Method for precise assembly of diaphragm and meter housing of a diaphragm gas meter

Abstract

This invention discloses a precise assembly method for the diaphragm and metering housing of a diaphragm gas meter, comprising the following steps: S1, assembling the diaphragm with the folded plate installed inside the mechanism, with the four corners of the diaphragm suspended from the suspension points at the four corners of the mechanism; S2, positioning the diaphragm using a diaphragm positioning module to ensure the diaphragm cavity depth reaches the designed depth; S3, gripping the metering housing and fastening it onto the mechanism, and pre-pressing the rivet teeth of the metering housing using a metering housing pre-pressing structure, wherein the diaphragm positioning module remains stationary during the pre-pressing process, and resets after the pre-pressing is completed. By precisely positioning the diaphragm and adjusting the diaphragm cavity depth, the uniformity of the contact position between the sealing ring on the metering housing and the diaphragm is ensured, thus guaranteeing the accuracy of the position of the metering housing and the diaphragm during the pre-pressing process, preventing diaphragm skew, reducing mechanical friction during diaphragm bulging, and improving the metering accuracy of the diaphragm meter. Compared with manual adjustment, this method significantly improves assembly efficiency and product consistency.

Description

Technical Field

[0001] This invention belongs to the field of gas meter manufacturing equipment, specifically relating to a method for precise assembly of the diaphragm and metering housing of a diaphragm gas meter. Background Technology

[0002] The diaphragm is one of the important components of a diaphragm gas meter. During the operation of the gas meter, the pressure of the gas causes the diaphragm assembly to bulge within the diaphragm cavity, which in turn drives the rocker arm to move and count. Existing diaphragm assemblies can be referenced from the patent with patent number "202223360566.4" entitled "A Gas Meter Diaphragm Assembly". The diaphragm is mainly engaged with the folding plate inside the mechanism through the rotation of the diaphragm clamp plate at the bottom. The four corners of the diaphragm are fixed to the four corners of the mechanism body at the suspension points. At this time, the diaphragm has a large range of motion. When the metering shell is fastened, the four sides of the diaphragm and its depth in the metering shell are fixed.

[0003] The applicant discovered in their research that the depth of the diaphragm cavity directly affects metering accuracy, and the initial fixing position of the diaphragm during installation directly affects the volume of the diaphragm cavity. Furthermore, the uniformity of the contact area between the diaphragm and the mechanism body after fixing directly affects the rotational friction of the rocker arm. Correspondingly, the position of the diaphragm also directly affects the sealing quality of the meter housing's sealing ring, thus affecting the sealing quality of the meter housing. In summary, the diaphragm position plays a crucial role in the gas meter assembly process during the pressing of the meter housing. In existing technologies, the assembly of the meter housing is mostly done manually, using manual operation to lift the folding plate connected to the rocker arm before pressing the meter housing in place. This involves manually adjusting the diaphragm cavity depth, which is inefficient and results in poor product consistency, severely impacting the quality of the gas meter. Summary of the Invention

[0004] In view of this, the present invention provides a method for precise assembly of the diaphragm and metering housing of a diaphragm gas meter, in order to solve the problems of inaccurate assembly position of the diaphragm and metering housing in the prior art, as well as low efficiency, poor product consistency and low yield.

[0005] The technical solution is as follows:

[0006] A method for precisely assembling the diaphragm and metering housing of a diaphragm gas meter, the key of which includes the following steps:

[0007] S1, Assemble the diaphragm with the folding plate installed inside the movement body, and suspend the diaphragm at the suspension points at the four corners of the movement body.

[0008] S2, the membrane is positioned by the membrane positioning module so that the membrane cavity depth reaches the designed depth;

[0009] S3, the metering shell is gripped and fastened to the core body, and the rivet teeth of the metering shell are pre-pressed by the metering shell pre-pressing structure. During the pre-pressing process, the diaphragm positioning module remains stationary. After the pre-pressing is completed, the diaphragm positioning module is reset.

