Foaming device and foaming method

Abstract

The present invention provides a foaming device (100) which discharges a foamable material (M) obtained by mixing a gas (G) into a viscous material of a resin (R) to disperse bubbles in the liquid of the viscous material, wherein the foaming device (100) includes: a pipe (10) allowing the resin and the gas to flow; a material supply unit (20) for supplying the viscous material into the pipe; a gas supply unit (32) for supplying the gas into the pipe; a first gear pump (31) disposed midway along the pipe; a second gear pump (33) which is disposed on the downstream side of the pipe relative to the first gear pump and which is rotationally driven at a higher speed than the first gear pump, thereby causing the gas to flow into the pipe and feeding the viscous material containing the gas to the downstream side of the pipe; a third gear pump (34) which is disposed on the downstream side of the pipe relative to the second gear pump and which is rotationally driven at the same speed as the second gear pump, thereby feeding the viscous material containing the gas further to the downstream side of the pipe; a mixer (41) which is disposed on the downstream side of the pipe relative to the third gear pump to disperse bubbles in the viscous material into the liquid of the viscous material; a discharge unit (45) which discharges the foamable material obtained as a result of the bubbles being dispersed in the liquid of the viscous material by the mixer; and a control unit (50) which controls a discharge operation for discharging the foamable material.

Description

[Technical field]

[0001] The present invention relates to a foaming device and a foaming method. [Background technology]

[0002] Conventionally, foams have been used as industrial sealing materials or vibration-proofing materials by mixing gas into liquid such as liquid resin, foaming the foamable material with bubbles dispersed in the liquid, and hardening or solidifying it. Known methods for producing foams include chemical foaming, in which two liquids, a base agent and a hardener, are mixed together to chemically foam, and mechanical foaming, in which gas is mechanically mixed into a one-liquid liquid.

[0003] Chemical foaming utilizes chemical reactions, so it is difficult to control the foaming ratio due to environmental factors such as temperature, humidity, and the mixed state of two or more liquids. In contrast, mechanical foaming mechanically mixes gas, so it is less susceptible to environmental factors and the foaming ratio can be controlled relatively easily. For this reason, it is desirable to use mechanical foaming for sealing materials and vibration-proofing materials for electronic and automotive parts, which require more precise control of the foaming ratio.

[0004] Mechanical foaming devices are mainly classified into plunger pump type and gear pump type. Gear pump type can deliver liquid quantitatively, so it is easier to control the foaming ratio than plunger pump type.

[0005] For example, the following Patent Document 1 discloses a gear pump type mechanical foaming device that includes two gear pumps arranged in a flow path through which liquid resin is delivered, and a gas supply unit that supplies gas into the flow path through an intake port provided in the flow path between the two gear pumps. In this device, the rotation speed of the gears of each gear pump is controlled to generate suction pressure (negative pressure) in the flow path between the gear pumps, thereby causing a desired amount of gas to flow into the flow path. In order to control the foaming ratio to an appropriate value, operation control is performed to adjust the suction pressure by controlling the rotation speed of each gear pump. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2005-152710 A Summary of the Invention

[0007] When two pumps are installed in a flow path as in Patent Document 1, the downstream pump needs to suck not only the liquid but also the gas required for foaming from the intake port due to the pressure difference, so it needs to rotate faster than the upstream pump. When the downstream pump is configured in this way, the load on the downstream pump becomes relatively high. In such a case, there is a risk that the mixture of liquid and gas sent from the downstream pump will be sent back to the upstream side due to fluctuations in the rotation speed or pressure of the downstream pump. In this way, the load on the downstream pump makes it difficult to send out liquid and gas at a constant ratio in the foaming device, and it becomes difficult to obtain a stable foaming ratio.

[0008] Therefore, an object of the present invention is to obtain a stable expansion ratio in a foaming device and a foaming method.

[0009] A foaming device according to an aspect of the present invention for solving the above problems mixes gas into a viscous material and discharges a foamable material in which bubbles are dispersed in the liquid. The foaming device has a flow path, a material supply unit, a gas supply unit, a first gear pump, a second gear pump, a third gear pump, a mixer, a discharge unit, and a control unit. The flow path distributes the viscous material and the gas. The material supply unit supplies the viscous material to the flow path. The gas supply unit supplies the gas to the flow path. The first gear pump is disposed in the middle of the flow path. The second gear pump is disposed downstream of the flow path from the first gear pump, and is driven to rotate at a higher speed than the first gear pump, thereby causing the gas to flow into the flow path and sending the viscous material containing the gas to the downstream side of the flow path. The third gear pump is disposed downstream of the flow path from the second gear pump, and is driven to rotate at the same speed as the second gear pump, thereby sending the viscous material containing the gas to the further downstream side of the flow path. The mixer is disposed downstream of the third gear pump in the flow path and disperses bubbles in the viscous material into the liquid viscous material. The discharge unit discharges the foamable material generated by dispersing the bubbles into the liquid viscous material by the mixer. The control unit controls the discharge operation to discharge the foamable material.

