JP4963929B2 - Flow control valve and method for manufacturing the flow control valve can - Google Patents

Description

  The present invention relates to a flow control valve used by being incorporated in an air conditioner, a refrigerator, or the like, and in particular, can obtain a required torque on the rotor side while achieving cost reduction, and has a joint strength at a welded portion. The present invention relates to a flow rate control valve capable of improving the flow rate and a method for manufacturing the flow rate control valve can.

  A conventional example of this type of flow control valve is shown in FIG. The illustrated flow control valve 10 ′ includes a valve body 21 having a valve chamber 21, a valve seat 22 (valve port 22 a), a flange-like member 23, and the like, and a valve body 24 a (valve shaft 24) that contacts and separates from the valve seat 22. The flow rate of a fluid such as a refrigerant is adjusted, and a cylindrical can with a lower opening having a hemispherical ceiling portion 60c is formed on the flange-like member 23 of the valve body 20 (a step portion 23a formed therein). The lower end portion 60b 'of 60' is hermetically joined by butt welding.

  A refrigerant introduction pipe 61 is connected to one side of the valve chamber 21 of the valve body 20, and a refrigerant outlet pipe 62 is connected to the lower side of the valve chamber 21.

  A rotor 30 'is disposed on the inner periphery of the can 60' with a predetermined gap α '. A yoke portion 60a' is disposed on the outer periphery of the cylindrical portion 60a 'of the can 60 so as to rotate the rotor 30'. 51, the stator 50 which consists of the bobbin 52, the stator coils 53 and 53, the resin mold cover 56, etc. is externally fitted.

  A drive mechanism is provided between the rotor 30 ′ and the valve shaft 24 to bring the valve body 24 a into and out of contact with the valve seat 22 using the rotation of the rotor 30 ′. This drive mechanism has a cylindrical guide bush 26 (fixed screw portion 25 formed on the outer periphery thereof) in which a lower end portion 26a is press-fitted and fixed to the valve body 20 and a valve shaft 24 is slidably inserted. And a moving screw portion 31 formed on the inner periphery of a cylindrical valve shaft holder 32 having a downward opening disposed on the outer periphery of the valve shaft 24 and the guide bush 26 and screwed into the fixed screw portion 25. )) (For details, refer to Patent Document 1 below).

  In the conventional flow control valve 10 ′ having such a configuration, a rare earth sintered magnet is used as the material of the rotor 30 ′. However, rare earth sintered magnets are very expensive although they have a very large coercive force. Therefore, it is considered to use a relatively inexpensive rare earth plastic magnet.

  However, since the rare earth plastic magnet is cheaper than the rare earth sintered magnet but has a small coercive force, it is necessary on the rotor 30 ′ side if the dimensions and the like of the can 60 ′ and the rotor 30 ′ are the same. Torque cannot be obtained. That is, the torque generated on the rotor 30 ′ side is determined by the distance from the yoke 51 to the rotor 30 ′, that is, the distance obtained by adding the gap α ′ between the can 60 ′ and the rotor 30 ′ to the thickness of the can 60 ′. Determined. However, if the gap α ′ is narrowed, the rotor 30 ′ may come into contact with the inner peripheral surface of the can 60 ′. Thus, it is considered to reduce the thickness of the can 60 '. However, if the thickness of the can 60 'is reduced, sufficient bonding strength cannot be obtained at the welded portion K (stepped portion 23a) between the lower end portion 60b' of the can 60 'and the valve body 20 (the flange member 23). , Become vulnerable. Here, in the flow rate control valve 10 ′ used in an air conditioner, a refrigerator, or the like, the can 60 ′ is filled with a refrigerant. In particular, carbon dioxide (gas) instead of a fluorocarbon refrigerant is used as the refrigerant. Is used, it is necessary to set the refrigerant pressure high. For this reason, the inside of the can 60 ′ becomes extremely high pressure. Sex is reduced.

  Therefore, the inventors of the present application can obtain the required torque even if a rare earth plastic magnet is used as the material of the rotor, and ensure sufficient bonding strength at the welded portion between the lower end of the can and the valve body. In order to be able to do so, a flow control valve was proposed in which the thickness of the cylindrical portion between the rotor and the stator was made thinner than the thickness of the lower end of the can, as described in Patent Document 2 below ( Hereinafter referred to as the previously proposed flow control valve).

