JP4461880B2 - Bell-type atomizing head and manufacturing method thereof - Google Patents

Description

  The present invention relates to a bell type atomizing head constituting a bell type atomizer of an electrostatic coating apparatus.

2. Description of the Related Art Conventionally, for example, a bell-type atomizer including a bell-shaped bell-type atomizing head is disposed at a tip portion of an electrostatic coating apparatus used for coating an outer plate of an automobile. This bell-type atomizing head applies centrifugal force to the paint supplied to the inner periphery of the bell-type atomizing head, and sends the paint to the opening end while spreading the paint in the form of a film along the inner peripheral surface in the outer peripheral direction. In addition, the paint or the like is made into an atomized state by discharging it from the opening end into a liquid string (see Patent Document 1).
In the electrostatic coating apparatus for the purpose of obtaining high coating efficiency (reducing the amount of paint used) by imparting (charging) a negative charge to the atomized paint or the like, the bell type atomizing head It is necessary for itself to have conductivity.

JP 59-82957 A

However, the conventional bell type atomizing head has the following problems. That is, for example, when a highly conductive material such as aluminum, duralumin, magnesium, or titanium alloy is used, a spark discharge phenomenon may occur between the bell-type atomizing head and the object to be coated (the object to be coated). There was a problem that there was.
Therefore, in the coating process using the conventional electrostatic coating apparatus, process control has to be strict for electrostatic safety, which has been an obstacle to improving production efficiency.

  The present invention has been made in view of such conventional problems, and is intended to provide an excellent bell-type atomizing head capable of achieving both high electrostatic safety and high coating efficiency and a method for manufacturing the same. is there.

A first invention is a bell-type atomizing head having a bell shape in which an opening diameter gradually increases from a base end portion to an opening end portion.
The bell type atomizing head is disposed on the outer peripheral side of the inner cylinder bell at least at the opening end, and is arranged on the outer peripheral side of the inner cylinder bell. This is a combination with an outer bell that forms the outer periphery of the atomizing head.
The inner cylinder bell is made of conductive ceramics, semiconductor ceramics or conductive resin having an electric specific resistance of 10 ⁻⁶ to 10 ⁸ Ωcm, and the outer cylinder bell is an insulating material having an electric specific resistance of 10 ⁹ Ωcm or more. Ri name from the material,
The bell-type atomizing head is configured to generate a corona discharge at the opening end by applying a high voltage to the inner bell .

The bell-type atomizing head according to the first aspect of the invention has the inner bell made of the low-resistance conductive material having an electrical specific resistance in the range of 10 ⁻⁶ to 10 ⁸ Ωcm on the inner peripheral side, It has a double structure in which the outer bell made of the high-resistance insulating material having an electric specific resistance of 10 ⁹ Ωcm or more is arranged on the outer peripheral side.
At least at the opening end of the bell-type atomizing head, the inner cylinder bell is on the inner peripheral side, and the outer cylinder bell is on the outer peripheral side.

The inner bell has an electric specific resistance (also referred to as specific electric resistance or volume resistivity) in the above range, and has appropriate electric characteristics. Therefore, when a high voltage is applied to the inner bell, an appropriate corona discharge can be generated at the opening end, and a sufficient charge can be applied to the paint passing therethrough for charging.
On the other hand, the outer cylinder bell has an electric specific resistance in the above range, and has an electric resistance high enough to prevent inadvertent spark discharge to an object to be coated or another grounding body.
Therefore, in the bell type atomizing head, it is possible to suppress with high certainty the possibility of spark discharge from the opening end toward the object to be coated.

  As described above, the bell-type atomizing head according to the first aspect of the present invention achieves both of the conflicting characteristics by increasing the chargeability of the paint particles while suppressing the possibility of occurrence of spark discharge, and electrostatic safety. And work efficiency at a high level. Further, this bell type atomizing head can reduce the amount of paint and organic solvent used for painting, for example, and is effective as an environmental measure in the painting process.

According to a second aspect of the present invention, there is provided an inner cylinder bell having a bell shape in which an opening diameter gradually increases from a base end side to an opening end, and an outer peripheral side of the inner cylinder bell, and the opening from the base end side to the opening. In the method for manufacturing a bell-type atomizing head that has a double structure in combination with an outer bell that has a bell shape that gradually increases in opening diameter toward the end,
A raw material for conductive ceramics having an electrical resistivity of 10 ⁻⁶ to 10 ⁸ Ωcm on the outer peripheral side of the mold having an outer peripheral shape corresponding to the desired shape of the opening end and inner peripheral surface of the bell-type atomizing head A first forming step of obtaining a pre-pressurized molded body that becomes the inner cylinder bell by firing by disposing the first raw material powder to be pre-pressurized from the outside;
Subsequent to the first forming step, a second raw material powder serving as a raw material for insulating ceramics having an electrical resistivity of 10 ⁹ Ωcm or more is provided on the outer peripheral side of the pre-pressed molded body disposed in the mold. The first press-molded body made of the pre-press-molded body is disposed on the inner peripheral side and is made of the second raw material powder, and the outer cylinder is formed by firing. A second molding step for obtaining a double-structured main molded body in which a second pressure molded body serving as a bell is arranged on the outer peripheral side;
A firing step for obtaining a fired body by firing or degreasing firing in a state where the molded body is separated from the mold;
And a finishing step of obtaining the bell-type atomizing head by processing the fired body (claim 5).

  In the second bell type atomizing head manufacturing method, in the first forming step, the forming die having an outer peripheral shape corresponding to a desired shape of the opening end portion and the inner peripheral surface of the bell type atomizing head. Is used to form the first pressure-molded body that is fired to form the inner cylinder bell. In addition, as said shaping | molding die, a metal mold | die, a rubber mold, a resin mold etc. can be used, for example.

And in the second molding step performed following the first molding step, the second raw material powder is arranged on the outer periphery of the first pressure-molded body in a state of being arranged in the mold, The second raw material powder is pressurized from the outside. As a result, a double-structured main molded body is obtained in which the second pressure molded body that is baked and becomes the outer cylinder bell is disposed on the outer peripheral side of the first pressure molded body. Then, the said sintered body is obtained by baking the said molded object at the said baking process.
In the finishing step, for example, the bell-shaped atomizing head can be completed by performing a machining step such as grinding or polishing on the inner and outer shapes of the fired body. In addition, as said finishing process, it is good also as what just checks the shaping | molding precision etc. of the said sintered body.

  As described above, in the method for manufacturing the bell-type atomization head according to the second aspect of the invention, the first forming step and the second forming step are combined, and the pressure forming of each raw material powder is performed in two steps. It is divided into two. According to each of the above two-step molding processes, the inner cylinder bell and the outer cylinder bell have a double structure, and the above-mentioned excellent quality that satisfies both electrostatic safety and coating efficiency. A bell-type atomizing head can be produced efficiently.

