JP6377914B2 - Plate heat exchanger and manufacturing method thereof - Google Patents

Description

  The present invention relates to a plate heat exchanger in which a plurality of heat transfer plates are stacked.

There are various types of heat exchangers, but plate heat exchangers have extremely high heat exchange performance, and are therefore used in electric water heaters, industrial equipment, automobile air conditioners, and the like.
In the plate heat exchanger, a heat exchange medium passage, that is, a hot medium passage and a cold medium passage are formed adjacent to each other by stacked plates, and a medium having a temperature difference flowing between the high temperature medium passage and the low temperature medium passage is provided. It is configured to exchange heat with each other by transferring heat.

For example, in Patent Document 1, a high-temperature flow path and a low-temperature flow path are obtained by laminating plates with wave shapes serving as flow paths and joining them by various joining methods (fastening with gaskets and screws, welding, brazing). Has created a structure that exists alternately.
On the other hand, from the viewpoint of improving the durability of the heat exchanger itself, a stainless steel plate excellent in corrosion resistance is used as a material metal plate. In addition, small and medium heat exchangers are often joined by brazing in consideration of pressure resistance.

JP 2010-85094 A

However, when laminating plates with corrugated shapes and trying to join them by brazing, it is possible to join by soldering, such as melting damage, cracking of the brazing part, lowering of corrosion resistance, channel burial due to molten brazing, etc. A bug may occur. In addition, there is a cost due to the use of brazing material.
On the other hand, as a method for suppressing a decrease in corrosion resistance of the joint, it is conceivable to apply solid phase diffusion bonding instead of brazing. Solid phase diffusion bonding is a bonding method that utilizes mutual diffusion of base material atoms generated at the bonding interface under high temperature pressure, and the bonded portion exhibits the same strength and corrosion resistance as the base material. On the other hand, the bonding force by solid phase diffusion is affected by the applied pressure and temperature at the bonding surface.

In particular, when a stainless steel plate is used as the material metal plate, the additive element has a strong influence on diffusion bonding of stainless steel, and when a large amount of easily oxidizable elements Al, Ti, Si are contained, a strong oxide or An oxide film may be formed to inhibit bonding.
The present invention has been devised in order to solve such a problem, and the joining of the end face and the flow path of the plate type component constituting the plate heat exchanger is replaced by solid phase diffusion instead of brazing. An object of the present invention is to easily manufacture a plate-type heat exchanger that ensures airtightness even when a stainless steel plate is used as a raw material by performing the bonding.

In order to achieve the object of the plate heat exchanger of the present invention, the parts constituting the heat exchanger case are box-shaped parts and projecting parts provided with tip pieces bent outward at substantially right angles to the peripheral flange portions. The frame parts are stacked in the order of the frame parts, the box-shaped parts, and the overhang parts, and the box-shaped parts are stacked on the overhang parts only at the top. A contact portion between the upper surface of the frame component and a flat portion in the vicinity of the flange of the box-shaped component, a contact portion between a tip piece of the box-shaped component and a peripheral portion of the overhang component, and a peripheral portion of the overhang component and the frame The contact portion on the lower surface of the component has a good bonding strength formed by solid phase diffusion bonding. It is preferable that the contact portion subjected to solid phase diffusion bonding has a bonding strength equivalent to the strength of the base material.

The box-shaped part is a press-molded product formed with two types of openings at symmetrical positions, one opening above the box-shaped part and the other opening inward of the box-shaped part, The projecting part is preferably a press-molded product formed in such a manner that two kinds of openings are formed at symmetrical positions, one is opened above the projecting part, and the other is opened below the projecting part. The box-shaped part has a predetermined flange height (referred to as a height from the upper flat portion to the tip piece of the flange part), but the opening of the box-shaped part and the opening of the overhanging part are box-shaped. It is preferable to form the sum of the opening height of the part and the opening height of the overhanging part in contact with the opening so as to be equal to the flange height of the box-type part. For example, the height of the opening is the box-type part. It is preferable that the height of the flange is 1/2.
The frame part has a box shape having a rectangular opening at the center and the same height as the flange height of the box part, and a protruding piece extending outward at a substantially right angle at the lower end of the peripheral part. It is preferable to provide.