[0010] Using the above scheme, before pre-pressing the metering shell, the diaphragm depth is first adjusted by the diaphragm positioning module, i.e., the diaphragm cavity volume is adjusted to ensure that the diaphragm cavity volume is appropriate. At the same time, the diaphragm edge extends outward evenly. Then, the metering shell is fastened and pre-pressed, which ensures the uniformity of the contact position between the sealing ring on the metering shell and the diaphragm, and prevents skewing. This reduces mechanical friction caused by diaphragm skewness in the later stage, improves the metering accuracy of the diaphragm, and greatly improves assembly efficiency and product consistency compared to manual adjustment.

[0011] Preferably, the diaphragm positioning module includes a guide rod and a rod drive mechanism for driving the guide rod to extend and retract horizontally;

[0012] In step S2, the guide rod, driven by the rod drive mechanism, extends horizontally into the movement body through the window on the front side. This design facilitates automated adjustment operations and further improves production efficiency.

[0013] Preferably, the front end of the folding plate has a sliding engagement portion that cooperates with the membrane clamping plate on the diaphragm. In step S2, after the guide rod extends into the mechanism body, its contact position with the membrane clamping plate corresponds to the lower side of the sliding engagement portion. Using this solution, the horizontality of the membrane clamping plate when it is lifted can be further guaranteed, improving the accuracy and reliability of the adjustment operation.

[0014] Preferably, the guide rod has a guide ramp and at least one horizontal step surface at its front end. When the guide rod extends into the mechanism body, the folding plate used to install the diaphragm is lifted by the horizontal step surface. With this design, the guide ramp ensures the guide rod extends below the folding plate, while the horizontal step surface better guarantees the folding plate's horizontality when lifted, preventing tilting to one side and further improving the accuracy of diaphragm posture adjustment. Furthermore, different step surfaces can accommodate adjustment needs at different depths, thus expanding its applicability.

[0015] As a preferred option, in step S3, the metering shell is enlarged before being fastened to the movement body. This method ensures a better fit between the metering shell and the movement body, preventing the rivet teeth from getting caught.

[0016] As a preferred option: in step S3, the metering shell is gripped and fastened to the core body by the metering shell gripping and releasing mechanism;

[0017] The metering shell gripping mechanism includes a robotic arm and a metering shell gripper assembly disposed at the free end of the robotic arm. The metering shell gripper assembly includes a connecting plate and a floating plate arranged opposite each other. A metering shell suction cup is fixed at the bottom of the floating plate, as well as a constraint structure adapted to the contour of the metering shell.

[0018] The connecting plate and the floating plate are slidably fitted together, and a locking mechanism is provided between them. During the gripping and fastening of the metering shell in step S3, the locking mechanism is in a locked state, and during the pre-pressing process, the locking mechanism is in an unlocked state. Using this scheme, during the gripping and releasing of the metering shell, the locking mechanism locks the connecting plate and the floating plate, which can fully ensure gripping stability. During the pre-pressing process, the locking mechanism unlocks, and the floating plate, along with the constraint structure, has a certain floating offset range, which can avoid or mitigate the deformation of the metering shell caused by hard contact fastening, ensuring that the finished product has good appearance quality.

[0019] As a preferred embodiment: In step S3, the metering shell pre-compression structure includes pre-compression cylinder A and pre-compression cylinder B corresponding to the front and rear sides of the core body, and the piston rod ends of the pre-compression cylinder A and pre-compression cylinder B are respectively connected to rivet head A and rivet head B.

[0020] During the pre-pressing process, the pre-tightening force provided by the pre-pressing cylinder B is greater than that of the pre-pressing cylinder A. When both riveting heads A and B are in contact with the riveting teeth of the metering housing, riveting head B remains stationary. This design ensures the overall stability of the movement during pre-pressing, preventing back-and-forth swaying and improving the reliability of the pre-pressing operation.

[0021] Preferably, in step S3, at least the rivet teeth at both ends along the length of the metering shell are pre-pressed, and the tilt angle of the rivet teeth after pre-pressing is greater than or equal to 45°. This method provides a better pre-pressing effect and prevents the metering shell from loosening before all the rivet teeth are properly riveted.

