A gage plate assembly and welding distortion control fixture and method of use

Abstract

The application discloses a kind of non-perforated plate assembly and welding deformation control tool and method, for assisting the welding of non-perforated plate and lower head of voltage stabilizer, comprising an outer cover ring, multiple pressing plates and multiple sets of fasteners outer cover ring and pressing plate are provided with threaded hole, by fastener connection and form the clamping gap for non-perforated plate installation, recess matched with non-perforated plate is also provided on pressing plate, so that multiple non-perforated plates are reliably clamped and fixed, ensure the position accuracy when assembling;Simultaneously in the welding process, tool provides strong rigid constraint, effectively resists the deformation caused by welding thermal stress, guarantees the dimensional stability after welding.The tool structure is simple, easy to manufacture, convenient to operate, effectively solves the problems of non-perforated plate assembly positioning difficulty, large welding deformation in the prior art, improves assembly accuracy and production efficiency.

Description

Technical Field

[0001] This invention relates to the field of shunt welding for voltage regulators, and particularly to a tooling and method for controlling welding deformation in the assembly of perforated plates. Background Technology

[0002] In pressurizers of nuclear power plants or related industrial equipment, the shunt is a key component, containing multiple perforated plates and shunt shrouds. Currently, the common manufacturing process for shunts is integral molding, followed by wire cutting to divide them into multiple independent parts, specifically multiple perforated plates and shunt shrouds. Subsequently, these perforated plates and shunt shrouds need to be precisely assembled and welded to the lower end cap of the pressurizer.

[0003] In existing technologies, to ensure accurate assembly positioning, the assembly process of the perforated plate and the diffuser cover typically involves first pre-spot welding the diffuser cover and multiple perforated plates into a single unit, and then welding this unit to the lower end cap of the voltage regulator. The drawbacks of this method are: firstly, due to the high accuracy requirements of the perforated plates, spot welding is difficult, and the welds need to be removed before subsequent overall welding, making alternating symmetrical welding impossible and the process cumbersome; secondly, during welding, the lack of effective fixation and support makes the perforated plates prone to welding deformation and positional shifts, causing them to tilt and fail to meet drawing requirements, thus affecting the subsequent assembly of the diffuser cover.

[0004] It is understood that the above statements only provide background information related to the present invention and do not necessarily constitute prior art. Summary of the Invention

[0005] The purpose of this invention is to provide a tooling and method for controlling the assembly and welding deformation of perforated plates, which solves the technical problems of difficult positioning, large welding deformation, and difficulty in meeting positional requirements in the assembly of perforated plates in the prior art, and realizes the precision assembly of perforated plates and effective control of welding deformation.

[0006] To achieve the above objectives, the present invention provides a tooling for controlling deformation during the assembly and welding of perforated plates, used to assist in the welding of perforated plates, comprising: The outer ring is a circular ring structure with multiple pairs of first threaded holes evenly distributed on it; multiple pressure plates are arranged circumferentially along the inner wall of the outer ring; each pressure plate is an arc-shaped plate with the same width as the outer ring, and each pressure plate has a pair of second threaded holes; multiple pairs of fasteners are used to fix the outer ring and each pressure plate through the first and second threaded holes, and to fix each non-perforated plate between the outer ring and the corresponding pressure plate; wherein, the number of pairs of first threaded holes is the same as the number of pressure plates, and is also the same as the number of non-perforated plates to be welded.

[0007] Preferably, the curvature of the inner side of the outer cover ring matches the curvature of the outer side of the non-perforated plate, the curvature of the outer side of the pressure plate matches the curvature of the inner side of the non-perforated plate, and the outer cover ring, the non-perforated plate, and the pressure plate are located on three coaxial spherical surfaces in sequence.

[0008] Preferably, the first threaded hole is a hole that penetrates radially along the outer ring, and the second threaded hole is a hole that penetrates radially along the pressure plate; and the first threaded hole and the second threaded hole have the same size, both matching the size of the fastener.

