JP2009031161A - Manufacturing method for pressure gauge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure gauge accurately measuring pressure while preventing its indicator from being displaced with the passage of time. <P>SOLUTION: According to this manufacturing method of a pressure gauge, after adjusting gain by plastically deforming a gain adjustment arm part 128 of a displacement enlarging link 124 with a gain adjustment part, a springback of the arm part 128 is caused to finish by waiting for a prescribed period of time (at least one hour) to elapse, and then, the indicator 110 is regularly inserted into an indicator shaft 108 in accordance with a scale 112. This allows the indicator 110 to indicate an accurate value in actual use, making it possible to accurately measure pressure. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a pressure gauge, and more particularly to a pressure gauge that indicates mechanical displacement with a pointer.

As a mechanical pressure gauge, for example, a pressure gauge using a Bourdon tube as shown in FIG. 1 is generally used (see, for example, Patent Document 1 for a similar configuration).
A Bourdon tube pressure gauge 100 shown in FIG. 1 includes a gauge body 104 that houses a substantially C-shaped Bourdon tube 102.

  In the Bourdon tube pressure gauge 100, as the pressure increases, the radius of curvature of the Bourdon tube 102 gradually increases due to elastic deformation, and the free end (tube tip) 102A is displaced. Since this displacement is a minute displacement, this displacement is mechanically enlarged through a displacement enlargement mechanism 106 shown below, and the dial scale 112 is instructed to be enlarged by the pointer 110 attached to the pointer shaft 108. Yes.

  The displacement enlarging mechanism 106 includes a Bourdon tube 102 having one end (fixed end) fixed to a pressure introduction tube 114 fixed to the gauge body 104, and a fixed piece (tube) fixed to the free end 102A of the Bourdon tube 102. A linear link 120 is provided through a first free fulcrum 118 provided on the tip side of the first part 116.

In the displacement enlarging mechanism 106, a pointer shaft 108 is rotatably inserted into a first bearing (not shown) provided at the center of the gauge body 104.
A pinion 122 is fixed to the pointer shaft 108.
The displacement enlarging mechanism 106 is provided on the gauge body 104, and the displacement enlarging link 124 with a gain adjusting portion is fixed to a second bearing (not shown) disposed at a position spaced from the first bearing described above. A shaft 126 is rotatably inserted.

The displacement magnifying link 124 with the gain adjusting portion is formed of a plastically deformable gain adjusting arm portion 128 that is formed in a substantially U shape from the shaft 126 to the link 120 side, and the gain adjusting arm portion 128 integrally. And a sector gear 130 which is connected to the pointer shaft 108 side from the shaft 126.
Here, the distal end of the gain adjustment arm portion 128 is connected to the end portion of the link 120 opposite to the first free fulcrum 118 side via the second free fulcrum 132. The sector gear 130 is engaged with a pinion 122 fixed to the pointer shaft 108.

The reference circle diameter of the sector gear 130 is set larger than the reference circle diameter of the pinion 122. Further, the reference circle radius of the sector gear 130 (dimension half the reference circle diameter) is set to be larger than the distance L1 from the axis of the shaft 126 to the second free fulcrum 132.
Therefore, the amount of displacement of the free end 102A of the Bourdon tube 102 is expanded by the ratio of the gear ratio and the reference circular radius of the sector gear 130 to the distance L1 from the axis of the shaft 126 to the second free fulcrum 132. The rotation angle of the pointer shaft 108 is enlarged.

Next, the assembly procedure of the Bourdon tube pressure gauge 100 will be described.
(1) The Bourdon tube 102 is attached to the gauge body 104.
(2) The link 120 and the displacement expansion link 124 are attached to the gauge body 104.
(3) The fixed piece (pipe tip) 116 of the Bourdon tube 102 and the link 120 are connected.

(4) Wear the scale 112.

(5) Insert the pointer shaft 108 into the bearing, and temporarily insert the pointer 110 into the pointer shaft 108.
(6) The gain adjustment arm portion 128 is expanded and contracted (plastically deformed) using a tool or the like to adjust the gain.
(7) The pointer 110 is fully inserted into the pointer shaft 108 in accordance with the scale 112 (offset adjustment).
(8) Install other parts such as cover glass (may be plastic).

