JP7709183B2 - Manufacturing method of diaphragm valve - Google Patents

Description

The present invention relates to a method for manufacturing a diaphragm valve.

2. Description of the Related Art Direct diaphragm valves (hereinafter simply referred to as "diaphragm valves") are used for ON/OFF control of process gases for semiconductor manufacturing (see, for example, Patent Document 1).
A diaphragm valve is a valve that opens and closes the flow path of a fluid by pressing a diaphragm with an opening and closing mechanism using an air cylinder to separate or bring the diaphragm and the valve seat into close contact, thereby controlling the flow and stop of the fluid. Diaphragm valves have the advantage that the controlled fluid is completely isolated from the opening and closing mechanism by the diaphragm, so there is little leakage or contamination.
This valve seat (hereinafter referred to as "seat") is made of a resin material such as PTFE, which has appropriate flexibility and high sealing performance in the closed state.
A sheet made of such a resin material gradually collapses when it comes into contact with the diaphragm many times by opening and closing after the start of use, and as a result, the gap between the sheet and the diaphragm in the open state gradually increases, causing a problem that the Cv value, which is an index of ease of flow, increases. To address this problem, a method has been proposed in which aging (break-in operation) is performed by performing opening and closing operations many times during the manufacturing and adjustment of the diaphragm valve, and after the change in the shape of the sheet due to opening and closing is completed, the gap between the sheet and the diaphragm is adjusted to a specified value, so that such changes do not occur after delivery to the customer (Patent Document 2).

Patent Document 2 describes such an aging method as opening and closing a specified number of times at a specified temperature (e.g., 200°C). Specifically, for a diaphragm with an outer diameter of 26 mm, aging is performed by opening and closing 3,000 to 10,000 times at full stroke (e.g., lift amount ΔS is 1.2 mm), and then the lift amount is adjusted to 55 to 70% of the full stroke (e.g., 0.7 mm) for use. It has been reported that this reduces changes in the shape of the resin valve seat during actual use, stabilizes the Cv value, which is an index of ease of flow, and ensures durability as it is used with a small stroke during actual use.

Patent No. 6336345 Patent No. 5331180

However, the method of Patent Document 2 has the following problems.
First, in this method, opening and closing aging is performed with the lift amount left unadjusted at full stroke, but when the lift amount is not adjusted, the lift amount varies, for example, within a range of 1.1 mm to 1.3 mm due to individual differences in the valve. If opening and closing aging is performed in this state, the impact force applied to the seat during opening and closing operations varies between diaphragm valves, and the effect of opening and closing aging also varies, resulting in variations in durability and flow characteristics between products. Such variations are undesirable in recent years, when there has been a growing demand to reduce machine differences.
Secondly, in the method of Patent Document 2, opening and closing aging is performed with a large lift amount of, for example, 1.2 mm before adjustment, so that the distortion amount ε of the diaphragm during opening and closing aging (when the outer diameter is D, the thickness is t, and the lift amount is ΔS, the distortion amount ε is thought to be proportional to tΔS/D) becomes large, and there is a concern that opening and closing aging may affect the durability of the diaphragm.

The object of the present invention is to provide a method for manufacturing a diaphragm valve that can solve the above problems, reduce the change in flow rate over time and the variation between products, and reduce the impact on the durability of the product.

The method for manufacturing a diaphragm valve of the present invention includes the steps of:
a body having a valve chamber that opens to an upper surface thereof, and a fluid inlet passage and a fluid outlet passage that open to a bottom surface of the valve chamber provided therein;
an annular seat disposed around an opening of the fluid inlet passage in a bottom surface of the valve chamber;
a diaphragm disposed to seal the valve chamber, the diaphragm elastically deforming to come into contact with and separate from the seat to close and open the fluid inlet passage;
a diaphragm operating portion having a tip portion which moves up and down while pressing the diaphragm to bring the diaphragm into contact with and away from the sheet;
A method for manufacturing a diaphragm valve comprising:
adjusting an amount of elevation of a tip end portion of the diaphragm operation portion when the diaphragm is pressed against the sheet and when the diaphragm is released from the sheet to a predetermined amount;
Thereafter, a break-in step is performed in which the diaphragm is brought into contact with and separated from the sheet a predetermined number of times by the diaphragm operating portion.

Preferably, the break-in step can be performed at a temperature within the range of 80°C to 150°C.

