Shield tunneling machine cutter ring remanufactured through laser cladding

Abstract

The utility model discloses a shield tunneling machine cutter ring remanufactured through laser cladding. The shield tunneling machine cutter ring comprises a hob hub, an annular blade part, a chamfer connecting part and a nickel-based tungsten carbide layer. The hob hub is of an annular hollow columnar structure, and the inner column wall of the hob hub is used for being connected with a shield tunneling machine cutterhead. The annular blade part comprises an upper plane, a lower plane and an arc end face connecting the upper plane and the lower plane, the upper plane is provided with a first cladding area, and the surface of the first cladding area is provided with a first microstructure; the lower plane is provided with a second cladding area, and the surface is provided with a second microstructure; the arc end face is provided with a third cladding area, and the surface is provided with a third microstructure. The chamfer connecting part is connected with the annular blade part and the hob hub, and the upper end of the chamfer connecting part is connected with the upper plane and the lower plane of the annular blade part through a first connecting point and a second connecting point respectively; the lower end of the chamfer connecting part is connected with the outer column wall of the hob hub through a third connecting point and a fourth connecting point; and the nickel-based tungsten carbide layer covers the surfaces of the first microstructure, the second microstructure and the third microstructure through laser cladding.

Description

Technical Field

[0001] This utility model relates to the field of tunnel boring machine cutter manufacturing technology, specifically to a tunnel boring machine cutter ring remanufactured using laser cladding. Background Technology

[0002] As the core equipment in tunnel boring machines (TBMs), the cutterhead of a tunnel boring machine directly bears the high-intensity impact loads, abrasive wear, and complex alternating stresses of the rock and soil during tunneling in hard rock strata. Traditional cutterheads are generally manufactured using integral forging or surface welding processes, which presents the following technical bottlenecks:

[0003] Short service life: Especially in hard rock formations such as quartzite (Mohs hardness ≥7), the wear rate of the blade edge is fast, and frequent replacement leads to project downtime and a significant increase in construction costs;

[0004] Low reusability: Once the cutter ring is worn out, it is usually scrapped, resulting in a waste of resources;

[0005] Performance limitations: The integral weld overlay is prone to peeling due to insufficient bonding strength, and the differential wear mechanism of different areas of the cutting edge (such as the upper plane, lower plane, and arc end face) lacks targeted optimization design.

[0006] Furthermore, critical components of the cutter ring (such as the connection between the annular cutting edge and the hob hub) are prone to fatigue cracking due to stress concentration, and the traditional chamfered structure design does not optimize the load transfer path, further exacerbating the risk of localized failure. The industry urgently needs a cutter ring that balances high wear resistance, reusability, and structural reliability to overcome existing technological bottlenecks. Utility Model Content

[0007] In order to overcome the shortcomings of the existing technology, the purpose of this utility model is to provide a shield machine cutter ring that is remanufactured using laser cladding, so as to solve the technical problems of short life, low reusability and limited performance of traditional shield machine cutter rings.

[0008] To solve the above problems, the technical solution adopted by this utility model is as follows:

[0009] A tunnel boring machine cutterhead remanufactured using laser cladding, comprising:

[0010] The cutterhead hub is a ring-shaped hollow columnar structure, and its inner columnar wall is used to connect with the cutterhead of the tunnel boring machine.

[0011] The annular cutting edge includes an upper plane, a lower plane, and an arc-shaped end face connecting the two, wherein:

[0012] The upper plane is provided with a first cladding area, and its surface has a first microstructure;

[0013] The lower plane is provided with a second cladding zone, and its surface has a second microstructure;

[0014] The arc-shaped end face is provided with a third cladding zone, and its surface has a third microstructure;

[0015] The chamfered connecting part connects the annular cutting edge and the hob hub, wherein:

[0016] The upper end of the chamfered connecting part is connected to the upper and lower planes of the annular cutting edge part through the first connection point and the second connection point, respectively.

[0017] The lower end of the chamfered connection is connected to the outer cylindrical wall of the hob hub through the third connection point and the fourth connection point;

[0018] Nickel-based tungsten carbide layers are applied to the surfaces of the first, second, and third microstructures via laser cladding.