[0010] In addition, a foaming method according to one aspect of the present invention mixes gas into a viscous material to produce a foamable material in which bubbles are dispersed in the liquid of the viscous material. In the foaming method, the second gear pump is rotated and driven faster than the first gear pump among a first gear pump, a second gear pump, and a third gear pump, which are arranged in order from the upstream side to the downstream side of a flow path through which the viscous material and the gas flow. Then, a suction pressure is generated between the first gear pump 31 and the second gear pump in the flow path to mix the gas. Then, the third gear pump is rotated and driven at the same speed as the second gear pump to send the viscous material containing the gas to a mixer that is arranged downstream of the third gear pump in the flow path and disperses bubbles in the viscous material in the liquid of the viscous material. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing a foaming device according to a first embodiment of the present invention. [Diagram 2]1 is a flowchart showing a foaming method according to a first embodiment of the present invention. [Diagram 3] FIG. 4 is a diagram showing a schematic view of a foaming device according to a modified example of the first embodiment. [Figure 4] FIG. 4 is a diagram showing a foaming device according to a second embodiment. [Diagram 5] 5 is a flowchart showing a foaming method using the foaming device of FIG. 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] (First embodiment) Hereinafter, an embodiment of the present invention will be described with reference to the attached drawings. Note that the following description does not limit the technical scope or meaning of terms described in the claims. Also, the dimensional ratios in the drawings are exaggerated for the convenience of explanation and may differ from the actual ratios.

[0013] (Foamable materials) The foamable material M obtained by the foaming device 100 and mechanical foaming method of this embodiment is generated by mixing gas G into liquid resin R (corresponding to a viscous material) and foaming (expanding) the gas G by dispersing air bubbles in the liquid viscous material.

[0014] Examples of applications of the foamable material M include electronic parts that require airtightness, sealing materials for waterproofing and dustproofing of cylinder head covers and oil pans of automobiles, etc. Applications of the foamed body include, in addition to the above, automobile engine room panels and potting of electronic parts that require cushioning properties, soundproofing, vibration-proofing and heat insulation materials for housing cases, etc.

[0015] In this specification, a mixture in which gas G is mixed into liquid resin R and air bubbles are dispersed in the liquid resin R is referred to as foamable material M, and a state in which the foamable material M is discharged from the foaming device 100 into the atmosphere and the gas G is foamed is referred to as a foam (bubble). Liquid resin R before hardening or solidification is simply referred to as resin R. The state in which "gas is mixed into resin" includes a state in which resin and gas exist alternately in a pipe and a state in which gas is finely dispersed in resin.

[0016] Examples of the resin R include room temperature curable compositions such as moisture curing and two-liquid mixtures, heat curable compositions, and photocurable compositions such as ultraviolet and visible light. The resin R may also be a thermoplastic resin that melts when heated and solidifies when cooled at room temperature. The resin R includes those that cure, crosslink, or solidify from a fluid state. Examples of the resin include silicone resin, modified silicone resin, acrylic resin, urethane acrylate resin, epoxy resin, polyurethane resin, polyester, polypropylene, polyethylene, polycarbonate, synthetic rubber, natural rubber, synthetic resin, and natural resin. The resin R includes those referred to as elastomers.

[0017] As the gas G, for example, nitrogen gas, carbon dioxide gas, air, etc. can be suitably used.

[0018] (Mechanical foaming device) 1 shows a schematic diagram of the overall configuration of the foaming device 100. The foaming device 100 generates a foamable material M in which gas G is mixed into resin R and air bubbles are dispersed in the liquid resin R, and discharges and foams the foamable material M to generate a foam.

[0019] 1, the foaming device 100 according to the present embodiment includes a material supplying unit 20, a pump unit 30, a mixer 41, a discharge unit 45, a third pressure sensor 46, and a control unit 50. Each unit of the device is connected by a pipe 10 that constitutes a flow path for sending out the resin R and the gas G. In this specification, the side where the material supplying unit 20 is arranged is referred to as the upstream side, and the side where the mixer 41 is arranged is referred to as the downstream side.

[0020] (Plumbing) The pipe 10 passes the resin R and the gas G. As shown in FIG. 1 , the pipe 10 includes a first pipe 11, a second pipe 12, a third pipe 13, a fourth pipe 14 (corresponding to a first region), a fifth pipe 15, and a sixth pipe 16.

[0021] The first pipe 11 connects the material supply unit 20 and a first gear pump 31 of the pump unit 30. The second pipe 12 connects the first gear pump 31 and a second gear pump 33 in the pump unit 30.

