JP2017096334A - Manufacturing method of high pressure tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress contraction of a liner in manufacturing of a high pressure tank, and suppress occurrence of an excessively large clearance between the liner and fiber-reinforced resin layer.SOLUTION: A manufacturing method of a high pressure tank includes the steps of: (a) forming a fiber-reinforced resin layer covering the periphery of a liner, by heating a workpiece to cure a fiber-reinforced resin material while imparting first pressure to the inside of the workpiece, in which the fiber-reinforced resin material is wound around the liner; and (b) cooling the workpiece. In the step (b), in a process of cooling the workpiece, at the time of start of cooling, inner pressure of the workpiece is lowered from the first pressure to second pressure lower than the first pressure, in a standby period after lowering the inner pressure of the workpiece, the inner pressure of the workpiece is kept at the second pressure, and in a pressure increasing period after the standby period, the inner pressure of the workpiece is increased from the second pressure.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a method for manufacturing a high-pressure tank.

  Conventional high-pressure tanks have a carbon fiber reinforced plastic layer or a glass fiber reinforced plastic layer around the liner (hereinafter these layers are collectively referred to as “fiber reinforced plastic layer” or “fiber reinforced resin layer”). It has a structure covered with a reinforcing layer. Such a high-pressure tank is usually manufactured by forming a work in which a fiber reinforced fiber reinforced resin material is wound around a liner and curing the fiber reinforced resin material layer by heating (heating) the work. For example, in Patent Document 1, the internal temperature of the workpiece is rapidly increased by increasing the temperature of the curing furnace and curing the fiber-reinforced resin material layer while applying the internal pressure of the workpiece, and then reducing the internal pressure of the workpiece. A method for manufacturing a high-pressure tank is described in which the workpiece is cooled also from the inside of the workpiece by being lowered to the bottom.

JP 2011-012764 A

  However, in the manufacturing method described in Patent Document 1, when the fiber reinforced resin material layer is cured, a compressive stress is applied to the liner due to the internal pressure applied to the liner and the thermal expansion of the liner. In this case, there is a possibility that the liner contracts due to creep caused by the applied compressive stress. The shrinkage of the liner may generate a gap between the fiber reinforced resin layer and the liner. If the amount of this gap is large, cracks may occur due to the expansion of the liner when the high-pressure tank is used in a low-temperature pressure state.

  In order to achieve at least a part of the problems described above, the present invention can be implemented as the following forms.

(1) According to one form of this invention, the manufacturing method of a high pressure tank is provided. In this high pressure tank manufacturing method, (a) a first pressure is applied to the inside of a work in which a fiber reinforced resin material is wound around a liner, and the work is heated to cure the fiber reinforced resin material. Forming a fiber reinforced resin layer covering the periphery of the liner; and (b) cooling the workpiece. In the process of cooling the workpiece, the step (b) reduces the internal pressure of the workpiece from the first pressure to a second pressure lower than the first pressure at the start of cooling; The internal pressure of the work is maintained at the second pressure in the standby period after the internal pressure is reduced; and the internal pressure of the work is increased from the second pressure in the pressure increase period after the standby period.
In the high pressure tank manufacturing method of the above aspect, in the cooling process, the internal pressure of the workpiece is reduced to the second pressure and maintained for the standby period, and then gradually increased from the second pressure during the pressure increase period. By applying pressure, creep due to tensile stress in the direction of expanding the liner can be generated in the liner. Thereby, when the fiber reinforced resin material is cured, the shrinkage of the liner caused by the creep due to the compressive stress applied to the liner due to the thermal expansion according to the first pressure and the curing temperature applied to the inside of the workpiece is suppressed. be able to. As a result, it is possible to suppress the occurrence of an excessively large gap between the fiber reinforced resin layer and the liner.

The pressure increase period may be started when it is estimated that the liner is separated from the fiber reinforced resin layer. Moreover, it is good also as starting after the time estimated that the said liner isolate | separated from the said fiber reinforced resin layer.
If it does in this way, it can control that the gap between the liner and fiber reinforced resin layer which generate | occur | produces when a liner isolate | separates from a fiber reinforced resin layer increases.

  In addition, this invention can be implement | achieved with various forms, for example, can be implement | achieved in aspects, such as a manufacturing method of a high pressure tank, a manufacturing apparatus of a high pressure tank.