  That is, as shown in FIG. 3A, in the previously proposed flow control valve, the wall thickness Ib of the lower end portion 60b of the can 60 is thicker than the wall thickness Ia of other portions. In other words, the portion other than the lower end portion 60b of the can 60 is thinned by ironing uneven thickness press (drawing) molding. More specifically, the wall thickness Ia of the portion (cylindrical portion 60a between the rotor 30 and the stator 50) involved in the torque obtained on the rotor 30 side is the conventional can 60 shown in FIG. The wall thickness Ib of the lower end portion 60b is made thinner than that of the conventional portion (Ib ′) (Ia ′ = Ib ′ in the conventional can 60 ′). .

  In this case, the outer diameter Da of the previously proposed flow control valve can 60 and the conventional one (Da ′) are the same, but the inner diameter Db of the can 60 and the outer diameter Ea of the rotor 30 are those of the conventional one (Db ', Ea') (larger thickness is smaller). Therefore, the distance from the yoke 51 of the stator 50 of the previously proposed flow control valve to the rotor 30 (the distance obtained by adding the gap α between the can 60 and the rotor 30 to the wall thickness Ia of the can 60) is shorter than that of the prior art. Has been.

  In this way, the thickness of the lower end portion 60b of the can 60 is made thicker than the thickness of the portion between the rotor 30 and the stator 50, in other words, the portion related to the torque obtained on the rotor side (the relationship between the rotor and the stator). By reducing the thickness of the cylindrical portion 60a) between the yoke 51 and the rotor 30 of the stator 50 (the thickness α of the can 60, the gap α between the can 60 and the rotor 30 is reduced). Therefore, even if an inexpensive rare earth plastic magnet is used as the rotor material, the required torque can be obtained and the thickness of the lower end of the can is increased. Can secure sufficient joint strength at the welded portion between the lower end of the valve and the valve body, and even when high-pressure carbon dioxide or the like is used as a refrigerant, gas leakage occurs. Kukunari, the reliability is improved.

JP 2001-50415 A JP 2006-70990 A

  By the way, since the can used in the above-described previously proposed flow rate control valve has an uneven thickness (forms a thin part and a thick part), an ironing uneven thickness press (drawing) molding is adopted for its manufacture. However, the ironing uneven thickness press molding has a problem that the manufacturing cost, particularly the molding time (man-hour) is increased and the die cost is increased. In addition, there is a problem that molding defects such as shock lines and heels due to high ironing are likely to occur, and further, the dimensional processing accuracy is slightly lower than that of cutting.

  The present invention has been made in view of such circumstances, and the object of the present invention is to obtain the required torque even when a rare earth plastic magnet is used as the material of the rotor, and to lower the lower end of the can. Sufficient joint strength can be secured at the welded part between the valve body and the valve body, the can manufacturing cost can be kept low, and molding defects such as shock lines and baldness are unlikely to occur. An object of the present invention is to provide a flow control valve capable of increasing accuracy and to provide a method for manufacturing the flow control valve can.

  In order to achieve the above object, a flow control valve according to the present invention includes a valve body that adjusts a flow rate of a fluid such as a refrigerant by a valve body that contacts and separates from a valve seat in a valve chamber, and a lower end portion of the valve body. Can be hermetically sealed by welding, a rotor disposed with a predetermined gap around the inner periphery of the can, a stator externally fitted to the can to rotationally drive the rotor, the rotor, and the rotor And a drive mechanism that is disposed between the valve body and uses the rotation of the rotor to bring the valve body into and out of contact with the valve seat, and the thickness of the lower end of the can is between the rotor and the stator. It is made thicker than the thickness of the part between.

Then, the can is made of a non-magnetic metal plate as a raw material, and the thickness of the portion between the rotor and the stator is the thickness of the lower end portion from the state of a thick drawn primary molded product having substantially the same thickness. The outer periphery of the portion between the rotor and the stator is cut so as to be thinner.

  In a preferred aspect, the can is formed in a cylindrical shape having a ceiling portion, and the ceiling portion and the lower end portion thereof have substantially the same thickness, and the outer periphery of the other cylindrical portion is cut to process the ceiling portion. And thinner than the lower end.

  In another preferred embodiment, the thickness of the boundary between the thick portion and the thin portion of the can is continuously changed so that no step is generated.