[0019] Preferably, both the hob hub and the annular cutting edge are made of die-forged steel, which is selected from 42CrMo steel or H13 steel, with a hardness of 55-60 HRC.

[0020] Preferably, the first microstructure, the second microstructure, and the third microstructure are independently selected surface structures, and are selected from any one of the following: groove structure, protrusion structure, and microporous structure.

[0021] Preferably, when the microstructure is a groove structure, its depth is 0.1–1.0 mm, its width is 0.2–2.0 mm, and the spacing between adjacent grooves is 0.5–5.0 mm;

[0022] When the microstructure is a protruding structure, its height is 0.05–0.8 mm, its base diameter is 0.1–1.5 mm, and its distribution density is 10–50 particles / cm². 2 ;

[0023] When the microstructure is a microporous structure, its pore size is 0.05–0.5 mm, pore depth is 0.1–0.8 mm, and pore density is 20–100 pores / cm³. 2 .

[0024] Preferably, the first microstructure is a groove structure, the second microstructure is a protrusion structure, and the third microstructure is a microporous structure.

[0025] Preferably, the thickness of the nickel-based tungsten carbide layer is 3.5-25 mm.

[0026] Preferably, the nickel-based tungsten carbide layer covering the first cladding zone extends to cover the second and third cladding zones, and the extended portion is located below the nickel-based tungsten carbide layer on the surface of the second and third cladding zones, forming a stepped composite structure.

[0027] Preferably, the area of ​​the extended portion covering the second and third cladding zones is 10%-15% of the surface area of ​​each cladding zone.

[0028] Preferably, the angle between the projections of the first connection point and the second connection point on the chamfered connection portion is 15-35 degrees, and the projection angle is defined as follows:

[0029] Draw the first cross-section of the chamfered connection part through the first connection point;

[0030] Draw the second tangential surface of the chamfered connection part through the second connection point;

[0031] Using the intersection of the first and second cut surfaces as a reference, measure the included angle between the two cut surfaces.

[0032] Preferably, the angle between the projections of the third connection point and the fourth connection point on the chamfered connection portion is 110-130 degrees, and the projection angle is defined as follows:

[0033] Draw the third tangent of the chamfered connection part through the third connection point;

[0034] Draw the fourth tangent of the chamfered joint through the fourth connection point;

[0035] Using the intersection of the third and fourth sectional planes as a reference, measure the included angle between the two sectional planes.

[0036] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0037] Wear resistance life doubled:

[0038] The upper and lower planes of the annular cutting edge and the arc end face are designed with three different microstructures: grooves, protrusions, and micropores, which significantly improves the bonding strength of the nickel-based tungsten carbide cladding layer, reduces the wear rate of the cutting edge in hard rock formations, and thus extends its service life.

[0039] Nickel-based tungsten carbide layers provide high impact and wear resistance, resisting abrasion from rocks and soil.

[0040] Breakthrough in anti-stripping performance:

[0041] The stepped composite cladding structure covers the junction of different cladding zones (extending area of ​​10%–15%), eliminating stress concentration at the "hard interface" and reducing the risk of cladding layer peeling.

[0042] The microporous structure forms a three-dimensional interlock on the arc end face, which significantly enhances the resistance to multi-directional composite wear.

[0043] Structural reliability optimization:

[0044] The chamfered connection adopts a differentiated included angle design (the included angle between the first and second connection points is 15–35°, and the included angle between the third and fourth connection points is 110–130°), which improves the efficiency of vertical impact load dispersion, reduces radial vibration amplitude, and improves fatigue life.

[0045] Eliminate stress concentration at the connection point of traditional blade rings and suppress the initiation of microcracks.

[0046] Remanufacturing is significantly more economical:

[0047] The worn blade base can be reused, and the cost of laser cladding remanufacturing is significantly lower than that of new products, thus significantly reducing the overall construction cost.

