An assembly and detection tool for a contact fitting of a gas-insulated switch

Abstract

The utility model provides a kind of for the assembly and detection tool of contact accessory of gas insulated switch, and contact accessory includes the first contact support seat, contact insulation cylinder and second contact support seat connected in turn axially, and assembly and detection tool includes the assembly part of being arranged along vertical axis and the detection part located in one side of assembly part;Assembly part includes: bottom positioning assembly, it includes bottom base, positioning disc and bearing unit including conical roller bearing, wherein, bearing unit connects bottom base and positioning disc;Positioning disc has the positioning surface for the radial positioning of first contact support seat;Main body frame, it is extended upwards from bottom base, and its bottom end is connected with positioning disc;And top positioning assembly, it is set in the top end of main body frame, including the linear centering unit for the radial positioning of second contact support seat.The utility model can use same tool to carry out assembly precision detection to contact accessory just after completing its assembly, and production efficiency is significantly improved.

Description

Technical Field

[0001] This disclosure belongs to the technical field of contact component assembly for gas-insulated switches, specifically relating to a tooling for assembling and testing contact components for gas-insulated switches. Background Technology

[0002] In gas-insulated switches, the precision requirements for the switching components are very high, which requires that the related components in the switching components have high assembly precision.

[0003] Contact accessories are common components in the circuit breaker assembly of gas-insulated switches. They typically consist of two contact supports and a contact insulating cylinder located between them. The main function of the contact supports is to support and fix the contacts, ensuring they are in the correct position; while the main function of the contact insulating cylinder is insulation, isolating the contacts from surrounding conductive parts. Contact accessories are usually assembled using specialized assembly fixtures. After assembly, they are removed from the fixtures and sent to specialized assembly accuracy testing equipment to check whether their assembly accuracy meets the requirements. Specifically, this includes checking the parallelism between the upper and lower surfaces of the contact accessory, and the coaxiality between the first and second contact supports. If the test results meet the assembly accuracy requirements, the contact accessory is then assembled with related components to form a contact for use in the circuit breaker assembly.

[0004] However, the process of removing the assembled contact components from the assembly fixture and then sending them to a specialized precision testing device to check the assembly accuracy is rather cumbersome, time-consuming, and labor-intensive. Utility Model Content

[0005] This disclosure solves the above and / or other technical problems and provides an assembly and testing fixture for contact components of gas-insulated switches. The fixture can be used to perform assembly accuracy testing on-site after the contact components are assembled. It is convenient to use and can significantly improve production efficiency.

[0006] To address the aforementioned technical problems, this disclosure provides an assembly and testing fixture for contact components of a gas-insulated switch. The contact component includes a first contact support, a contact insulation cylinder, and a second contact support connected axially in sequence. The assembly and testing fixture includes an assembly section arranged along a vertical axis and a testing section located on one side of the assembly section. The assembly section includes: a bottom positioning assembly comprising a bottom base, a positioning disk, and a bearing unit, wherein the bearing unit connects the bottom base and the positioning disk, and the bearing unit includes a tapered roller bearing; the positioning disk has a positioning surface for radially positioning the first contact support; a main frame extending upward from the bottom base, the bottom end of the main frame being connected to the positioning disk; and a top positioning assembly disposed at the top of the main frame, including a linear centering unit for radially positioning the second contact support.

[0007] The assembly and testing fixture for contact components of gas-insulated switches disclosed herein includes an assembly section for assembling the contact components. The assembly section uses a positioning plate in the bottom positioning assembly to position the first contact support seat in the contact component, and a linear centering unit in the top positioning assembly to position the second contact support seat, thereby ensuring the installation accuracy of the contact components. Furthermore, the assembly and testing fixture also includes a testing section located on one side of the assembly section. During the rotation of the contact component after assembly, the testing section can obtain corresponding testing data to determine whether the parallelism between the upper and lower surfaces of the contact component and the coaxiality between the two contact supports meet the accuracy requirements. It should be noted that the rotation process of the contact component during one rotation should have almost no impact on the already assembled components. The original state of the assembled contact components (the rotation will not cause significant misalignment between the first and second contact supports) is maintained. This disclosure further includes a bearing unit, including tapered roller bearings, in the bottom positioning assembly. This bearing unit connects the positioning disc and the bottom base. During the rotation of the assembled contact components and the positioning disc relative to the bottom base, the tapered roller bearings provide high rotational accuracy, ensuring that the original state of the contact components remains almost unchanged. Thus, after rotation and testing, the relative positions of the components within the contact components will not change significantly compared to before rotation. By ensuring the installation accuracy of the contact components during assembly, the contact components after testing can still maintain very close accuracy.