Further, the top surface flat portion of the front Symbol box-shaped element, the height triangular or trapezoidal or square cross-sectional shape is formed the same fins as flange height, flange near flat tip piece of the laminated upper part is stacked lower part When the fins are brought into contact with each other, the tips of the fins come into contact with each other, and the flow path joint formed by solid-phase diffusion bonding at the contact part has a bonding strength equivalent to the strength of the base material. It is preferable.
A fin component with a cross-sectional shape of a triangle, trapezoid, or quadrangle and the same height as the flange height is inserted between two stacked box-shaped components, and the top piece of the stacked component is placed on the flat part near the flange of the stacked component. When the contact is made, the tip of the fin part comes into contact with the upper flat portion of the box-type part, and the flow path joint is formed by solid-phase diffusion bonding at the contact part. Also good.

When the plate heat exchanger having the above shape is manufactured using a stainless steel plate as a raw material, a ferritic single-phase stainless steel plate or austenite system having chemical components of 0.1 Si + Ti + Al <0.15 mass% and a surface roughness Ra ≦ 0.3 μm A laminated assembly of box-shaped parts using a stainless steel plate is heated in a furnace in an atmosphere having a heating temperature of 1100 ° C. or higher and 1250 ° C. or lower and a pressing force of 0.3 MPa or higher and 0.9 MPa or lower and 1 × 10 ⁻² Pa or lower. Then, it is manufactured by solid phase diffusion bonding. Here, 1 × 10 ⁻² Pa or less indicates the atmospheric pressure when the heating temperature is reached. If the atmospheric pressure in the furnace being heated is lowered to the pressure or lower, then an inert gas such as Ar, He, N ₂ or the like may be introduced into the furnace.
A martensitic stainless steel plate having a chemical composition of 0.1 Si + Ti + Al <0.15 mass% and a surface roughness Ra ≦ 0.4 μm is used. When Ra <0.3 μm, the heating temperature is 1000 ° C. or higher and 1250 ° C. or lower, 0 In the case of 3 μm <Ra ≦ 0.4 μm, the heating temperature is 1100 ° C. or higher and 1250 ° C. or lower, and the applied pressure is 0.3 MPa or higher and 0.9 MPa or lower and 1 × 10 ⁻² Pa or lower in a furnace. Manufactured by phase diffusion bonding. Here, 1 × 10 ⁻² Pa or less indicates the atmospheric pressure when the heating temperature is reached. If the atmospheric pressure in the furnace being heated is lowered to the pressure or lower, then an inert gas such as Ar, He, N ₂ or the like may be introduced into the furnace.
A duplex stainless steel plate having a chemical composition of 0.1Si + Ti + Al <0.15% by mass is used, the heating temperature is 1000 ° C. or higher and 1250 ° C. or lower, and the applied pressure is 0.1 MPa or higher and 0.9 MPa or lower, 1 × 10 ⁻² Pa. When heating in a furnace in the following atmosphere, even a steel plate having a surface roughness Ra ≦ 2.0 μm can be sufficiently solid phase diffusion bonded. Here, 1 × 10 ⁻² Pa or less indicates the atmospheric pressure when the heating temperature is reached. If the atmospheric pressure in the furnace being heated is lowered to the pressure or lower, then an inert gas such as Ar, He, N ₂ or the like may be introduced into the furnace.

According to the present invention, the end faces of the plate-type components constituting the plate heat exchanger and the flow path can be joined without using a brazing material such as Cu or Ni. It is possible to perform bonding while suppressing occurrence of damage, cracking of the brazed part, deterioration of corrosion resistance, channel burial due to molten brazing, and the like. Moreover, since it can join without using expensive brazing materials, such as Cu and Ni, cost reduction and weight reduction can be achieved.
Furthermore, since solid phase diffusion bonding is sufficiently performed, the bonding portion can exhibit bonding strength comparable to that of the base material.
Furthermore, by using a stainless steel plate as the material steel plate, a plate heat exchanger excellent in durability can be provided at low cost.

It is a figure explaining the structure of the conventional laminated plate type heat exchanger. It is a figure which shows the flow-path structure of the conventional laminated plate type heat exchanger. It is a figure which shows the flow path and cross-sectional structure of the laminated plate type heat exchanger of this invention. It is a perspective view which shows the shape of a box-type component, an overhang | projection component, and a frame component. It is a figure which shows the various components shape and size of the heat exchanger produced in the Example. It is a figure explaining the aspect which provided the fin in the flat part of the box-type components in this invention. It is a figure explaining the aspect by which the fin component was inserted between the two box-shaped components laminated | stacked in this invention. It is a figure which shows a heat pattern when solid-phase diffusion bonding is carried out in an Example. It is a figure explaining the pressurization form at the time of solid-phase diffusion bonding in an Example.

