JP4031406B2 - Bracket brazing method and Coriolis meter to flow tube - Google Patents

Description

  The present invention relates to a bracket brazing method for a flow tube of a Coriolis meter and a Coriolis meter.

  The Coriolis meter supports both ends of the flow tube through which the fluid to be measured flows. When the flow tube is vibrated in the direction perpendicular to the flow direction around the support point, the Coriolis force acting on the flow tube is proportional to the mass flow rate. It is a mass flow meter that uses The flow tube in the Coriolis meter is known in various shapes such as a curved tube, a straight tube, or an arcuate tube. Regardless of the shape, a drive device that drives the flow tube at the center thereof, A pair of vibration detection sensors are provided that are installed at symmetrical positions on both sides and detect a phase difference proportional to the Coriolis force.

  FIG. 6 is a schematic configuration diagram showing an example of such a conventional parallel double-bow curved tube type Coriolis mass flow meter (see, for example, Patent Document 1). FIG. 6 is a partial cross-sectional view (left side) viewed from the front and a side view (right side) cut at the manifold section, assuming that the inlet pipe and the outlet pipe are mounted horizontally. The measurement fluid flows in from the external flow pipe connected via the flange 18 and is equally branched into the two flow tubes 1 and 2 at the inlet side manifold. Then, at the outlet side of the flow tubes 1 and 2, they merge at the outlet side manifold 25 and flow out to the external flow pipe connected via the flange 19. The flow tubes 1 and 2 are composed of two parallel arcuate curved tubes, and the two flow tubes 1 and 2 are placed in opposite phases by a driving device 15 composed of a coil and a magnet at the center. Resonant drive. In addition, a pair of vibration detection sensors 16 and 17 composed of coils and magnets are installed at symmetrical positions on both the left and right sides with respect to the mounting position of the driving device 15 to detect a phase difference proportional to the Coriolis force. Yes.

  In the central portion of the arcuate flow tube, the drive device 15 has a drive device coil attached to one flow tube 1 and a drive device magnet attached to the other flow tube 2 via attachments. In the pair of vibration detection sensors 16 and 17, on both sides of the driving device 15, a detection sensor magnet is attached to one flow tube 1 and a detection sensor coil is attached to the other flow tube 2 via attachments.

  FIG. 7 shows a conventional technique for brazing a coil bracket, which is a fixture for attaching a coil, to a flow tube. In the illustrated case, since the coil bracket is plate-shaped, the wax between the bracket and the tube has a fillet shape. This plate-shaped coil bracket deforms bimetallicly in response to temperature fluctuations, and the sensor coil is attached to the deforming coil bracket, so that the flow tube of the coil mounted on the bracket The relative position from the point changed, causing the zero point movement.

FIG. 8 is a diagram for explaining the deformation of such a coil bracket. When the temperature is high, due to the difference in elongation between the coil bracket and the wax, as shown in FIG. 8A, when the coil bracket tip approaches the flow tube side, and conversely, when the temperature is low, FIG. As shown in (2), the metal bracket is deformed so that the tip of the coil bracket moves away from the flow tube side.
JP 2001-174307 A

  When joining an additive such as a bracket to the Coriolis meter flow tube by brazing, etc., the linear expansion coefficient of the wax and the linear expansion coefficient of the flow tube or bracket are different. Deformation occurs. The coil bracket is usually made of stainless steel as in the case of the flow tube, but it has also been confirmed by experiments that the above-described deformation occurs when such a stainless steel material is brazed. As a result, the relative position changes from the flow tube of the coil mounted on the bracket, causing the zero point movement.

  By minimizing the fillet by minimizing the applied wax, it is possible to minimize bimetallic deformation due to thermal changes, but the joining becomes uncertain and stress tends to concentrate, and the strength and rigidity are also reduced. To do. Therefore, a certain amount of fillets must be allowed. If the presence of a certain amount of fillet is allowed, the coil bracket is deformed bimetallicly due to a heat change.