  In another preferred embodiment, a step portion is formed in the valve body, and a lower end portion of the can is engaged with the step portion and sealed and joined by butt welding.

On the other hand, the manufacturing method according to the present invention is for manufacturing a cylindrical flow rate control valve can having a ceiling portion in which the thickness of the lower end portion is thicker than the thickness of the portion between the rotor and the stator. A cylindrical thick primary molded product having a ceiling part, which is substantially the same thickness as a whole by drawing from a non-magnetic metal plate as a raw material, from the state of the thick primary molded product, The outer periphery of the cylindrical portion between the rotor and the stator is cut so that the thickness of the cylindrical portion between the rotor and the stator is thinner than the thickness of the lower end portion.

  In the flow control valve according to the present invention, the thickness of the lower end portion of the can is made thicker than the thickness of the cylindrical portion between the rotor and the stator. In other words, the thickness of the portion (cylindrical portion between the rotor and the stator) involved in the torque obtained on the rotor side is made thinner than the conventional one, and the distance from the stator yoke to the rotor (the thickness of the can) And the distance obtained by adding the gap between the can and the rotor) is shortened.

  As a result, even if an inexpensive rare earth plastic magnet is used as the rotor material, the required torque can be obtained and the thickness of the lower end of the can is increased. Sufficient joint strength can be ensured at the welded portion, and even when high-pressure carbon dioxide or the like is used as a refrigerant, gas leakage or the like is less likely to occur, and reliability is improved.

  In addition to the above, the flow control valve can according to the present invention can be obtained by performing normal drawing (press) molding from the state of a thick-drawn primary molded product having substantially the same overall thickness between the rotor and the stator. Since the cylindrical part between the rotor and stator is made by cutting the outer periphery of the cylindrical part so that the cylindrical part in between is thinner than the thickness of the lower end part, Compared to the case of manufacturing, the molding time (man-hour) is shortened, the mold cost is low, and the manufacturing cost can be kept low. In addition, molding defects such as shock lines and barbs are unlikely to occur, and the cylindrical portion (the outer diameter) between the rotor and stator is formed by cutting, so that the dimensional processing accuracy can be increased. The advantages are also obtained.

Hereinafter, an embodiment of a flow control valve of the present invention will be described with reference to the drawings.
FIG. 1 is a longitudinal sectional view of an embodiment of a flow control valve according to the present invention. In FIG. 1, parts corresponding to the respective parts of the flow control valve 10 ′ shown in FIG. 4 are given the same reference numerals.

  A flow control valve 10 shown in FIG. 1 has a valve chamber 21, a valve seat 22 (valve port 22a), a flange-like member 23 and the like, and a needle-like valve body 24a that contacts and separates from the valve seat 22 to supply refrigerant. A valve body 20 for adjusting the passage flow rate, a can 40 (which will be described in detail later) whose lower end portion 40b is hermetically joined to the valve body 20 by welding, and a predetermined gap α in the inner periphery of the can 40. The rotor 30 is disposed, and a stator 50 that is externally fitted to the can 40 to rotationally drive the rotor 30.

  A refrigerant introduction pipe 61 for introducing carbon dioxide (gas) as a refrigerant into the valve chamber 21 is connected to one side of the valve chamber 21 of the valve body 20, and below the valve chamber 21, A refrigerant outlet pipe 62 is connected.

  The stator 50 includes a yoke 51 made of a magnetic material and upper and lower stator coils 53, 53 wound around the yoke 51 via a bobbin 52. The rotor 30 and the stator 50 constitute a stepping motor.

  Here, a rare earth plastic magnet such as Nd—Fe—B is used as the material of the rotor 30.

  The can 40 is made of a non-magnetic metal plate such as stainless steel as a material and is formed into a cylindrical shape having a hemispherical ceiling portion 40c by a method as described later, and a lower end portion (opening edge portion) 40b thereof. Is made thicker than the thickness of the cylindrical portion 40a between the rotor 30 and the stator 50, and the lower end portion 40b thereof is fixed to the upper portion of the valve body 20 and is made of a stainless steel bowl-like member 23. Are sealed and joined by butt welding (welded portion K), and the inside is kept airtight.