As described above, the plate-type heat exchanger is configured such that the heat exchange medium passages, that is, the passages of the high temperature medium and the low temperature medium are formed adjacent to each other by the stacked plates, and the temperature difference flowing between the high temperature medium passage and the low temperature medium passage The mediums having the above are configured to exchange heat with each other by transferring heat.
As a simple structure, for example, as shown in FIGS. 1 and 2, a plurality of box-shaped parts having the same shape are manufactured, and the box-shaped parts rotated by 180 ° are stacked on the box-shaped parts, and further the box-shaped parts are stacked. It is assumed that a heat exchanger is constructed by repeating this.

And in order to make the said laminated body function as a heat exchanger, it is necessary to airtightly join an upper part and a lower part in the contact part of the peripheral part of a laminated box-type component, and an opening peripheral part.
In the present invention, as a box-shaped part, the steel plate is pressed, the flange is slightly opened downward, and two types of openings are provided at symmetrical positions, one of which is lower than half the flange height. A box-shaped part is formed that opens above the rectangular plate-type part and the other is opened inward of the rectangular plate-type part at a height lower than ½ of the flange height. An attempt was made to stack plate parts into a plate heat exchanger.

However, with the box-shaped parts of the above shape, a flow path cannot be formed even if they are simply stacked. Therefore, a box-shaped part is placed on the lowermost frame part and extended between the two box-shaped parts. I decided to sandwich the parts.
That is, a box-shaped part, an overhang part, and a frame part shown in FIG. The box-shaped part shown in FIG. 3 (c) corresponds to the box-shaped part shown in FIG. 3 (b) inverted in the vertical direction and then inverted in the horizontal plane. First, the box-shaped component shown in FIG. 3B is placed on the frame component, and the overhang component is placed thereon. Next, the placement of the frame part, the box-type part, and the overhang part is repeated on the overhang part. Finally, a box-shaped part shown in FIG. 3C is placed on the overhanging part to form a laminate as shown in FIG.
In addition, a bottom plate and a joint are separately prepared and assembled to the above laminated body to obtain an assembled body as shown in FIG.

Here, it is necessary to hermetically join the upper part and the lower part, but there is no brazing, and when trying to apply solid-phase diffusion joining by applying a load from above and below to the contact part of the flange, as described above In such a laminated structure, since the area of the bonding surface is small, sufficient solid phase diffusion bonding cannot be performed.
Therefore, it is necessary to devise the shape of the flange portion.
Therefore, in the present invention, the flange portion on the periphery of the box-type component is provided with a tip piece bent outward at a substantially right angle. This tip piece is referred to as “tip piece b” in FIG.

Specifically, as shown in FIG. 3 (b), the box-shaped part is composed of a rectangular plate, a flange is provided on the periphery, two types of openings are provided at symmetrical positions on the upper surface, and one of the rectangular plates is The other end of the rectangular plate is opened in the upward direction, and the other end is provided with a tip piece b bent outward at a substantially right angle at the lower end of the peripheral flange. (In addition, the flange vicinity flat part in a box-type component points to the flat part located in the upper surface of the said box-type component continuously from the upper end of a flange, and is located on the opposite side to the front piece b in the said box-type component.)
Further, as shown in FIG. 3B, the overhanging part has two kinds of openings at symmetrical positions, one opening upward, and the other opening downward, which is more than the outer shape of the box-shaped part. It is assumed to consist of a slightly larger rectangular plate.
As shown in FIG. 3 (b), the box-shaped part has a flange height from the upper flat portion of the rectangular plate to the flange lower end, and the two types of openings of the box-shaped part or the overhang part are Any of these may be formed at a height that is ½ of the height of the flange of the box-type component. Moreover, one opening may be lower than the height of 1/2 of the flange height of the box-type component, and the other opening may be higher than the flange height of the box-type component.

Furthermore, the frame part is a box-shaped product having a rectangular opening at the center and the same height as the flange height of the box-shaped component, as seen in FIG. And a tip piece f bent outward at a substantially right angle.
In order to actually construct a plate heat exchanger, a joint connected to the bottom plate, the medium supply port, and the medium discharge port is required in addition to the box-shaped component, the overhang component, and the frame component.
Each of these members can be easily molded by a press molding method using an appropriately shaped die.