  Conventionally, there was no countermeasure against deformation due to brazing. Such deformation is an amount of change that causes a problem in a small sensor having a small phase difference due to Coriolis force, and is not a problem in a large sensor having a large phase difference. In order to solve the deformation problem due to brazing, as shown in FIG. 9, it is conceivable to form a coil bracket along the tube so that the amount of brazing applied is minimized. However, although such a configuration is effective against bimetallic deformation, it becomes a precision cast product or a machined product, and a coil bracket must be prepared for each tube outer diameter size. It was disadvantageous.

  SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems, and when brazing a coil bracket to a tube, it is an object of simplifying the structure and surely joining it and minimizing bimetallic deformation due to thermal changes. .

  The brazing method for brazing the bracket to the flow tube of the Coriolis meter of the present invention brazes the bracket having at least a brazed portion in a plate shape and the flow tube. A feature of the present invention is that the opposite surface of the plate-like bracket facing the flow tube is coated with wax to offset the deformation due to the heat change, thereby preventing the bimetallic deformation of the bracket.

  Also, the brazing method of the present invention provides a thin plate with a gap provided on the opposite surface of the plate-like bracket facing the flow tube, and poured and applied the brazing into this gap to offset deformation due to thermal changes. It is characterized by preventing bimetallic deformation of the bracket.

  In addition, the brazing method of the present invention is characterized in that a rod-like member is inserted into a braze fillet between the bracket and the flow tube to prevent the bracket from being bimetallicly deformed as resistance against bending of the bracket.

  Further, the Coriolis meter of the present invention, in which one drive device composed of a magnet and a coil and a pair of detection sensors are attached to the flow tube, has a bracket attached to the flow tube and attached to the magnet or coil. The bracket has at least a brazed plate shape. The plate-shaped bracket is configured to be coated with wax on the opposite surface facing the flow tube so as to offset the deformation due to the heat change, thereby preventing the bimetallic deformation of the bracket.

  In addition, the Coriolis meter of the present invention provides a gap on the opposite surface of the plate-shaped bracket facing the flow tube, and a thin plate is applied to the gap. It is characterized in that it is configured to prevent the bimetallic deformation of the bracket.

  In addition, the Coriolis meter of the present invention is characterized in that a rod-shaped member is inserted into the filler fillet between the bracket and the flow tube to prevent the bracket from being bent as a resistance against bending of the bracket.

  According to the present invention, when the bracket is brazed to the flow tube, the structure can be simply and reliably joined, and bimetallic deformation due to thermal change can be minimized.

  As a result, the relative position of the coil mounted on the bracket from the flow tube does not change, and no zero point movement occurs.

  Hereinafter, the present invention will be described based on examples. FIG. 1 shows a cross-sectional view of two parallel flow tubes cut at a vibration detection sensor mounting portion. As shown in the drawing, the magnet constituting the detection sensor is attached to one of the flow tubes via a fixture. A coil assembly including a coil is attached to a coil bracket, and the coil bracket is fixed to the other flow tube by brazing which is a feature of the present invention.

  FIG. 2 is a diagram showing a first example of brazing according to the present invention. As shown in FIG. 2, normal brazing is performed on the flow tube side of the bracket. At the same time, in order to prevent deformation due to thermal changes of the bracket, brazing is applied to the opposite surface of the brazing portion of the bracket, and vacuum brazing is performed. The bracket has a predetermined width in the tube length direction, but the wax flows and adheres to both sides of the bracket over the predetermined width, so that the deformation due to the above-described thermal change is offset. Is possible. It is sufficient that the solder applied to the opposite surface of the bracket brazing portion is injected so that the brazing portion and the bracket brazing portion are infiltrated so as to have the same coating range, and can be easily controlled. In order to limit the application range, a commercially available paint can be used. In short, when a predetermined amount of paste-like wax is injected and placed, and then vacuum brazed (heated), the wax penetrates thinly with fluidity, but the wax is applied where the paint is applied. It can be prevented from being applied.