[0008] Furthermore, the bearing unit includes a first planar bearing and a second planar bearing, and the first planar bearing, the tapered roller bearing, and the second planar bearing are connected sequentially along the vertical axis.

[0009] Furthermore, the positioning plate has a positioning countersunk platform to form the positioning surface, and a connecting hole is provided; the connecting member extending in the vertical direction passes through the opening on the first contact support base and enters the connecting hole.

[0010] Furthermore, a locking hole is provided on the bottom base; a locking pin extending in the vertical direction can pass through the opening on the positioning plate and enter the locking hole.

[0011] Furthermore, the top positioning assembly includes a steel top base and a steel positioning connector disposed below the steel top base. The steel top base can be coaxially connected to the second contact support, and the steel positioning connector is coaxially connected to the main frame. The steel top base and the steel positioning connector are connected through the linear centering unit.

[0012] Furthermore, the linear centering unit is at least one linear sliding bearing disposed on the top surface of the steel positioning connector.

[0013] Furthermore, the number of the linear sliding bearings is three, and they are arranged in a circumferential direction.

[0014] Furthermore, a positioning connection groove is provided at the top of the main frame, and the steel positioning connector is located in the positioning connection groove.

[0015] Furthermore, the detection unit is located on the bottom base.

[0016] Furthermore, the detection unit includes a support rod and a first detection dial indicator and a second detection dial indicator disposed on the support rod, wherein the first detection dial indicator and the second detection dial indicator are respectively disposed at positions corresponding to the first contact support seat and the second contact support seat.

[0017] Other beneficial effects of the present invention will be explained in detail through the introduction of specific technical features and technical solutions in specific embodiments. Those skilled in the art should be able to understand the beneficial technical effects brought about by these technical features and technical solutions through the introduction of these technical features and technical solutions. Attached Figure Description

[0018] The accompanying drawings, which are included to provide a further understanding of this disclosure and form part of this disclosure, illustrate exemplary embodiments of the present disclosure and are used to explain the disclosure, but do not constitute an undue limitation of the disclosure. In the drawings: Figure 1 This is one of the three-dimensional structural schematic diagrams of an embodiment of the assembly and testing fixture for contact accessories of gas-insulated switches disclosed herein; Figure 2This is a cross-sectional perspective view of one embodiment of the assembly and testing fixture for contact accessories of gas-insulated switches disclosed herein (the first and second testing dial indicators are omitted). Figure 3 This is a partial three-dimensional structural schematic diagram of one embodiment of the assembly and testing fixture (steel top base hidden) for contact accessories of gas-insulated switches disclosed herein. Figure 4 This is a three-dimensional structural schematic diagram of one embodiment of the bearing unit disclosed herein; Figure 5 yes Figure 2 A magnified structural diagram at point A; Figure 6 yes Figure 2 A magnified structural diagram at point B; Figure 7 This is the second three-dimensional structural schematic diagram of one embodiment of the assembly and testing fixture for contact accessories of gas-insulated switches disclosed herein.

[0019] Explanation of icon numbers: Detailed Implementation

[0020] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this disclosure or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0021] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this disclosure. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise.