A tip piece b is provided at the flange part of the peripheral edge of the box-shaped part, and a tip piece f is provided at the peripheral lower end of the frame part, and the overhanging part is made slightly larger than the outer shape of the box-shaped part, so that FIG. 3C is overlaid on the box-shaped part shown in FIG. 3C, and the frame part shown in FIG. The peripheral edge of the frame and the tip piece f of the frame part are densely stacked.
If weight is applied from above and below based on this form, solid phase diffusion bonding is easily performed at the three layers.

By the way, in a heat exchanger, the path | route of a heat exchange medium, ie, the path | route of a high temperature medium, and a low temperature medium is comprised adjacently, and the medium sent through a path | route performs the heat exchange effect | action. For this reason, in order to increase the efficiency of the heat exchange action, it is effective to widen the partition wall surface that separates the passage of the high temperature medium and the low temperature medium.
Therefore, in the present invention, fins having a triangular, trapezoidal, or quadrangular cross-sectional shape are provided on the upper flat portion of the box- shaped component.

Specifically, as shown in FIG. 4 (a), a fin having the same cross-sectional shape as a triangle, trapezoid, or quadrangle and having a height equal to the flange height is placed on the upper flat portion of the box-shaped part in the inner direction of the box-shaped part. Form. When the box-shaped parts having fins formed on the flat upper surface, the overhang parts and the frame parts shown in FIGS. 4B and 4C, and the parts shown in FIG. The assembly is as shown in FIG.
Note that the box-shaped part shown in FIG. 4A and the box-shaped parts 1 and 2 shown in FIG. 5 are different depending on the presence or absence of fin formation. 2 having fins not shown is used.

The box-shaped parts 1 and 2 have exactly the same shape. When the box-shaped part 1 is turned 180 degrees in the reverse direction, the box-shaped part 2 is obtained. However, when fins are formed on the box-shaped parts 1 and 2, the fins are formed inward in the box-shaped part 1, but the fins are formed inward in the box-shaped part 2.
When the assembly as described above is held under high temperature in a state where a weight is applied from above and below, solid phase diffusion bonding is performed at A, B, C, D, E and F in FIG. Both of them are solid-phase diffusion bonded at the contact portion to form a flow path bonding portion.

Rather than providing fins in the box-shaped component itself, fin components may be inserted between the stacked upper and lower box-shaped components.
That is, when the components as shown in FIG. 5 are stacked in the same manner as in the embodiment shown in FIG. 3 while the fin components 1 and 2 are inserted, an assembly as shown in FIG. 7 is obtained.
At this stage, it is kept at a high temperature in a state where a load is applied from above and below in the same manner as described above. In this case, in addition to A, B, C, D, E, and F in FIG. 6, a contact portion between the tip of the fin part and the flat part of the box-shaped part indicated by G, H, and I in FIG. 7. In addition, solid phase diffusion bonding is performed at the contact portion between the tip of the fin component and the overhang component.

As described above, the structure of the plate heat exchanger of the present invention has been described. However, as described in the problem section, the plate heat exchanger of the present invention has durability in an environment where corrosion resistance is required. In order to have it, it is preferable to use a stainless steel plate as the material steel plate.
However, when a stainless steel plate is used as the material steel plate, the additive elements strongly influence the diffusion bonding of stainless steel, and if there are a lot of easily oxidizable elements such as Al, Ti, Si, a strong oxide or oxide on the surface of the joint interface May form a film and inhibit bonding.
Therefore, when producing the plate heat exchanger of the present invention using a stainless steel plate as a raw material, the content of the easily oxidizable elements Al, Ti, Si is limited, and the surface properties and solid phase of the material stainless steel plate are limited. It was decided to define the pressure and heating temperature during diffusion bonding.

There is no restriction | limiting in the basic composition of the stainless steel to be used. Ferrite single-phase stainless steel sheet, austenitic stainless steel sheet, martensitic stainless steel sheet, or duplex stainless steel sheet having a general composition defined by JIS or the like can be used.
If a large amount of easily oxidizable elements such as Al, Ti, and Si is contained, a strong oxide or oxide film is formed on the surface of the bonding interface and the bonding is inhibited. Therefore, the total amount is limited. Details will be given in the description of the examples. However, when 0.1Si + Ti + Al is 0.15% by mass or more, oxidation inside the bonded product has progressed, and bonding becomes insufficient.

  As a stainless steel plate to be used, C: 0.0001 to 0.15%, Si: less than 1.5%, Mn: 0.001 to 1.2%, P: 0.001 to 0.045% in mass%. , S: 0.0005 to 0.03%, Ni: 0 to 0.6%, Cr: 11.5 to 32.0%, Cu: 0 to 1.0%, Mo: 0 to 2.5%, Al: less than 0.15%, Ti: 0 to 0.15%, Nb: 0 to 1.0%, V: 0 to 0.5%, N: 0 to 0.025%, balance Fe and inevitable impurities A ferrite single phase type is preferable.