It is a schematic sectional drawing which shows the structure of a high pressure tank typically. It is explanatory drawing which shows the example of the manufacturing apparatus which enforces the manufacturing method of a high pressure tank. It is explanatory drawing which shows the procedure of the manufacturing method of a high pressure tank. It is explanatory drawing which shows the relationship between the furnace temperature, the internal pressure of a workpiece | work, the stress of a liner, and the creep distortion of a liner.

  FIG. 1 is a schematic cross-sectional view schematically showing the configuration of a high-pressure tank manufactured by the manufacturing method of the embodiment of the present invention. The high-pressure tank 10 includes a liner 110, a fiber reinforced resin layer 140 that covers the liner 110, and caps 120 and 130 provided at both ends in the liner axis CX direction.

  The liner 110 is a hollow tank container, and is a joined product of a pair of liner parts divided into two at the center in the longitudinal direction. Each of the two-part liner parts is molded with a resin having an appropriate gas barrier property, such as nylon resin, and the liner parts of the molded parts are joined and laser welded to the joined parts. Is formed. Through this part joining, the liner 110 includes spherical dome portions 112 on both sides of the cylindrical cylinder portion 111 in the liner axis CX direction, and an internal space (also referred to as “storage space”) 114 for storing gas. Will be provided.

  The fiber reinforced resin layer 140 is impregnated with a fiber reinforced resin material (thermosetting resin material) wound so as to cover the liner 110 and the peripheral portion of the caps 120 and 130 excluding the opening facing the liner axis CX direction. The outer layer of the liner 110 and the bases 120 and 130 are covered by curing the layer of the fibers. The winding of the fiber reinforced resin material is preferably performed by a filament winding method. An epoxy resin is generally used as the thermosetting resin material of the fiber reinforced resin material, but a thermosetting resin such as a polyester resin or a polyamide resin can also be used. In addition, as a reinforcing fiber (sliver fiber) to be wound around the liner, glass fiber, carbon fiber, aramid fiber, etc. are used, and a plurality of types of fibers (for example, glass fiber and carbon fiber) are sequentially wound. Thus, the fiber reinforced resin material layer can be formed by laminating resin material layers composed of different types of fibers. In this embodiment, a fiber reinforced resin material having conductivity using carbon fibers and epoxy resin is used.

  The caps 120 and 130 are made of a lightweight metal such as aluminum or an alloy thereof, and are provided in the dome portion 112 of the liner 110 around the liner axis CX. Female threads are engraved on the inner peripheral surfaces of the openings of the caps 120 and 130, and the male screws of functional parts such as pipes and valve assemblies are screwed into the female screws, so that other parts can be connected to the cap 120. , 130 can be connected by screwing. In FIG. 1, an example in which the valve assembly VA is connected to the base 120 is indicated by a two-dot chain line.

  For example, in the high-pressure tank 10 provided in the fuel cell system, the storage space 114 and a gas flow path (not shown) are connected via the valve assembly VA, and the storage space 114 is filled with hydrogen as a fuel gas. At the same time, hydrogen is released from the storage space 114 and used for power generation of the fuel cell.

  FIG. 2 is an explanatory diagram illustrating an example of a manufacturing apparatus that performs a method for manufacturing a high-pressure tank according to an embodiment of the present invention. The manufacturing apparatus 1000 includes a curing furnace 20, rotating rods (rotating units) 30 and 40, a gas piping system 50, and a control unit 60.

  The curing furnace 20 includes a furnace space in which a workpiece 10P having an uncured fiber reinforced resin material layer 140P is set. The workpiece 10 </ b> P is set in the furnace space with the rotating rods 30 and 40 attached to the openings of the caps 120 and 130. In addition, in the process of the hardening process mentioned later, the workpiece | work 10P can be heated uniformly by rotating the rotating bars 30 and 40 suitably with a drive device not shown. A temperature sensor 24 that measures the temperature in the curing furnace 20 (hereinafter also referred to as “furnace temperature”), that is, the ambient temperature of the workpiece 10 </ b> P is provided in the curing furnace 20.