  Here, the can 40 of the present embodiment is manufactured as follows. That is, first, as shown in FIG. 2 (A), a cylindrical thick-walled drawing having a ceiling portion 40c having the same overall thickness (Ia = Ib = Ic) by ordinary drawing (press) molding. A primary molded product 40F is obtained. Next, as shown in FIG. 2B, from the state of the thick-drawn primary molded product 40F, the thickness of the cylindrical portion 40a between the rotor 30 and the stator 50 is obtained. In order to make Ia thinner than the thickness Ib of the lower end portion 40b, the outer periphery of the cylindrical portion 40a between the rotor 30 and the stator 50 is cut. Thereby, the thickness Ia of the cylindrical portion 40a between the rotor 30 and the stator 50 is made thinner (for example, about half) than the thickness Ib (= Ic) of the lower end portion 40b and the ceiling portion 40c. .

  In this case, the outer diameter Da and inner diameter Db of the can 40 of this embodiment and the outer diameter Ea of the rotor 30 are the same as those of the can 60 of the previously proposed flow control valve shown in FIG. In addition, the distance from the yoke 51 of the stator 50 of the present embodiment to the rotor 30 (the distance obtained by adding the gap α between the can 40 and the rotor 30 to the thickness Ia of the can 40) is also the value of the previously proposed flow control valve. It is the same as that.

  Note that the boundary portion between the thick portion and the thin portion of the can 40 of the present embodiment, that is, the boundary portion 40 i between the lower end portion 40 b and the cylindrical portion 40 a between the rotor 30 and the stator 50 has a step. R is given so as not to occur, and the thickness is continuously changed. In addition, the thickness of the boundary portion 40j between the ceiling portion 40c and the cylindrical portion 40a is continuously changed so that no step is generated. As described above, the thickness of the boundary portions 40i and 40j between the thick portion and the thin portion is continuously changed, so that the stress concentration on the boundary portions 40i and 40j is alleviated and the pressure strength is improved. .

  The valve body 24a is formed at the lower end of the valve shaft 24 made of brass. The drive mechanism for bringing the valve body 24a into and out of contact with the valve seat 22 includes a cylindrical guide bush 26 into which the valve shaft 24 is slidably inserted, and a cylindrical valve shaft with a lower opening disposed on the outer periphery thereof. The guide bush 26 is press-fitted (or screwed) and fixed to a fitting hole 42 provided in the valve body 20, and the center of the guide bush 26 is fixed to the guide bush 26. A male screw portion 25 is formed in the vicinity of this portion, and the valve shaft holder 32 is formed with a female screw portion (moving screw portion) 31 that is screwed into the male screw portion (fixed screw portion) 25 of the guide bush 26, and its nadir. An upper small diameter portion of the valve shaft 24 is inserted through the central portion. The upper end portion of the upper small diameter portion of the valve shaft 24 is press-fitted and fixed to a nut 33 placed on the top surface of the bottom of the valve shaft holder 32.

  The valve shaft 24 is always biased downward by a buffering coil spring 34 that is mounted between the top of the valve shaft holder 32 and the intermediate stepped portion of the valve shaft 24. A pressure equalizing hole 32 a for equalizing the pressure in the valve chamber 21 and the can 40 is formed on the side surface of the guide bush 26.

  A return spring 35 made of a coil spring is provided on the top of the valve shaft holder 32. The return spring 35 abuts against the inner surface of the can 40 when the fixed screw portion 25 of the guide bush 26 and the moving screw portion 31 of the valve shaft holder 32 are disengaged, and the fixed spring portion 25 and the moving screw portion 31. It works to restore the screwing.

  The valve shaft holder 32 and the rotor 30 are coupled via a support ring 36, and the support ring 36 is formed of a brass metal ring inserted when the rotor 30 is formed in this embodiment. The upper protrusion of the valve shaft holder 32 is caulked and fixed to the support ring 36, whereby the rotor 30, the support ring 36, and the valve shaft holder 32 are integrally connected.

  A lower stopper body (fixed stopper) 27 constituting one of the stopper mechanisms is fixed to the guide bush 26, and an upper stopper body (moving stopper) 37 constituting the other of the stopper mechanism is fixed to the valve shaft holder 32. Yes.