[0048] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0049] Figure 1 This is a first structural diagram of the shield machine cutterhead ring according to an embodiment of this utility model;

[0050] Figure 2 This is a second structural diagram of the shield machine cutterhead ring according to an embodiment of this utility model;

[0051] Figure 3 This is the third structural diagram of the shield machine cutterhead ring according to an embodiment of this utility model;

[0052] Figure 4 This is the fourth structural diagram of the shield tunneling machine cutterhead according to an embodiment of this utility model;

[0053] Figure 5 This is the fifth structural diagram of the shield machine cutterhead ring according to an embodiment of this utility model;

[0054] Figure 6 This is a cross-sectional view of the cutterhead ring of the tunnel boring machine according to an embodiment of this utility model.

[0055] Explanation of reference numerals in the attached figures: 1. Hob hub; 2. Annular cutting edge; 21. Upper plane; 211. First cladding zone; 22. Lower plane; 221. Second cladding zone; 23. Arc end face; 231. Third cladding zone; 3. Chamfered connection; 4. First connection point; 5. Second connection point; 6. Third connection point; 7. Fourth connection point. Detailed Implementation

[0056] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0057] At the same time, it should be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn according to actual scale.

[0058] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.

[0059] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0060] like Figures 1 to 6 As shown, this embodiment provides a tunnel boring machine cutter ring remanufactured using laser cladding, including: a rolling cutter hub 1, an annular cutting edge 2, a chamfered connecting part 3, and a nickel-based tungsten carbide layer.

[0061] The cutter hub 1 is an annular hollow columnar structure. Its inner column wall is used to connect with the cutterhead of the tunnel boring machine, transmit torque and load, and support the annular cutting edge 2.

[0062] The annular cutting edge 2 includes an upper plane 21, a lower plane 22, and an arc-shaped end face 23 connecting the two, wherein:

[0063] The upper plane 21 is provided with a first cladding area 211, and its surface has a first microstructure;

[0064] The lower plane 22 is provided with a second cladding area 221, and its surface has a second microstructure;

[0065] The arc end face 23 is provided with a third cladding area 231, and its surface has a third microstructure.

[0066] The annular cutting edge 2 directly contacts the rock and soil, bearing the main cutting and wear, and the microstructure enhances the bonding force of the cladding layer.

[0067] The chamfered connecting part 3 connects the annular cutting edge 2 and the hob hub 1, wherein:

[0068] The upper end of the chamfered connecting part 3 is connected to the upper plane 21 and lower plane 22 of the annular blade part 2 through the first connecting point 4 and the second connecting point 5, respectively.

[0069] The lower end of the chamfered connecting part 3 is connected to the outer column wall of the hob hub 1 through the third connecting point 6 and the fourth connecting point 7;

[0070] The chamfered connection 3 optimizes the stress transmission path and reduces local stress concentration.

[0071] Nickel-based tungsten carbide layers are applied to the surfaces of the first, second, and third microstructures via laser cladding.

[0072] Nickel-based tungsten carbide layers provide high impact and wear resistance, resisting abrasion from rocks and soil.

[0073] Preferably, the nickel-based tungsten carbide layer uses the nickel-based tungsten carbide composite alloy powder disclosed in the existing literature (CN115976390A-Nickel-based tungsten carbide composite alloy powder and its application and preparation method of nickel-based tungsten carbide composite coating), and the disclosed laser cladding process parameters (keeping the temperature of the annular blade 2 at 240℃~270℃, laser cladding power 1.5kW~3kW, the annular blade 2 rotates with the rotary table during the cladding process, the actual cladding speed is 8mm / s~25mm / s, the overlap rate is 45%~55%, the laser spot diameter is φ2.5-3.5mm, the coaxial powder feeding method is adopted, the powder feeding rate is 20g / min~40g / min, and the argon flow rate is 18L / min~22L / min). The nickel-based tungsten carbide composite alloy powder and laser cladding process parameters provided above are only one example. Other existing nickel-based tungsten carbide composite alloy powder and laser cladding process parameters that can be used to perform laser cladding on the annular blade 2 and form a nickel-based tungsten carbide layer can also be adopted.

[0074] Preferred, such as Figure 6 As shown, the hobbing cutter hub 1, the annular cutting edge 2, and the chamfered connecting part 3 are integrally formed.

[0075] It needs to be further explained that this embodiment solves the industry pain points of easy wear, low reusability and performance limitations of shield machine cutter rings by combining microstructure design, chamfer stress optimization and laser cladding layer, and provides a high-performance and low-cost remanufacturing solution for tunnel engineering.