Preferably, a configuration can be adopted that is the upper limit temperature of the operating temperature range of the diaphragm valve.

Preferably, the diaphragm is a circular laminate with an outer diameter of 14.5 mm to 26.5 mm, made of a laminate of stainless steel thin plates and nickel-cobalt alloy thin plates, and the predetermined number of times is at least 10,000 times.

Preferably, the predetermined amount of elastic deformation stroke is 0.3 mm to 0.4 mm.

Preferably, the configuration can further include a step of adjusting the Cv value of the diaphragm valve after the break-in step.

According to the present invention, the amount of rise (hereinafter referred to as the "lift amount") of the tip of the diaphragm operating portion when the diaphragm is pressed against the seat and when it is released is adjusted, and then a predetermined number of opening and closing operations (hereinafter referred to as "opening and closing aging") are performed. Therefore, during opening and closing aging, there is no variation in the lift amount between individual valves, and variations in durability and flow rate changes between individual valves due to variations in the effects of opening and closing aging can be reduced.
In addition, since opening and closing aging is performed with a small lift amount (for example, 0.3 mm lift amount at the time of product shipment), the adverse effect on the durability of the diaphragm is small. From experience, with a lift amount of 0.3 mm, the durability of the diaphragm is 40 million opening and closing cycles, so there is thought to be no problem even if opening and closing aging is performed 10,000 times.

1 is a schematic cross-sectional view showing a diaphragm valve according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of the diaphragm in FIG. 1 when the diaphragm is in a natural shape. FIG. 2 is an enlarged cross-sectional view showing a state in which the diaphragm is in contact with a seat in FIG. 1 . FIG. 2 is an enlarged cross-sectional view showing a state in which the diaphragm is separated from the seat in FIG. 3 is a flowchart showing a manufacturing method according to an embodiment of the present invention. FIG. 13 is an explanatory diagram showing an opening and closing aging method. FIG. 4 is an explanatory diagram showing a method for measuring a Cv value. 13 is a graph showing a change in Cv value due to switching aging. 1 is a graph showing a change in Cv value due to exposure to an open circuit at 120° C. FIG. 4 is a diagram illustrating factors that cause a change in the shape of a sheet.

(Diaphragm valve according to an embodiment of the present invention)
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this embodiment, an NC (normally closed) type direct diaphragm valve, which is the same as that of Patent Document 2, will be described as an example. Fig. 1 is a schematic cross-sectional view of this direct diaphragm valve. Fig. 2 is an enlarged cross-sectional view of Fig. 1 when the diaphragm is in its natural shape, Fig. 3 is an enlarged cross-sectional view showing the state in which the diaphragm abuts against the seat in Fig. 1, and Fig. 4 is an enlarged cross-sectional view showing the state in which the diaphragm is separated from the seat in Fig. 1.

In Figure 1, 1 is the body, 2 is the diaphragm, 3 is the pressure adapter, 4 is the bonnet, 5 is the threaded portion, 6 is the spring, 7 is the diaphragm pressure, 8 is the stem, 9 is the actuator, 10 is the fluid inlet, 11 is the fluid outlet, 12 is the valve chamber, 13 is the seat, 14 is the drive shaft, 15 is the stroke adjustment mechanism, 16 is the solenoid valve, and 17 is the proximity switch.

The body 1 is made of stainless steel and is formed in a roughly cross shape, with a fluid inlet 10 and a fluid outlet 11 on both sides, and a concave valve chamber 12 with an open top that communicates with the fluid inlet 10 and the fluid outlet 11 at the top. A sheet 13 made of synthetic resin (PFA, PA, PI, PCTFE, etc.) is fitted and fixed to the bottom of the valve chamber 12. In this embodiment, the sheet 13 is fixed in the valve insertion groove by so-called crimping.

The diaphragm 2 is disposed above the seat 13, and while maintaining the airtightness of the valve chamber 12, its center moves up and down to come into contact with and leave the seat 13. In this embodiment, the diaphragm 2 is formed into a circular inverted dish shape by bulging the center of a thin metal plate (thickness 0.15 mm) such as special stainless steel and a thin nickel-cobalt alloy plate (thickness 0.15 mm) upward, and three of these inverted dish-shaped special stainless steel thin plates and one nickel-cobalt alloy thin plate are closely stacked to form an inverted dish shape. The peripheral portion of the diaphragm 2 is placed on the protrusion on the inner peripheral surface of the valve chamber 12, and the lower end of the bonnet 4 inserted into the valve chamber 12 is screwed into the threaded portion 5 of the body 1, so that the diaphragm 2 is pressed against the protrusion side of the body 1 via the stainless steel press adapter 3, and is fixed in an airtight state. The nickel-cobalt alloy thin film is disposed on the gas-contact side.