[0022] As a preferred option, in step S3, the core body is positioned using a core body fixing structure during the pre-pressing process. This approach prevents the core body from shaking, which could affect the pre-pressing effect and ensures the consistency of position among the metering shell, diaphragm, and core body during the pre-pressing process.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] The precise assembly method for the diaphragm and metering housing of the diaphragm gas meter provided by this invention adjusts the diaphragm cavity depth by precisely positioning the diaphragm, ensuring the uniformity of the contact position between the sealing ring on the metering housing and the diaphragm. This ensures the accuracy of the position of the metering housing and the diaphragm during the pre-pressurization process, prevents diaphragm skewing, reduces mechanical friction during diaphragm bulging, and improves the metering accuracy of the diaphragm meter. Compared with manual adjustment, it greatly improves assembly efficiency and product consistency. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the equipment used in the implementation of the present invention;

[0026] Figure 2 for Figure 1 Top view;

[0027] Figure 3 This is a top view of the structure above workbench C;

[0028] Figure 4 A 3D view of the diaphragm positioning module;

[0029] Figure 5 This is a top view of 4.

[0030] Figure 6 A side view of another embodiment of the guide rod;

[0031] Figure 7 A three-dimensional diagram of the metering shell gripper assembly;

[0032] Figure 8 for Figure 7 Axonometric drawing;

[0033] Figure 9 Enlarged layout diagram of the mounting base fixing structure, the mechanism fixing structure, the diaphragm positioning module, and the metering shell pre-compression structure;

[0034] Figure 10 for Figure 9 The front view;

[0035] Figure 11 This is a schematic diagram of the metering shell adjustment module structure;

[0036] Figure 12 for Figure 11 Front view;

[0037] Figure 13 This is a schematic diagram of the tooth expander seat structure. Detailed Implementation

[0038] The present invention will now be described in further detail with reference to the accompanying drawings.

[0039] refer to Figures 1 to 13The precise assembly method of the diaphragm and metering housing of the diaphragm gas meter shown mainly includes the following steps: Step S1, assemble the diaphragm with the folded plate installed in the mechanism body, and suspend the diaphragm at the suspension points at the four corners of the mechanism body; Step S2, position the diaphragm through the diaphragm positioning module 700 so that the diaphragm cavity depth reaches the design depth (referring to the vertical distance of the diaphragm relative to the bottom of the diaphragm cavity determined by calculation); Step S3, grab the metering housing and fasten it to the mechanism body, and pre-press the rivet teeth of the metering housing through the metering housing pre-pressing structure. During the pre-pressing process, the diaphragm positioning module 700 remains stationary. After the pre-pressing is completed, the diaphragm positioning module 700 resets.

[0040] Step S1 is a routine operation and will not be described in detail here. The following mainly focuses on the pre-pressurization assembly system used in steps S2 and S3 to further explain this application. As shown in the figure, the pre-pressurization assembly system mainly includes the movement component transport line L and the placement seat N. The movement component structure in this application refers to the patent with patent number "202022713612.9" entitled "A Novel Diaphragm Gas Meter Movement Structure", and the placement seat can refer to the patent with patent number "202323087586.3" entitled "A Diaphragm Processing Production Line".

[0041] The movement assembly transport line is equipped with a metering shell pre-assembly station in its transport direction. The metering shell pre-assembly station is equipped with a placement seat fixing structure, a movement body fixing structure, a diaphragm positioning module 700, a metering shell gripping and releasing mechanism 800, and a metering shell pre-pressing structure.

[0042] During operation, the placement seat fixing structure is used to fix the placement seat in the metering shell pre-assembly station, the core body fixing structure is used to keep the core body in the placement seat relatively fixed to the placement seat, the diaphragm positioning module 700 is used to adjust the diaphragm cavity depth, and step S3 is mainly completed by the metering shell gripping and releasing mechanism 800 and the metering shell pre-pressing structure. The metering shell gripping and releasing mechanism 800 is used to grip the metering shell and fasten it to the core body in the placement seat, and the metering shell pre-pressing structure is used to pre-press the metering shell on the core body in the placement seat.