According to a third aspect of the present invention, there is provided an inner cylinder bell having a bell shape in which an opening diameter is gradually increased from the base end side to the opening end, and an outer peripheral side of the inner cylinder bell, and the opening from the base end side. In the method for manufacturing a bell-type atomizing head that has a double structure in combination with an outer bell that has a bell shape that gradually increases in opening diameter toward the end,
A metal working step of forming the inner bell made of metal,
An assembling step of combining the inner cylindrical bell obtained in the metal working step with a forming die having an outer peripheral shape corresponding to at least the opening end of the bell type atomizing head;
By placing a raw material powder, which is a raw material of an insulating material having an electrical resistivity of 10 ⁹ Ωcm or more, on the outer peripheral side of the inner bell combined with the mold, the inner bell is pressed from the outside. Is formed on the inner peripheral side, and is formed from the raw material powder, and a molding step for obtaining a main molded body obtained by arranging the pressure molded body that becomes the outer cylinder bell by firing on the outer peripheral side;
And a firing step of obtaining the bell-type atomizing head by firing the main molded body in a state of being separated from the mold (claim 8).

In the method for manufacturing the bell-type atomizing head of the third invention, after the metal working step for forming the inner cylindrical bell made of metal is performed, the molding die used for the molding step and the inner cylindrical bell are used. The above assembling process is performed.
As the mold, a mold, a rubber mold or the like can be used. Further, as the metal working step, for example, various methods such as a method for obtaining the inner cylinder bell by a processing method such as a metal powder metallurgy method, a method for obtaining the inner cylinder bell using a machining process such as a cutting process, etc. There is something.

In the molding step to be performed thereafter, a raw material powder serving as a raw material of an insulating material having an electrical specific resistance of 10 ⁹ Ωcm or more is arranged on the outer periphery of the inner cylindrical bell combined with the mold, and the raw material powder Is pressurized from the outside. Thereby, the said molded object formed by arrange | positioning the said press-molded body which becomes a said outer cylinder bell by baking on the outer peripheral side of the said inner cylinder bell is obtained. Further, in the firing step, the molded body is fired in a state separated from the molding die to obtain the bell type atomizing head.
In addition, as a post-process of the firing process, for example, the bell-type atomizing head may be subjected to a machining process such as grinding or polishing to complete the bell-type atomizing head as a final product. it can.

  As described above, in the method for manufacturing the bell-type atomizing head according to the third aspect of the invention, the inner cylinder bell and the above-described process are performed by the molding process performed after the inner cylinder bell is combined with the mold in the assembly process. The bell-type atomizing head having an excellent quality that achieves both electrostatic safety and coating efficiency can be efficiently produced by exhibiting a double structure comprising an outer cylinder bell.

4th invention is arrange | positioned at the outer peripheral side of the inner cylinder bell which has a bell shape from which an opening diameter becomes large gradually from the base end part side to an opening end part, and the said opening from the said base end part side In the method for manufacturing a bell-type atomizing head that has a double structure in combination with an outer bell that has a bell shape that gradually increases in opening diameter toward the end,
A metal working step for forming the inner bell made of metal, a shape corresponding to the opening end of the bell-type atomizing head, and an outer periphery of a forming die having an outer peripheral shape substantially coinciding with the outer peripheral shape of the inner cylindrical bell A molding step of obtaining a pressure molded body that becomes the outer cylinder bell by firing by disposing a raw material powder that is a raw material of an insulating material having an electrical specific resistance of 10 ⁹ Ωcm or more on the side and pressurizing from the outside When,
A firing step of firing the pressure-molded body in a state separated from the mold and obtaining the outer cylinder bell;
A method for manufacturing a bell-type atomizing head, comprising: a joining step of joining the outer-tube bell to the outer peripheral side of the inner cylinder bell to obtain the bell-type atomizing head (claim 10). .

In the bell-type atomizing head manufacturing method according to the fourth aspect of the present invention, the inner cylinder bell made of metal is formed in the metal processing step, while in the molding step, it is fired to become the outer cylinder bell. The said pressure-molded body is formed separately.
Thereafter, in the joining step, the outer cylinder bell is joined to the outer peripheral side of the inner cylinder bell to produce the bell-type atomizing head.

As described above, in the bell-type atomizing head manufacturing method according to the fourth aspect of the invention, the inner cylinder bell and the outer cylinder bell are separately manufactured, and then both are joined to each other to form the bell-type atomization head. The head can be manufactured efficiently.
In addition, for example, if the outer peripheral surface of the inner cylinder bell and the inner peripheral surface of the outer cylinder bell are processed by being bonded together, the bondability between the two can be further improved.

5th invention is arrange | positioned at the outer peripheral side of the inner cylinder bell which has a bell shape from which an opening diameter becomes large gradually from the base end part side to an opening end part, and the said opening from the said base end part side In the method for manufacturing a bell-type atomizing head that has a double structure in combination with an outer bell that has a bell shape that gradually increases in opening diameter toward the end,
A metal working step of forming the inner bell made of metal,
An assembly step for combining the inner bell obtained in the metal processing step with an injection mold having at least an outer peripheral shape corresponding to the opening end of the bell-type atomizing head;
Injection that obtains the bell-type atomizing head by injecting a resin material for injection molding onto the outer peripheral side of the inner cylinder bell combined with the mold and molding the outer cylinder bell integrally with the inner cylinder bell A bell-type atomizing head manufacturing method comprising: a molding step (claim 14).

  In the manufacturing method of the bell type atomizing head according to the fifth aspect of the present invention, after the metal working step for forming the inner cylindrical bell made of metal is performed, the mold and the inner cylindrical bell used in the injection molding step The above assembling process is performed in combination.

  In the subsequent injection molding step, the resin material for injection molding is injected to the outer periphery of the inner cylindrical bell combined with the mold, and the outer cylindrical bell is molded integrally with the inner cylindrical bell. By doing so, the bell type atomizing head is obtained.

  As described above, in the bell-type atomizing head manufacturing method according to the fifth aspect of the invention, the inner cylinder bell and the inner cylinder bell are formed by the injection molding process performed after the inner cylinder bell is combined with the mold by the assembly process. The bell-type atomizing head having an excellent quality that has both the electrostatic safety and the coating efficiency can be efficiently produced by exhibiting a double structure including the outer cylinder bell.

According to a sixth aspect of the present invention, there is provided an inner cylinder bell having a bell shape with an opening diameter gradually increasing from the base end side to the opening end, and an outer peripheral side of the inner cylinder bell, and the opening from the base end side to the opening. In the method for manufacturing a bell-type atomizing head that has a double structure in combination with an outer bell that has a bell shape that gradually increases in opening diameter toward the end,
An inner bell forming step for producing the inner bell;
In the manufacturing method of the bell type atomizing head, an insulating layer disposing step of disposing an insulating layer made of an insulating material as the outer cylindrical bell on the outer peripheral side of the inner cylindrical bell is performed .