  Further, in mass%, C: 0.0001 to 0.15%, Si: less than 1.5%, Mn: 0.001 to 2.5%, P: 0.001 to 0.045%, S: 0 0.005 to 0.03%, Ni: 6.0 to 28.0%, Cr: 15.0 to 26.0%, Cu: 0 to 3.5%, Mo: 0 to 7.0%, Al: Less than 0.15%, Ti: 0 to 0.15%, Nb: 0 to 1.0%, V: 0 to 0.5%, N: 0 to 0.3%, balance Fe and inevitable impurities An austenitic material may be used.

  Further, by mass, C: 0.15 to 1.5%, Si: less than 1.5%, Mn: 0.001 to 1.0%, P: 0.001 to 0.045%, S: 0 .0005 to 0.03%, Ni: 0.05 to 2.5%, Cr: 13.0 to 18.5%, Cu: 0 to 0.2%, Mo: 0 to 0.5%, Al: Less than 0.15%, Ti: 0-0.15%, Nb: 0-0.2%, V: 0-0.2%, B: 0-0.01%, N: 0.005-0. It may be a martensitic material composed of 1%, the balance Fe and inevitable impurities.

Furthermore, by mass%, C: 0.0001 to 0.15%, Si: 0.001 to 1.5%, Mn: 0.001 to 1.0%, P: 0.001 to 0.045% , S: 0.0005 to 0.03%, Ni: 0.05 to 6.0%, Cr: 13.0 to 25.0%, Cu: 0 to 0.2%, Mo: 0 to 4.0 %, Al: less than 0.15%, Ti: 0 to 0.15%, Nb: 0 to 0.2%, V: 0 to 0.2%, N: 0.005 to 0.2%, balance Fe Further, a ferrite + martensite two-phase system or a ferrite + austenite two-phase system composed of inevitable impurities may be used.
In order to ensure manufacturability, the above-described stainless steel can be added with 0 to 0.01% of B and 0 to 0.1% of Ca, Mg, or REM with at least one kind.

In solid phase diffusion bonding, since the metals to be bonded are bonded to each other in a strongly pressed state, the surface roughness of both of them affects the bondability.
Details of this surface roughness will be given in the description of the examples, but depending on the contact surface pressure between the metals to be joined, solid phase diffusion joining is performed at a heating temperature of 1100 ° C. with a pressure of 0.3 MPa. The surface roughness is relatively Ra ≦ 2.0 μm for the dual-phase stainless steel sheet that is relatively easy to diffusion-bond, and Ra ≦ 0.4 μm for the martensitic stainless steel sheet. Other ferritic single-phase stainless steel sheets that are difficult to diffusion-bond Or, in the case of an austenitic stainless steel plate, Ra ≦ 0.3 μm is required.

The pressure applied between the two stainless steel plates used for diffusion bonding is 0.1 MPa or more for the duplex stainless steel, and 0.3 MPa or more for the ferrite single phase, austenitic, or martensitic stainless steel plate. If the applied pressure is less than these values, heating to a higher temperature is required to form a sound joint interface, which is not preferable as a product as described later. If the applied pressure is more than these values, diffusion bonding can be performed with relatively simple equipment.
It is preferable to use a metal weight for applying the pressing force in the vertical direction. The weight is preferably made of heat-resistant ferritic stainless steel having excellent heat resistance and low thermal expansion. The applied pressure is obtained by dividing the weight load by the vertical joint area.

  The greater the pressure applied during heating, the easier it is to destroy the passive film and oxide film on the bonding surface, which are factors that hinder the bonding, and the contact area (border contact area) of the microscopic irregularities on the steel sheet surface is likely to increase. The atomic diffusion range is expanded and diffusion bonding becomes easy. On the other hand, when the weight becomes large due to the increased pressure, load collapse due to instability of the center of gravity and shape defects due to uneven load are likely to occur. Moreover, since the ratio of the weight to the allowable load of the hearth or the feed rail is increased by increasing the weight load, the amount of products that can be mounted is limited, and the mass productivity is significantly reduced. Further, when the applied pressure is excessive, the product is deformed and the appearance is remarkably impaired. Therefore, it is desirable that the applied pressure is 0.9 MPa or less that does not impair the appearance of the product.