  The gas piping system 50 includes a main piping 51 and a furnace piping 52. The main pipe 51 is provided with a pressure regulating valve 511, a back pressure valve 512, pumps 513 and 515, and a pressure sensor 514. The in-furnace piping 52 branches from the main piping 51 and extends into the curing furnace 20, and is attached to the base 120 of the workpiece 10 </ b> P via the rotating rod 30. The pump 515 and the pressure regulating valve 511 are disposed on the upstream side of the branch position to the in-furnace piping 52. The back pressure valve 512 and the pump 513 are arranged on the downstream side from the branch position to the in-furnace piping 52. The pressure sensor 514 is disposed between the pressure regulating valve 511 and the back pressure valve 512, and can detect the internal pressure (internal pressure) of the workpiece 10P. By adjusting the pressure regulating valve 511, the back pressure valve 512, and the pumps 513 and 515 of the main pipe 51, the internal pressure of the workpiece 10P connected to the furnace pipe 52 can be adjusted.

  The controller 60 controls the operation of the curing furnace 20 based on the furnace temperature detected by the temperature sensor 24, and based on the pressure detected by the pressure sensor 514, the pressure regulating valve 511, the back pressure valve 512, and the pumps 513, 515. The internal pressure of the workpiece 10P is adjusted by adjusting the above, and the drive circuit (not shown) is controlled to control the rotation of the rotary bars 30 and 40. The control part 60 performs the hardening process of the fiber reinforced resin material layer 140P of the workpiece | work 10P set to the manufacturing apparatus 1000 by these control.

  2B, two conductive terminals 22a and 22b are attached to the work 10P set in the curing furnace 20 along the circumferential direction on the outer peripheral surface of the work 10P. The terminals 22a and 22b are connected to the control unit 60, respectively. The controller 60 can measure the resistance value between the two conductive terminals 22a and 22b. The resistance value measured by the two conductive terminals 22a and 22b will be described later.

  FIG. 3 is an explanatory diagram showing a procedure of a method for manufacturing a high-pressure tank as an embodiment of the present invention. FIG. 4 is an explanatory view showing the relationship among the furnace temperature, the workpiece internal pressure, the liner stress, and the liner creep strain in the manufacturing method of FIG. In FIG. 4, a change in the embodiment is indicated by a solid line, and a change in the comparative example is indicated by a one-dot chain line.

  First, in step S10 of FIG. 3, the workpiece 10P having the uncured fiber reinforced resin material layer 140P is set in the furnace space of the curing furnace 20 (see FIG. 2).

  Next, Step S20 to Step S40 are curing steps in which the fiber reinforced resin material layer 140P of the workpiece 10P is cured to form the fiber reinforced resin layer 140 that covers the periphery of the liner 110. Specifically, in step S20, the internal pressure of the workpiece 10P is set to the first pressure P1, and in step S30, the inside of the curing furnace 20 is heated to set the furnace temperature to room temperature Tn (for example, 25 ° C.). To a curing temperature Tc (for example, 160 ° C.), and in step S40, the furnace temperature is maintained at the curing temperature Tc until the curing is completed after the furnace temperature reaches the curing temperature Tc. The fiber reinforced resin material layer 140P is cured.

  In the period of the curing process of Step S20 to Step S40, the internal pressure applied to the workpiece 10P is kept at the first pressure P1. The first pressure P1 is higher than the atmospheric pressure Pn in order to maintain the shape until the fiber reinforced resin material layer 140P is cured, and from the gas pressure (1 MPa) defined as the high pressure gas by the high pressure gas safety method. It is preferable that the pressure is low. In this example, P1 = (0.85 + Pn) = 0.95 MPa with respect to Pn = 0.10 MPa.

  In the process of waiting for the completion of curing in step S40, the furnace temperature is maintained at the curing temperature Tc. The curing temperature Tc is a temperature for curing the thermosetting resin material (in this example, epoxy resin) included in the fiber reinforced resin material.

  In FIG. 4, the internal pressure setting in step S20 is executed at time t0, the temperature increase in step S30 is executed between time t0 and time t2, and the curing completion waiting in step S40 is executed between time t2 and time t3. By doing so, an example is shown in which the curing process of step S20 to step S40 is executed between time t0 and time t3. The curing completion waiting periods t2 to t3 can be set by obtaining in advance an experiment the time required to cure the fiber reinforced resin material layer 140P at the curing temperature Tc. In addition, the hardening process of a comparative example is the same as embodiment.

  Steps S50 to S90 in FIG. 3 are cooling steps for cooling the workpiece 10P by lowering the furnace temperature from the curing temperature Tc to the room temperature Tn.