[0022] See appendix Figure 1-7 This disclosure provides an assembly and testing fixture for contact components of a gas-insulated switch. The contact components include a first contact support 200, a contact insulation cylinder 300, and a second contact support 400 connected axially in sequence. The assembly and testing fixture includes an assembly section 100 arranged along a vertical axis and a testing section 500 located on one side of the assembly section 100; The assembly unit 100 includes: The bottom positioning assembly 110 includes a bottom base 112, a positioning disk 111, and a bearing unit 120. The bearing unit 120 connects the bottom base 112 and the positioning disk 111, and includes a tapered roller bearing 122. The positioning disk 111 has a positioning surface for radial positioning of the first contact support 200. The main frame 130 extends upward from the bottom base 112, and the bottom end 131 of the main frame 130 is connected to the positioning plate 111; and The top positioning assembly 140 is disposed at the top 132 of the main frame 130 and includes a linear centering unit 143 for radial positioning of the second contact support 400.

[0023] The assembly and testing fixture for contact components of gas-insulated switches provided in this disclosure can be applied, for example, to the circuit breaker assembly (model 475-06540-001) of Siemens' 8DQ1-6 gas-insulated switch. In this circuit breaker assembly, the permissible deviation of the parallelism between the upper and lower surfaces of the contact components is typically within 0.4 mm, and the permissible deviation of the coaxiality between the first contact support 200 and the second contact support 400 is typically within 0.5 mm. The assembly and testing fixture for contact components of gas-insulated switches provided in this disclosure can meet the accuracy requirements with a high probability.

[0024] The assembly and testing fixture for contact components of gas-insulated switches disclosed herein can perform assembly and assembly accuracy testing of contact components, including a first contact support 200, a contact insulation cylinder 300, and a second contact support 400, using a single fixture. In the contact components, the second contact support 400 is located at the bottom, the contact insulation cylinder 300 is located in the middle, and the first contact support 200 is located at the top. During assembly, the first contact support 200, the contact insulation cylinder 300, and the second contact support 400 are only pre-connected (pre-connection is a preliminary connection, such as loosely bolting at the connection point, not a tight connection), transforming these three components from being independent to being pre-connected together, so that they can be placed as a single unit on the positioning plate in the bottom positioning assembly of the assembly and testing fixture. Then, after the positions of the first contact support 200 and the second contact support 400 are precisely positioned by the bottom positioning component 110 and the top positioning component 140 in the assembly and testing fixture, the first contact support 200 is then fastened to the contact insulation cylinder 300 (e.g., by tightening bolts), and the second contact support 400 is also fastened to the contact insulation cylinder 300. This completes the assembly of the contact accessories.

[0025] Specifically, the assembly and testing fixture includes an assembly section for assembling contact components. The positioning plate 111 in the bottom positioning component 110 positions the first contact support 200 in the contact components, and the linear centering unit 143 in the top positioning component 140 positions the second contact support 400, thereby ensuring the installation accuracy of the contact components. In this regard, considering the need for accurate positioning of the first contact support 200 located at the lower part of the contact accessory, the bottom positioning component 110 includes a positioning disk 111, and the positioning disk 111 has a positioning surface that can radially position the first contact support 200. With the help of this positioning surface, the first contact support can be accurately positioned relative to the bottom base 112. Considering the need for accurate positioning of the second contact support 400 located at the upper part of the contact accessory, this disclosure provides a main frame 130 extending upward from the bottom base 112, and a top positioning component 140 is provided at the top 132 of the main frame 130. The top positioning component 140 has a linear centering unit 143 for radial positioning of the second contact support 400. After the first contact support 200 and the second contact support 400 are accurately positioned, the first contact support 200, the contact insulating cylinder 300, and the second contact support 400 can be fastened together. Those skilled in the art will understand that, as an assembly tool itself, the machining accuracy of its structural components such as the bottom base 112, positioning disk 111, and main frame 130, as well as the assembly accuracy between these components, are strictly guaranteed, and the assembly accuracy of the contact accessories will not exceed the allowable deviation range due to the structural reasons of the assembly tool itself.