The heating temperature for diffusion bonding is set to 1000 ° C. or higher for a duplex stainless steel plate and martensitic stainless steel plate, and to 1100 ° C. or higher for a ferrite single phase stainless steel plate or an austenitic stainless steel plate. If these temperatures are not reached, sufficient diffusion bonding cannot be performed.
Generally, the solid phase diffusion of the stainless steel surface layer starts around 900 ° C. In particular, when heated to 1100 ° C. or higher, atomic diffusion becomes active and diffusion bonding is facilitated in a short time, but when heated to 1300 ° C. or higher, high-temperature strength is reduced and crystal grains are easily coarsened. When the high-temperature strength is reduced, the joined parts undergo significant thermal deformation during heating, and the product appearance is impaired. Further, when the crystal grains become coarse, the base material strength is lowered and the corrosion resistance is deteriorated. Therefore, the inventors have studied a heating temperature that allows diffusion bonding at as low a temperature as possible. As a result, the chemical composition, the surface roughness, and the applied pressure described above are followed, and the heating temperature at the time of joining is 1100 ° C. to 1250 ° C., a two-phase stainless steel plate or a martensite system for a ferrite single-phase stainless steel plate or austenitic stainless steel plate. It has been found that a stainless steel sheet may be in the range of 1000 ° C. to 1250 ° C., and in the dissimilar material bonding, it may be in the range of 1100 ° C. to 1250 ° C.

Diffusion bonding between stainless steel plates can be performed by heating and holding the members to be bonded in an atmosphere in which the pressure is set to 1 × 10 ⁻² Pa or less by evacuation. Sufficient diffusion bonding cannot be performed in an atmosphere exceeding 1 × 10 ⁻² Pa.
When the atmospheric pressure is higher than 1 × 10 ⁻² Pa (> 1 × 10 ⁻² Pa), the oxygen contained in the stainless steel remains, and an oxide film is generated on the surface of the bonding surface during heating, so that the bonding property is remarkably increased. Inhibit. When the atmospheric pressure is higher than 1 × 10 ⁻² Pa, that is, when the atmospheric pressure is set to 1 × 10 ⁻² Pa or less, the oxide film on the surface layer becomes extremely thin and is the optimum condition for diffusion bonding. Note that, as described above, after the atmospheric pressure is set to 1 × 10 ⁻² Pa or less, an inert gas such as Ar, He, or N ₂ can be sealed and bonded.

As a heating method, a method of uniformly heating the entire member in the furnace with a heater is adopted. What is necessary is just to set the heating holding time in the range of 30-120 min.
From the viewpoint of mass productivity, it is better that the heating and holding time is as short as possible. However, a heating time of 30 minutes or more is required to uniformly apply heat to the entire bonded component and sufficiently excite atomic diffusion. On the other hand, when a holding time of 120 min or more is given, the crystal grains grow to such an extent that the base material strength and corrosion resistance are affected. Therefore, a preferable holding time was set to 30 to 120 min.

Each component having the dimensions shown in FIG. 5 is prepared from various stainless steel plates having a thickness of 0.05 to 1 mm having the composition shown in Table 1, and the flat part of the box-type component as shown in FIG. A heat exchanger having fins and a heat exchanger having a shape in which the fin parts 1 and 2 are inserted into the box-shaped part as shown in FIG. 7 were made. Here, as a whole, rectangular bodies each having a width of 50 mm, a length of 100 mm, and a height of 50 mm were stacked, and the overhang width of the tip piece was set to 5 mm.
Various stainless steel plates with surface roughness of 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 1.0 μm, 2.0 μm and 3.0 μm were used. In this example, the surface roughness is given by pickling or polishing, but it may be given by a method such as a rolling roll.

The temporarily assembled heat exchanger is put into a horizontal vacuum furnace, and after the atmospheric pressure reaches 1 × 10 ⁻³ Pa, it is heated with the heat pattern shown in FIG. 8, and the heating chamber temperature is changed from 950 ° C. to 1300 ° C. The heat exchanger was manufactured by changing the solid phase diffusion bonding.
At this time, the heat exchanger temporarily assembled using the auxiliary tool shown in FIG. 9 was subjected to solid phase diffusion bonding in a state where a load changed from 0.1 MPa to 1.1 MPa was applied.
As shown in FIG. 9, the load was applied in such a manner that a weight made of SUS430 was placed. And the outer periphery of the heat exchanger temporarily assembled by CC composite via the molybdenum plate was restrained so that a load might not be distributed outside.
About the obtained heat exchanger, an internal oxidation state was observed and a pressure resistance test was performed.
For the observation of the internal oxidation state, the obtained heat exchanger was cut, and the internal oxidation state was visually observed as to whether or not the oxidation was progressing.
In the pressure test, the joints B, C, and D in FIG. 5 are closed and water is injected from the joint A to apply pressure to the inside, and there is no leakage or breakage at an internal pressure of 3 MPa. Was determined to be acceptable.