[0043] Key reference Figures 4 to 6 In this application, the diaphragm positioning module 700 includes a guide rod 710 and a rod drive mechanism 720 that drives the guide rod 710 to extend and retract horizontally. It is located on one side of the metering shell pre-assembly station. The guide rod 710 can extend into the core body in the placement seat under the drive of the rod drive mechanism 720 and lift the diaphragm in the core body horizontally to the designed height. In the specific implementation of step S2, the guide rod 710 extends into the inner cavity from the window on the front side of the core body (during the pre-pressing process, the core body is in an inverted position. For ease of distinction, the side used to install the valve grille is called the front side, and the opposite side is the rear side). In this embodiment, the rod drive mechanism 720 adopts a slide cylinder structure.

[0044] The guide rod 710 can be composed of a rod body 711 and a rod head 712. The rod head 712 is detachably connected to the rod body 711, such as by threaded connection or snap-fit. The guide rod 710 is generally circular, and the end of the rod body 711 has a square fixing head 715.

[0045] The guide rod 710 of this application has at least a guide ramp 713 at its front end. The guide ramp 713 can lift the folded plate and better extend under the folded plate. Furthermore, at least one or more horizontal step surfaces 714 can be sequentially provided behind the guide ramp 713, such as... Figure 6 As shown, the adjacent horizontal step surfaces 714 have a slope transition or a smooth arc transition, which can fully ensure the horizontality of the folding plate when the guide rod 710 extends into the mechanism body and lifts the folding plate through the horizontal step surface 714.

[0046] Given that the existing folding plate has a sliding engagement part that cooperates with the membrane clamping plate at the bottom of the diaphragm, when implementing step S2, it is preferable that after the guide rod 710 extends into the core body, the guide inclined surface 713 or the horizontal step surface 714 is guided to the lower side of the sliding engagement part corresponding to the contact position of the membrane clamping plate. This part is basically the middle area of ​​the diaphragm. By ensuring the horizontality of the membrane clamping plate lifting, the uniformity of the diaphragm extension can be better guaranteed.

[0047] refer to Figures 1 to 3 , Figure 7 and Figure 8 The metering shell gripping mechanism 800 used in step S3 mainly includes a robotic arm 810 and a metering shell gripper assembly 820 connected to the free end of the robotic arm 810. The metering shell gripper assembly 820 includes a connecting plate 821 and a floating plate 822 arranged vertically opposite each other. A metering shell suction cup 823 is fixed at the bottom of the floating plate 822, as well as a constraint structure adapted to the contour of the metering shell. The connecting plate 821 and the floating plate 822 are slidably engaged and can slide horizontally. A locking mechanism 830 is provided between the two, which can lock the connecting plate 821 and the floating plate 822.

[0048] In this embodiment, the locking mechanism 830 includes a locking cylinder 831 and a locking seat 832 respectively disposed on the floating plate 822 and the connecting plate 821. The piston rod of the locking cylinder 831 has a locking tongue 833 that engages with the locking seat 832. When the piston rod of the locking cylinder 831 is pushed out, the locking tongue 833 engages with the locking seat 832, thereby achieving the purpose of locking the connecting plate 821 and the floating plate 822. In this embodiment, the locking seat 832 has a V-shaped groove. Of course, in addition to the above method, a locking pin can also be injected to engage with a pin hole. During the grasping and fastening of the metering shell in step S3, the locking mechanism 830 is in a locked state. During the pre-pressing process, the locking mechanism 830 is in an unlocked state.