[0022] The third pipe 13 connects the gas supply unit 32 and the second pipe 12. The fourth pipe 14 connects the second gear pump 33 and the third gear pump 34 that constitute the pump unit 30. The fifth pipe 15 connects the third gear pump 34 of the pump unit 30 and the mixer 41.

[0023] The sixth pipe 16 connects the mixer 41 and the discharge part 45. Although the diameters of the first pipe 11 to the sixth pipe 16 are configured to be uniform, for example, an on-off valve 35 may be provided on the second pipe 12 at a position close to the second gear pump 33. This configuration makes it easier to draw in gas from the gas supply part 32 described later. Also, by providing a nozzle smaller than the diameter of the pipes, the foaming ratio can be stabilized.

[0024] The material from which the pipe is made is not particularly limited as long as it is a material that is not easily deformed by the pressure inside the pipe 10, and for example, a metal such as SUS can be suitably used.

[0025] (Material supply department) The material supply unit 20 supplies the resin R to the piping 10. As shown in Fig. 1, the material supply unit 20 is connected to a first gear pump 31 of the pump unit 30 via a first piping 11. The material supply unit 20 is composed of, for example, a tank for storing the resin R, a pump for pressure-feeding the resin R, a replaceable cartridge, a pail can, etc.

[0026] (Pump section) As shown in FIG. 1, the pump section 30 includes a first gear pump 31, a gas supply section 32, a second gear pump 33, a third gear pump 34, an on-off valve 35, a first pressure sensor 36, and a second pressure sensor 37.

[0027] The first gear pump 31 is disposed in the middle of the pipe 10. Specifically, the first gear pump 31 is disposed downstream of the material supply unit 20.

[0028] (Gas supply section) The gas supply unit 32 is disposed between the first gear pump 31 and the second gear pump 33, and supplies the gas G to the second pipe 12 and the third pipe 13 that constitute the pipe 10.

[0029] The gas supply unit 32 supplies the gas G to the pipe 10. The gas supply unit 32 pressure-feeds the gas G pressurized at a predetermined pressure or at atmospheric pressure to the second pipe 12 and the third pipe 13. The gas supply unit 32 includes a gas tank for storing the gas G, and a gas supply port provided so as to be able to send the gas G from the gas tank to the second pipe 12. The gas supply unit 32 supplies the gas G to the second pipe 12 by utilizing the suction pressure generated in the second pipe 12 during the discharge operation as a suction pressure for sucking in the gas G. The foaming ratio of the bubbles can be adjusted by adjusting the pressure of the gas G supplied from the gas supply unit 32.

[0030] The second pipe 12 has an intake port provided to allow the gas G delivered from the gas supply unit 32 to flow into the pipe 10. A part of the flow path of the second pipe 12 is configured so that the resin R and the gas G are mixed (including a state in which the resin R and the gas G are not mixed).

[0031] The second gear pump 33 is disposed downstream of the piping 10 relative to the first gear pump 31. The second gear pump 33 is driven to rotate at a higher speed than the first gear pump 31, thereby generating a suction pressure for causing gas to flow into the piping 10, and sends the resin R containing the gas G to the downstream side of the piping 10.

[0032] The third gear pump 34 is disposed downstream of the piping 10 relative to the second gear pump 33. The third gear pump 34 is rotationally driven at the same speed as the second gear pump 33, thereby sending the resin R containing the gas G further downstream of the piping 10.

[0033] The first gear pump 31, the second gear pump 33, and the third gear pump 34 can be configured by a known gear pump that has gears and transports a fluid by utilizing the space between the teeth of each gear. The first gear pump 31, the second gear pump 33, and the third gear pump 34 each have a drive gear and a driven gear that rotates in response to the drive gear.

[0034] The drive gear of the first gear pump 31 is driven by a motor M1. The drive gear of the second gear pump 33 is driven by a motor M2. The drive gear of the second gear pump 33 and the drive gear of the third gear pump 34 are configured to be coaxial as shown by the axis CL in Fig. 1. In other words, the drive gear of the third gear pump 34 is driven by the same motor M2 as the drive gear of the second gear pump 33.

[0035] Gear pumps deliver a constant, stable amount of fluid, and the amount of fluid delivered can be adjusted relatively easily by adjusting the rotation speed of the gears. For example, an external gear pump equipped with two gears that are rotated simultaneously by meshing teeth can be used as the gear pump.

[0036] During the discharge operation, the second gear pump 33 is rotated and driven at a higher speed than the first gear pump 31. The amount (volume) of resin R flowing out of the second pipe 12 by the second gear pump 33 is greater than the amount (volume) of resin R flowing into the second pipe 12 by the first gear pump 31. Therefore, a suction pressure is generated in the second pipe 12 according to the volume of the resin R reduced.

[0037] The on-off valve 35 is configured to be able to switch the communication state between the second pipe 12 and the gas supply unit 32.

[0038] The on-off valve 35 is disposed between the gas supply port of the gas supply unit 32 and the second pipe 12, and is configured to be able to open and close the intake port.

