a hydrogen atmosphere. In addition, it is preferable that the heat treatment temperature in the annealing step is 1000 to 1500° C., and the heat treatment time is 5 to 30 minutes.

As mentioned above, the tungsten wire returns in shape after being unloaded from the mandrel in the winding process due to its high rigidity. That is, the outer diameter of the final product is increased compared to when wound on a mandrel. In addition, residual stress acts on the wire due to the winding operation. Therefore, it is necessary to relieve residual stress and eliminate deformation by performing the above-mentioned annealing step.

If the coil component is directly incorporated into the magnetron without performing the above-mentioned heat treatment for eliminating deformation, deformation due to heat such as brazing during magnetron assembly increases, deteriorating the yield of the magnetron. In addition, there is a possibility of deformation due to heat when the magnetron is used.

In this embodiment, heat treatment (annealing treatment) is performed in a reducing atmosphere with the coil wound on the mandrel in order to reduce dimensional deviation and eliminate deformation caused by returning the coil component from the mandrel. .

As shown in Fig. 5, since the heat treatment is performed at the same time in the state where the coil component 3a is wound directly around the mandrel 2a, the heat treatment can be performed in a state in which the shape return and deformation of the coil are small, so that the variation in the size of the coil component can be reduced , and can improve the dimensional accuracy. In addition, the effect of eliminating deformation and the effect of reducing and removing impurities can also be obtained through a reducing atmosphere. In addition, surface discoloration of the silk can also be suppressed by performing annealing in a reducing atmosphere.

Hydrogen gas is preferable as a reducing atmosphere in the said annealing process. As long as it is hydrogen, impurities such as carbon adhering to the surface of the wire can be easily reduced and removed, and embrittlement of the tungsten wire caused by impurities can be prevented. In addition, it is preferable that the heat treatment temperature is 1000 to 1500°C. When the heat treatment temperature is lower than 1000°C, the effect of eliminating deformation is low, and even if it exceeds 1500°C, no better effect of eliminating deformation can be obtained. In addition, tungsten may recrystallize and deteriorate the characteristics.

In addition, the heat treatment time is preferably 5 to 30 minutes. If the heat treatment time is less than 5 minutes, the effect of eliminating deformation is insufficient, and if the heat treatment time is more than 30 minutes, no better effect can be obtained. Preferably at a temperature of 1050 to 1350° C. for 10 to 20 minutes.

In addition, it is preferable that the supply amount of hydrogen gas in the atmosphere of the annealing step is 700 standard liters (NL)/hour (H) or more. Reducing gases such as hydrogen can also exert the effect of removing impurities as described above. Therefore, it is preferable to circulate hydrogen gas through the heat treatment furnace in the annealing step, and maintain a state where hydrogen gas is in contact with the surface of the coil component. The upper limit of the supply amount of hydrogen gas is not particularly limited, but it is preferably 1700 standard liters/hour or less in consideration of the load on the supply device. More preferably, it is 900 to 1300 standard liters/hour.

In addition, in this embodiment, since the annealing treatment is performed in a state in which the coil member is wound around the mandrel, the handleability of the product is good. If the mandrel is removed before the annealing process, and a plurality of coil components are put into a single container for annealing treatment, the coil components are entangled with each other, and complicated work is required to take out the entangled coil components after annealing.

In contrast, in the present embodiment, as shown in FIG. 5 , since the annealing treatment is performed with the coil component 3a wound around the mandrel 2a, the coil components are not entangled. Therefore, the mandrel 2a wound with the coil member 3a can be arranged in the annealing container (heat treatment furnace) vertically and horizontally, and further in the height direction, and the processing amount that can be annealed at one time is increased, thereby greatly improving mass productivity.

Next, after the annealing heat treatment step is completed, a step of pulling out the mandrel is implemented.

FIG. 6 is a front view showing a state in which the mandrel 2 is removed from the coil component 3 through the first cutting step and the annealing step from the state shown in FIG. 2 . The winding length in the embodiment shown in FIG. 6 represents an example in which the length 2L is twice the length L of the coil component required as a product.

Moreover, you may perform the 2nd cutting process which cuts the obtained coil component 3 again as needed after a drawing process. When the coil component after the extraction step shown in FIG. 6 can be used as a direct-heated cathode for a magnetron, that is, when the winding length 2L is directly the product length, the second cutting step is not required.