[0009] Preferably, on the inner side of the outer cover ring, a first arc is formed between the two first threaded holes included in each pair of first threaded holes; on the outer side of the pressure plate, a second arc is formed between the two second threaded holes included in each pair of second threaded holes; the central angles of the first arc and the second arc are the same.

[0010] Preferably, each of the first threaded holes corresponds one-to-one with each of the second threaded holes and is located on the same straight line.

[0011] Preferably, the central angle of each pressure plate is less than 360° / N, where N is the number of pressure plates and N is an integer greater than or equal to 2; N pressure plates are evenly installed on the inner wall of the outer cover ring along the circumferential direction of the outer cover ring, and each pressure plate does not contact other adjacent pressure plates.

[0012] Preferably, each of the pressure plates has a groove on its outer side, which is located between the two second threaded holes, and the width of the groove matches the width of the non-perforated plate, and the depth of the groove is less than or equal to the thickness of the non-perforated plate.

[0013] Preferably, multiple pressure plates are installed and fixed to the inner side of the outer cover ring by the fasteners, and a clamping gap is provided between the outer side of the pressure plate and the inner side of the outer cover ring. The end of the non-perforated plate is inserted into the clamping gap and engages with the groove on the pressure plate.

[0014] This invention also provides a method for using a tooling for controlling deformation during the assembly and welding of perforated plates, applied to the tooling described above, with specific steps including: Step 1: Arrange multiple pressure plates circumferentially along the inner wall of the outer cover ring, and align each pair of second threaded holes on each pressure plate with each pair of first threaded holes on the outer cover ring. Insert a fastener into each pair of aligned first and second threaded holes to initially fix the pressure plates, and leave a clamping gap between the inner side of the outer cover ring and the outer side of the pressure plates for the installation of the holeless plate. Step 2: Insert the ends of the non-perforated plate to be welded into the clamping gap between the pressure plate and the outer cover ring, and adjust the position of the non-perforated plate so that it engages with the groove on the pressure plate to initially fix the non-perforated plate; Step 3: Place the installed non-perforated plate and the tooling together into the lower end cap of the voltage regulator. Check whether the non-perforated plate to be welded meets the assembly position requirements. If there are any non-perforated plates that do not meet the requirements, adjust the tooling and fine-tune the position of the non-perforated plate until all the non-perforated plates to be welded meet the assembly requirements. Step 4: Retighten the fasteners, and while the tooling is in a tight position, weld all the welds between the perforated plates and the lower end cap of the voltage regulator; Step 5: After welding is completed and cooling is achieved, unscrew all the fasteners to remove the outer cover ring and multiple pressure plates, thus completing the welding of the non-perforated plate.

[0015] Preferably, in step 3, adjusting the tooling includes: adjusting the position of the tooling circumferentially to adjust the position of all the non-perforated plates as a whole; and adjusting the insertion depth and level of each non-perforated plate by loosening the corresponding fasteners.

[0016] In summary, compared with the prior art, the tooling and method for controlling deformation during assembly and welding of perforated plates provided by this invention have at least the following advantages: Multiple perforated plates are reliably clamped and fixed into a single unit by the outer cover ring and pressure plate, ensuring positional accuracy during assembly; simultaneously, during welding, the tooling provides strong rigid constraints, effectively resisting deformation caused by welding thermal stress and ensuring dimensional stability after welding. This tooling has a simple structure, is easy to manufacture, and convenient to operate, significantly improving production efficiency and product qualification rate. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the integrally formed structure of the distributor in this invention; Figure 2 This is a schematic diagram of the tooling for controlling deformation during the assembly and welding of the perforated plate in this invention. Figure 3 This is a schematic diagram of the AA cross-section of the tooling for controlling deformation during the assembly and welding of the perforated plate in this invention; Figure 4 This is a schematic diagram of the outer ring structure of the non-perforated plate assembly and welding deformation control fixture in this invention; Figure 5 This is a schematic diagram of the pressure plate structure of the tooling for controlling deformation during assembly and welding of the perforated plate in this invention.