[0039] The on-off valve 35 is configured to include a known needle valve. The on-off valve 35 includes a needle-shaped valve body to which a biasing force is applied in a valve closing direction to close the intake port, a piston connected to the valve body and moving the valve body in a valve opening direction to open the intake port, and a cylindrical portion forming an accommodation space to accommodate the valve body and the piston. The accommodation space of the cylindrical portion communicates with the gas supply port and the second pipe 12 via the intake port. The on-off valve 35 may be configured as a suck-back valve or a ball valve other than the above.

[0040] During the discharge operation, as shown in FIG. 1, the first gear pump 31, the gas supply unit 32, the second gear pump 33, and the third gear pump 34 are driven, and the on-off valve 35 is opened to send the viscous material containing gas to the mixer 41.

[0041] The first pressure sensor 36 is configured to be able to measure (detect) an inter-pump pressure P1 (corresponding to a first pressure) between the first gear pump 31 and the second gear pump 33 in the second pipe 12.

[0042] The second pressure sensor 37 is configured to be able to measure (detect) an inter-pump pressure P2 (corresponding to the second pressure) between the second gear pump 33 and the third gear pump .

[0043] The mixer 41 is disposed downstream of the third gear pump 34 in the piping 10, and agitates the resin R containing the gas G delivered by the third gear pump 34 to generate bubbles, and disperses the bubbles in the resin R in the liquid resin R to generate a foamable material M. The mixer 41 is disposed downstream of the third gear pump 34 in the piping 10, and between the pump unit 30 and the discharge unit 45. As shown in FIG. 1, the mixer 41 includes a housing 41a and a rotor 41b.

[0044] 1, the housing 41a includes an inlet portion (not shown), an outlet portion (not shown), a mixing chamber (not shown), and a housing protrusion 41c. The inlet portion is configured to allow the gas-containing resin R to flow in from the piping 10. The outlet portion is configured to allow the foamable material M to be delivered to the discharge portion 45. The mixing chamber is disposed between the inlet portion and the outlet portion, and forms a space in which the gas-containing resin R is mixed.

[0045] A plurality of housing protrusions 41c are provided on the inner wall surface of the housing that forms the mixing chamber. The housing protrusions 41c are configured to be arranged at intervals with the blades of the rotor 41b in the axial direction of the rotor 41b. The housing protrusions 41c are arranged at predetermined angular intervals along the circumferential direction of the inner wall surface of the mixing chamber that is formed in a substantially cylindrical shape.

[0046] In this embodiment, the housing protrusions 41c are arranged at equal angular intervals in both the axial and circumferential directions. However, the housing protrusions 41c do not have to be arranged at equal intervals in either the axial or circumferential directions as long as this does not affect the characteristics of the foam. The mixer 41 is also connected to a chiller (not shown), which allows the temperature at the mixer 41 to be adjusted.

[0047] The rotor 41b is configured to include a substantially cylindrical shape similar to the shape of the mixing chamber. The rotor 41b is configured to be rotatable by a motor (not shown). The rotor 41b has blades provided on the side surface of the cylindrical shape as shown in FIG. 1. The blades of the rotor 41b are arranged at predetermined intervals in the axial direction of the rotor 41b, similar to the housing protrusions 41c.

[0048] The rotor 41b has a plurality of blades arranged at predetermined angular intervals in the circumferential direction of the rotor 41b. In this embodiment, the blades of the rotor 41b are arranged at equal intervals in the axial and circumferential directions. However, as with the housing protrusions 41c, the blades of the rotor 41b are not limited to being spaced at equal intervals in the axial and circumferential directions as long as they do not affect the characteristics of the foam.

[0049] The discharge unit 45 includes a nozzle that discharges the foamable material M generated by dispersing air bubbles in the liquid resin R by the mixer 41 as a foam, a main body having a communication passage that sends the foamable material M stirred by the mixer 41 to the nozzle, and an openable and closable discharge valve. The nozzle serves as a discharge port and discharges the foamable material M generated by dispersing air bubbles in the liquid resin R by the mixer 41. The discharge valve is preferably a needle valve, and it is more preferable that the discharge port of the nozzle and the tip of the needle valve are close to each other. The third pressure sensor 46 is configured to be able to detect (measure) the discharge pressure P3 of the foamable material M immediately before being discharged in the communication passage.

[0050] (Control unit) The control unit 50 controls each part of the device to perform a discharge operation for discharging the foamable material M as a foam. The control unit 50 also controls the discharge operation of the foamable material M by receiving a discharge signal from the user (discharge signal ON), and can control the discharge operation to stop by no longer receiving the discharge signal (discharge signal OFF).

[0051] (Mechanical foaming method) Hereinafter, with reference to FIG. 2, a mechanical foaming method for producing a foam using the foaming device 100 will be described.