[0076] Background Description: The cutterhead of a tunnel boring machine (TBM) is subjected to extremely high loads (rock and soil impact, friction and wear, and complex stress) during the tunneling process. Based on this:

[0077] In one possible embodiment, both the hob hub 1 and the annular cutting edge 2 are made of forged steel, which is selected from 42CrMo steel or H13 steel, with a hardness of 55-60 HRC.

[0078] Further explanation is needed regarding 42CrMo steel: a medium-carbon alloy structural steel containing chromium (Cr) and molybdenum (Mo), exhibiting excellent hardenability and high fatigue strength. Since the cutterhead of a tunnel boring machine needs to operate under impact loads for extended periods, the toughness of 42CrMo effectively resists stress fracture.

[0079] H13 steel: hot work die steel, containing vanadium (V) and silicon (Si), with stable high-temperature hardness (still maintaining HRC 50+ at >500℃), strong resistance to thermal fatigue, and suitable for local high-temperature environments caused by frictional heating during tunneling in hard rock formations.

[0080] When the hardness is ≥55 HRC, the material can resist abrasive wear from hard rocks and soils such as quartzite (Mohs hardness 7), thereby effectively reducing the wear rate.

[0081] Excessive hardness (>60 HRC) can easily lead to brittle fracture, while insufficient hardness (<55 HRC) results in inadequate wear resistance. 55–60 HRC is the optimal balance point, ensuring that the matrix has sufficient compressive strength and impact toughness.

[0082] Background Description: The annular cutting edge 2 of the tunnel boring machine cutterhead faces multi-directional wear (such as vertical pressure, lateral shear, and rotational friction) during tunneling. Traditional integral coatings are prone to peeling due to insufficient adhesion. Based on this:

[0083] In one possible embodiment, the first microstructure, the second microstructure, and the third microstructure are independently selected surface structures, and are selected from any of the following: groove structure, protrusion structure, and microporous structure.

[0084] It needs to be further explained that, due to the different wear mechanisms of different parts of the cutting edge (such as the arc end face 23 which needs to take into account both impact and sliding friction), this embodiment can improve the performance of weak areas by independently selecting the microstructure.

[0085] In one possible embodiment, when the microstructure is a groove structure, its depth is 0.1–1.0 mm, its width is 0.2–2.0 mm, and the spacing between adjacent grooves is 0.5–5.0 mm;

[0086] When the microstructure is a protruding structure, its height is 0.05–0.8 mm, its base diameter is 0.1–1.5 mm, and its distribution density is 10–50 particles / cm². 2 ;

[0087] When the microstructure is a microporous structure, its pore size is 0.05–0.5 mm, pore depth is 0.1–0.8 mm, and pore density is 20–100 pores / cm³. 2 .

[0088] The groove structure needs further explanation:

[0089] Width 0.2–2.0 mm: Too narrow a width can lead to insufficient filling of the cladding material, while too wide a width can weaken the strength of the substrate;

[0090] Spacing 0.5–5.0 mm: Ensures uniform stress distribution and avoids local crack propagation.

[0091] Protruding structure:

[0092] Bottom diameter 0.1–1.5 mm: Diameter <0.1 mm is prone to breakage, while diameter >1.5 mm weakens the anchoring effect;

[0093] Density 10–50 particles / cm 2Excessive density leads to stress concentration, while insufficient density results in inadequate bonding strength.

[0094] Microporous structure:

[0095] A pore size of 0.05–0.5 mm facilitates the penetration of cladding material particles.

[0096] In one possible embodiment, the first microstructure is a groove structure, the second microstructure is a protrusion structure, and the third microstructure is a micropore structure.

[0097] Further explanation is needed: the groove structure depth (0.1–1.0 mm) forms a mechanical interlocking groove, and the cladding material, once filled, creates a "mortise and tenon effect," significantly improving shear resistance. Applicable working conditions: upper plane 21 (withstanding vertical impact and compressive stress).

[0098] The raised structure height (0.05–0.8 mm) serves as an anchor point, increasing the contact area of ​​the nickel-based tungsten carbide layer and effectively improving the bonding strength. Applicable working conditions: lower plane 22 (subject to rotational friction and bending stress).