[0049] The constraint structure mainly includes a straightening plate 824 corresponding to the four sides of the protruding part of the metering shell. The lower end of the straightening plate 824 has a conforming inclined surface adapted to the side of the protruding part of the metering shell. To further improve the gripping and releasing stability, in another embodiment, the constraint structure also includes positioning posts 825 corresponding to the four corner through holes of the metering shell. When the metering shell suction cup 823 grips the metering shell, the lower end face of the positioning post 825 abuts against the upper surface of the outer edge of the metering shell. On this basis, at least two diagonally arranged positioning posts 825 have limiting heads 8250 at their lower ends. The size of the limiting head 8250 is similar to that of the metering shell. The four corner through holes of the measuring shell are adapted to each other. When the measuring shell is grasped, the limiting head 8250 can extend into the corresponding through holes to further limit the posture of the measuring shell. It should be noted that in order to improve the positioning effect and prevent interference with the movement body when the measuring shell is placed, the lower end of the positioning post 825 has a relief countersunk hole adapted to the suspension points at the four corners of the movement body. If the lower end of the positioning post is provided with a limiting head 8250, the limiting head 8250 also has a relief countersunk hole adapted to the suspension point. That is, the outer diameter of the limiting head 8250 is consistent with the four corners of the measuring shell, and the inner diameter is consistent with the size of the suspension point.

[0050] refer to Figures 8 to 11 To improve the system's compactness and convenience, a workbench C900 is provided for the pre-assembly station of the metering shell, as shown in the figure. The aforementioned placement seat fixing structure M, the core body fixing structure 950, the diaphragm positioning module 700, the metering shell gripping and placing mechanism 800, and the metering shell pre-pressing structure are all set on the workbench C900. The core component transport line L passes over the workbench C900.

[0051] As shown in the figure, a metering shell adjustment module 910 is also provided on one side of the metering shell pre-assembly station on the workbench C900. A metering shell pallet stacking station and a metering shell feeding robot arm 920 are provided on one side of the workbench C900. The metering shell pallet stacking station is used to stack the pallets 600 containing the metering shells. The metering shell feeding robot arm 920 is used to grab the metering shells from the metering shell pallet stacking station and place them into the metering shell adjustment module 910. The metering shells are flipped so that the concave cavity is horizontal and facing down by the metering shell adjustment module 910.

[0052] In step S3, the metering shell is expanded and then fastened to the core body. Specifically, the metering shell adjustment module 910 mainly includes an adjustment platform 911 and a metering shell flipping structure and a metering shell expanding structure set on the adjustment platform 911, as shown in the figure. The metering shell flipping structure can refer to the patent with patent number "202122860827.8" and name "Diaphragm Gas Meter Metering Shell Sealing Device". It mainly includes a flipping seat 912 and a corresponding profile tooling 913. The flipping seat 912 has a corresponding clamping structure and a flipping cylinder. The metering shell feeding robot arm 920 can grab the metering shell and place it on the flipping seat 912. After being flipped 180° by the flipping cylinder, it is fastened to the profile tooling 913 with the concave cavity facing down.

[0053] The difference in this embodiment is that, in order to better adapt to the metering shell gripping mechanism 800, that is, to adapt to the structure of the limiting head 8250, the copying tool 913 has countersunk holes 9130 that correspond one-to-one with the limiting head 8250.

[0054] As shown in the figure, the tooth expansion structure mainly includes a tooth expansion seat 914, a tooth expansion guide rail 915 on the adjustment platform 911 that slides with the tooth expansion seat 914, and a tooth expansion cylinder 916 for driving the tooth expansion seat 914 to slide horizontally. The tooth expansion seat 914 can slide down the tooth expansion cylinder 916 to be directly above the copying tool 913.

[0055] The tooth-expanding seat 914 has an open, downward-facing cavity whose structure and size are adapted to the outer contour of the measuring case. The four sides of the copying fixture 913 have tooth-expanding inclined surfaces. When the measuring case is placed on the copying fixture 913, the rivet teeth on the measuring case contact the tooth-expanding inclined surfaces. The bottom of the copying fixture 913 has a copying lifting cylinder 917. When the tooth-expanding seat 914 is directly above the copying fixture 913, the copying lifting cylinder 917 pushes the copying fixture 913, along with the measuring case on it, into the cavity of the tooth-expanding seat 914. Under the action of the tooth-expanding inclined surfaces, the rivet teeth are pushed outwards, which is beneficial for later fastening onto the movement. Compared to traditional tooth-expanding structures, simultaneous tooth expansion on all four sides of the measuring case results in a more uniform tooth-expanding effect, which is beneficial for maintaining consistency.