[0052] FIG. 2 is a flow chart illustrating a mechanical foaming method according to one embodiment of the present invention.

[0053] In the foaming method, gas G is mixed into resin R to disperse bubbles in the liquid resin R, thereby generating a foamable material M. As shown in Fig. 2, the foaming method generally includes a discharge operation (S2 to S5), which will be described in detail below.

[0054] When the user turns on the power of the foaming device 100, the control unit 50 operates the mixer 41 in the operation preparation state (S1). The mixer 41 can be in a constant operation state at least during the operation preparation state. The control unit 50 also controls the material supply unit 20 to supply the resin R to the pipe 10.

[0055] Next, the control unit 50 receives a signal for starting control of the dispensing operation of the foamable material M by the user's operation (dispensing signal ON, S2).

[0056] Next, the control unit 50 drives and rotates the first gear pump 31 and the second gear pump 33 so that the second gear pump 33 is faster than the first gear pump 31. In addition, the control unit 50 drives and rotates the third gear pump 34 at the same speed as the second gear pump 33 by taking advantage of the fact that they are coaxial.

[0057] As a result, the amount of resin R flowing out of the second pipe 12 by the second gear pump 33 becomes greater than the amount (volume) of resin R flowing into the second pipe 12 by the first gear pump 31. Therefore, in the second pipe 12, a suction pressure is generated according to the volume of the resin R reduced.

[0058] Next, the control unit 50 opens the on-off valve 35 to communicate the second pipe 12 with the gas supply unit 32. At this time, the gas G is sucked from the gas supply unit 32 by the suction pressure in the second pipe 12, and the gas G that has been pumped and pressurized by the gas supply unit 32 or that is at atmospheric pressure is mixed into the second pipe 12 through the third pipe 13.

[0059] It is preferable to open the on-off valve 35 after a predetermined time, for example, 0.1 to 0.5 seconds, has elapsed since the first gear pump 31 and the second gear pump 33 were rotated and driven. This allows the second pipe 12 to communicate with the gas supply unit 32 while a suction pressure is being generated in the second pipe 12, thereby preventing the resin R from flowing back into the gas supply unit 32.

[0060] In addition, by opening the on-off valve 35 after a predetermined time has elapsed, the on-off valve 35 is opened when the pressure in the flow path between the first gear pump 31 and the second gear pump 33 becomes lower than the pressure of the gas being supplied, thereby enabling a stable supply of gas.

[0061] The gas G drawn into the second gear pump 33 is sent to the mixer 41 by the third gear pump 34 together with the resin R. The resin R containing the gas pumped from the third gear pump 34 flows into the mixing chamber from the inlet of the mixer 41. The third gear pump 34 is controlled coaxially with the second gear pump 33, so that the resin R containing the gas is sent to the mixer 41.

[0062] When the rotor 41b is rotated by the motor, the blades of the rotor 41b rotate around the axis of the rotor 41b and, together with the housing protrusions 41c, agitate the resin R containing the gas in the mixing chamber. As a result, the gas G in the resin R is finely divided and dispersed by shear force, and the foamable material M is generated. The rotation speed of the rotor 41b can be, for example, 1 to 100 rpm.

[0063] Next, the foamable material M generated by the mixer 41 is sent from the outlet of the mixer 41 to a communication passage provided in the discharge part 45. As a result, the foamable material M is discharged from the nozzle through the communication passage into the atmosphere (S3). The gas G of the foamable material M discharged into the atmosphere is released from the pressurized state, and expands and hardens or solidifies in a foamed state to generate a foam.

[0064] For convenience of explanation, the operations in S3 of FIG. 2 are explained in chronological order, but in reality, the operations may be performed almost simultaneously.

[0065] The control unit 50 performs control so as to stop the discharge operation when the signal indicating the discharge operation of the foamable material M is no longer received (discharge signal OFF) due to the user's operation (S4). In response to this, the control unit 50 performs control so as to stop the first gear pump 31, the second gear pump 33, and the third gear pump 34. Then, the control unit 50 performs control so as to close the on-off valve 35 and close the discharge valve of the discharge unit 45 (S5). Note that in the case of a continuous operation in which the discharge operation is performed continuously, the configuration may be such that the process returns to S2 after S5 and the operations of S2 to S5 are performed a predetermined number of times.

[0066] As described above, the foaming device 100 according to this embodiment mixes the gas G into the resin R and discharges the foamable material M in which the gas bubbles are dispersed in the liquid resin R. The foaming device 100 includes a piping 10, a material supply unit 20, a gas supply unit 32, a first gear pump 31, a second gear pump 33, a third gear pump 34, a mixer 41, a discharge unit 45, and a control unit 50.

[0067] The pipe 10 passes resin R and gas G. The material supply unit 20 supplies resin R to the pipe 10. The gas supply unit 32 supplies gas G to the pipe 10. The first gear pump 31 is disposed midway along the pipe 10.