[0099] Pore ​​density of microporous structure (20–100 pores / cm³) 2 This process promotes the penetration of the cladding material into the substrate, forming a three-dimensional interlock, which significantly enhances the resistance to peeling. Applicable working conditions: 23 arc end face (multi-directional composite wear area).

[0100] In one possible embodiment, the thickness of the nickel-based tungsten carbide layer is 3.5-25 mm. The lower limit of 3.5 mm ensures the cladding layer completely covers the microstructure, preventing localized wear penetration; the upper limit of 25 mm prevents excessive thickness from causing substrate deformation or interlayer delamination.

[0101] Background Description: The cladding layer of the tunnel boring machine cutterhead may peel off at the junction of different regions (first, second, and third cladding zones) on the annular cutting edge 2 due to stress concentration. Based on this:

[0102] In one possible embodiment, the nickel-based tungsten carbide layer covering the first cladding region 211 extends to cover the second cladding region 221 and the third cladding region 231, and the extended portion is located below the nickel-based tungsten carbide layer on the surface of the second cladding region 221 and the third cladding region 231, forming a stepped composite structure.

[0103] It needs further explanation that the extended section avoids the formation of a "hard interface" at the joint between the independent cladding layers of different cladding zones, which would easily lead to cracks and peeling under stress.

[0104] In one possible embodiment, the area of ​​the extended portion covering the second cladding region 221 and the third cladding region 231 is 10%-15% of the surface area of ​​each cladding region.

[0105] Further explanation is needed: when the extension area is less than 10%, the interface strengthening effect is insufficient (bonding strength only increases by less than 15%); when the extension area is greater than 15%, the heat-affected zone expands, increasing the risk of substrate deformation. The extension acts as a "transition layer," mitigating the difference in thermal expansion coefficients between the upper cladding layer and the substrate.

[0106] Background Description: The chamfered connecting part 3 of the tunnel boring machine cutterhead ring plays a crucial role in transferring the load of the annular cutting edge 2 to the cutterhead hub 1. The design of the included angle at its connection point directly affects structural stability and fatigue life. Improper design of the included angle at the connection point leads to stress concentration (especially in the arc transition zone), inducing fatigue cracks. Under vibration loads, fracture of the connecting part causes the entire cutterhead ring to fail. Based on this:

[0107] In one possible embodiment, the included angle between the projections of the first connection point 4 and the second connection point 5 onto the chamfered connection portion 3 is 15-35 degrees, and the included angle is defined as follows:

[0108] Draw the first cross-section of the chamfered connecting part 3 through the first connection point 4;

[0109] Draw the second cut surface of the chamfered connecting part 3 through the second connection point 5;

[0110] Using the intersection of the first and second cut surfaces as a reference, measure the included angle between the two cut surfaces.

[0111] Further explanation is needed regarding the 15–35° angle between the first and second connection points: the small angle design allows the vertical impact load of the annular blade 2 to be evenly distributed along the first and second tangential surfaces, effectively reducing the stress peak value; and suppressing the initiation of microcracks at the junction of the annular blade 2 and the chamfered connection 3.

[0112] When the included angle is less than 15°, the overlapping area of ​​the cut surfaces is too small, and the stress is not sufficiently dispersed; when the included angle is greater than 35°, the vertical load component increases, resulting in excessive shear stress at the first and second connection points.

[0113] In one possible embodiment, the included angle between the projections of the third connection point 6 and the fourth connection point 7 onto the chamfered connection portion 3 is 110-130 degrees, and the included angle is defined as follows:

[0114] Draw the third cut surface of the chamfered connection part 3 through the third connection point 6;

[0115] Draw the fourth tangent of the chamfered connection part 3 through the fourth connection point 7;

[0116] Using the intersection of the third and fourth sectional planes as a reference, measure the included angle between the two sectional planes.

[0117] Further explanation is needed regarding the angle of 110–130° between the third and fourth connection points: This large angle design optimizes the radial load transmission path, enhances the vibration resistance of the hob hub 1, effectively reduces the vibration amplitude, avoids local deformation of the outer column wall of the hub, and significantly improves the radial stiffness.