On the other hand, as shown in FIG. 2 and FIG. 6, when the length of the coil member 3 necessary as a direct-heating cathode for a magnetron is specified as L, as long as the coil member wound on the mandrel 2 is When the length is doubled (2L) or more, mass productivity can be improved.

In addition, the above-mentioned second cutting step can be performed according to the cutting operation shown in FIG. 7 . That is, it is preferable to include a step of inserting the fixing jig 4a for fixing the cut portion of the coil component 3 into the hollow portion of the coil component 3, and cutting the cutting tool 5 by moving in a direction perpendicular to the fixing jig 4a. Coil part 3. After the fixing jig 4a is inserted into the hollow portion of the coil component 3 and the coil component 3 is fixed, the coil component 3 can be cut to a predetermined product length L by pressing the cutter 5 in a direction perpendicular to the fixing jig 4a. . As long as the cutting direction of the cutter 5 is fixed, the cuts of the coil components 3 can be made uniform. If the slits are the same, the directionality can be ignored when the magnetron is incorporated, so that the assembly manufacturability of the magnetron can be improved.

According to the manufacturing method of the coil component of this embodiment mentioned above, the variation of the average outer diameter D1 of a coil component can be controlled to D1±0.1 mm, and further can be controlled to D1±0.05 mm. For example, when the average outer diameter D1 of the coil component is set to 4 mm, the outer diameter D1 of the obtained coil component is within the range of 4±0.1 mm. In addition, disconnection accidents can be reduced. Therefore, when the initial input amount of tungsten wire is defined as 100, more than 90 can be made into a coil component, and a manufacturing yield of more than 90%, and furthermore, more than 95% can be achieved.

Moreover, you may implement the process of cleaning a coil component after a 2nd cutting process as needed. In addition, regarding the average outer diameter D1 of the coil component shown in FIG. 6, the average value can be calculated|required by measuring the diameter of the coil component 3 at arbitrary 5 places in the axial direction. In addition, the variation of the outer diameter of the coil component 3 can be compared with the average outer diameter D1 by selecting the maximum outer diameter and the minimum outer diameter of the coil component 3 .

Such a coil component is suitable as a directly heated cathode component for a magnetron. The size of the coil member used for the direct heating cathode for magnetron is not particularly limited, but when used for a magnetron for microwave oven, it is preferably 2 to 6 mm in outer diameter and 10 to 20 mm in length. In other words, the present invention is a manufacturing method excellent in mass productivity of a coil component having such a size.

According to the above-mentioned manufacturing method, even if a coil component having a coil length (L) of 10 mm or more is manufactured using a thin tungsten wire having a wire diameter of 1 mm or less, and furthermore, 0.7 mm or less, it is possible to provide control of outer diameter deviation with respect to the average outer diameter D1 A coil component with a small deviation in the outer diameter within the range of ±0.1 mm, further within the range of ±0.05 mm. In addition, although the upper limit of the length (L) of the coil component which is a final product is not specifically limited, It is preferable that the upper limit of the coil length is 50 mm or less, More preferably, it is 20 mm or less.

Next, specific embodiments of the present invention will be specifically described with reference to the following examples.

(Examples 1-4, Comparative Examples 1-3)

A tungsten wire (wire diameter: 0.5 mm) containing 1.0 mass % of thorium in terms of oxide was prepared. Using this tungsten wire, a coil member for a direct-heated cathode for a magnetron with an outer diameter of 4 mm and a length of 13 mm was produced by combining the following steps.

Then, the average grain size of the crystal grains of the tungsten wire constituting each coil component produced by each manufacturing method, the aspect ratio of the crystal grains at the surface part and the central part of the tungsten wire, and the deviation (dimensions) of the outer diameter of the coil component Accuracy) and product yield are measured.

In addition, the average grain size of the crystal grains of each tungsten wire and the aspect ratio of the crystal grains in the surface part and the central part of the tungsten wire were measured in the manner shown in FIG. 8 . In addition, the maximum value of the deviation of the outer diameter of the coil component from the outer diameter of the mandrel with an outer diameter of 4 mm was obtained as the deviation (dimensional accuracy) of the outer diameter of the coil component, and the total weight of the obtained coil component and the input weight were obtained. The ratio of the weight of the tungsten wire (the total weight of the obtained coil component/the total weight of the charged tungsten wire) was taken as the product yield.