  In the bell-type atomizing head manufacturing method according to the sixth aspect of the present invention, after the inner cylinder bell is manufactured, the insulating layer serving as the outer cylinder bell is formed on the outer periphery of the inner cylinder bell in the insulating layer disposing step. To obtain the bell type atomizing head.

  As described above, in the bell-type atomizing head manufacturing method according to the sixth aspect of the invention, the bell-type atomization head is provided by disposing the insulating layer serving as the outer-tube bell on the outer periphery of the inner-tube bell. The head can be manufactured efficiently.

In the first invention, the insulating material is preferably an insulating ceramic or an insulating resin (claim 2).
In this case, by applying a high voltage to the inner cylinder bell made of the conductive material, paint or the like can be charged efficiently on the inner peripheral surface of the inner cylinder bell. Spark discharge can be reliably suppressed by the outer cylinder bell.
Further, as the conductive material, a composite material in which conductive particles such as carbon, carbide, boride, silicide, nitride, ceramics, and perovskite oxide are added to silicon nitride, sialon, alumina, zirconia, etc. It can also be used.

In particular, when the inner cylinder bell and the outer cylinder bell are formed of a ceramic material, the ceramic material exhibits a combination of ceramic materials having a small difference in thermal expansion coefficient or at least one of high strength and high toughness. By configuring the outer cylinder bell, the conductivity and mechanical strength of the bell-type atomizing head can be made compatible.
Alternatively, in the case of a combination of the inner cylinder bell made of a ceramic material and the outer cylinder bell made of a resin material, the inner cylinder bell can be protected by the outer cylinder bell exhibiting high elasticity.

Further, the bell-type atomizing head has a bell shape in which an opening diameter gradually increases from the base end side to the opening end, and from the base end side to the opening end. It is preferable to exhibit a double structure composed of the above-mentioned outer bell having a bell shape whose opening diameter is gradually increased.
In this case, the mechanical strength of the whole bell type atomizing head can be improved by configuring the whole bell type atomizing head to have a double structure.

In addition, an annular groove forming region formed by arranging a large number of atomizing grooves radially formed from the center to the outer periphery of the bell type atomizing head is formed at the opening end. Yes,
Preferably, the atomizing groove is formed by combining an inner cylinder groove portion formed on the outer surface of the inner cylinder bell and an outer cylinder groove portion formed on the outer surface of the outer cylinder bell.

  In this case, the coating material supplied into the bell-type atomizing head rotating at high speed through the atomizing groove formed in the annular groove forming region of the opening end, by the action of centrifugal force, It can discharge smoothly and with high uniformity in the radial direction from the opening end. Then, it is possible to realize high-precision atomization in which paint or the like is discharged in a thread form from the opening end and a droplet having a uniform particle diameter is formed from the tip.

  In the second to fourth inventions, the outer bell can be molded using a plaster mold and a low pressure injection molding method. In the injection molding method, first, the inner cylinder bell can be injection molded, and then the outer cylinder bell can be injected. Furthermore, a bell-shaped atomizing head having a predetermined shape can be formed by performing simultaneous firing while applying pressure using a hot press process, a HIP (Hot Isostatic Pressing) process, or the like.

In the second invention, the pressure applied to the first raw material powder in the first molding step is set lower than the pressure applied to the second raw material powder in the second molding step. (Claim 6).
In this case, the amount of spring back of the pre-pressed molded body in the first molding step can be reduced, and the possibility that the pre-pressed molded body is damaged during the second molding step can be suppressed. And while the joining property of the said inner cylinder bell and the said outer cylinder bell can be improved, the uniformity of shrinkage | contraction at the time of shaping | molding can be improved.

Moreover, it is preferable that at least one of the first molding step and the second molding step is a step using CIP or WIP, press molding, a slip casting method, or a low pressure injection method ( Claim 7).
In this case, the first molding step or the second molding step can be efficiently performed to perform molding with high accuracy.

  In the third aspect of the invention, the inner diameter of the mold is determined by taking into account the amount of spring back at the time of molding, the amount of shrinkage at the time of firing, and the thermal expansion difference between the mold and the insulating material. It is preferable to adjust the outer cylinder bell and the inner cylinder bell so as to be integrated while preventing cracking of the mold atomizing head.

The insulating material is preferably a ceramic material.
In this case, the pressure-molded body formed in the molding step becomes the outer bell having appropriate electrical characteristics by subsequent firing.
And if the said joining process is implemented, the said inner cylinder bell consisting of the metal of an inner peripheral side and the said outer cylinder bell which has the electrical insulation of an outer peripheral side will be combined, and high coating efficiency and electrostatic safety | security The bell-type atomizing head that is compatible with the properties can be produced.
Further, the inner cylinder bell can be produced by a metal powder metallurgy method, a metal injection molding method, or the like.

In the fourth invention, at the time of joining the inner cylindrical bell and the outer cylindrical bell, the outer peripheral surface of the inner cylindrical bell and the inner peripheral surface of the outer cylindrical bell are rubbed together to improve the bondability. It is preferable.
The insulating material is preferably a ceramic material or a resin material.
In this case, the pressure-molded body formed in the molding step becomes the outer bell having appropriate electrical characteristics by subsequent firing.

  In the molding step, the die or rubber die having an outer peripheral shape corresponding to at least the opening end portion of the bell-type atomizing head and a core metal having substantially the same shape as the inner cylindrical bell are combined. Using the molding die, the raw material powder is axially uniaxially pressed or isotropically pressed from the outside, and in the joining step, as the previous step, the inner peripheral surface of the outer cylinder bell obtained in the firing step is used. It is preferable to carry out a machining step for machining into a shape that can be fitted to the inner cylinder bell (claim 12).

  In this case, the pressure-molded body with high shape accuracy can be obtained by the molding step. Moreover, according to the said shaping | molding die which combined the said metal mold | die or the said rubber mold, and the said core metal, after implementing the said shaping | molding process, the said pressure molding body can be easily removed from the said shaping | molding die.

Moreover, it is preferable that the said metal core is a shape which considered the dimensional deformation which arises in the shaping | molding process and baking process of the said outer cylinder bell (Claim 13).
In this case, it is possible to further improve the shape accuracy of the pressure-molded body to be molded.