In this embodiment, the diaphragm 2 has an outer diameter of 26 mm for a valve with a fluid passage inner diameter of 6.35 mmφ and a radius of curvature of the bulge of 60 mm. In addition, there are diaphragms with an outer diameter of 20 mm and a radius of curvature of 62.6 mm for a valve with a fluid passage inner diameter of 6.35 mmφ, and diaphragms with an outer diameter of 15 mm and a radius of curvature of 62.6 mm for a small valve with a diameter of 6.35 mm.

The bonnet 4 is formed in a cylindrical shape and is inserted into the valve chamber 12 of the body 1 and fixed to the body 1 by tightening it into the threaded portion 5 provided on the inner surface of the valve chamber 12.

The stem 8 is inserted into the lower end of the bonnet 4 so that it can move up and down freely, and a synthetic resin diaphragm retainer 7 is fitted to the lower end surface, which abuts against the upper central surface of the diaphragm 2.

More specifically, the stem 8 is inserted into the bonnet 4 so that a polyimide diaphragm retainer 7 attached to the lower end face can move up and down to abut against the diaphragm 2, and is pressed downward by the elastic force of the spring 6 via the diaphragm retainer 7, causing the center of the diaphragm 2 to abut against the seat 13. In addition, the drive shaft 14 of the actuator 9 for operating the stem is fixed to the upper end of the stem 8.

The stem 8 is provided with a flange 8a at its lower part, and when the valve is fully closed (when the center of the diaphragm 2 is in contact with the seat 13), the flange 8a comes into contact with the upper surface of the pressure adapter 3, thereby preventing the stem 8 from descending unnecessarily.

The stroke adjustment mechanism 15 is composed of a lock nut 15a screwed onto the support tube 9a of the actuator 9, which is screwed and fixed to the top surface of the bonnet 4, and adjusts the lift amount ΔS by adjusting the screw-in height position of the support tube 9a into the bonnet 4.

The solenoid valve 16 is fixed directly to the top surface of the actuator 9 and controls the flow of the drive fluid (air) A supplied to the actuator 9. The actuator 9 is directly attached to the solenoid valve 16 in order to reduce the space in the drive fluid passage as described below, thereby improving the responsiveness of the valve opening and closing operation (reducing the opening and closing operation time).

The proximity switch 17 is used to detect the change in lift amount ΔS when the valve is opened or closed, and the lift amount ΔS itself. It is fixed to the top side of the actuator 9, and detects the lift amount ΔS by measuring the gap ΔG with the piston 9c.

Next, the operation of the diaphragm valve of this embodiment will be described. The valve shown in Figure 1 is configured as an NC (normally closed) type, and the diaphragm 2 is normally pressed downward via the stem 8 by the elastic force of the spring 6, and the nickel-cobalt alloy thin plate on its lower surface (gas-contacting surface) is in contact with the seat 13. The pressing force of the stem 8 is adjusted by the spring 6, and the amount of descent of the stem 8 is regulated by the pressure adapter 3.

When driving fluid A is supplied to the actuator 9, the driving shaft 14 is pulled upward by the lift amount ΔS via the piston 9c. As a result, the diaphragm 2 returns to its original shape with the center bulging upward due to its elastic force, and the valve opens. The lift amount ΔS is adjusted to a predetermined value by the lock nut 15a of the stroke adjustment mechanism 15.