  First, in step S50, heating control in the furnace of the curing furnace 20 that has been performed is stopped, and cooling of the workpiece 10P is started. The workpiece 10P is cooled by cooling the inside of the curing furnace 20 and lowering the furnace temperature from the curing temperature Tc to the room temperature Tn. For example, it is possible to perform cooling by ventilation in the furnace of the curing furnace 20 or natural heat dissipation.

  When the cooling is started, the internal pressure of the workpiece 10P is reduced from the first pressure P1 to the second pressure P2 in step S60. The decompression is preferably started immediately at the start of cooling (ie, simultaneously with the start of cooling). In step S70, after the pressure is reduced to the second pressure P2, the second pressure P2 is kept on standby until the standby period elapses. In step S80, the internal pressure of the workpiece 10P is increased from the second pressure P2 until the pressure increasing period elapses after the standby period has elapsed (that is, at the start of the pressure increasing period). In step S90, Wait until the furnace temperature drops to room temperature Tn and cooling is complete. In step S80, it is preferable to increase the pressure to the first pressure P1. The second pressure P2 is lower than the first pressure P1 (0.95 MPa in this example) and is close to the atmospheric pressure Pn. In this example, P2 = (0.1 + Pn) = 0.2 MPa with respect to Pn = 0.1 MPa in this example.

  In FIG. 4, the pressure reduction in step S60 is executed between time t3 and time t4, the standby at the second pressure P2 in step S70 is executed in the standby period from time t4 to time t5, and time t5 to time t6. In this example, the pressure increase in step S80 is executed during the pressure increase period, and the cooling completion wait in step S90 is executed between time t6 and time t8. In the cooling process of the comparative example, it is assumed that the first pressure P1 is maintained without changing the internal pressure of the workpiece 10P during the cooling process (indicated by a one-dot chain line).

  Here, as shown in FIG. 4, in the curing step and the cooling step, the liner 110 is subjected to stress and stress along the circumferential direction of the liner 110 according to the furnace temperature and the internal pressure of the liner 110. Corresponding creep distortion occurs. 4 shows the stress assumed according to the furnace temperature and the internal pressure of the liner 110, and the creep strain shown in FIG. 4 shows the creep strain assumed according to the stress.

  First, the stress and creep strain in the curing process will be described. At the temperature rise start time t0, a positive stress (also referred to as “tensile stress”) is generated in the liner 110 in accordance with the internal pressure (first pressure P1). In the temperature rising period from time t0 to time t2, the positive stress decreases and the negative stress (also referred to as “compressive stress”) increases in accordance with the expansion of the liner 110 due to the temperature increase. While the stress applied to the liner 110 is a tensile stress, the creep strain on the + side (also referred to as “tensile creep”) gradually increases. The increase in tensile creep acts in the direction in which the adhesion between the liner 110 and the fiber reinforced resin layer 140 increases in the high-pressure tank 10 after manufacture. From time t1 when the stress changes from the plus side to the minus side, a negative creep strain corresponding to the compressive stress (also referred to as “compressive creep”) occurs, and the compressive creep according to the compressive stress. Will increase. The increase in the compression creep acts in the direction in which the gap between the liner 110 and the fiber reinforced resin layer 140 increases in the high-pressure tank 10 after manufacture.

  In the period waiting for the completion of curing from time t2 to time t3, the furnace temperature is maintained at the curing temperature Tc, so that the increase in compressive stress stops, but the compressive creep corresponding to the compressive stress gradually increases with time. To go. However, as the compressive creep increases, the compressive stress gradually decreases, and the increase rate of the compressive creep gradually decreases accordingly.

  When a constant internal pressure (first pressure P1) is applied to the liner 110 as in the comparative example in the period of the cooling process from the time t3 to the time t8, the liner 110 contracts according to the decrease in the furnace temperature. The compressive stress decreases. However, since the compressive stress due to the first pressure P1 is applied to the liner 110, the compression creep increases in response to this while the rate of increase gradually decreases. Then, at time t7, when the stress applied to the liner 110 changes from the minus side (compressive stress) to the plus side (tensile stress), the compression creep slightly decreases according to the increase in tensile stress until cooling is completed at time t8. To do. In the case of the comparative example, shrinkage corresponding to the compression creep at time t8 occurs in the liner 110, and a large gap may occur between the liner 110 and the fiber reinforced resin layer 140.