In the sixth aspect of the invention, in the inner cylinder bell forming step, the outer peripheral side of the forming die having an outer peripheral shape corresponding to the desired shape of the opening end portion and the inner peripheral surface of the bell type atomizing head is provided. By placing a raw material powder that is a raw material of conductive ceramics having a specific resistance of 10 ⁻⁶ to 10 ⁸ Ωcm and pressurizing from the outside, a main formed body that becomes the inner bell is obtained by firing, It is preferable to obtain the inner cylinder bell by firing or degreasing firing the main molded body in a state separated from the mold .
In this case, the inner cylinder bell made of conductive ceramics can be accurately formed by the inner cylinder bell forming step.

In the inner cylinder bell forming step, the inner cylinder bell made of metal is preferably produced by metal processing .
In this case, the inner cylinder bell made of metal can be obtained by the inner cylinder bell forming step. In addition, as a metal working method for producing the inner cylinder bell, for example, the inner cylinder bell is obtained by using a machining method such as a metal powder metallurgy method or a machining method such as a cutting process. There are various ways such as

The insulating layer is preferably a SiO ₂ layer, an alumina layer, a ZrO ₂ layer, a TiO ₂ layer, or a glass layer .
In this case, it is possible to effectively suppress the possibility of occurrence of discharge sparks by the outer cylinder bell.
Incidentally, the SiO ₂ layer or alumina layer, for example, can be formed by spraying a SiO ₂ or alumina on the outer periphery of the inner tube bell. Further, for example, the glass layer can be formed by applying a solution-like low-melting glass on the outer peripheral surface of the inner cylinder bell while rotating the inner cylinder bell about the axis.

Example 1
This example is an example relating to the bell-type atomizing head 1 having a double structure composed of an inner cylinder bell 11 and an outer cylinder bell 12. The contents of this example will be described with reference to FIGS.
As shown in FIG. 1, the bell-type atomizing head 1 of this example has a bell shape in which the opening diameter gradually increases from the base end portion 10 to the opening end portion 19.
The bell-type atomizing head 1 is disposed at least at the opening end 19 on the inner cylindrical bell 11 that forms the inner peripheral side of the bell-type atomizing head 1 and on the outer peripheral side of the inner cylindrical bell 11. And the outer bell 12 which forms the outer peripheral side of the bell-type atomizing head 1.
Here, the inner cylinder bell 11 is made of a conductive material having an electric specific resistance of 10 ⁻⁶ to 10 ⁸ Ωcm, and the outer cylinder bell 12 is made of an insulating material having an electric specific resistance of 10 ⁹ Ωcm or more.
This content will be described in detail below.

As shown in FIG. 1, the bell-type atomizing head 1 of this example includes an inner cylindrical bell 11 having a bell shape in which the opening diameter gradually increases from the base end 10 side to the opening end 19, and the base end 10 side. From the opening end 19 to the opening end 19, a double structure comprising an outer cylindrical bell 12 having a bell shape whose opening diameter gradually increases is exhibited.
The inner cylinder bell 11 of this example is formed of conductive ceramics having an electrical specific resistance of 10 ⁻⁶ to 10 ⁸ Ωcm. The outer bell 12 of this example is formed of an insulating ceramic having an electrical specific resistance of 10 ⁹ to 10 ¹³ Ωcm.

  An annular groove forming region in which a large number of atomizing grooves 21 formed radially from the center of the bell type atomizing head 1 to the outer periphery are arranged at the opening end 19 of the bell type atomizing head 1. 2 is formed. In particular, in the bell type atomizing head 1 of this example, as shown in FIG. 2A, the inner cylinder groove 121 formed on the inner cylinder bell 11 and the outer cylinder groove 122 formed on the outer cylinder bell 12 are combined. An atomizing groove 21 is formed. Instead of this, the inner cylinder groove portion 121 of the inner cylinder bell 11 may be omitted, and the atomization groove 21 may be configured only by the outer cylinder groove portion 122 of the outer cylinder bell 12.

  As shown in FIG. 2 (B), the atomization groove 21 of the present example has a depth D within a range of 0.05 to 1.0 mm (0.2 mm in this example) and the innermost circumferential side. The arrangement pitch P is in the range of 0.05 to 1.0 mm (in this example, 0.2 mm). And the surface of the said atomization groove | channel 21 exists in the range whose surface roughness Rz is 100 micrometers or less (in this example, 20 micrometers).

Next, a method for manufacturing the bell-type atomizing head 1 of this example will be described.
In the manufacturing method of the bell type atomizing head 1 of this example, the opening end 19 of the bell type atomizing head 1 and the outer peripheral side of the mold 5 (FIG. 3) having an outer peripheral shape corresponding to the desired shape of the inner peripheral surface. The first raw material powder serving as the raw material of the conductive ceramics exhibiting an electric specific resistance of 10 ⁻⁶ to 10 ⁸ Ωcm is disposed and pressurized from the outside, whereby the first additive that becomes the inner cylinder bell 11 is formed by firing. Following the first molding step (see FIG. 4) for obtaining the pressure-molded body 110, and the first molding step, an electrical resistivity is provided on the outer peripheral side of the pressure-molded body 110 disposed in the mold 5. By placing the second raw material powder as the raw material of the insulating ceramic exhibiting 10 ¹¹ Ωcm or more and pressurizing from the outside, the first pressure-molded body is disposed on the inner peripheral side, and the second 2nd pressure molding which consists of the above raw material powder and becomes the outer cylinder bell by firing A second molding step (see FIG. 6) for obtaining a double-structured main molded body 127 in which the body 120 is arranged on the outer peripheral side, and the main molded body 127 is fired in a state separated from the mold 5. A firing step for obtaining a fired body (not shown) and a finishing step for processing the fired body to obtain the bell-type atomizing head 1 (FIG. 1) are performed.

In carrying out the first molding step, as shown in FIGS. 1 and 3, the outer periphery corresponding to the desired shape of the opening end 19 including the atomizing groove 21 of the bell-type atomizing head 1 and the inner peripheral surface 15. A mold 5 having a shape is prepared.
As shown in FIG. 3, the mold 5 is disposed above the body part 53, a disk-shaped bottom part 50, a body part 53 formed by combining a plurality of substantially conical or cylindrical shapes formed on the upper surface thereof. And a cylindrical end shaft portion 54. Further, the mold 5 includes a flat portion 51 having a flat surface state on the outer peripheral portion of the bottom portion 50, and a groove forming portion 52 that exists in an annular shape between the inner peripheral side and the body portion 53. Become.

  The groove forming portion 52 is a portion for forming the groove forming region 2 of the bell-type atomizing head 1 (FIG. 1) to be manufactured and the atomizing groove 21 constituting the same, and the transfer shape corresponding to these is formed. Have. And the surface roughness of the surface of each groove | channel provided in the groove | channel formation part 52 of the metal mold | die 5 is set to Rz = 7micrometer, and the dimension (FIG. 2 (B)). Note that all dimensions of the mold 5 are designed to be slightly larger than the dimensions of the desired bell-type atomizing head 1 in consideration of shrinkage dimensions in the firing step described later.