(Manufacturing method according to an embodiment of the present invention)
Next, a manufacturing method of the present invention for such a diaphragm valve will be described.
The manufacturing method of this embodiment includes, as a break-in (aging) method, a step of adjusting the amount of lift (hereinafter referred to as "lift amount") of the tip of the diaphragm operation part when the diaphragm is pressed against the seat and when it is released, and then performing a predetermined number of opening and closing operations (hereinafter referred to as "opening and closing aging"), and further adjusting the flow lift. Figure 5 shows a flowchart of this embodiment.
The manufacturing method of this embodiment is as follows:
(a) a part manufacturing process;
(b) a parts cleaning and baking process;
(c) a valve assembly process; and
(d) aging (break-in);
(e) Inspection process (He leak inspection, pressure inspection, cleanliness inspection, etc.);
Includes.
The manufacturing method of the present invention is characterized by the (d) aging (break-in) method. The other steps (a), (b), (c), and (e) are the same as those of the conventional method, so detailed explanations of these steps will be omitted.
The (d) aging step in this embodiment includes (d1) lift amount adjustment, (d2) opening and closing aging, and (d3) flow rate lift adjustment (Cv value adjustment).

(d1) Lift Amount Adjustment This is a process for adjusting the amount of lift (i.e., the "lift amount") of the tip of the diaphragm operation portion when the diaphragm is pressed against the sheet and when it is released from the sheet.
The purpose of this process is to ensure that the aging effect of the seat due to opening and closing in the (d2) opening and closing aging described below is consistent between each valve, and to prevent the load on the diaphragm due to opening and closing aging from becoming excessive and affecting the valve lifespan.
The lift amount is set to a predetermined value between 0.3 and 0.4 mm.

The reason for this is that in open-close aging, the greater the lift amount, the greater the impact force when closing, and therefore it is thought that the aging effect is also greater; however, in the Cv value stability evaluation described below, a sufficient stabilizing effect was obtained with open-close aging with a lift amount of 0.3 mm.
As will be described later, regarding the amount of distortion ε of the diaphragm during opening and closing aging (when the outer diameter is D, the thickness is t, and the lift amount is ΔS, the amount of distortion ε is considered to be proportional to tΔS/D), if the lift amount ΔS is up to 0.3 to 0.4 mm, in all cases where the diaphragm outer diameter is 26 mm, 20 mm, or 15 mm, the amount of distortion ε is smaller than in the case of opening and closing aging in Patent Document 2. Furthermore, from experience, with an actual lift amount of 0.3 mm, the durability of the diaphragm is an actual value of 40 million opening and closing cycles, and therefore the effect of opening and closing aging on durability is considered to be small.

A specific method is, for example, to monitor the height position of the piston 9c with the proximity switch 17 of the diaphragm valve shown in Figure 1, while turning the operating air on and off to measure the change in height position, which is taken as the lift amount. By rotating the actuator 9 screwed into the bonnet 4 and adjusting the vertical position of the actuator 9 so that this lift amount is, for example, 0.3 mm, the upper limit position of the diaphragm retainer 7 connected to the actuator 9 via the drive shaft 14 and stem 8 is adjusted. After adjustment, the lock nut 15a screwed into the outer circumferential thread of the support cylinder 9a of the actuator 9 is tightened to fix it in place.

(d2) Open-close aging Open-close aging is a process in which the valve is opened and closed many times under high temperature conditions to impact-press the seat with the diaphragm many times.
The purpose of this process is to complete the aging process of the seat by open/close aging, so that no such changes will occur after delivery to the customer.
The switching aging is carried out under the conditions shown in Table 1, for example.
For the reasons mentioned above, the "lift amount" is set to a predetermined value between 0.3 mm and 0.4 mm, but in this embodiment it is set to 0.3 mm.
Since a normally closed diaphragm valve is used in this embodiment, the pressing force of the spring 6 becomes the pressing force for the closing operation.
The "opening and closing environment temperature" is not limited to 120°C, but can be any temperature between 80°C and 150°C. However, it is preferable to set the temperature as high as possible within the usable temperature range of the product, as this will promote the aging effect. The maximum usable temperature for the resins that make up the sheet, such as PTFE and PFA, is about 260°C, so there is no problem with opening and closing aging within the above temperature range.
The reason why the "number of opening and closing times" was set at 10,000 times is that the evaluation results of the change in Cv value due to opening and closing aging described later showed that the Cv value stabilized after 10,000 opening and closing times, and good results were also obtained for the change in Cv value due to leaving it open at 120° C. As mentioned above, based on experience, if the actual lift amount is 0.3 mm, the durability of the diaphragm is 40 million opening and closing times in actual performance, so it is possible to perform opening and closing aging up to about 300,000 times if necessary.