The process for forming the coil component is as follows.

Step A1: The tungsten wire was supplied from the wire reel to the vicinity of the mandrel while applying a back tension of 4.5 kg/cm.

Step A2: When feeding the tungsten wire while applying a back tension of 4.5 kg/cm from the wire reel to the vicinity of the mandrel, there is a step of heating the tungsten wire with a combustion flame using a mixed gas of hydrogen and air.

Step A3: Feed the tungsten wire from the wire reel to the vicinity of the mandrel without applying back tension.

Step B1: A tungsten wire was wound around a mandrel (outer diameter: 2.9 mm×length: 200 mm) at a rotational speed of 800 rpm.

Step B2: A tungsten wire was wound around a mandrel (outer diameter: 2.9 mm×length: 200 mm) at a rotational speed of 1300 rpm.

Step C1: Winding is performed until the length of the coil component reaches 130 mm, and then a cutting step is performed. In addition, the winding is adjusted so that the pitch P becomes 1.1 to 1.2 mm.

Step D1: 40 mandrels wound with coils were placed in an annealing container, the supply rate of hydrogen gas was set at 1000 standard liters/hour, and annealing was performed at a heat treatment temperature of 1300° C. for 15 minutes.

Step D2: No annealing treatment is performed.

Step D3: 40 mandrels in a coil-wound state were placed in an annealing vessel (heat treatment furnace), and annealed at 1300° C. for 15 minutes in the air.

Step E1: pulling out the mandrel.

Step F1: A fixing jig was inserted into the hollow portion of the coil component, and the coil component was cut by moving the cutter in a direction perpendicular to the fixing jig to obtain a coil component having a length of 13 mm.

Example 1: Process A1 → Process B1 → Process C1 → Process D1 → Process E1 → Process F1

Example 2: Process A2 → Process B1 → Process C1 → Process D1 → Process E1 → Process F1

Example 3: Process A3 → Process B1 → Process C1 → Process D1 → Process E1 → Process F1

Example 4: Process A1 → Process B2 → Process C1 → Process D1 → Process E1 → Process F1

Comparative Example 1: Process A1→Process B1→Process C1→Process D2→Process E1→Process F1

Comparative example 2: Process A3→process B1→process C1→process D2→process E1→process F1

Comparative Example 3: Process A1→Process B1→Process C1→Process D3→Process E1→Process F1

The characteristics of the coil components of the respective examples and comparative examples manufactured through the combination of the above steps were measured, and the results shown below were obtained.

Table 1

As clearly shown in the results shown in Table 1 above, the dimensional accuracy of the coil components obtained by the manufacturing method of this example was all within the range of ±0.1, and high dimensional accuracy was obtained. In addition, by comparing Example 1 with Example 3, it was found that when the yarn is wound while applying back tension, there are few broken wires and the yield is improved. In addition, from the comparison of Example 1 and Example 2, it is known that Example 2 in which the wire is heated by a combustion flame has less disconnection and improved yield. In addition, as in Example 4, when the rotational speed (winding speed) exceeds 1000 rpm, the number of disconnections increases and the yield decreases.

In addition, it is clear from the comparison of Example 1 and Comparative Example 1 that the dimensional accuracy of the coil component can be greatly improved by performing annealing in a reducing atmosphere.

In addition, regarding the yields in Comparative Examples 1 to 3, those that can be used as coil components are all counted as good products. However, when the allowable range of dimensional accuracy is specified as ±0.1mm, the yield drops significantly. The finished product of Comparative Example 1 The yield was 0.70, the yield of Comparative Example 2 was 0.54, and the yield of Comparative Example 3 was 0.55.

(Embodiments 5-7)

Coil components of Examples 5 to 7 were manufactured by combining the following steps.

Step B3: A tungsten wire was wound around a mandrel (outer diameter: 2.9 mm×length: 200 mm) at a rotational speed of 500 rpm.

Step B4: A tungsten wire was wound around a mandrel (outer diameter: 2.2 mm×length: 200 mm) at a rotational speed of 800 rpm.