[0068] The second gear pump 33 is disposed downstream of the piping 10 relative to the first gear pump 31. The second gear pump 33 is rotated and driven at a higher speed than the first gear pump 31 to cause the gas G to flow into the piping 10 and to send the resin R containing the gas G to the downstream side of the piping 10. The third gear pump 34 is disposed downstream of the second gear pump 33 relative to the piping 10 and is rotated and driven at the same speed as the second gear pump 33 to send the resin R containing the gas G further downstream of the piping 10.

[0069] The mixer 41 is disposed downstream of the third gear pump 34 in the piping 10, and disperses air bubbles in the resin R into the liquid resin R. The discharge unit 45 discharges the foamable material M in which the air bubbles have been dispersed into the liquid resin R by the mixer 41. The control unit 50 controls the discharge operation for discharging the foamable material M.

[0070] By configuring in this way, the load on the second gear pump 33 can be eliminated or reduced. This stabilizes the mixture ratio of the resin R and the gas G, and stabilizes the foaming ratio of the foamable material M discharged from the discharge part 45. Furthermore, since the foaming device 100 has the third gear pump 34 in addition to the first gear pump 31 and the second gear pump 33, the discharge at the initial start can be stabilized without adjustment.

[0071] In addition, the drive gear of the third gear pump 34 is configured to be driven by the same motor M2 as the drive gear of the second gear pump 33. This makes it possible to eliminate or reduce the pressure difference between the second gear pump 33 and the third gear pump 34. This contributes to realizing a stable mixture ratio of the resin R and the gas G discharged from the discharge portion 45 by eliminating or reducing the load on the second gear pump 33.

[0072] In addition, the foaming method according to this embodiment mixes gas G into resin R and disperses the air bubbles in the liquid resin R to generate a foamable material M. In this foaming method, of a first gear pump 31, a second gear pump 33, and a third gear pump 34 arranged in this order from the upstream side to the downstream side of a pipe 10 through which the resin R and the gas G circulate, the second gear pump 33 is rotated and driven at a higher speed than the first gear pump 31.

[0073] Then, a suction pressure is generated between the first gear pump 31 and the second gear pump 33 in the pipe 10 to mix in the gas G. Then, the third gear pump 34 is rotated at the same speed as the second gear pump 33 to send the resin R containing the gas G to a mixer 41 that is disposed downstream of the third gear pump 34 in the pipe 10 and disperses air bubbles in the resin R.

[0074] This makes it possible to eliminate or reduce the load on the second gear pump 33, thereby stabilizing the mixture ratio of the resin R and the gas G discharged from the discharge portion 45, and thereby stabilizing the foaming ratio of the foamable material M.

[0075] (Modification of the first embodiment) 3 is a diagram showing a foaming device 100a according to a modified example of the first embodiment. The foaming device 100a is different from the first embodiment in that the drive gear of the third gear pump 34a is driven by a motor M3 different from the drive gear of the second gear pump 33. In addition, the control unit 50a constituting the foaming device 100a is different from the first embodiment in that it controls each part of the device including the third gear pump 34a.

[0076] In this modification, the second gear pump 33 and the third gear pump 34a are not driven by the same motor M2, but the third gear pump 34a is driven by a motor M3 different from the motor M2. The control unit 50a controls each part of the device so that the second gear pump 33 and the third gear pump 34 operate in the same manner, as in the first embodiment. Other matters are the same as in the first embodiment, and therefore description thereof will be omitted.

[0077] Second embodiment Fig. 4 is a schematic diagram of a foaming device 100b according to a second embodiment of the present invention, and Fig. 5 is a flow chart showing a foaming method using the foaming device 100b according to the second embodiment. The foaming device 100b according to the second embodiment is configured differently from the foaming device 100 according to the first embodiment in that a circulation path is provided in the foaming device 100b according to the second embodiment.

[0078] As shown in FIG. 4, the foaming device 100b includes a pipe 10b, a material supply unit 20, a pump unit 30b, a mixer 41, a discharge unit 45, a third pressure sensor 46, circulation valves 47 and 48, and a control unit 50b.

[0079] (Plumbing) The piping 10b includes a first pipe 11, a second pipe 12, a third pipe 13, a fourth pipe 14, a fifth pipe 15, a sixth pipe 16, and a seventh pipe 17. The first pipe 11 to the sixth pipe 16 have the same configuration as the piping 10 of the foaming device 100 of the first embodiment, and therefore the description thereof will be omitted.

[0080] The seventh pipe 17 connects between the region downstream of the discharge portion 45 and the fourth pipe 14 disposed in the first region between the second gear pump 33 and the third gear pump 34a. In this specification, the fourth pipe 14 downstream of the connection portion with the seventh pipe 17 and the fifth pipe 15, the sixth pipe 16, and the seventh pipe 17 correspond to a circulation path connecting the region between the second gear pump 33 and the third gear pump 34a.