[0118] When the included angle is less than 110°, the radial support is insufficient, and the uneven load during tunneling leads to premature bearing damage; when the included angle is greater than 130°, the chamfered connection 3 is excessively extended, and deformation defects are easily generated during hot working.

[0119] The above embodiments are merely preferred embodiments of this utility model and should not be construed as limiting the scope of protection of this utility model. Any non-substantial changes and substitutions made by those skilled in the art based on this utility model shall fall within the scope of protection claimed by this utility model.

Claims

1. A tunnel boring machine cutterhead remanufactured using laser cladding, characterized in that, include: The cutterhead hub is a ring-shaped hollow columnar structure, and its inner columnar wall is used to connect with the cutterhead of the tunnel boring machine. The annular cutting edge includes an upper plane, a lower plane, and an arc-shaped end face connecting the two, wherein: The upper plane is provided with a first cladding area, and its surface has a first microstructure; The lower plane is provided with a second cladding zone, and its surface has a second microstructure; The arc-shaped end face is provided with a third cladding zone, and its surface has a third microstructure; The chamfered connecting part connects the annular cutting edge and the hob hub, wherein: The upper end of the chamfered connecting part is connected to the upper and lower planes of the annular cutting edge part through the first connection point and the second connection point, respectively. The lower end of the chamfered connection is connected to the outer cylindrical wall of the hob hub through the third connection point and the fourth connection point; Nickel-based tungsten carbide layers are applied to the surfaces of the first, second, and third microstructures via laser cladding.

2. The shield machine cutterhead ring according to claim 1, characterized in that, Both the hobbing cutter hub and the annular cutting edge are made of die-forged steel, which is selected from 42CrMo steel or H13 steel, with a hardness of 55-60 HRC.

3. The shield machine cutterhead ring according to claim 1, characterized in that, The first microstructure, the second microstructure, and the third microstructure are independently selected surface structures, and are selected from any of the following: groove structure, protrusion structure, and microporous structure.

4. The shield machine cutterhead ring according to claim 3, characterized in that, When the microstructure is a groove structure, its depth is 0.1–1.0 mm, its width is 0.2–2.0 mm, and the spacing between adjacent grooves is 0.5–5.0 mm; When the microstructure is a protruding structure, its height is 0.05–0.8 mm, its base diameter is 0.1–1.5 mm, and its distribution density is 10–50 particles / cm². 2 ; When the microstructure is a microporous structure, its pore size is 0.05–0.5 mm, pore depth is 0.1–0.8 mm, and pore density is 20–100 pores / cm³. 2 .

5. The shield machine cutterhead ring according to claim 4, characterized in that, The first microstructure is a groove structure, the second microstructure is a protrusion structure, and the third microstructure is a microporous structure.

6. The shield machine cutterhead ring according to any one of claims 1-5, characterized in that, The thickness of the nickel-based tungsten carbide layer is 3.5-25 mm.

7. The shield machine cutterhead ring according to claim 6, characterized in that, The nickel-based tungsten carbide layer covering the first cladding zone extends to cover the second and third cladding zones, and the extended portion is located below the nickel-based tungsten carbide layer on the surface of the second and third cladding zones, forming a stepped composite structure.

8. The shield machine cutterhead ring according to claim 7, characterized in that, The extended portion covers 10%-15% of the surface area of ​​the second and third cladding zones.

9. The shield machine cutterhead ring according to claim 1, characterized in that, The angle between the projections of the first connection point and the second connection point on the chamfered connection portion is 15-35 degrees, and the projection angle is defined as follows: Draw the first cross-section of the chamfered connection part through the first connection point; Draw the second tangential surface of the chamfered connection part through the second connection point; Using the intersection of the first and second cut surfaces as a reference, measure the included angle between the two cut surfaces.

10. The shield machine cutterhead ring according to claim 9, characterized in that, The angle between the projections of the third connection point and the fourth connection point on the chamfered connection portion is 110-130 degrees, and the projection angle is defined as follows: Draw the third tangent of the chamfered connection part through the third connection point; Draw the fourth tangent of the chamfered joint through the fourth connection point; Using the intersection of the third and fourth sectional planes as a reference, measure the included angle between the two sectional planes.

Images