Step D4: Make 40 mandrels with coils wound on them, put them in an annealing container, set the supply rate of hydrogen gas at 1000 standard liters/hour, and perform annealing treatment at a heat treatment temperature of 1200°C for 20 minutes .

Example 5: Process A2 → Process B3 → Process C1 → Process D1 → Process E1 → Process F1

Example 6: Process A2 → Process B4 → Process C1 → Process D1 → Process E1 → Process F1

Example 7: Process A2 → Process B1 → Process C1 → Process D4 → Process E1 → Process F1

The characteristics of the coil components of the respective examples manufactured through the combination of the above steps were measured, and the results shown below were obtained.

Table 2

As clearly shown in the results shown in Table 2 above, Example 5 and Example 7 produced by the production method in which the ratio of the outer diameter of the coil component to the outer diameter of the mandrel is within the preferred range of the present invention has excellent performance in both dimensional accuracy and yield. get good results.

On the other hand, as in Example 6, when the ratio (coil component outer diameter/mandrel outer diameter) exceeds the preferable range, the dimensional accuracy decreases.

(Embodiments 8-9)

The coil component of Example 8 was manufactured by the same manufacturing process as Example 2 except having set the outer diameter D1 of a coil component to 5.0 mm, and the outer diameter D2 of a mandrel to 3.8 mm. On the other hand, except that the outer diameter D1 of the coil component was set to 3.5 mm and the outer diameter D2 of the mandrel was set to 2.7 mm, the same manufacturing process as in Example 2 was performed to produce the coil component of Example 9. The same characteristic measurement was performed on each of the obtained coil components, and the results shown in Table 3 below were obtained.

table 3

As clearly shown by the results shown in Table 3 above, it was found that good dimensional accuracy and yield were obtained in the coil components of the respective examples even when the outer diameter of the coil components was changed.

(Examples 10-11)

Next, except that the tungsten wire was changed to a wire (wire diameter: 0.7 mm) containing 0.5% by mass of thorium in terms of oxide, the same process as in Example 2 was carried out to produce a coil component of Example 10. In addition, the coil component of Example 11 was manufactured by the same manufacturing process as Example 2 except having changed tungsten wire into the wire (wire diameter 0.3 mm) containing 2.0 mass % of thorium in terms of oxide. The same characteristic measurement was performed on each of the obtained coil components, and the results shown in Table 4 below were obtained.

Table 4

As clearly shown by the results shown in Table 4 above, it was found that good dimensional accuracy and yield were obtained in the coil components of the respective examples even when the wire diameter of the tungsten wire or the thorium content were changed.

(Example 12-16)

The coil components of Examples 12 to 16 were manufactured by adopting the manufacturing process of Example 1 or Example 2, and changing the length (L) of the coil component as shown in Table 5. Furthermore, in Example 15 and Example 16, city gas (combustible gas mainly composed of methane gas) was used as the mixed gas for the combustion flame used in step A2. The same characteristic measurement was performed on each of the obtained coil components, and the results shown in Table 5 below were obtained.

table 5

As clearly shown by the results shown in Table 5 above, it was found that coil components with high dimensional accuracy (small variation in outer diameter) and high yield could be obtained even if the length of the coil component was changed.

(Example 17, 18)

Except having changed the process D1 into the following process D5 and process D6, the coil component was manufactured in the same process as Example 1, and the same measurement was performed.

Step D5: 40 mandrels with coils wound thereon were placed in an annealing container, the supply rate of hydrogen gas was set at 1000 standard liters/hour, and annealing was performed at a heat treatment temperature of 1700° C. for 30 minutes.

Step D6: 40 mandrels with coils wound thereon were placed in an annealing container, the supply rate of hydrogen gas was set at 1000 standard liters/hour, and annealing was performed at a heat treatment temperature of 1500° C. for 100 minutes.

Example 17: Process A1 → Process B1 → Process C1 → Process D5 → Process E1 → Process F1

Example 18: Process A1 → Process B1 → Process C1 → Process D6 → Process E1 → Process F1

Table 6

As clearly shown by the results shown in Table 6 above, it was found that when the preferred manufacturing conditions were not satisfied as in Examples 17 and 18, the growth of tungsten crystal grains was large and the variation in shape was large.