[0026] Furthermore, the assembly and testing fixture also includes a testing unit 500 located on one side of the assembly unit 100. During the process of rotating the contact component after assembly, the testing unit 500 can obtain data related to the parallelism between the upper and lower surfaces of the contact component and the coaxiality between the two contact support seats, so that the user can determine whether the contact component meets the accuracy requirements. It is worth noting that, in order to ensure the stability of the rotation of the contact component and to ensure that the rotation process of one revolution has almost no impact on the original state of the assembled contact component (the rotation will not cause significant misalignment between the first contact support and the second contact support), this disclosure also provides a bearing unit 120, including a tapered roller bearing 122, in the bottom positioning assembly 110. The bearing unit 120 connects the positioning disk 111 and the bottom base 112. During the rotation of the assembled contact component and the positioning disk 111 relative to the bottom base 112, the tapered roller bearing 122's high rotational accuracy ensures that the original state of the contact component remains almost unchanged. Thus, after the rotation is completed and the inspection is finished, the relative positional relationship between the components in the contact component will not change significantly compared to before the rotation. By ensuring the installation accuracy of the contact component during assembly, the contact component after inspection can still have very close accuracy.

[0027] The assembly and testing fixture for contact components of gas-insulated switches provided in this disclosure ensures high assembly accuracy during the assembly process and enables the testing of assembly accuracy after assembly. The same fixture allows for convenient and quick assembly and accuracy testing of contact components, greatly improving production efficiency.

[0028] Furthermore, see the appendix in particular. Figure 4 The bearing unit 120 includes a first planar bearing 121 and a second planar bearing 123, and the first planar bearing 121, the tapered roller bearing 122 and the second planar bearing 123 are connected in sequence along the vertical axis.

[0029] By combining the first planar bearing 121, the tapered roller bearing 122, and the second planar bearing 123, the rotational accuracy of the bearing unit 120 can be further improved compared to using only the tapered roller bearing 122. This makes the state of the contact component more stable and the change compared to when it is assembled is almost negligible during the rotation of the assembled contact component and the positioning disk 111 relative to the bottom base 112. By ensuring the installation accuracy of the contact component during assembly, the contact component after testing can still have almost the same accuracy.

[0030] Furthermore, see the appendix in particular. Figure 1 ,2 6. The positioning plate 111 has a positioning countersunk to form a positioning surface and a connecting hole. The vertically extending connector 113 passes through the opening on the first contact support 200 and enters the connection hole.

[0031] Specifically, the positioning platform can be formed on the upper surface of the positioning disk 111, and its inner surface in the circumferential direction can form a positioning surface for radial positioning of the first contact support 200.

[0032] The connecting hole on the positioning disk 111 cooperates with the vertically extending connecting piece 113 to connect the first contact support 200 and the positioning disk 111 together. During the rotation of the contact accessory, the positioning disk 111 can rotate together. Through the bearing unit 120, including the tapered roller bearing 122, which ensures high rotational accuracy, the state of the contact accessory can be stabilized, thereby ensuring that the relative positional relationship between the components in the contact accessory will not change beyond the allowable expectation compared to before rotation.

[0033] Furthermore, see the appendix in particular. Figure 1 A locking hole is provided on the bottom base 112; The locking pin 114, which extends vertically, can pass through the opening on the positioning plate 111 and enter the locking hole.

[0034] The bottom base 112 is stationary. When the locking pin 114 is inserted into the locking hole, the positioning disk 111 is fixedly connected to the bottom base 112. At this time, the rotation of the positioning disk 111 is restricted, and it cannot rotate even under external force. Consequently, the first contact support 200, which is fixedly connected to the positioning disk 111, also cannot rotate. This disclosure ensures that the contact component rotates only when rotation is permitted (normally, rotation is only required when checking its assembly accuracy).

[0035] Furthermore, see the appendix in particular. Figure 2 and 5 The top positioning assembly 140 includes a steel top base 141 and a steel positioning connector 142 disposed below the steel top base 141. The steel top base 141 can be coaxially connected to the second contact support 400, and the steel positioning connector 142 is coaxially connected to the main frame 130. The steel top base 141 and the steel positioning connector 142 are connected by a linear centering unit 143.