[0081] (Material supply department) The material supply unit 20 is similar to that of the foaming device 100 of the first embodiment, and therefore a description thereof will be omitted.

[0082] (Pump section) As shown in FIG. 5, the pump section 30b includes a first gear pump 31, a gas supply section 32, a second gear pump 33, a third gear pump 34a, an on-off valve 35, a first pressure sensor 36, a second pressure sensor 37, and a switching valve 38 (corresponding to a third valve).

[0083] The first gear pump 31, the gas supply unit 32, the second gear pump 33, the on-off valve 35, the first pressure sensor 36, and the second pressure sensor 37 are configured similarly to the foaming device 100 according to the first embodiment, and therefore the description thereof will be omitted. The third gear pump 34a is configured to be operated by the motor M3, similarly to the foaming device 100a according to the modified example of the first embodiment.

[0084] The switching valve 38 is arranged in the fourth pipe 14, which corresponds to the first region between the second gear pump 33 and the third gear pump 34, and is configured to be able to open and close the flow path between the second gear pump 33 and the third gear pump 34a.

[0085] The switching valve 38 is not particularly limited, but may be configured by a full-bore ball valve or the like that has no (or little) flow resistance.

[0086] (Mixer, discharge section, third pressure sensor, circulation valve) The mixer 41, the discharge part 45 and the third pressure sensor 46 are similar to those of the foaming device 100 of the first embodiment, and therefore the description thereof will be omitted. The circulation valve 47 corresponds to the first valve in this specification, and the circulation valve 48 corresponds to the second valve.

[0087] The circulation valve 47 is disposed in the seventh pipe 17 constituting the circulation path. The circulation valve 48 is disposed downstream of the circulation valve 47 in the seventh pipe 17 constituting the circulation path.

[0088] (Control unit) The control unit 50b controls each part of the device to switch between the discharge operation and the circulation operation in the pipe 10b including the circulation path. During the discharge operation, the control unit 50b closes the circulation valves 47 and 48, opens the switching valve 38, and drives the first gear pump 31, the second gear pump 33, and the third gear pump 34a to feed the resin R containing the gas G into the mixer 41.

[0089] The control unit 50b controls each part of the device to close the switching valve 38 during the circulation operation, open the circulation valves 47 and 48, and drive the first gear pump 31, the second gear pump 33, and the third gear pump 34a. This causes the resin R containing the gas G to circulate through the circulation path and the mixer 41, and the foamed state of the foamable material M is maintained.

[0090] (Foaming method) Next, a foaming method using the foaming device 100b according to this embodiment will be described.

[0091] When the user turns on the power supply of the foaming device 100b, the control unit 50b operates the mixer 41 in a state of preparation for operation (S11). The control unit 50b also controls the material supply unit 20 to supply the resin R to the pipe 10b. Next, the control unit 50b controls the switching valve 38 to close and the circulation valves 47 and 48 to open (S12).

[0092] Next, the control unit 50b drives the third gear pump 34a (S13), whereby the foamable material M in the circulation path circulates within the circulation path.

[0093] When the control unit 50b receives a discharge signal from the user's action (discharge signal ON, S14), the control unit 50b performs control to stop the third gear pump 34a, close the circulation valves 47 and 48, and open the switching valve 38 (S15).

[0094] Next, the control unit 50b drives and rotates the first gear pump 31 and the second gear pump 33 so that the second gear pump 33 is faster than the first gear pump 31. In addition, the control unit 50b drives and rotates the third gear pump 34a at the same speed as the second gear pump 33.

[0095] Then, the control unit 50b performs control to open the on-off valve 35 and open the discharge valve of the discharge unit 45 (S16). As a result, similar to the first embodiment, the resin R containing the gas G is sent to the mixer 41, and the foamable material M in which the gas G is dispersed and mixed into the resin M1 is generated and discharged from the nozzle of the discharge unit 45.

[0096] When the control unit 50b stops receiving the discharge signal due to the user's operation (discharge signal OFF, S17), the control unit 50b performs control to stop the first gear pump 31, the second gear pump 33, and the third gear pump 34a. Then, the control unit 50b performs control to close the on-off valve 35 and close the discharge valve of the discharge unit 45 (S18). Note that in the case of a continuous operation in which discharge operations are performed continuously, the configuration may be such that the process returns to S12 after S18 and the operations of S12 to S18 are performed a predetermined number of times.

[0097] As described above, the foaming device 100b according to this embodiment has a circulation path in which the pipe 10b connects the area downstream of the discharge part 45 and the first area between the second gear pump 33 and the third gear pump 34a. The foaming device 100 includes circulation valves 47 and 48 and a switching valve 38.