According to the present invention, it is possible to greatly reduce the deviation in the outer diameter of the coil component formed of the tungsten wire and the disconnection of the tungsten wire. Therefore, the manufacturing yield of coil components with high dimensional accuracy can be greatly improved. In addition, it is possible to provide a high-quality coil component with reduced variation in the outer diameter of the coil component and stable characteristics.

Claims (22)

1. A manufacturing method of a coil component formed by tungsten wire, characterized in that, possesses the following steps: The winding process of winding the tungsten wire around the mandrel; The first cutting process of cutting the tungsten wire after the winding process; An annealing process in which a coil is wound on a mandrel and heat-treated in a reducing atmosphere; The process of pulling out the mandrel from the coil after heat treatment, The winding step includes a step of supplying the tungsten wire while applying a back tension of 3 kg/cm or more to the tungsten wire, and a step of winding the tungsten wire around the mandrel at a rotational speed of 300 to 1000 rpm, The ratio D1/D2 of the outer diameter D1 of the coil component to the outer diameter D2 of the mandrel is within a range of 1.2 to 1.5. 2. The method for manufacturing a coil component according to claim 1, wherein a second cutting step of cutting the coil component is performed after the drawing step. 3. The method for manufacturing a coil component according to claim 1 or 2, wherein the wire diameter of the tungsten wire is set to be 1 mm or less. 4. The method for manufacturing a coil component according to claim 1 or 2, wherein the tungsten wire contains 0.4 to 3% by mass of thorium in terms of oxide. 5. The method for manufacturing a coil component according to claim 1 or 2, further comprising a step of heating the tungsten wire before the winding step. 6. The method for manufacturing a coil component according to claim 5, wherein the step of heating the tungsten wire is performed with a combustion flame. 7. The method of manufacturing a coil component according to claim 6, wherein the combustion flame is a flame formed by burning a combustible gas. 8. The method of manufacturing a coil component according to claim 7, wherein the combustible gas is a mixed gas mixed with the air. 9. The method for manufacturing a coil component according to claim 1 or 2, wherein the reducing atmosphere for performing the annealing step is a hydrogen atmosphere. 10 . The method for manufacturing a coil component according to claim 9 , wherein the supply rate of the hydrogen gas into the atmosphere is 700 standard liters/hour or more. 11 . 11. The method for manufacturing a coil component according to claim 1 or 2, wherein the heat treatment temperature in the annealing step is 1000-1500°C. 12. The method for manufacturing a coil component according to claim 1 or 2, wherein the heat treatment time in the annealing step is 5 to 30 minutes. 13. The method for manufacturing a coil component according to claim 2, wherein in the second cutting step, a fixing jig is inserted into the hollow portion of the coil component, and the cutting tool is oriented in a direction perpendicular to the fixing jig. The process of moving and cutting coil parts. 14. The manufacturing method of a coil component according to claim 1 or 2, wherein the coil component is a direct-heating cathode component for a magnetron. 15. A coil component formed by a tungsten wire with a wire diameter of 1 mm or less, characterized in that: the coil component is obtained by the method for manufacturing a coil component according to claim 1, and when the average outer diameter is defined as D1, the outer diameter The deviation is within the range of D1±0.1mm, where the unit of D1 is mm. 16. The coil component according to claim 15, wherein the diameter of the tungsten wire is less than 0.7mm. 17. The coil component according to claim 15 or 16, characterized in that: the deviation of the outer diameter is within the range of D1±0.05mm. 18. The coil component according to claim 15 or 16, wherein the tungsten wire contains 0.4 to 3% by mass of thorium in terms of oxide. 19. The coil component according to claim 15 or 16, characterized in that the length of the coil component is more than 10 mm. 20. The coil component according to claim 15 or 16, characterized in that the coil component is a direct-heating cathode component for a magnetron. 21. The coil component according to claim 15 or 16, wherein the average aspect ratio of the crystal grains in the surface portion of the tungsten wire is less than 3, and the average aspect ratio of the crystal grains in the central portion is 3 or more. 22. The coil component according to claim 21, wherein the tungsten constituting the tungsten wire has an average grain size of 6 μm or less.

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