  As shown in FIG. 4, the first forming step includes a first raw material powder serving as a raw material for the conductive ceramics in a gap between the mold 5 and the rubber mold 6 combined on the outer peripheral side of the mold 5. And pressurizing the first raw material powder from the outside. This is a step of obtaining the first pressure-molded body 110 having the shape of the inner opening end 119 and the shape of the inner peripheral surface 15 obtained by transferring the outer peripheral shape of the mold 5. In this example, as shown in the figure, the mold 5 and the raw material powder were covered with the rubber mold 6, and the first pressure-molded body 110 was produced by CIP treatment in which pressure was applied from the outside of the rubber mold 6.

Here, in this example, Y ₂ O ₃ , MgAl ₂ O ₄ , and SiC are in a ratio of 1: 0.7: 1.4 (wt% ratio) as the raw material powder that is the raw material of the conductive ceramic. What was mixed with was used. The pressure condition for the CIP treatment was set to 0.1 t / square cm.
By performing this CIP process, as shown in FIG. 5, the first raw material powder is pressed against the mold 5 by the pressure from the rubber mold 6, and in the groove forming portion 52, the groove shape becomes the first additive. It is transferred to the inner opening end 119 of the compact 110.

The second molding step is a step performed after the first molding step by replacing the rubber mold 6 with another rubber mold 7 as shown in FIG. Here, in the gap between the mold 5 and the first pressure-molded body 110 and the rubber mold 7 combined on the outer peripheral side, the second raw material powder as the raw material of the insulating ceramic is disposed and added. Press. As a result, as shown in FIG. 5, the second pressure molding has an outer opening end portion 129 to which the groove shape of the groove forming portion 52 of the mold 5 is transferred on the outer peripheral side of the first pressure molded body 110. The molded body 127 in which the body 120 is integrally arranged is obtained.
In this example, as shown in the figure, the second molding step was performed by CIP processing in which pressure was applied from the outside of the rubber mold 7.

Here, in this example, Si ₂ N ₄ , Y ₂ O ₃ , and MgAl ₂ O ₄ are mixed at 1: 0.07: 0.04 (wt% ratio) as a raw material powder that is a raw material of the insulating ceramic. ) Was used at a ratio of). The pressure condition for the CIP treatment was 2 t / square cm.

  Next, the main body 127 obtained in the second molding step was fired in a state where it was separated from the mold 5 to obtain a fired body (not shown). In this example, after the molded body 127 is separated from the mold 5 from the mold 5 and separated from the rubber mold 7, machining is performed to adjust the outer peripheral shape of the molded body 127 to a desired shape. The firing process was performed.

In the firing step, the main compact 127 was embedded in a mixed powder of a material and BN, and gas pressure sintering was performed under the condition of maintaining the temperature at 1700 ° C. for 5 hours in a nitrogen (N ₂ ) atmosphere. The gas pressure, that is, the pressure of nitrogen as the atmospheric gas was 9.5 kg / square cm.
Next, in this example, in order to dispose the coating material diffusion plate 81 (see FIG. 7) inside the bell-type atomizing head 1, grinding finishing for adjusting the internal dimensions was performed. Thereby, the bell type atomization head 1 of this example is completed.

  As shown in FIG. 7, the bell-type atomizing head 1 becomes a bell-type atomizer with a paint diffusion plate 81 having a paint injection port 811 and the like disposed therein. Used by connecting to the rotating shaft 82. A supply pipe 83 for supplying paint is provided at the center of the rotating shaft 82, and this is connected to the base end portion 10 of the bell type atomizing head 1. Further, around the bell-type atomizing head 1, an air blowing portion 84 for ejecting compressed air from an air blowing port 85 is disposed. Further, a voltage is applied to the bell-type atomizing head 1 via the rotating shaft 82 in order to charge the paint particles 91 (FIG. 8).

  As shown in FIGS. 7 and 8, when the bell-type atomizing head 1 is disposed in the electrostatic coating apparatus 8 and is actually rotated, the bell-type atomizing head 1 is used. The paint 9 moves from the base end 10 side to the opening end 19 side along the inner peripheral surface 15. As shown in FIG. 8, the paint 9 that has reached the groove forming region 2 of the opening end 19 flows while the flow direction thereof is regulated by the many atomizing grooves 21, and the thread-like liquid is discharged from each of the atomizing grooves 21. As a flow 90, it is scattered at a substantially constant rate outside the bell-type atomizing head 1.

  Then, the liquid flow 90 becomes paint particles 91 which are fine droplets, and is uniformly scattered to obtain an atomized state. At this time, since the dimensional specifications (depth D, pitch P, etc., see FIG. 2B) of the atomizing groove 21 are set as described above, the scattering state can be made uniform, Since the atomization groove | channel 21 has said surface roughness, the flow of a coating material can be made smooth and a more uniform atomization state can be obtained.

Further, as described above, the bell-type atomizing head 1 of this example includes the inner cylinder bell 11 made of conductive ceramics and the outer cylinder bell 12 made of insulating ceramics. Here, the electrical specific resistance of the inner bell 11 is 10 ⁷ Ωcm. The electrical specific resistance of the outer bell 12 is 10 ¹² Ωcm.

  According to the bell-type atomizing head 1 of this example in which the inner cylinder bell 11 having conductivity is arranged on the inner peripheral side, the paint particles 91 can be charged and charged with high reliability. Further, in the bell type atomizing head 1 of the present example in which the outer cylindrical bell 12 having a high insulating property is disposed on the outer peripheral side, the coating is remarkably compared with the conventional bell type atomizing head made entirely of a conductive material. Spark discharge to the object can be suppressed.

In the bell-type atomizing head 1 of the present example, the inner cylinder bell 11 exhibits conductivity that can give a sufficient charge to the paint particles 91, while the outer cylinder bell 12 causes inadvertent spark discharge to the object to be coated. Has sufficient electrical resistance to prevent
Therefore, the bell type atomizing head 1 of this example can achieve both electrostatic safety and coating efficiency. Furthermore, in this example, the entire inner bell 11 is formed of conductive ceramics. Therefore, compared with the case where the conventional metal material and resin material are used, it is hard to wear and exhibits excellent durability.

  As described above, the bell-type atomizing head 1 of the present example can achieve high coating efficiency by reliably charging the paint particles and the like, and has a high safety and excellent quality that suppresses the risk of spark discharge. It is what you have.

In addition, as a shape of the opening edge part of a bell type atomizing head, it can replace with the shape of this example, and can also be made into the shape illustrated in FIGS.
As shown in FIG. 9, when the tip of the inner cylinder bell 11 has a convex shape, corona discharge with a high electric field density can be formed on the inner peripheral side of the tip of the inner cylinder bell 11.