In the Bourdon tube pressure gauge 100 having such a displacement magnifying mechanism 106, there is a variation in the dimensional accuracy of each part, etc., so that the pointer display is calibrated after assembly.
For example, after attaching the pointer 110 to the pointer shaft 108, a predetermined pressure, for example, 200 kPa or 400 kPa, is applied to read the pointer scale, and a difference between the value of the predetermined pressure and the value of the pointer scale when operating the hand is refrained.
When the value is lower than the predetermined pressure, the gain is low, and when the value is higher than the predetermined pressure, the gain is high.
Therefore, the gain adjusting arm 128 is plastically deformed with radio pliers or the like, and the distance L1 from the axis of the shaft 126 to the second free fulcrum 132 is adjusted so that the value indicated by the pointer 110 matches a predetermined pressure. To do.
JP 2002-131157 A

  In such a Bourdon tube pressure gauge 100, the pointer 110 may not show 200 kPa as time passes, for example, at 200 kPa. That is, there is a problem that even if it is accurate immediately after manufacture, it becomes inaccurate with time.

  The present invention has been made to solve the above-described problem, and provides a pressure gauge manufacturing method capable of obtaining a pressure gauge capable of accurately measuring pressure while suppressing deviation of a pointer that occurs over time. Is the purpose.

As a result of various investigations and studies by the inventor, the following has been found.
When a part is plastically deformed for gain adjustment, a so-called spring in which the plastically deformed part returns in the opposite direction to bending (stretching) after a certain amount of time has elapsed due to residual stress generated at that time. It turns out that the pointer moves because of the back.

  The present invention has been made in view of the above-mentioned fact, and the invention according to claim 1 is a deformation member that elastically deforms in response to an introduced pressure, and a displacement expansion that mechanically expands the displacement of the deformation member. Means, a shaft rotated by the displacement enlarged by the displacement magnifying means, a pointer engaged with the shaft, a scale indicating pressure, and the displacement magnifying means are plastically deformed at least partially. A pressure gauge manufacturing method comprising: an adjustment unit that can adjust an amount of enlargement of displacement by: a step of temporarily fixing a pointer to a shaft; a step of plastically deforming the adjustment unit to adjust gain; and a scale And a step of permanently fixing the pointer to the shaft, and at least one hour or more is required from the step of adjusting the gain until the pointer is permanently fixed.

Next, a method for manufacturing the tube pressure gauge according to claim 1 will be described.
(1) The pointer is temporarily fixed to the shaft by the step of temporarily fixing the pointer to the shaft.
(2) The gain of the displacement enlarging means is adjusted by performing a gain adjustment process by plastically deforming the adjustment unit.
(3) The pointer is permanently fixed to the shaft through a process of permanently fixing the pointer to the shaft in accordance with the scale.

  Next, gain adjustment will be described below.

When the measurement pressure is introduced into the deformable member, the deformable member is elastically deformed, so that the displacement is mechanically expanded by the displacement enlarging means and the shaft is rotated. Since the pointer is engaged with the shaft, the pointer rotates according to the deformation of the deformation member.
Although the deformation amount of the deformation member is very small, this deformation can be expanded by the displacement expansion means.

The amount of enlargement (gain) of this displacement can be adjusted by plastically deforming the adjusting portion.
The gain adjustment is performed as follows, for example.
For example, in a no-pressure state, the pointer is assembled so that the pointer indicates zero, and then the pointer scale is read by applying a predetermined pressure force.

  When the pointer does not show a predetermined pressure value, the gain is low, and when the pointer exceeds the predetermined pressure value, the gain is high, so that the pointer shows a predetermined value on the scale. In addition, the adjustment portion is plastically deformed to adjust the gain.

  Here, in the pressure gauge manufacturing method according to claim 1, at least one hour or more is required from the step of adjusting the gain to the actual fixing of the pointer, and during that time, the inside of the adjustment unit is caused by plastic deformation. Deformation (springback) due to the generated residual stress is almost settled, and the deviation of the pointer that occurs after the pointer is permanently fixed can be greatly reduced.

  In addition, it is more preferable to leave 72 hours or more from the step of adjusting the gain until the pointer is permanently fixed.