As a result, in the stainless steel plate satisfying 0.1Si + Ti + Al <0.15% by mass, there was no problem in the internal oxidation state under any conditions.
It is considered that the surface oxidation of the stainless steel plate did not occur because it was heating in an atmosphere of 1 × 10 ⁻² Pa or less. On the other hand, when a stainless steel plate satisfying 0.1Si + Ti + Al ≧ 0.15% by mass was used, an oxide film of a temper color was observed on the surface and inside. It is presumed that easily oxidizable elements were oxidized by heating during bonding.
Table 2, Table 3, and Table 4 show the results of pressure tests of a heat exchanger constructed of a box-shaped part having a thickness of 0.4 mm, a fin part, and a bottom plate having a thickness of 1.0 mm.

Table 2 shows the results when a pressure resistance test was performed in which an internal pressure of 3 MPa was applied to a material subjected to solid phase diffusion bonding under conditions of an applied pressure of 0.1 MPa to 1.1 MPa and a heating temperature of 950 ° C. to 1300 ° C. The results under the conditions of applied pressure of 0.1 MPa, 0.3 MPa, 0.5 MPa, 0.7 MPa, 0.9 MPa, and 1.1 MPa are shown in one frame from the left. Symbol ○ indicates that there is no leak in the pressure test result, and symbol △ indicates that there is no leak in the pressure test, but significant deformation occurs in the product due to excessive pressure or heating temperature, and symbol × indicates that the result of the pressure test is leaky. Or indicates that there was a break.
Under the conditions where the heating temperature is 1300 ° C. or the applied pressure is 1.1 MPa, satisfactory pressure resistance performance is obtained for any steel type, but the product is deformed and the appearance of the product is impaired. On the other hand, a stainless steel plate satisfying 0.1Si + Ti + Al <0.15% by mass is a ferrite single phase system or austenite system, Ra is 0.3 μm or less, a heating temperature is 1100 ° C. or more and 1250 ° C. or less, and a pressing force is 0.3 MPa. It can be seen that bonding can be sufficiently performed at 0.9 MPa and the appearance is good. When Ra was 0.4 μm or more, a product with sufficient bonding strength and good appearance could not be obtained under any conditions.
In the martensite system, the applied pressure is 0.3 MPa to 0.9 MPa, Ra ≦ 0.3 μm, the heating temperature is 1000 ° C. to 1250 ° C., and 0.3 μm <Ra ≦ 0.4 μm It can be seen that bonding can be sufficiently performed under the conditions of 1100 ° C. or higher and 1250 ° C. or lower and the appearance is also good. When Ra was 1.0 μm or more, a product with sufficient bonding strength and good appearance could not be obtained under any conditions.
In the duplex stainless steel sheet, it can be seen that Ra is 2.0 μm or less, the heating temperature is 1000 ° C. or more and 1250 ° C. or less, and the pressing force is 0.1 MPa or more and 0.9 MPa. When Ra was 3.0 μm, a product with sufficient bonding strength and good appearance could not be obtained under any conditions.

  Table 3 shows the result of solid phase diffusion bonding of a temporary assembly of a heat exchanger in which different steel types having a surface roughness Ra of 0.3 μm are combined under conditions of a temperature of 1100 ° C. and a pressure of 0.3 MPa. It is a result when performing a pressure | voltage resistant test on the same conditions as. The symbol ◯ indicates that the pressure test result indicates no leakage, and the symbol X indicates that the pressure test result indicates leakage or breakage. Both heat exchangers are sufficiently solid phase diffusion bonded.

Table 4 shows a heat exchanger temporary assembly made of materials with different plate thicknesses, manufactured a heat exchanger by solid phase diffusion bonding, and conducted an internal pressure test under various load internal pressure conditions. It is a result. The material is sample no. 2. Column A is the heat exchanger (Fig. 6) in which box-shaped components with fins formed on the top flat portion of the box-shaped component are stacked, and column B is the heat stacked by inserting the fin components between the two box-shaped components. It is a result about an exchanger (FIG. 7). Further, the symbol ◯ indicates that the pressure test result is no leak, and the symbol X indicates that the pressure test result is leaked or broken.
It can be seen that a material plate thickness of 0.3 mm or more can sufficiently withstand the internal pressure as a heat exchanger. When the material plate thickness was less than 0.3 mm, solid phase diffusion was sufficient, but breakage occurred at the portion where the plate thickness decreased during press working.
In addition, there was no influence of the installation form of a fin.