[0018] In the diagram: 1-outer ring, 11-first threaded hole, 2-pressure plate, 21-second threaded hole, 22-groove, 3-bolt, 4-nut, 5-perforated plate, 6-diverter. Detailed Implementation

[0019] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, further illustrates the tooling and method for controlling deformation during the assembly and welding of the perforated plate proposed in this invention. The advantages and features of this invention will become clearer from the following description. It should be noted that the drawings are in a very simplified form and use non-precise proportions, intended only to facilitate and clearly illustrate the embodiments of this invention. Please refer to the drawings to make the objectives, features, and advantages of this invention more apparent and understandable. It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are only for illustrative purposes and to enable those skilled in the art to understand and read them, and are not intended to limit the implementation conditions of this invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by this invention, should still fall within the scope of the technical content disclosed in this invention.

[0020] like Figure 1 As shown, the distributor is a one-piece hemispherical structure. Wire cutting the distributor yields several non-perforated plates 5 and a distributor shroud 6. The non-perforated plates 5 are arc-shaped, meaning each non-perforated plate 5 has a circular arc cross-section. During assembly, the non-perforated plates 5 are first welded to the lower end cap of the voltage regulator, and then the distributor shroud 6 is welded on. This allows the distributor, composed of the non-perforated plates 5 and the distributor shroud 6, to be assembled and welded together with the lower end cap of the voltage regulator.

[0021] like Figures 2 to 5 As shown, the non-perforated plate assembly and welding deformation control fixture provided by the present invention is used to assist in the welding of the non-perforated plate 5 to the lower end cap of the voltage regulator. It includes: an outer ring 1, which is a circular ring structure with multiple pairs of first threaded holes 11 evenly formed thereon (e.g., ...). Figure 4 (As shown); multiple pressure plates 2 are arranged circumferentially along the inner wall of the outer cover ring 1; each pressure plate 2 is an arc-shaped plate, that is, the cross-section of each pressure plate 2 is an arc structure, its width is the same as the width of the outer cover ring 1, and each pressure plate 2 is provided with a pair of second threaded holes 21 (as shown). Figure 5 (as shown); multiple pairs of fasteners are used to fix the outer cover ring 1 and each of the pressure plates 2 through the first threaded hole 11 and the corresponding second threaded hole 21, and to fix each of the non-perforated plates 5 between the outer cover ring 1 and the corresponding pressure plate 2.

[0022] It can be understood that the number of pairs of the first threaded holes 11 is the same as the number of pressure plates 2, and both are determined according to the number of the non-perforated plates 5 to be welded. That is, one non-perforated plate 5 needs to have a pair of the first threaded holes 11 and a corresponding pressure plate 2 on the outer cover ring 1.

[0023] The outer cover ring 1 and the pressure plate 2 are both made of stainless steel.

[0024] like Figure 3 As shown, each of the fasteners includes: a bolt 3, the size of which matches the first threaded hole 11 and the second threaded hole 21, which passes through the first threaded hole 11 on the outer ring 1 and the corresponding second threaded hole on the pressure plate 2 to connect each pressure plate 2 to the outer ring 1; and a nut 4, the size of which matches the bolt 3, which is used to cooperate with the bolt 3 to fix the connection between the outer ring 1 and each pressure plate 2.

[0025] The curvature of the inner side of the outer cover ring 1 matches the curvature of the outer side of the non-perforated plate 5, and the curvature of the outer side of the pressure plate 2 matches the curvature of the inner side of the non-perforated plate 5. That is, the outer cover ring 1, the non-perforated plate 5, and the pressure plate 2 are located on three coaxial spherical surfaces in sequence, with the outer cover ring 1 located on the outermost spherical surface and the pressure plate 2 located on the innermost spherical surface.