  As shown in FIG. 10, when the tip of the outer cylinder bell 12 is protruded from the tip of the inner cylinder bell 11, a corona discharge field having a high electric field density can be formed in the vicinity of the tip of the inner cylinder bell 11. The effect of being able to suppress the occurrence of spark discharge is obtained.

As shown in FIG. 11, when the tip of the inner cylinder bell 11 has a convex shape, corona discharge can be generated intensively on the inner peripheral side of the tip of the inner cylinder bell 11.
As shown in FIG. 12, when the entire tip of the inner cylinder bell 11 has a protruding shape, corona discharge can be generated on the inner and outer peripheral sides of the tip of the inner cylinder bell 11.

(Example 2)
In this example, the material of the inner bell 11 is changed to metal based on the bell-type atomizing head of the first embodiment. The contents will be described with reference to FIGS.
The inner cylinder bell 11 of this example is made of the material Mo, and exhibits an electric specific resistance of 6 × 10 ⁻⁸ Ωcm. The shape specification of the inner cylinder bell 11 is the same design specification as the inner cylinder bell of the first embodiment. Further, the shape specification of the entire bell-type atomizing head 1 of the present example configured using the inner bell 11 is also the same design specification as the bell-type atomizing head of the first example.

A method of manufacturing the bell type atomizing head 1 of this example will be described.
In this manufacturing method, a metal working step for forming an inner cylinder bell 11 made of metal, and a mold 5 having an outer peripheral shape corresponding to the opening end 19 of the bell-type atomizing head 1 to be obtained are provided on the inner cylinder bell. 11 and the outer periphery of the inner cylinder bell 11 combined with the mold 5 are arranged with raw material powder as a raw material of an insulating material having an electric resistivity of 10 ¹² Ωcm to 10 ¹³ Ωcm from the outside. A molding step of pressing to form a main molded body 127 in which the pressure molded body 120 that becomes the outer cylindrical bell is disposed by firing on the outer peripheral side of the inner cylindrical bell 11, and this main molded body 127 is used as the mold 5. And a firing step of obtaining the bell-type atomizing head 1 (FIG. 1) by firing in a separated state.

The metal working step is a step of cutting out the inner cylinder bell 11 having substantially the same shape as the inner cylinder bell of the first embodiment from a substantially cylindrical member made of material molybdenum. In the assembly step, the inner cylinder bell 11 is combined with the mold 5 having an outer peripheral shape corresponding to at least the opening end 19 of the bell-type atomizing head 1.
Here, the mold 5 has a groove forming portion 52 having a shape corresponding to the opening end portion 19 of the bell-type atomizing head 1 to be obtained. Therefore, in the assembly process, the inner cylinder bell 11 can be accurately positioned by matching the groove forming part 52 of the mold 5 with the inner cylinder groove part 121 of the inner opening end 119 of the inner cylinder bell 11. Therefore, in the main molded body 127 produced using this mold 5, the groove shape of the opening end can be formed with high accuracy, and the inner cylinder bell 11 and the pressure molded body 120 on the outer peripheral side thereof are formed. There is little possibility that the grooves will shift.

Then, in the molding step, the raw material powder that is the raw material of the insulating material having an electric specific resistance of 10 ¹² Ωcm to 10 ¹³ Ωcm is disposed on the outer periphery of the inner cylinder bell 11 combined with the mold 5, By pressing the powder from the outside, a main molded body 127 is obtained in which a pressure molded body 120 that becomes the outer cylindrical bell 12 is disposed on the outer peripheral side of the inner cylindrical bell 11 by subsequent firing. In the present example, as in Example 1, the molding step was performed by CIP treatment in which pressure was applied from the outside of the rubber mold 7 disposed on the outer peripheral side of the inner cylinder bell 11. In this example, the same raw material powder as the second raw material powder of Example 1 was used.

  By performing this CIP process, as shown in FIG. 14, the raw material powder is pressed against the outer peripheral surface of the inner cylinder bell 11 and the groove forming portion of the mold 5 by the pressure from the rubber mold 7 and formed from the raw material powder. The groove shape of the groove forming portion 52 is transferred to the pressure formed body 120.

Then, the said molded object 127 which combined the inner cylinder bell 11 and the press-molded body 120 is baked by the said baking process, and the bell-type atomization head 1 (FIG. 1) is obtained.
And according to the bell type atomizing head 1 of the present example, which has a double structure in which a metal inner cylindrical bell 11 made of molybdenum and an outer cylindrical bell 12 made of insulating ceramics are combined, the above-mentioned example 1 Similar to the bell-type atomizing head, paint particles and the like can be efficiently charged on the inner peripheral surface of the inner bell 11 exhibiting conductivity, and also exhibits electrical insulation that forms the outer peripheral side of the opening end 19. Discharge sparks can be reliably prevented by the outer cylinder bell.

Other configurations and operational effects are the same as those in the first embodiment.
Furthermore, an injection mold is used in place of the mold 5 of this example, and an injection molding resin material is used on the outer peripheral side of the inner bell 11 instead of the powder material. Thus, a resin-made outer cylinder bell can be formed, and a bell-type atomizing head having substantially the same shape as the present example as a whole can be produced.

(Example 3)
In this example, the bell-type atomizing head of the second embodiment is an example in which a metallic inner cylinder bell 11 made of geralumin and an outer cylinder bell made of the above insulating ceramics are joined using an adhesive. The contents will be described with reference to FIGS.
In the manufacturing method of the bell type atomizing head 1 of this example, the metal processing step of forming the inner cylinder bell 11 made of metal and the outer peripheral shape of the opening end 19 of the bell type atomizing head 1 and the inner cylinder bell 11 are substantially omitted. On the outer periphery of the mold 5 having the matched outer peripheral shape, a raw material powder serving as a raw material of an insulating material exhibiting an electric specific resistance of 10 ¹² Ωcm to 10 ¹³ Ωcm is placed and pressurized from the outside. A molding step for obtaining a pressure molded body 120 that becomes the outer cylindrical bell 12 by firing, a firing step for firing the pressure molded body 120 in a state separated from the mold 5, and obtaining the outer cylindrical bell 12, and an inner cylindrical bell 11 The outer cylinder bell 12 is joined to the outer peripheral side of the outer circumference of the outer circumference side to obtain the bell-type atomizing head 1.