  In the invention according to claim 2, the base member and one fixed end portion are fixed to the base member, the measurement pressure is introduced therein, and the free end side is displaced by elastic deformation due to the pressure change. A Bourdon tube, a first bearing provided on the base member, a first shaft inserted into the first bearing, a pressure indicating needle engaged with the first shaft, and the first A first gear that is coaxially attached to the shaft, a second bearing point that is provided on the base member and is spaced from the first fulcrum, and one end portion of which is spaced from the base member. A link connected to the free end side of the Bourdon tube through a first free fulcrum, a second shaft inserted into the second bearing, and formed on the link side from the second shaft; The second fixed fulcrum and the other end of the link are connected to the base A gain adjusting arm portion that can be connected via a second free fulcrum spaced from the material and can change the distance between the second shaft and the second free fulcrum by plastic deformation, and the gain adjusting arm portion. A pointer drive member provided with a second gear formed on the first shaft side from the second shaft and meshed with the first gear, and provided rotatably around the second bearing; , A scale, and a method of manufacturing a pressure gauge, the step of attaching a Bourdon tube to the gauge body, the step of connecting the link and the pointer drive member, and the second shaft of the pointer drive member as the second A step of inserting the bearing into the bearing, a step of connecting the Bourdon tube and the link, a step of attaching the scale to the base member, a step of inserting the first shaft into the first bearing, and a temporary pointer on the first shaft; The process of fixing and plastically deforming the gain adjustment arm In-adjustment step and a step of permanently fixing the pointer to the first axis so as to match the scale, and at least one hour or more is required from the step of adjusting the gain until the pointer is permanently fixed. It is characterized by.

  Next, the manufacturing method of the pipe pressure gauge of Claim 2 is demonstrated.

(1) The Bourdon tube is attached to the gauge body through a process of attaching the Bourdon tube to the gauge body.
(2) The link and the pointer driving member are connected through a step of connecting the link and the pointer driving member.
(3) By passing through the step of inserting the second shaft of the pointer driving member into the second bearing, the second shaft is inserted into the second bearing, and the second shaft is relative to the second bearing. It can turn freely.
(4) The Bourdon tube and the link are connected through the step of connecting the Bourdon tube and the link.

(5) The scale is attached to the base member through the step of attaching the scale to the base member.
(6) By passing through the step of inserting the first shaft into the first bearing, the first shaft is inserted into the first bearing, and the first shaft is rotatable with respect to the first bearing. Become.
(7) By passing through the step of temporarily fixing the pointer to the first shaft, the pointer is temporarily fixed to the first shaft.
(8) The gain adjustment arm is plastically deformed and gain adjustment is performed by performing a gain adjustment process by plastically deforming the gain adjustment arm.

The gain adjustment will be described below.
When the measurement pressure is introduced into the Bourdon tube, the Bourdon tube is elastically deformed and the free end is displaced. Displacement of the free end of the Bourdon tube rotates the pointer driving member via the link, the second gear of the pointer driving member rotates the first gear of the pointer, and the pointer rotates according to the displacement of the Bourdon tube To do. That is, the displacement of the free end of the Bourdon tube is expressed as the displacement (rotation) of the pointer. Although the displacement amount of the free end of the Bourdon tube is very small, this displacement can be enlarged by the pointer driving member and the first gear.

The displacement expansion amount (gain) can be adjusted by plastically deforming the gain adjusting arm and changing the distance between the second fixed fulcrum and the second free fulcrum.
For example, in a no-pressure state, the pointer is assembled so that the pointer indicates zero, and then the pointer scale is read by applying a predetermined pressure.

  If the pointer does not show a predetermined pressure value, the gain will be low, and if the pointer exceeds a predetermined pressure location, the gain will be high, so the pointer will show a predetermined value on the scale. Then, the gain adjusting arm is plastically deformed to adjust the distance between the second fixed fulcrum and the second free fulcrum (that is, gain adjustment).

(9) After performing gain adjustment, a step of permanently fixing the pointer to the first axis is performed in accordance with the scale, and the pointer is permanently fixed to the first axis.
In addition, the order of said (1)-(6) can be changed suitably.

Here, in the method for manufacturing a tube pressure gauge according to claim 2, at least one hour or more is required from the step of adjusting the gain until the pointer is permanently fixed, and during that time, the gain adjusting arm portion is deformed by plastic deformation. The deformation (springback) due to the residual stress generated in the inside of the needle is almost settled, and the deviation of the pointer that occurs after the pointer is permanently fixed can be greatly reduced.
In addition, it is more preferable to leave 72 hours or more from the step of adjusting the gain until the pointer is permanently fixed.