[0056] To further improve the adaptability and ease of assembly and disassembly of the metering shell adjustment module 910, in this embodiment, the metering shell adjustment module 910 is supported on the workbench C900 by an intermediate plate 918, as shown in the figure. The intermediate plate 918 has an adjustment guide rail arranged along its length direction, and the adjustment platform 911 slides with the adjustment guide rail. At the same time, the intermediate plate 918 is provided with a driver for driving the adjustment platform 911 to slide along the adjustment guide rail. Correspondingly, the intermediate plate 918 has a cylinder clearance groove 9180 corresponding to the contour lifting cylinder 917. With the above structure, on the one hand, the height space is fully utilized to install the contour lifting cylinder 917, the overall structure is more compact, and the longitudinal position can be adjusted as needed in the later stage, so that it can be better adapted to the metering shell feeding robot arm 920 and the metering shell gripping and releasing mechanism 800.

[0057] The mechanism body fixing structure 950 mainly includes a horizontally arranged mechanism body fixing cylinder 951 and a mechanism body fixing seat 952 connected to the piston rod end of the mechanism body fixing cylinder 951, as shown in the figure. The mechanism body fixing seat 952 has a top head 953 adapted to the positioning post on the side of the mechanism body. After the placement seat is in the metering shell pre-assembly station, the placement seat is first fixed by the placement seat fixing structure, and then the mechanism body can be fixed by the mechanism body fixing structure 950.

[0058] refer to Figures 1 to 3 , Figure 8 and Figure 9 As shown, the pre-compression structure of the metering shell in this application includes pre-compression cylinders A930 and B940, which are positioned opposite each other on both sides of the metering shell pre-assembly station. The piston rod ends of pre-compression cylinders A930 and B940 are respectively connected to riveting heads A931 and B941. The pre-tightening force provided by pre-compression cylinder B940 is greater than that of pre-compression cylinder A930. In short, the cylinder diameter of pre-compression cylinder B940 is larger than that of pre-compression cylinder A930. During the pre-compression process, the pre-tightening force provided by pre-compression cylinder B940 is greater than that of pre-compression cylinder A930. When both riveting heads A931 and B941 are in contact with the riveting teeth of the metering shell, riveting head B941 remains stationary.

[0059] In the specific implementation of step S3, in order to further ensure the pre-tightening effect, at least the rivet teeth at both ends of the metering shell along the length direction are pre-pressed, and the tilt angle of the rivet teeth after pre-pressing is greater than or equal to 45°, that is, the tilt angle of the rivet teeth of rivet head A931 and rivet head B941 is greater than or equal to 45°. During the implementation process, if the space and the rivet tooth distribution position allow, the three rivet teeth evenly distributed along the length direction of the metering shell are pre-pressed.

[0060] refer to Figures 1 to 13The method for precisely assembling the diaphragm and metering housing of the diaphragm gas meter shown in this invention is as follows: In the station above the metering housing pre-assembly station, the diaphragm is assembled with the folding plate installed in the core body, ensuring that the four corners of the diaphragm are suspended on the suspension points at the four corners of the core body. Then, it is transported to the metering housing pre-assembly station via the placement seat N and the core assembly transport line L. First, the placement seat N is fixed by the placement seat fixing structure, and then the core body is fixed by the core body fixing structure 950.

[0061] When the diaphragm positioning module 700 operates, the guide rod 710 extends through the front window of the mechanism body, raising the diaphragm clamp to the designed height. This ensures that the edge of the diaphragm extends outwards evenly to cover the end face of the mechanism body. Then, the metering shell gripping mechanism 800 grips the expanded-tooth metering shell and fastens it onto the mechanism body. Next, the metering shell pre-pressing structure performs riveting pre-pressing. It should be noted that the locking mechanism 830 is in a locked state during the gripping of the metering shell and fastening it onto the mechanism body. When the metering shell pre-pressing structure operates, the locking mechanism 830 is in an unlocked state. After the pre-pressing is completed, the diaphragm positioning module 700 operates to remove the guide rod 710 from the mechanism body and reset it.