The metal working step is a step of cutting out the inner cylinder bell 11 having substantially the same shape as the inner cylinder bell 11 of the first embodiment from a substantially cylindrical member made of the material geralumin.
On the other hand, the molding step is a step of using a mold 5 having an outer peripheral shape that substantially matches the outer peripheral shape of the opening end 19 of the bell-type atomizing head 1 and the inner cylindrical bell 11. In this step, the raw material powder as the raw material of the insulating ceramic is placed in the gap between the combined mold 5 and rubber mold 7, and the outer peripheral shape of the mold 5 is transferred by pressurizing the raw material powder. A pressure-molded body 120 is obtained. In this example, as shown in the figure, the mold 5 and the raw material powder were covered with the rubber mold 7, and the pressure-molded body 120 was produced by CIP processing in which pressure was applied from the outside of the rubber mold 7.

In the firing step, the pressure-molded body 120 removed from the mold 5 is fired to obtain a fired body. In this example, in order to correct the shape of the fired body, machining is performed so that the inner peripheral surface can be rubbed with the outer periphery of the inner cylindrical bell 11 to obtain the outer cylindrical bell 12 (see FIG. 1).
Thereafter, in the joining step, the separately formed inner cylinder bell 11 and outer cylinder bell 12 are bonded and joined. In this example, an adhesive made of Araldite (registered trademark) is applied to the contact surface between the inner cylinder bell 11 and the outer cylinder bell 12, and both are firmly joined by pressing, as shown in FIG. As shown, a bell-type atomizing head 1 was obtained.

And according to the bell-type atomizing head 1 of this example, which has a double structure in which a metal inner cylinder bell 11 made of geralumin and an outer cylinder bell 12 made of insulating ceramics are combined, the above-mentioned example 1 Similar to the bell-type atomizing head, paint particles and the like can be efficiently charged on the inner peripheral surface of the inner bell 11 exhibiting conductivity, and also exhibits electrical insulation that forms the outer peripheral side of the opening end 19. The outer tube bell 12 can reliably prevent discharge sparks on the object to be coated.
Other configurations and operational effects are the same as in the second embodiment.

Example 4
This example is an example of a bell type atomizing head in which an outer cylinder bell as a thick film-like insulating layer is combined on the outer peripheral side of the inner cylinder bell. This will be described with reference to FIG.
The bell-type atomizing head 1 of this example is disposed on the outer peripheral side of the inner cylinder bell 11 and the inner cylinder bell 11 having a bell shape whose opening diameter gradually increases from the base end 10 side to the opening end 19. A double structure in which the outer cylindrical bell 12 having a bell shape whose opening diameter gradually increases from the base end 10 side to the opening end 19 is combined.
In the method for manufacturing the bell-type atomizing head 1, an electrical specific resistance of 10 is provided on the outer peripheral side of a mold having an outer peripheral shape corresponding to a desired shape of the opening end 10 and the inner peripheral surface of the bell-type atomizing head 1. ^A molding step of obtaining a molded body that becomes the inner cylinder bell 11 by firing by disposing a raw material powder that is a raw material of conductive ceramics exhibiting ⁻⁶ to 10 ⁸ Ωcm and pressurizing from the outside; Is fired or degreased and fired in a state separated from the mold, and an insulating layer made of an insulating material is provided on the outer peripheral side of the inner cylinder bell 11 as an outer cylinder bell 12. And a layer disposing step.
This will be described below.

The inner bell 11 of this example is substantially the same as the overall shape of the bell-type atomizing head of the first embodiment. And this inner cylinder bell 11 is obtained by baking the obtained molded object after implementing the said shaping | molding process using the metal mold | die which is not shown in figure.
Then, the greater the insulating layer distribution設工, on the outer peripheral side of the inner cylinder bell 11 obtained as described above, disposing the insulating layer 12a made of SiO _2.

In the insulating layer disposing step of this example, the SiO ₂ layer of 0.5 mm to 1 mm as the outer cylinder bell 12 is formed on the outer peripheral surface of the inner cylinder bell 11 by spraying SiO ₂ from the outer circumference side of the inner cylinder bell 11. That is, the insulating layer 12a is provided.
In place of the SiO ₂ layer of this example, an alumina layer can be formed as the insulating layer 12a. In addition, a glass layer can be provided as the insulating layer 12a. As a method for forming this glass layer, for example, there is a method in which a melted low melting glass is applied to the outer peripheral surface of the inner bell 11 while rotating. At this time, if a squeegee made of metal is used and the glass layer is formed while adjusting the thickness of the low melting point glass to be applied, the formation accuracy can be improved.

Sectional drawing which shows the cross-section of the bell-type atomization head in Example 1, 2 or 3. FIG. The expanded sectional view which expands and shows the opening edge part of the bell type atomization head in Example 1 (a figure which expands the A section in FIG. 1). The perspective view which shows the metal mold | die in Example 1. FIG. Explanatory drawing explaining the 1st shaping | molding process in Example 1. FIG. Explanatory drawing explaining how to form an atomization groove | channel in the 1st shaping | molding process in Example 1. FIG. Explanatory drawing explaining the 2nd shaping | molding process in Example 1. FIG. Sectional drawing which shows the structure of the periphery of the bell type atomization head in the electrostatic coating apparatus in Example 1. Explanatory drawing explaining a mode that a coating particle is atomized from the bell-type atomization head in Example 1. FIG. The expanded sectional view which expands and shows the opening edge part of the other bell type atomization head in Example 1 (a figure expanding A part in Drawing 1). The expanded sectional view which expands and shows the opening edge part of the other bell type atomization head in Example 1 (a figure expanding A part in Drawing 1). The expanded sectional view which expands and shows the opening edge part of the other bell type atomization head in Example 1 (a figure expanding A part in Drawing 1). The expanded sectional view which expands and shows the opening edge part of the other bell type atomization head in Example 1 (a figure expanding A part in Drawing 1). Sectional drawing which shows the cross-section of the inner cylinder bell in Example 2 or 3. FIG. Explanatory drawing explaining the formation process in Example 2. FIG. Explanatory drawing explaining the formation process in Example 3. FIG. Sectional drawing which shows the cross-section of the bell-type atomization head in Example 4. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bell type | mold atomization head 10 Base end part 11 Inner cylinder bell 12 Outer cylinder bell 19 Opening end part 110,120 Pressure-molded body 127 Main molded body 2 Groove formation area 21 Atomization groove 5 Mold 6, 7 Rubber mold 8 Electrostatic coating equipment

Claims (14)