[0026] Furthermore, the first threaded hole 11 is a hole opened along the radial direction of the outer cover ring 1 and penetrates the outer cover ring 1; the second threaded hole 21 is a hole opened along the radial direction of the pressure plate 2 and penetrates the pressure plate 2.

[0027] On the inner surface of the outer ring 1, the two first threaded holes 11 in each pair of first threaded holes 11 are spaced apart, forming a first arc between each pair of first threaded holes 11. On the outer surface of the pressure plate 2, the two second threaded holes 21 in each pair of second threaded holes 21 are similarly spaced apart, forming a second arc between each pair of second threaded holes 21. The central angles of the first and second arcs are the same, so that each first threaded hole 11 and each second threaded hole 21 can be located on the same straight line, ensuring that each first threaded hole 11 and each second threaded hole 21 correspond one-to-one. This allows a bolt 3 to pass through one first threaded hole 11 and one corresponding second threaded hole 21 simultaneously, thereby uniformly fixing each pressure plate 2 to the outer ring 1.

[0028] Furthermore, the central angle of each pressure plate 2 is less than 360° / N, where N is the number of pressure plates 2 and N is an integer greater than or equal to 2. Thus, N pressure plates 2 can be evenly installed on the inner wall of the outer cover ring 1 along the circumferential direction of the outer cover ring 1, and each pressure plate 2 does not contact other adjacent pressure plates 2.

[0029] like Figure 5 As shown, each of the pressure plates 2 has a groove 22 on its outer side. The groove 22 is located between the two second threaded holes 21, and the width of the groove 22 matches the width of the non-perforated plate 5. The depth of the groove 22 is less than or equal to the thickness of the non-perforated plate 5, so that the non-perforated plate 5 can engage with the groove 22.

[0030] Furthermore, multiple pressure plates 2 are installed and fixed to the inner side of the outer cover ring 1 by the bolts 3 and the nuts 4. A clamping gap is left between the outer side of the pressure plate 2 and the inner side of the outer cover ring 1, so that the end of the non-perforated plate 5 can be inserted into the clamping gap and engaged with the groove 22 on the pressure plate 2. Tightening the nuts 4 can fix the end of a non-perforated plate 5 in the tooling of the present invention by using one pressure plate 2, the outer cover ring 1, and two sets of bolts 3 and nuts 4, thereby preventing the non-perforated plate 5 to be welded from radial and circumferential positional displacement and welding deformation.

[0031] In the first preferred embodiment of the present invention, the radius of the distributor is 259±1 mm, and the number of the cut-out non-perforated plates 2 is 12 pieces, so that 12 pairs of the first threaded holes are opened on the outer cover ring 1, and the number of pressure plates 2 is 12 pieces.

[0032] Further, in the first preferred embodiment, the width of the non-perforated plate 2 is 51 (+0.5 / 0) mm, and the length is 83 mm; the outer diameter of the outer ring 1 is 267.5 mm, the inner diameter is 235 mm, and the width along the spherical surface is 60 mm; the central angle of the first arc between each pair of first threaded holes 11 and the second arc between each pair of second threaded holes 21 is 18.3°±0.5°, and the diameter of the first threaded hole 11 and the second threaded hole 21 is 13.5 mm; the outer diameter of the pressure plate 2 is 229.94 mm, the inner diameter is 213 mm, the width along the spherical surface is 60 mm, and the central angle of the pressure plate 2 is 28°±0.5°; the bolt 3 is a hexagonal head bolt, and the nut 4 is a hexagonal head nut.