  As described above, according to the pressure gauge manufacturing method of the present invention, there is an effect that the pressure can be accurately measured after gain adjustment.

  Hereinafter, the manufacturing method of the pressure gauge concerning the embodiment of the present invention is explained. The Bourdon tube pressure gauge manufactured by the pressure gauge manufacturing method of the present embodiment has the same structure as that shown in FIG.

Next, an example of the manufacturing method of the pressure gauge of this embodiment is demonstrated.
(1) The Bourdon tube 102 is fixed to the pressure introduction tube 114 of the gauge body 104.
(2) The link 120 and the displacement expansion link 124 with the gain adjusting portion are connected by the pin-shaped second free fulcrum 132.
(3) Insert the shaft 126 of the displacement magnifying link 124 with the gain adjusting portion into the second bearing (not shown) of the gauge body 104.
(4) The fixed piece 116 provided at the tip of the Bourdon tube 102 and the link 120 are connected by a pin-shaped first free fulcrum 118.

(5) The pointer shaft 108 is inserted into a first bearing (not shown) of the gauge body 104 and the pinion 122 and the sector gear 130 are engaged with each other.
(6) The scale 112 is attached to the gauge body 104.
(7) Adjust the gain.
First, the pointer 110 is attached (temporarily fixed) to the pointer shaft 108.
The value indicated by the pointer shaft 108 is read in a non-pressure state, and then a fluid (air or the like) having a predetermined pressure is applied to the Bourdon tube 102 to read the value indicated by the pointer shaft 108, and the difference between the read values is refrained.

  When the difference between the values is lower than the pressure applied to the Bourdon tube 102, the gain of the displacement enlarging mechanism 106 is low, so the gain adjustment arm 128 is adjusted. Specifically, the gain adjusting arm portion 128 is plastically deformed using a tool such as radio pliers, and the distance L1 from the axis of the shaft 126 to the second free fulcrum 132 is shortened. Thereafter, the value indicated by the pointer shaft 108 when the pressure is zero is read again, and the value indicated by the pointer shaft 108 when a predetermined pressure is applied is read. Whether the difference between the values matches the applied pressure. To see. If they do not match, the adjustment is performed again.

On the other hand, when the value difference is higher than the pressure applied to the Bourdon tube 102, the gain of the displacement magnifying mechanism 106 is high, and thus the gain adjustment arm 128 is adjusted. Specifically, the gain adjusting arm portion 128 is plastically deformed using a tool such as radio pliers, and the distance L1 from the axis of the shaft 126 to the second free fulcrum 132 is increased. Thereafter, the value indicated by the pointer shaft 108 when the pressure is zero is read again, and the value indicated by the pointer shaft 108 when a predetermined pressure is applied is read. Whether the difference between the values matches the applied pressure. To see. If they do not match, the adjustment is performed again.
Thus, the gain adjustment is completed.

(8) After the gain adjustment, the Bourdon tube pressure gauge 10 is left for a predetermined time.
The predetermined time here is 1 hour or more, preferably 24 hours or more, and more preferably 72 hours or more. By leaving the Bourdon tube pressure gauge 10, the return deformation (springback) due to the internal stress of the gain adjusting arm portion 128 is settled.
(9) After leaving for a predetermined time, when the pressure of the Bourdon tube 102 is 200 kPa, for example, if the pointer 110 does not indicate 200 kPa of the scale 112, the pointer 110 is moved so that the pointer 110 indicates 200 kPa of the scale 112. This is inserted into 108 (offset adjustment).
Thereafter, the Bourdon tube pressure gauge 10 is completed by attaching parts such as a cover glass covering the pointer 110 and the scale 112 to the gauge body 104.

As described above, according to the pressure gauge manufacturing method of the present embodiment, after the gain adjustment, the Bourdon tube pressure gauge 10 is left for a predetermined time, and the return deformation (spring back) due to the internal stress of the gain adjustment arm 128 is performed. Therefore, the pointer 110 can indicate an accurate value in actual use.
In addition, you may change the order of the process of (1)-(6) suitably.

[Other Embodiments]
In the above embodiment, the shape of the Bourdon tube 102 is substantially C-shaped, but the Bourdon tube 102 may have another shape such as a spiral shape or a helical shape.
The present invention is not limited to a Bourdon tube type pressure gauge, but can be applied to any pressure gauge that adjusts gain by plastic deformation of parts, and can be applied to pressure gauges other than the Bourdon tube type.