  In the flow control valve 10 having such a configuration, when the stator coils 53 and 53 are energized in one direction to be excited, the rotor 30 and the valve shaft with respect to the guide bush 26 fixed to the valve main body 20. When the holder 32 is rotated in one direction and the screw feed between the fixing screw portion 25 of the guide bush 26 and the moving screw portion 31 of the valve shaft holder 32, for example, the valve shaft holder 32 is moved downward and the valve body 24a is moved to the valve body 24a. The valve port 22a is closed by being in pressure contact with the seat 22.

  When the valve port 22a is closed, the upper stopper body 37 is not yet in contact with the lower stopper body 27, and the rotor 30 and the valve shaft holder 32 further rotate and descend while the valve body 24a closes the valve port 22a. . At this time, since the valve shaft holder 32 is lowered with respect to the valve shaft 24, the descent force of the valve shaft holder 32 is absorbed by the compression coil spring 34 being compressed. Thereafter, when the rotor 30 further rotates and the valve shaft holder 32 is lowered, the upper stopper body 37 comes into contact with the lower stopper body 27, and the lowering of the valve shaft holder 32 is forced even if energization to the stator coils 53, 53 is continued. Is stopped.

  On the other hand, when the stator coils 53 and 53 are energized by energizing in the other direction, the rotor 30 and the valve shaft holder 32 are rotated in the opposite direction to the guide bush 26 fixed to the valve body 20, and the guide bush. By the screw feed between the fixed screw portion 25 of 26 and the moving screw portion 31 of the valve shaft holder 32, the valve shaft holder 32 is now moved upward, and the valve body 24 a at the lower end of the valve shaft 24 is separated from the valve seat 22. The valve port 22a is opened, and the refrigerant passes through the valve port 22a. In this case, the effective opening area of the valve port 22a, that is, the flow rate of the refrigerant can be adjusted by the rotation amount of the rotor 30, and the rotation amount of the rotor 30 is controlled by the number of pulses. Can be adjusted.

  In the flow control valve 10 of the present embodiment configured as described above, the can 40 is manufactured as follows. That is, first, as shown in FIG. 2 (A), a cylindrical thick-walled drawing having a ceiling portion 40c having the same overall thickness (Ia = Ib = Ic) by ordinary drawing (press) molding. A primary molded product 40F is obtained. Next, as shown in FIG. 2B, from the state of the thick-drawn primary molded product 40F, the thickness of the cylindrical portion 40a between the rotor 30 and the stator 50 is obtained. In order to make Ia thinner than the thickness Ib of the lower end portion 40b, the outer periphery of the cylindrical portion 40a between the rotor 30 and the stator 50 is cut. Thereby, the thickness Ia of the cylindrical portion 40a between the rotor 30 and the stator 50 is made thinner (for example, about half) than the thickness Ib (= Ic) of the lower end portion 40b and the ceiling portion 40c. .

  In this case, the outer diameter Da and inner diameter Db of the can 40 of this embodiment and the outer diameter Ea of the rotor 30 can be made the same as those of the can 60 of the previously proposed flow control valve shown in FIG. In addition, the distance from the yoke 51 of the stator 50 of the present embodiment to the rotor 30 (the distance obtained by adding the gap α between the can 40 and the rotor 30 to the thickness Ia of the can 40) is also the value of the previously proposed flow control valve. It can be the same.

  Note that the boundary portion between the thick portion and the thin portion of the can 40 of the present embodiment, that is, the boundary portion 40 i between the lower end portion 40 b and the cylindrical portion 40 a between the rotor 30 and the stator 50 has a step. R is given so as not to occur, and the thickness is continuously changed. In addition, the thickness of the boundary portion 40j between the ceiling portion 40c and the cylindrical portion 40a is continuously changed so that no step is generated. As described above, the thickness of the boundary portions 40i and 40j between the thick portion and the thin portion is continuously changed, so that the stress concentration on the boundary portions 40i and 40j is alleviated and the pressure strength and the like are improved. To do.