  FIG. 3 is a diagram showing a second example of brazing according to the present invention. (A) is a perspective view of a brazing part, (B) is sectional drawing. As in the first example, not only the brazed portion of the bracket but also the opposite surface thereof is coated with a braze and vacuum brazed. The braze on the opposite surface is between the bracket and the thin plate. It differs from the first example in that it is poured into the gap and applied. Since the effect of inhibiting deformation also changes depending on the solder coating area and thickness, a thin plate is attached to the target part of the bracket by spot welding, etc., so that the solder flows into the gap between the thin plate and the bracket (about 0.2 mm or less). Thus, the coating amount can be made almost constant. Deformation due to the brazed portion of the bracket will be offset by the presence of the opposite braze. Further, the presence of the thin plate makes it possible to keep the thickness of the applied solder constant and to substantially limit the range in which the solder is applied within the thin plate area.

  FIG. 4 is a diagram showing a third example of brazing according to the present invention. The bracket is brazed on the flow tube side as in the above example. At the time of brazing, a rod-shaped (solid) member made of the same material as the flow tube and bracket is embedded in the fillet portion. It is sufficient that the length of the rod-like member is substantially equal to the brazing length in the flow tube flow direction. As shown, two are used on both sides. As a result, the proportion of the wax can be reduced without reducing the rigidity of the fillet portion of the wax, and resistance to bending of the bracket can be achieved. In this way, bimetallic deformation can be suppressed.

  FIG. 5 is a diagram showing a fourth example of brazing according to the present invention. It differs only in the point which replaced with the rod-shaped (solid) member in a 3rd example, and used the cylindrical rod-shaped member. Similarly to the third example, the resistance against bending of the bracket can be obtained by inserting a rod-shaped member.

  In the above description, the case where the coil assembly of the detection sensor is attached to the bracket has been described as an example. However, the present invention can be equally applied to the attachment of the coil assembly of the driving device, and further, detection. It can also be applied to the attachment of a sensor or a magnet of a driving device.

  The above-described excellent effects of the present invention were confirmed by tests. The specifications of the coil bracket and flow tube used for the test are as shown in Tables 1 and 2.

First test (test of bracket with conventional technology configuration)
As described in the prior art with reference to FIG. 7, the amount of thermal deformation of the coil bracket in a state where the coil bracket (Table 1) is brazed to each type of flow tube (Table 2) was examined. As shown in FIG. 10 (A), the measurement arm was fixed to the coil contact surface of the coil bracket so as to face the coil, and the gap W on the opposite side of the cantilever was measured. The gap was measured using a gap gauge in a temperature environment of about 20 ° C (room temperature) and about 300 ° C.

  The combination of each type of flow tube and coil bracket caused thermal deformation of about 0.01mm to 0.03mm. Each time heat was applied, both ends of the bracket (coil contact surface) warped and deformed in the direction of falling to the tube side. The amount of deformation is almost the same for each type.

Second test (test of coil bracket alone)
As shown in FIG. 10B, the measurement arm was attached to the coil bracket alone so as to be cantilevered, and the gap W was measured. As a result of measurement, it became clear that the bracket alone does not cause thermal deformation.

Third test (test of the configuration of FIG. 3 of the present invention)
As described above with reference to FIG. 3, the thermal deformation when the plate was brazed to the coil side plane of the bracket was examined. It was verified whether it was possible to cancel the thermal deformation in the state where the bracket was brazed to the tube by applying brazing (brazing the plate) to the coil side plane of the bracket. By optimally selecting the board dimensions (flow tube B: outer diameter φ6.0, wall thickness 0.3 mm, board dimensions are 6 mm wide and 4-5 mm long), it was possible to completely suppress thermal deformation. Although the plate thickness was changed to 0.1 mm and 0.5 mm, the same effect was obtained on the thermal deformation of the bracket, so the bracket deformation depends on the solder coating (penetration) area regardless of the plate thickness. I understood.