FIG. 6 is an explanatory diagram showing the opening and closing aging method.
The test equipment shown in Figure 6 allows three diaphragm valves configured as air-operated valves to be aged in parallel by opening and closing. Each diaphragm valve is placed in a thermostatic chamber set at a temperature of 120°C, with the primary side open to atmospheric pressure and the secondary side evacuated by a vacuum pump.
Nitrogen gas (0.5 MPa) is supplied as operating air to the solenoid valve 16 (see FIG. 1) of each diaphragm valve (air operated valve) from the operation unit, and a signal for turning the solenoid valve ON/OFF is also supplied from the operation unit.
This allows the door to be opened and closed a predetermined number of times at a predetermined opening and closing speed.

(d3) Flow rate lift adjustment (Cv value adjustment)
In this process, after aging, the lift amount is adjusted again so that the Cv value, which represents the ease with which the controlled fluid flows when the valve is fully open, becomes a predetermined value.
Although this step is not essential to the present invention, it is preferable to carry out this step since it is a step to confirm whether a predetermined flow rate can be obtained when fully opened under high temperature conditions (e.g., 120°C) where the sheet expands and the flow path is likely to be narrowed. For this purpose, it is preferable to set the temperature in this step as high as possible within the usable temperature range of the product.
The lift amount adjustment method in this step is the same as in (d1), in that the actuator 9 screwed into the bonnet 4 is rotated to adjust the vertical position of the actuator 9.
When the fluid is a gas, the Cv value can be calculated by the following formula (1).
In equation (1), Qg [m ³ /h (standard conditions)] is the gas flow rate at standard conditions (15°C, 760 mmHgabs), t [°C] is the gas temperature, Gg is the gas specific gravity (when air = 1), P ₁ [MPa abs] is the primary absolute pressure, and P ₂ [MPa abs] is the secondary absolute pressure.

Figure 7 is an explanatory diagram showing the Cv value measurement method. Using the Cv value measurement test device shown in Figure 7, the mass flow rate Qg of nitrogen gas N2 supplied from the N2 (nitrogen gas) supply source is measured with a mass flow control device MFC, and the nitrogen gas N2 is heated to a specified temperature (120°C) and passed through the diaphragm valve of the test specimen (open state with a specified lift amount) and released to the atmosphere via the dry pump DP. The pressures on the primary and secondary sides of the diaphragm valve at this time are measured with pressure gauges P and P, respectively. The measurement results are used to calculate the Cv value according to the above formula (1).

(Effects of the embodiment of the present invention)
FIG. 8 is a graph showing the change in Cv value due to switching aging.
In this evaluation, three test valves were used and subjected to open/close aging with a lift of 0.3 mm. Each valve was removed from the open/close aging apparatus shown in Figure 6 after 10,000 experimental open/close cycles, and the Cv value was measured using the Cv measurement test apparatus shown in Figure 7.
The test conditions are shown in Table 2.
As a result, as shown in the graph in FIG. 8, the Cv value of each valve increased by approximately 15% from the initial Cv value of 0.117, and it can be seen that the change in the Cv value stabilized after aging with 10,000 opening and closing operations.

Next, FIG. 9 is a graph showing the change in Cv value when left open at 120° C.
Three valves that had been aged by opening and closing 10,000 times with a lift of 0.3 mm and three valves that had not been aged by opening and closing were used to compare and evaluate the change in Cv value when left open at 120°C.
The test conditions are shown in Table 3.
As a result, as shown in FIG. 9, in the valve without open-close aging, the Cv value decreased by about 30% after one hour of open-close time, whereas in the valve that had been aged with open-close, almost no decrease in the Cv value was observed.

The reason why the change in Cv value due to subsequent open-close aging at 120° C. is thus reduced is believed to be as follows.
As shown in FIG. 10, before open-close aging, there are gaps between the molecules of the resin material, such as PTFE or PFA, that constitutes the sheet, and therefore the sheet has room to deform by the amount of the gaps.
Next, the sheet is subjected to open-close aging at 120°C. The sheet is repeatedly pressed and crushed, eliminating gaps between the molecules and leaving no room for deformation, stabilizing the shape.
Furthermore, when exposed to 120°C, the gaps between the crushed molecules widen slightly, increasing the room for deformation. However, since the room for deformation is now smaller than before open-close aging, it is believed that the amount of deformation is smaller.