In the bell-type atomizing head having a bell shape in which the opening diameter gradually increases from the base end portion to the opening end portion,
The bell type atomizing head is disposed on the outer peripheral side of the inner cylinder bell at least at the opening end, and is arranged on the outer peripheral side of the inner cylinder bell. This is a combination with an outer bell that forms the outer periphery of the atomizing head.
The inner cylinder bell is made of conductive ceramics, semiconductor ceramics or conductive resin having an electric specific resistance of 10 ⁻⁶ to 10 ⁸ Ωcm, and the outer cylinder bell is an insulating material having an electric specific resistance of 10 ⁹ Ωcm or more. Ri name from the material,
A bell-type atomizing head configured to generate corona discharge at the opening end by applying a high voltage to the inner cylinder bell . 2. The bell type atomizing head according to claim 1, wherein the insulating material is an insulating ceramic or an insulating resin.   3. The bell-type atomizing head according to claim 1, wherein the bell-type atomizing head has a bell shape with an opening diameter gradually increasing from the base end side to the opening end, and from the base end side. A bell-type atomizing head characterized by exhibiting a double structure comprising the above-described outer bell having a bell shape with an opening diameter gradually increasing toward an opening end. The atomizing groove formed radially from the center of the bell type atomizing head to the outer periphery is arranged at a predetermined pitch at the opening end. An annular groove forming region is formed,
The said atomization groove | channel is a bell type atomization head characterized by combining the inner cylinder groove part formed in the outer surface of the said inner cylinder bell, and the outer cylinder groove part formed in the outer surface of the said outer cylinder bell. An inner cylinder bell having a bell shape with an opening diameter gradually increasing from the base end side to the opening end, and an outer diameter of the inner cylinder bell arranged on the outer peripheral side of the inner cylinder bell from the base end side to the opening end. In a method for manufacturing a bell-type atomizing head having a double structure in combination with an outer bell having a bell shape that gradually increases,
A raw material for conductive ceramics having an electrical resistivity of 10 ⁻⁶ to 10 ⁸ Ωcm on the outer peripheral side of the mold having an outer peripheral shape corresponding to the desired shape of the opening end and inner peripheral surface of the bell-type atomizing head A first forming step of obtaining a pre-pressurized molded body that becomes the inner cylinder bell by firing by disposing the first raw material powder to be pre-pressurized from the outside;
Subsequent to the first forming step, a second raw material powder serving as a raw material for insulating ceramics having an electrical resistivity of 10 ⁹ Ωcm or more is provided on the outer peripheral side of the pre-pressed molded body disposed in the mold. The first press-molded body made of the pre-press-molded body is disposed on the inner peripheral side and is made of the second raw material powder, and the outer cylinder is formed by firing. A second molding step for obtaining a double-structured main molded body in which a second pressure molded body serving as a bell is arranged on the outer peripheral side;
A firing step for obtaining a fired body by firing or degreasing firing in a state where the molded body is separated from the mold;
And a finishing step of obtaining the bell-type atomizing head by processing the fired body.   6. The pressurizing force acting on the first raw material powder in the first forming step is set to be lower than the pressurizing force acting on the second raw material powder in the second forming step. A manufacturing method of a bell type atomizing head characterized by the above.   7. The method according to claim 5, wherein at least one of the first molding step and the second molding step is a step using CIP or WIP, press molding, slip casting, or low pressure injection. A method for manufacturing a bell-type atomizing head, wherein An inner cylinder bell having a bell shape with an opening diameter gradually increasing from the base end side to the opening end, and an outer diameter of the inner cylinder bell arranged on the outer peripheral side of the inner cylinder bell from the base end side to the opening end. In a method for manufacturing a bell-type atomizing head having a double structure in combination with an outer bell having a bell shape that gradually increases,
A metal working step of forming the inner bell made of metal,
An assembling step of combining the inner cylindrical bell obtained in the metal working step with a forming die having an outer peripheral shape corresponding to at least the opening end of the bell type atomizing head;
By placing a raw material powder, which is a raw material of an insulating material having an electrical resistivity of 10 ⁹ Ωcm or more, on the outer peripheral side of the inner bell combined with the mold, the inner bell is pressed from the outside. Is formed on the inner peripheral side, and is formed from the raw material powder, and a molding step for obtaining a main molded body obtained by arranging the pressure molded body that becomes the outer cylinder bell by firing on the outer peripheral side;
And a firing step of obtaining the bell-type atomizing head by firing the main molded body in a state of being separated from the molding die.   9. The method for manufacturing a bell type atomizing head according to claim 8, wherein the insulating material is a ceramic material. An inner cylinder bell having a bell shape with an opening diameter gradually increasing from the base end side to the opening end, and an outer diameter of the inner cylinder bell arranged on the outer peripheral side of the inner cylinder bell from the base end side to the opening end. In a method for manufacturing a bell-type atomizing head having a double structure in combination with an outer bell having a bell shape that gradually increases,
A metal working step for forming the inner bell made of metal, a shape corresponding to the opening end of the bell-type atomizing head, and an outer periphery of a forming die having an outer peripheral shape substantially coinciding with the outer peripheral shape of the inner cylindrical bell A molding step of obtaining a pressure molded body that becomes the outer cylinder bell by firing by disposing a raw material powder that is a raw material of an insulating material having an electrical specific resistance of 10 ⁹ Ωcm or more on the side and pressurizing from the outside When,
A firing step of firing the pressure-molded body in a state separated from the mold and obtaining the outer cylinder bell;
A method of manufacturing a bell-type atomizing head, comprising: a step of joining the outer cylinder bell to the outer peripheral side of the inner-tube bell to obtain the bell-type atomizing head.   11. The method for manufacturing a bell type atomizing head according to claim 10, wherein the insulating material is a ceramic material or a resin material.   In Claim 10 or 11, in the forming step, at least a metal mold or rubber mold having an outer peripheral shape corresponding to the opening end of the bell type atomizing head, and a core metal having substantially the same shape as the inner bell The raw material powder is uniaxially pressed in the axial direction or isotropically pressed from the outside in the axial direction. In the joining step, the outer cylinder bell obtained in the firing step is used as the previous step. A method for manufacturing a bell-type atomizing head, wherein a machining step is carried out for machining the inner peripheral surface of the cylinder into a shape that can be fitted into the inner bell.   13. The method for manufacturing a bell-type atomizing head according to claim 12, wherein the cored bar has a shape that takes into account dimensional deformation that occurs in the molding process and firing process of the outer cylinder bell. An inner cylinder bell having a bell shape with an opening diameter gradually increasing from the base end side to the opening end, and an outer diameter of the inner cylinder bell arranged on the outer peripheral side of the inner cylinder bell from the base end side to the opening end. In a method for manufacturing a bell-type atomizing head having a double structure in combination with an outer bell having a bell shape that gradually increases,
A metal working step of forming the inner bell made of metal,
An assembly step for combining the inner bell obtained in the metal processing step with an injection mold having at least an outer peripheral shape corresponding to the opening end of the bell-type atomizing head;
Injection that obtains the bell-type atomizing head by injecting a resin material for injection molding onto the outer peripheral side of the inner cylinder bell combined with the mold and molding the outer cylinder bell integrally with the inner cylinder bell A bell-type atomizing head manufacturing method comprising: a molding step.

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