Claims (8)

The parts constituting the heat exchanger case are composed of a box-shaped part, a projecting part and a frame part provided with a tip piece bent outward at a substantially right angle to the peripheral flange part, and the frame part is directed upward from the bottom plate. The box-shaped part is laminated in the order of the overhanging part, and the box-shaped part is laminated on the overhanging part only at the uppermost part, and the upper surface of the frame part and the flat part near the flange of the box-shaped part The contact part of the box-shaped part, the contact part of the peripheral part of the projecting part, and the contact part of the peripheral part of the projecting part and the lower part of the frame part are solid phase diffusion bonded. Plate-type heat exchanger characterized by having a high bonding strength.   The box-shaped part is a press-molded product formed with two types of openings at symmetrical positions, one opening above the box-shaped part and the other opening inward of the box-shaped part, The overhang component is a press-molded product formed in a shape in which two types of openings are formed at symmetrical positions, one is opened above the overhang component, and the other is opened under the overhang component. The plate heat exchanger according to claim 1, wherein the sum of the height of the opening and the height of the opening of the overhanging part in contact with the opening is equal to the flange height of the box-shaped part.   The frame part has a rectangular opening at the center and a box shape having the same height as the flange height of the box part, and includes a protruding piece extending outward at a substantially right angle at the lower end of the peripheral part. The plate type heat exchanger according to claim 1 or 2. The top surface flat portion of the front Symbol box-shaped element, height cross-sectional shape triangular or trapezoidal or square are formed the same fins as flange height, the tip piece of the laminated upper part is a flange near the flat portion of the laminate lower part The tip of the said fins contact | abut when making it contact | abut, Both are formed by solid-phase diffusion bonding in the said contact part, The flow-path junction part is formed in any one of Claims 1-3 The plate heat exchanger as described. A fin component with a cross-sectional shape of a triangle, trapezoid, or quadrangle and the same height of the flange is inserted between two stacked box-shaped components, and the top piece of the stacked component is the flat portion near the flange of the stacked component The tip of the fin part comes into contact with the upper flat portion of the box-shaped part when the two are brought into contact with each other, and both are solid-phase diffusion bonded at the contact part to form a flow path joint. The plate type heat exchanger in any one of -3. A method for producing a plate heat exchanger according to any one of claims 1 to 5, wherein the ferritic single-phase stainless steel has chemical components of 0.1Si + Ti + Al <0.15% by mass and a surface roughness Ra ≦ 0.3 μm. Using a steel plate or an austenitic stainless steel plate, a laminated assembly of box-shaped parts is heated at a temperature of 1100 ° C. to 1250 ° C., a pressing force of 0.3 MPa to 0.9 MPa, and an atmospheric pressure of 1 × 10 ⁻² Pa. A method for producing a plate heat exchanger, characterized by heating in the following furnace and solid phase diffusion bonding. It is a manufacturing method of the plate type heat exchanger in any one of Claims 1-5, Comprising: The chemical component uses the martensitic stainless steel plate of 0.1Si + Ti + Al <0.15 mass%, and lamination | stacking of box-type components When the surface roughness Ra ≦ 0.3 μm, the heating temperature is 1000 ° C. to 1250 ° C., and when the surface roughness 0.3 μm <Ra ≦ 0.4 μm, the heating temperature is 1100 ° C. to 1250 ° C. A method for producing a plate heat exchanger, characterized in that solid-phase diffusion bonding is performed by heating in a furnace having a pressure of 0.3 MPa to 0.9 MPa and an atmospheric pressure of 1 × 10 ⁻² Pa or less. . It is a manufacturing method of the plate type heat exchanger in any one of Claims 1-5, Comprising: A chemical component is 0.1Si + Ti + Al <0.15 mass%, Surface roughness Ra <= 2.0micrometer, Duplex stainless steel plate The laminated assembly of box-shaped parts is heated in a furnace having a heating temperature of 1000 ° C. to 1250 ° C., a pressing force of 0.1 MPa to 0.9 MPa, and an atmospheric pressure of 1 × 10 ⁻² Pa or less. And a solid phase diffusion bonding method for producing a plate heat exchanger.

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