(Summary of effects)
(1) Effect of Opening and Closing Aging on Cv Value Stabilization It was confirmed that the opening and closing aging of this embodiment had a sufficient effect of reducing the change in Cv value over time, even with a small lift amount of 0.3 mm, and an effect of reducing the change in Cv value when placed in an open position at 120°C.
In open-close aging, the larger the lift amount, the greater the impact force when closing, and therefore it is thought that the aging effect is also greater. However, in this embodiment, a sufficient effect was obtained even with a lift amount of 0.3 mm, which is smaller than the lift amount of approximately 1.1 mm in the open-close aging in the case of Patent Document 2.

(2) Effect of opening and closing aging on diaphragm durability Although no experiments were conducted on this point this time, it is based on experience that if the lift amount used is 0.3 mm, the diaphragm has an actual durability of 40 million opening and closing cycles, so aging through opening and closing about 10,000 times is thought to pose no problem to the durability of the diaphragm.
Let us consider the case where the lift amount ΔS during opening and closing aging is 0.4 mm. When the outer diameter of the diaphragm is D, the thickness is t, and the lift amount is ΔS, the distortion amount ε due to the opening and closing of the diaphragm is considered to be proportional to tΔS/D. When the diaphragm outer diameter D = 26 mm, tΔS/D = 0.015t, when the diaphragm outer diameter D = 20 mm, tΔS/D = 0.02t, and even when the diaphragm outer diameter D = 15 mm, tΔS/D = 0.027t. In all cases, the distortion amount ε is smaller than the case of Patent Document 2 (outer diameter 26 mm, lift amount 1.1 mm, tΔS/D = 0.042t), and even in this case, the effect of opening and closing aging on the diaphragm life is considered to be small.

The present invention is not limited to the above-described embodiment, and those skilled in the art can make various additions and modifications within the scope of the present invention.
For example, in this embodiment, the manufacturing method of the present invention is applied to a diaphragm valve configured as an air-operated valve using an air cylinder as an actuator, but the manufacturing method of the present invention is not limited to this and can also be applied to a diaphragm valve using a solenoid or a piezoelectric element as an actuator.

1: Body 2: Diaphragm 3: Pressing adapter 4: Bonnet 5: Threaded portion 6: Spring 7: Diaphragm presser 8: Stem 8a: Flange portion 9: Actuator 9a: Supporting cylinder portion (piston)
10: Fluid inlet 11: Fluid outlet 12: Valve chamber 13: Seat 14: Drive shaft 15: Stroke adjustment mechanism 15a: Lock nut 16: Solenoid valve 17: Proximity switch ΔS: Lift amount D: Outer diameter t of diaphragm: Thickness ε: Amount of distortion

Claims (4)

a body having a valve chamber that opens to an upper surface thereof, and a fluid inlet passage and a fluid outlet passage that open to a bottom surface of the valve chamber provided therein;
an annular seat disposed around an opening of the fluid inlet passage in a bottom surface of the valve chamber;
a diaphragm disposed to seal the valve chamber, the diaphragm elastically deforming to come into contact with and separate from the seat to close and open the fluid inlet passage;
a diaphragm operating portion having a tip portion which moves up and down while pressing the diaphragm to bring the diaphragm into contact with and away from the sheet;
A method for manufacturing a diaphragm valve comprising:
adjusting an amount of elevation of a tip end portion of the diaphragm operation portion when the diaphragm is pressed against the sheet and when the diaphragm is released from the sheet to a predetermined amount;
Then, a break-in step is performed by causing the diaphragm to come into contact with and separate from the seat a predetermined number of times using the diaphragm operation unit,
the diaphragm is a circular laminate having an outer diameter of 14.5 mm to 26.5 mm and made of a laminate of stainless steel thin plates and nickel-cobalt alloy thin plates, the predetermined number of times is at least 10,000 times,
The predetermined amount is 0.3 mm to 0.4 mm.
A method for manufacturing a diaphragm valve. The method for manufacturing a diaphragm valve according to claim 1, wherein the break-in step is performed at a temperature within a range of 80°C to 150°C. The method for manufacturing a diaphragm valve according to claim 2, wherein the temperature is the upper limit temperature of the operating temperature range of the diaphragm valve. The method for manufacturing a diaphragm valve according to any one of claims 1 to 3 further comprises a step of adjusting the Cv value of the diaphragm valve after the break-in step.