[0033] This invention also provides a method for using a tooling for controlling deformation during the assembly and welding of perforated plates, the specific steps of which include: Step 1: Arrange multiple pressure plates 2 circumferentially along the inner wall of the outer cover ring 1, and align each pair of second threaded holes 21 on each pressure plate 2 with each pair of first threaded holes 11 on the outer cover ring 1. Insert a bolt 3 into each pair of aligned first threaded holes 11 and second threaded holes 21, and place a nut 4 at one end of the bolt 3. Initially fix the pressure plate 2 by tightening the nut 4, and leave a clamping gap between the inner side of the outer cover ring 1 and the outer side of the pressure plate 2 for the installation of the holeless plate 5.

[0034] Step 2: Insert the ends of the non-perforated plate 5 to be welded into the clamping gap between the pressure plate 2 and the outer cover ring 1, and adjust the position of the non-perforated plate 5 so that it engages with the groove 22 on the pressure plate 2. Tighten the nut 4 to initially fix the non-perforated plate 5.

[0035] Step 3: Place the installed non-perforated plate 5 along with the tooling into the lower end cap of the voltage regulator. Check whether the non-perforated plates 5 to be welded meet the assembly position requirements. If any non-perforated plates 5 do not meet the requirements, adjust the position of the tooling in a circumferential manner to adjust the position of all the non-perforated plates 5 as a whole, or loosen the corresponding nuts 4 to fine-tune the insertion depth and level of each non-perforated plate 5 until all the non-perforated plates 5 to be welded meet the assembly requirements.

[0036] Step 4: Retighten the nut 4, and while the tooling is secure, weld the welds between all the perforated plates 5 and the lower end cap of the voltage regulator.

[0037] Step 5: After welding is completed and cooling is achieved, unscrew all the nuts 4 and bolts 3 to remove the outer cover ring 1 and multiple pressure plates 2, thus completing the welding of the non-perforated plate 5.

[0038] In summary, this invention provides a fixture and method for controlling deformation during the assembly and welding of perforated plates. Multiple perforated plates are reliably clamped and fixed into a single unit using an outer cover ring and pressure plate, ensuring positional accuracy during assembly. Simultaneously, during welding, the fixture provides strong rigid constraints, effectively resisting deformation caused by welding thermal stress and guaranteeing dimensional stability after welding. This fixture has a simple structure, is easy to manufacture, and convenient to operate, significantly improving production efficiency and product qualification rate.

[0039] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0040] In the description of this invention, it should be understood that the terms "center," "height," "thickness," "upper," "lower," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0041] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0042] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0043] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A tooling for controlling deformation during assembly and welding of a perforated plate, used to assist in welding a perforated plate (5), characterized in that, include: The outer ring (1) is a circular structure with multiple pairs of first threaded holes (11) evenly opened on it. Multiple pressure plates (2) are arranged circumferentially along the inner wall of the outer cover ring (1); each pressure plate (2) is an arc-shaped plate with the same width as the outer cover ring (1), and each pressure plate (2) has a pair of second threaded holes (21). Multiple pairs of fasteners are used to fix the outer cover ring (1) and each of the pressure plates (2) through the first threaded hole (11) and the second threaded hole (21), and to fix each of the non-perforated plates (5) between the outer cover ring (1) and the corresponding pressure plate (2); The number of the first threaded holes (11) is the same as the number of the pressure plates (2), and both are the same as the number of the holeless plates (5) to be welded.

2. The tooling for controlling deformation during assembly and welding of the non-perforated plate as described in claim 1, characterized in that, The curvature of the inner side of the outer cover ring (1) matches the curvature of the outer side of the non-perforated plate (5), and the curvature of the outer side of the pressure plate (2) matches the curvature of the inner side of the non-perforated plate (5). The outer cover ring (1), the non-perforated plate (5), and the pressure plate (2) are located on three coaxial spherical surfaces in sequence.

3. The tooling for controlling deformation during assembly and welding of the non-perforated plate as described in claim 1, characterized in that, The first threaded hole (11) is a hole that passes through the outer ring (1) radially, and the second threaded hole (21) is a hole that passes through the pressure plate (2) radially; and the first threaded hole (11) and the second threaded hole (21) have the same size, both matching the size of the fastener.