Fourth test (actual Coriolis meter test)
An actual Coriolis meter (flow tube B in Table 2) pick-off sensor coil bracket with a countermeasure against plate brazing was manufactured, and a temperature zero drift test was conducted to confirm its effect.

  The dimensions of the plate to be brazed to the bracket were 6 mm wide, 5 mm long, and 0.1 mm thick. When the temperature zero drift test was conducted, good characteristics of 0.0032% of the maximum normal flow rate 32 kg / min / ° C (at 50 ° C) and 0.0009% of the maximum normal flow rate 32 kg / min / ° C (at 80 ° C) were achieved.

It is a figure which shows sectional drawing which cut | disconnected the vibration detection sensor and two parallel flow tubes. It is a figure which shows the 1st example of brazing by this invention. It is a figure which shows the 2nd example of brazing by this invention. It is a figure which shows the 3rd example of brazing by this invention. It is a figure which shows the 4th example of brazing by this invention. It is a schematic block diagram which shows an example of the conventional parallel 2 bow-shaped curved tube type Coriolis mass flowmeter. It is a figure which shows the prior art which brazes the coil bracket which is a fixture which attaches a coil to a flow tube. It is a figure explaining a deformation | transformation of a coil bracket. It is a figure explaining the technique which can solve the deformation | transformation problem by brazing. It is a figure explaining the structure which measures the thermal deformation of a coil bracket, (A) is the state brazed to the flow tube, (B) has shown the structure measured with a coil bracket single-piece | unit.

Explanation of symbols

1, 2 Flow tube 15 Driving device 16, 17 A pair of vibration detection sensors 18 Flange 19 Flange 25 Outlet side manifold

Claims (6)

In the brazing method of brazing the bracket to the flow tube of the Coriolis meter,
Braze at least the bracket where the brazing part is plate-like and the flow tube,
Applying wax on the opposite surface facing the flow tube of the plate-shaped bracket, offsetting deformation due to thermal change, preventing bimetallic deformation of the bracket,
A brazing method characterized by that. In the brazing method of brazing the bracket to the flow tube of the Coriolis meter,
Braze at least the bracket where the brazing part is plate-like and the flow tube,
On the opposite surface of the plate-shaped bracket facing the flow tube, a gap is provided and a thin plate is attached. prevent,
A brazing method characterized by that. In the brazing method of brazing the bracket to the flow tube of the Coriolis meter,
Braze at least the bracket where the brazing part is plate-like and the flow tube,
By inserting a rod-like member into the filler fillet between the bracket and the flow tube, as a resistance against bending of the bracket, preventing bimetallic deformation of the bracket,
A brazing method characterized by that. In a Coriolis meter in which one driving device and a pair of detection sensors each composed of a magnet and a coil are attached to a flow tube,
A bracket to which a magnet or a coil is attached that is brazed to the flow tube, and the bracket has a plate shape at least at a brazing portion,
The opposite surface facing the flow tube of the plate-like bracket was coated with wax to compensate for deformation due to thermal change and to prevent bimetallic deformation of the bracket.
Coriolis meter characterized by that. In a Coriolis meter in which a single drive device and a pair of detection sensors each composed of a magnet and a coil are attached to a flow tube,
The bracket has a magnet or a coil attached to the flow tube, and the bracket has at least a brazed plate shape,
On the opposite side of the plate-shaped bracket facing the flow tube, a thin plate is attached with a gap, and solder is poured into the gap to apply it, offsetting deformation due to thermal change, and bimetal deformation of the bracket. Configured to prevent,
Coriolis meter characterized by that. In a Coriolis meter in which a single drive device and a pair of detection sensors each composed of a magnet and a coil are attached to a flow tube,
A bracket to which a magnet or a coil is attached that is brazed to the flow tube, and the bracket has a plate shape at least at a brazing portion,
As a resistance against bending of the bracket by inserting a rod-like member in the fillet portion of the wax between the bracket and the flow tube, it is configured to prevent bimetallic deformation of the bracket.
Coriolis meter characterized by that.

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