[0062] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention. Those skilled in the art, under the guidance of the present invention, can make various similar representations without departing from the spirit and claims of the present invention, and such modifications all fall within the protection scope of the present invention.

Claims

1. A method of precision assembly of a diaphragm and a meter housing of a diaphragm gas meter, characterized in that, Includes the following steps: S1, Assemble the diaphragm with the folding plate installed inside the movement body, and suspend the diaphragm at the suspension points at the four corners of the movement body. S2, the diaphragm is positioned by the diaphragm positioning module (700) so that the diaphragm cavity depth reaches the designed depth; S3, grab the metering shell and fasten it onto the core body, and pre-press the rivet teeth of the metering shell through the metering shell pre-pressing structure. During the pre-pressing process, the diaphragm positioning module (700) remains stationary. After the pre-pressing is completed, the diaphragm positioning module (700) is reset. The diaphragm positioning module (700) includes a guide rod (710) and a rod drive mechanism (720) for driving the guide rod (710) to extend and retract horizontally. In step S2, the guide rod (710) extends horizontally into the movement body from the window on the front side of the movement body under the drive of the rod drive mechanism (720); The front end of the folding plate has a sliding engagement part that cooperates with the membrane clamping plate on the diaphragm. In step S2, when the guide rod (710) extends into the core body, its contact position with the membrane clamping plate corresponds to the lower side of the sliding engagement part. The front end of the guide rod (710) is provided with a guide slope (713) and at least one horizontal step surface (714). When the guide rod (710) extends into the core body, the folding plate used to install the diaphragm is lifted by the horizontal step surface (714).

2. The diaphragm and meter case precision assembly method for a membrane gas meter of claim 1, wherein: In step S3, the measuring shell is expanded with teeth and then fastened onto the movement body.

3. The method for precisely assembling the diaphragm and metering housing of a diaphragm gas meter according to claim 1 or 2, characterized in that: In step S3, the metering shell is gripped and fastened to the core body by the metering shell gripping and releasing mechanism (800); The metering shell gripping mechanism (800) includes a robotic arm (810) and a metering shell gripper assembly (820) disposed at the free end of the robotic arm (810). The metering shell gripper assembly (820) includes a connecting plate (821) and a floating plate (822) arranged opposite each other. A metering shell suction cup (823) is fixed at the bottom of the floating plate (822), as well as a constraint structure adapted to the contour of the metering shell. The connecting plate (821) and the floating plate (822) are slidably engaged, and a locking mechanism (830) is provided between them. During the grasping and fastening of the metering shell in step S3, the locking mechanism (830) is in a locked state, and during the pre-pressing process, the locking mechanism (830) is in an unlocked state.

4. The method for precise assembly of the diaphragm and metering housing of a diaphragm gas meter according to claim 1 or 2, characterized in that: In step S3, the metering shell pre-compression structure includes pre-compression cylinder A (930) and pre-compression cylinder B (940) on the front and rear sides of the corresponding core body. The piston rod ends of the pre-compression cylinder A (930) and pre-compression cylinder B (940) are respectively connected to riveting head A (931) and riveting head B (941). During the pre-pressing process, the pre-pressing force provided by the pre-pressing cylinder B (940) is greater than the pre-pressing force of the pre-pressing cylinder A (930). When both the riveting head A (931) and the riveting head B (941) are in contact with the riveting teeth of the metering shell, the riveting head B (941) can remain stationary.

5. The method for precise assembly of the diaphragm and metering housing of a diaphragm gas meter according to claim 4, characterized in that: In step S3, the rivet teeth at least on both ends of the metering shell along the length direction are pre-pressed, and the tilt angle of the rivet teeth after pre-pressing is greater than or equal to 45°.

6. The method for precise assembly of the diaphragm and metering housing of a diaphragm gas meter according to claim 4, characterized in that: In step S3, the movement body is positioned by the movement body fixing structure during the pre-pressing process.

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