4. The tooling for controlling deformation during assembly and welding of the non-perforated plate as described in claim 3, characterized in that, On the inner side of the outer ring (1), a first arc is formed between the two first threaded holes (11) included in each pair of first threaded holes (11); on the outer side of the pressure plate (2), a second arc is formed between the two second threaded holes (21) included in each pair of second threaded holes (21); the central angle of the first arc and the second arc are the same.

5. The tooling for controlling deformation during assembly and welding of the non-perforated plate as described in claim 4, characterized in that, Each of the first threaded holes (11) corresponds one-to-one with each of the second threaded holes (21) and is located on the same straight line.

6. The tooling for controlling deformation during assembly and welding of the non-perforated plate as described in claim 1, characterized in that, The central angle of each pressure plate (2) is less than 360° / N, where N is the number of pressure plates (2) and N is an integer greater than or equal to 2; N pressure plates (2) are evenly installed on the inner wall of the outer cover ring (1) along the circumferential direction of the outer cover ring (1), and each pressure plate (2) does not contact other adjacent pressure plates (2).

7. The tooling for controlling deformation during assembly and welding of the non-perforated plate as described in claim 1, characterized in that, Each of the pressure plates (2) has a groove (22) on its outer side, which is located between the two second threaded holes (21), and the width of the groove (22) matches the width of the non-perforated plate (5), and the depth of the groove (22) is less than or equal to the thickness of the non-perforated plate (5).

8. The tooling for controlling deformation during assembly and welding of the non-perforated plate as described in claim 7, characterized in that, Multiple pressure plates (2) are installed and fixed to the inner side of the outer cover ring (1) by the fasteners. A clamping gap is provided between the outer side of the pressure plate (2) and the inner side of the outer cover ring (1). The end of the holeless plate (5) is inserted into the clamping gap and engages with the groove (22) on the pressure plate (2).

9. A method for using a tooling for controlling deformation during assembly and welding of a perforated plate, applied to the tooling described in claims 1-8, characterized in that, The specific steps include: Step 1: Arrange multiple pressure plates (2) circumferentially along the inner wall of the outer cover ring (1), and align each pair of second threaded holes (21) on each pressure plate (2) with each pair of first threaded holes (11) on the outer cover ring (1). Insert a fastener into each pair of aligned first threaded holes (11) and second threaded holes (21) to initially fix the pressure plate (2), and leave a clamping gap between the inner side of the outer cover ring (1) and the outer side of the pressure plate (2) for the installation of the holeless plate (5). Step 2: Insert the ends of the non-perforated plate (5) to be welded into the clamping gap between the pressure plate (2) and the outer cover ring (1), and adjust the position of the non-perforated plate (5) so that it engages with the groove (22) on the pressure plate (2) to initially fix the non-perforated plate (5). Step 3: Place the installed non-perforated plate (5) along with the tooling into the lower end cap of the voltage regulator. Check whether the non-perforated plate (5) to be welded meets the assembly position requirements. If there is a non-perforated plate (5) that does not meet the requirements, adjust the tooling and fine-tune the position of the non-perforated plate (5) until all the non-perforated plates (5) to be welded meet the assembly requirements. Step 4: Retighten the fasteners, and while the fixture is in a tight position, weld the welds between all the non-perforated plates (5) and the lower end cap of the voltage regulator; Step 5: After welding is completed and cooling is achieved, all fasteners are unscrewed to remove the outer cover ring (1) and multiple pressure plates (2), and the welding of the non-perforated plate (5) is completed.

10. The method of using the non-perforated plate assembly and welding deformation control fixture as described in claim 9, characterized in that, In step 3, adjusting the tooling includes: adjusting the position of the tooling in a circumferential manner to adjust the position of all the non-perforated plates (5) as a whole; and adjusting the insertion depth and level of each non-perforated plate (5) by loosening the corresponding fasteners.

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