  On the other hand, in the case of the embodiment, after cooling is started at time t3 of the cooling process period from time t3 to time t8, the internal pressure of the liner 110 is reduced, and between time t3 and time t4, The internal pressure of the liner 110 is rapidly reduced from the first pressure P1 to the second pressure P2. In accordance with this steep pressure reduction, the compressive stress applied to the liner 110 also sharply decreases. Time t4 is the elapsed time from time t3 determined by the response time.

  In the standby period from time t4 to time t5, since the internal pressure of the liner 110 is reduced to the second pressure P2, the shrinkage of the liner 110 accompanying the decrease in the furnace temperature and the shrinkage of the liner 110 accompanying the compression creep are performed. Is possible. For this reason, the liner 110 actually contracts with time, and the compressive stress and compressive creep gradually decrease accordingly.

  At time t5, when the stress changes from a negative stress to a positive stress, the compressive stress applied to the liner 110 disappears, and a tensile stress corresponding to the internal pressure is generated. This means that when the liner 110 contracts, the liner 110 is separated from the fiber reinforced resin layer 140 and is in a non-contact state. That is, time t5 indicates a time when the liner 110 is separated from the fiber reinforced resin layer 140 and is in a non-contact state. However, since the shrinkage force of the liner 110 due to a decrease in the furnace temperature and the shrinkage force of the liner 110 due to compression creep are stronger than the tensile stress corresponding to the internal pressure, if the internal pressure is maintained at a reduced pressure, the liner The shrinkage of 110 continues and the gap between the liner 110 and the fiber reinforced resin layer 140 increases.

  Therefore, in the present embodiment, control for gradually increasing the internal pressure of the liner 110 is executed in the pressure increasing period from time t5 to time t6. The example of FIG. 4 shows a state where the pressure is gradually increased from the second pressure P2 to the first pressure P1 so as to become the first pressure P1 at time t6. The time t6 is a time when the temperature becomes equal to or lower than a temperature Te (also referred to as “shrinkage end temperature Te”, for example, 40 ° C.) at which it can be determined that the thermal contraction due to the cooling of the liner 110 has stopped. Then, in the period of waiting for cooling completion from time t6 to time t8, the internal pressure of the liner 110 is maintained at the first pressure P1, the temperature in the furnace is lowered to room temperature Tn, and the cooling is completed, and then the cooling is finished. .

  Here, the speed of the pressure increase during the pressure increase period can reduce the compression creep due to the tensile stress applied to the liner 110 by the pressure increase, but the liner 110 excessively expands due to the tensile stress and again becomes the fiber reinforced resin layer 140. It is preferable to limit to a size that does not allow contact. In this way, by gradually increasing the internal pressure of the liner 110 while limiting the speed of pressure increase, the compression creep can be reduced by the tensile stress applied to the liner 110 by the pressure increase. Thereby, in the high-pressure tank 10 after completion of cooling (after manufacture), it is possible to suppress an excessive increase in the gap between the liner 110 and the fiber reinforced resin layer 140 generated by compression creep.

  Whether the liner 110 and the fiber reinforced resin layer 140 are in contact (non-separation) or non-contact (separation) is determined between the two conductive terminals 22a and 22b (see FIG. 2). It can be detected by measuring the resistance. Specifically, when the liner 110 is not in contact with (separated from) the fiber reinforced resin layer 140, the internal pressure of the liner 110 is high and compared to the resistance value in a state where the liner 110 is in contact with the fiber reinforced resin layer 140. Since it becomes low, the change to the non-contact state of the liner 110 can be detected by detecting whether or not the resistance value has fallen below a predetermined threshold value. Conversely, by detecting whether or not the resistance value exceeds the threshold value, it is possible to detect a change in the contact state of the liner 110. Accordingly, a change in resistance value is detected, and pressure increase is started from time t5 when it is estimated that the liner 110 has separated from the fiber reinforced resin layer 140, and the pressure is increased so that the liner 110 does not contact the fiber reinforced resin layer 140 again. Control of pressure increase from time t5 to time t6 may be executed while limiting the pressure speed. Note that the internal pressure at time t6 when the furnace temperature becomes equal to or lower than the shrinkage end temperature Te is not limited to the first pressure P1, but may not reach the first pressure P1, and the first pressure P1. May be exceeded. Also in this case, the shrinkage of the liner 110 is suppressed while maintaining the non-contact (separated) state of the liner 110 with respect to the fiber reinforced resin layer 140 until the shrinkage end temperature Te at which the shrinkage of the liner 110 due to cooling converges. It is preferable to increase the pressure at a pressure increase rate that can be achieved.