  As described above, in the flow control valve 10 of the present embodiment, the wall thickness Ib of the lower end portion 40 b of the can 40 is thicker than the wall thickness Ia of the portion between the rotor 30 and the stator 50. In other words, the thickness Ia of the portion related to the torque obtained on the rotor side is made thinner than the conventional one, and the distance from the yoke 51 of the stator 50 to the rotor 30 (the thickness Ia of the cylindrical portion 40a of the can 40) is reduced. The distance obtained by adding the gap α is shortened. As a result, even if an inexpensive rare earth plastic magnet is used as the material of the rotor 30, the required torque can be obtained and the lower end portion 40b of the can 40 is thickened. And a sufficient weld strength (K) between the valve body 20 and the valve body 20 (saddle-shaped member 23), and even when high-pressure carbon dioxide or the like is used as a refrigerant, gas leakage is less likely to occur, Reliability can be improved.

  In addition to the above, the flow control valve can 40 of the present embodiment is a thick drawn primary molded product 40F, which is obtained by ordinary drawing (press) molding and has the same overall thickness (Ia = Ib = Ic). From the state, the outer periphery of the cylindrical portion 40a between the rotor 30 and the stator 50 is cut so that the cylindrical portion 40a between the rotor 30 and the stator 50 is thinner than the thickness of the lower end portion 40b. Therefore, as compared with the case where the can is manufactured by ironing uneven thickness press molding, the molding time (man-hour) is shortened, the mold cost is low, and the manufacturing cost can be kept low. In addition, molding defects such as shock lines and heels are unlikely to occur, and the cylindrical portion 40a (outer diameter) between the rotor 30 and the stator 50 is formed by cutting. The advantage that it can be increased is also obtained.

The longitudinal cross-sectional view which shows one Embodiment of the flow control valve which concerns on this invention. The figure which is provided for description of the production method and structure of the can used in the flow control valve shown in FIG. (A) is an enlarged view showing the periphery of the can of the previously proposed flow control valve, and (B) is an enlarged view showing the periphery of the can of the conventional flow control valve shown in FIG . The longitudinal cross-sectional view which shows an example of the conventional flow control valve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Flow control valve 20 Valve main body 21 Valve chamber 22 Valve seat 23 Gutter-like member 23a Step part 24 Valve shaft 24a Valve body 25 Fixing screw part (male screw part)
26 Guide bush 27 Lower stopper 30 Rotor 31 Moving screw part (female screw part)
32 Valve shaft holder 33 Push nut 34 Compression coil spring 35 Return spring 36 Support ring 37 Upper stopper body 40 Can 40a Cylindrical portion 40b Lower end portion 40c Ceiling portion 50 Stator

Claims (5)

A valve body that adjusts a flow rate of a fluid such as a refrigerant by a valve body that contacts and separates from a valve seat in the valve chamber;
A can whose lower end is sealed and joined to the valve body by welding;
A rotor disposed with a predetermined gap around the inner periphery of the can;
A stator externally fitted to the can for rotationally driving the rotor;
A drive mechanism that is disposed between the rotor and the valve body, and uses the rotation of the rotor to contact and separate the valve body from the valve seat;
A flow control valve in which the thickness of the lower end of the can is thicker than the thickness of the portion between the rotor and the stator,
The can is made of a non-magnetic metal plate as a raw material in a thick drawn primary molded product with the same overall thickness, and the thickness of the portion between the rotor and the stator is thinner than the thickness of the lower end portion. The flow rate control valve is characterized in that the outer periphery of the portion between the rotor and the stator is cut.   The can is formed in a cylindrical shape having a ceiling part, and the ceiling part and the lower end part thereof have substantially the same thickness, and the outer periphery of the other cylindrical part is cut and processed from the ceiling part and the lower end part. The flow control valve according to claim 1, wherein the flow control valve is thinned.   The flow control valve according to claim 1 or 2, wherein a thickness of a boundary portion between the thick portion and the thin portion of the can is continuously changed so that no step is generated.   The step part is formed in the said valve main body, The lower end part of the said can is engaged with this step part, and it seal-joins by butt-welding. Flow control valve. A method for manufacturing a cylindrical flow control valve can having a ceiling portion, wherein the thickness of the lower end portion is thicker than the thickness of the cylindrical portion between the rotor and the stator,
By using a non-magnetic metal plate as a raw material , a cylindrical thick-walled primary molded product having a ceiling portion, which has the same overall thickness, is obtained. From the state of the thick-drawn primary molded product, the rotor and stator A cylindrical portion between the rotor and the stator, the outer periphery of the cylindrical portion between the rotor and the stator is cut so that the thickness of the cylindrical portion between the rotor and the stator is thinner. Production method.

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