(Test Example 1)
In order to confirm the effect of the present invention, one type of Bourdon tube pressure gauge manufactured by the manufacturing method of the conventional example and two types of Bourdon tube pressure gauges manufactured by the manufacturing method of the present invention are prepared, and gain adjustment is performed for each. The needle was fully pointed (fixed to the pointer shaft), and after 3 days, an air pressure of 200 kPa was applied to compare the needle readings.
Table 1 below lists the number of pressure gauges produced by manufacturing 10 test pieces for each type of pressure gauge and dividing the readings in 1 kPa increments.

From the test results, it can be seen that the pressure gauge manufactured by the manufacturing method of the conventional example has many display variations, and the display of the pressure gauge manufactured by the manufacturing method of the present invention is accurate.
In addition, it is understood that the display is more accurate when the pointer is completely inserted three days after the gain adjustment.

It is a front view which shows the internal structure of a Bourdon tube pressure gauge.

Explanation of symbols

10 Bourdon tube pressure gauge 102 Bourdon tube 102A Free end 104 Gauge body (base member)
106 Displacement magnification mechanism 108 Pointer shaft (first fixed fulcrum)
110 Pointer 114 Pressure introducing pipe 116 Fixed piece 118 First free fulcrum 120 Link 122 Pinion (first gear)
124 Displacement expansion link with gain adjustment part (pointer drive member)
126 axis (second fixed fulcrum)
128 Gain adjustment arm 130 Sector gear (second gear)
132 second free fulcrum FL1 first virtual straight line FL2 second virtual straight line L1 distance θ angle

Claims (3)

A deformable member that elastically deforms according to the introduced pressure;
Displacement magnifying means for mechanically magnifying the displacement of the deformable member;
An axis that rotates by the displacement enlarged by the displacement magnifying means;
A pointer that engages the shaft;
A scale to indicate pressure,
An adjustment unit provided in the displacement enlarging means, and capable of adjusting the amount of enlargement of the displacement by plastically deforming at least a part thereof;
A pressure gauge manufacturing method comprising:
A step of temporarily fixing the pointer to the shaft;
A step of plastically deforming the adjustment portion to adjust the gain;
A process of permanently fixing the pointer to the shaft to match the scale,
Have
A method for producing a pressure gauge, characterized in that at least one hour or more is left from the step of adjusting the gain until the pointer is permanently fixed. A base member;
A Bourdon tube in which one fixed end is fixed to the base member, a measurement pressure is introduced therein, and the free end side is displaced elastically by a pressure change;
A first bearing provided on the base member;
A first shaft inserted into the first bearing;
A pressure indicator for engagement with the first shaft;
A first gear coaxially attached to the first shaft;
A second bearing point provided on the base member and disposed at a position spaced from the first fulcrum;
A link having one end connected to the free end side of the Bourdon tube via a first free fulcrum spaced from the base member;
A second shaft inserted into the second bearing;
The second fixed fulcrum formed on the link side from the second shaft and the other end of the link are connected via a second free fulcrum spaced from the base member, and the second shaft and the A gain adjusting arm that can change the distance from the second free fulcrum by plastic deformation, and the first gear that is connected to the gain adjusting arm and is formed on the first shaft side from the second shaft. A pointer drive member provided with a second gear meshed with the second bearing and rotatably provided around the second bearing;
A method of manufacturing a pressure gauge with a scale,
Attaching the Bourdon tube to the gauge body;
Connecting the link and the pointer driving member;
Inserting the second shaft of the pointer drive member into the second bearing;
Connecting the Bourdon tube and the link;
Attaching the scale to the base member;
Inserting the first shaft into the first bearing;
Temporarily fixing the pointer to the first shaft;
A step of plastically deforming the gain adjustment arm and adjusting the gain;
A step of permanently fixing the pointer to the first shaft so as to match the scale;
Have
A method for producing a pressure gauge, characterized in that at least one hour or more is left from the step of adjusting the gain until the pointer is permanently fixed.   The method for manufacturing a pressure gauge according to claim 1 or 2, wherein a period of 72 hours or more is left from the step of adjusting the gain until the pointer is permanently fixed.

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