  In the above description, the time when it is estimated that the liner 110 has been separated from the fiber reinforced resin layer 140 is detected using the detection of the resistance change between the conductive terminals 22a and 22b. An example has been described in which the pressure is gradually increased from a certain time t5 while the pressure increasing speed is limited so that the contact state is not reached again. However, the time t5 at which the pressure increase is started is not limited to the time when the liner 110 is estimated to be separated from the fiber reinforced resin layer 140, and may be a time after the time when it is estimated that the liner 110 is separated. In this case as well, the contraction of the liner 110 is controlled by expanding the contraction of the liner 110 generated from the time of separation until the start of pressure increase and controlling the speed of pressure increase so that the pressure does not come into contact again. Can be suppressed. As a result, it is possible to suppress the occurrence of an excessively large gap between the fiber reinforced resin layer 140 and the liner 110.

  In addition, an experiment is performed in advance to determine each time t4, t5, t6, t8, and a pressure increase rate is determined. Based on this, a pressure reduction period, a standby period, a pressure increase period, and a cooling completion wait The high pressure tank may be manufactured by determining the period of time and executing the control of the furnace temperature and the control of the internal pressure. In this way, it is possible to simplify the manufacturing by omitting detection of a change in the contact state or non-contact state between the liner 110 and the fiber reinforced resin layer 140. It should be noted that a strain sensor is provided between the fiber reinforced resin material layer 140P and the liner 110 to measure the strain generated in the liner 110 when a manufacturing schedule such as time and pressure increase speed is set by experiment in advance. By doing so, it is possible to use means for detecting contact / non-contact between the liner 110 and the fiber reinforced resin layer 140. In particular, when the fibers constituting the fiber reinforced resin layer are not conductive carbon fibers but non-conductive fibers such as glass fibers, the strain sensor is used to form the liner 110 and the fiber reinforced resin layer 140. This is effective for detecting a contact / non-contact state between the two.

  The present invention is not limited to the above-described embodiments, examples, and modifications, and can be realized with various configurations without departing from the spirit thereof. For example, the technical features in the embodiments, examples, and modifications corresponding to the technical features in each embodiment described in the summary section of the invention are to solve some or all of the above-described problems, or In order to achieve part or all of the above-described effects, replacement or combination can be performed as appropriate. Further, if the technical feature is not described as essential in the present specification, it can be deleted as appropriate.

DESCRIPTION OF SYMBOLS 10 ... High pressure tank 10P ... Workpiece 110 ... Liner 111 ... Cylinder part 112 ... Dome part 114 ... Internal space (storage space)
DESCRIPTION OF SYMBOLS 120,130 ... Base 140 ... Fiber reinforced resin layer 140P ... Fiber reinforced resin material layer 20 ... Curing furnace 22a, 22b ... Conductive terminal 24 ... Temperature sensor 30, 40 ... Rotary rod 50 ... Gas piping system 51 ... Main piping 52 ... Furnace Inner piping 511 ... Pressure regulating valve 512 ... Back pressure valve 513 ... Pump 514 ... Pressure sensor 515 ... Pump 60 ... Control unit 1000 ... Manufacturing equipment VA ... Valve assembly CX ... Liner axis Tc ... Curing temperature Te ... Shrink end temperature Tn ... Room temperature Pn ... Atmospheric pressure P1 ... first pressure P2 ... second pressure t0-t8 ... time

Claims (1)

A method for manufacturing a high-pressure tank, comprising:
(A) While applying a first pressure to the inside of the work around which the fiber reinforced resin material is wound around the liner, the work is heated to cure the fiber reinforced resin material, thereby surrounding the liner. Forming a fiber reinforced resin layer to be coated;
(B) a step of cooling the workpiece;
With
In the process of cooling the workpiece, the step (b)
At the start of cooling, the internal pressure of the workpiece is reduced from the first pressure to a second pressure lower than the first pressure,
In the standby period after reducing the internal pressure of the work, the internal pressure of the work is maintained at the second pressure,
In the pressure increasing period after the waiting period, the internal pressure of the work is increased from the second pressure.
Manufacturing method of high-pressure tank.

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