[0098] The circulation valve 47 is disposed in the seventh pipe 17 in the circulation path. The circulation valve 48 is disposed downstream of the circulation valve 47 in the circulation path. The switching valve 38 is disposed in the fourth pipe 14, which is the first region between the second gear pump 33 and the third gear pump 34a. The control unit 50b closes the circulation valves 47, 48 during the discharge operation, opens the switching valve 38, and drives the third gear pump 34a to rotate, thereby feeding the foamable material M to the mixer 41.

[0099] In addition, during circulation operation, the control unit 50b opens the circulation valves 47, 48 and closes the switching valve 38, and rotates the third gear pump 34a to circulate the foamable material M within the circulation path and the mixer 41, thereby maintaining the foamable material M in a foamed state.

[0100] This makes it possible to maintain or facilitate the maintenance of a state in which the foamable material M is uniformly dispersed in the circulation path constituting the pipe 10b. Also, it is possible to prevent or suppress a decrease in the foaming ratio that may occur when the discharge of the foamable material M is stopped.

[0101] The present invention is not limited to the above-mentioned embodiment, and various modifications are possible within the scope of the claims. In the above, the control units 50, 50a, and 50b receive the discharge signal by the user's operation, but the present invention is not limited to this. In addition to the above, the control unit may be configured to receive the discharge signal from another upper device.

[0102] This application is based on Japanese Patent Application No. 2020-201002, filed on December 3, 2020, the disclosure of which is incorporated by reference in its entirety. [Explanation of symbols]

[0103] 100, 100a, 100b foaming device, 10, 10b piping (flow path), 14 4th piping (circulation path, 1st area), 15 5th piping (circulation path), 16 No. 6 piping (circulation path), 17 7th piping (circulation path), 20 Material supply department, 32 gas supply section, 31 First gear pump, 33 Second gear pump, 34, 34a third gear pump, 38 Switching valve (third valve), 41 Mixer, 45 Discharge part, 47 Circulation valve (first valve), 48 Circulation valve (second valve), 50, 50a, 50b control unit, M foam material, R resin (viscous material), G gas, P1 pump pressure (first pressure) P2 Pump-to-pump pressure (second pressure).

Claims

1. A foaming device that mixes gas into a viscous material and discharges a foamable material in which air bubbles are dispersed in the viscous material, A flow path through which the viscous material and the gas flow; a material supply unit that supplies the viscous material to the flow path; a gas supply unit that supplies the gas to the flow path; A first gear pump disposed in the flow path; a second gear pump that is disposed downstream of the flow path relative to the first gear pump and is rotationally driven at a higher speed than the first gear pump, thereby causing the gas to flow into the flow path and sending the viscous material containing the gas to the downstream side of the flow path; a third gear pump that is disposed downstream of the second gear pump in the flow path and is rotationally driven at the same speed as the second gear pump to pump the viscous material containing the gas further downstream in the flow path; a mixer disposed downstream of the third gear pump in the flow path, the mixer dispersing air bubbles in the viscous material into the liquid viscous material; a discharge section that discharges the foamable material in which bubbles have been dispersed in the viscous material liquid by the mixer; A foaming device having a control unit that controls a discharge operation for discharging the foamable material.

2. 2. The foaming device of claim 1, wherein the drive gear of the third gear pump is driven by the same motor as the drive gear of the second gear pump.

3. The foaming device according to claim 1 , wherein the drive gear of the third gear pump is driven by a different motor than the drive gear of the second gear pump.

4. the flow path has a circulation path connecting a region downstream of the discharge portion and a first region between the second gear pump and the third gear pump, The foaming device includes a first valve disposed in the circulation path, a second valve disposed downstream of the first valve in the circulation path, and a third valve disposed in the first region, The control unit is During the discharge operation, the first valve and the second valve are closed, the third valve is opened, and the third gear pump is rotationally driven to feed the viscous material containing the gas into the mixer; The foaming device according to any one of claims 1 to 3, wherein during operation in the circulation path, the third valve is closed, the first valve and the second valve are opened, and the third gear pump is rotationally driven to circulate the viscous material containing the gas within the circulation path and the mixer, thereby maintaining a foamed state of the foamable material.

5. The foaming device according to any one of claims 1 to 4, wherein the control unit controls each part of the device and controls the discharge operation.

6. A foaming method for producing a foamable material by mixing a gas into a viscous material and dispersing air bubbles in the liquid of the viscous material, comprising the steps of: A foaming method comprising the steps of: of a first gear pump, a second gear pump, and a third gear pump arranged in order from the upstream side to the downstream side of a flow path through which the viscous material and the gas flow, rotating the second gear pump at a speed faster than the first gear pump to generate suction pressure between the first gear pump and the second gear pump in the flow path and mix in the gas; and rotating the third gear pump at the same speed as the second gear pump to send the viscous material containing the gas to a mixer that is arranged downstream of the third gear pump in the flow path and disperses air bubbles in the viscous material into the liquid viscous material.

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