[0036] Specifically, the steel positioning connector 142 is located at the top 132 of the main frame 130 and is coaxially connected to the main frame 130. The accurate positioning of the second contact support 400 can be achieved with the help of the steel top base 141, because the steel top base 141 and the steel positioning connector 142 are connected by a linear centering unit 143. With the help of the linear centering unit 143, the position of the steel top base 141 can be accurately positioned relative to the steel positioning connector 142 (and the accurate positioning of the steel positioning connector 142 depends on its coaxial connection with the main frame 130, and the main frame 130 can be kept in a predetermined position due to the fixed connection between its bottom end 131 and the positioning disk 111). In this way, the second contact support 400, which is coaxially connected to the steel top base 141, can be positioned with high precision. The coaxial connection between the steel top base 141 and the second contact support 400 can be achieved, for example, by bolted fasteners. After the steel top base 141 is positioned at the appropriate position on the steel top base 141 by the linear centering unit 143, the second contact support 400 is accurately positioned by aligning the bolt holes on the steel top base 141 with the corresponding bolt holes on the second contact support 400, inserting bolts and tightening them.

[0037] By making both the positioning connector and the top base out of steel, wear on their contact surfaces can be effectively reduced, significantly extending the service life of the assembly and testing fixture.

[0038] Furthermore, see the appendix in particular. Figure 3 The linear centering unit 143 is at least one linear sliding bearing disposed on the top surface of the steel positioning connector 142.

[0039] Linear sliding bearings allow objects to slide with low friction along a straight line, i.e., to guide in a straight line with high precision. Compared with the use of traditional locating pins for guiding and positioning in a straight line, the linear sliding bearings used in this disclosure can significantly improve positioning accuracy.

[0040] Furthermore, see the appendix in particular. Figure 3 There are three linear sliding bearings, arranged in a circumferential direction.

[0041] By using three linear sliding bearings as linear centering units 143, the positioning accuracy in the linear direction can be further optimized through the three-point positioning principle.

[0042] Furthermore, see the appendix in particular. Figure 2 and 5 The top 132 of the main frame 130 is provided with a positioning connection groove, and the steel positioning connector 142 is located in the positioning connection groove.

[0043] The opening of the positioning connection groove helps to achieve precise positioning of the steel positioning connector 142 relative to the main frame 130 (the circumferential surface of the positioning connection groove can become the radial positioning surface of the steel positioning connector 142), thereby the steel top base 141 can be precisely positioned relative to the steel positioning connector 142, thus ensuring the precise positioning of the second contact insulation seat 200 coaxially connected to the steel top base 141.

[0044] Furthermore, see the appendix in particular. Figure 1 and 7 The detection unit 500 is located on the bottom base 112.

[0045] By configuring the present invention in this way, the inspection unit 500 and the assembly unit 100 can be integrated on the same bottom base 112, thereby improving the overall integrity of the assembly and inspection fixture, which can be moved and used as a whole. It also has the advantages of compact structure, relatively small footprint, and more convenient use, and there is no need to set up a special inspection unit base for the inspection unit 500.

[0046] Furthermore, see the appendix in particular. Figure 1 and 7 The detection unit 500 includes a support rod 510 and a first detection dial indicator 520 and a second detection dial indicator 530 disposed on the support rod 510. The first detection dial indicator 520 and the second detection dial indicator 530 are respectively disposed at positions corresponding to the first contact support seat 200 and the second contact support seat 400.

[0047] In one embodiment, when performing surface parallelism testing for the assembly accuracy of the assembled contact components, a second dial indicator 530 is used to detect the parallelism between the upper surface 410 and the lower surface of the contact component. Specifically, during this parallelism test, the surface being tested is the upper surface of the contact component (because the lower surface of the contact component, i.e., the lower surface of the first contact support 200, has achieved a high-precision horizontal alignment through its positioning connection with the positioning disk 111 in the bottom positioning assembly, and can be used as a reference plane), i.e., the upper surface 410 of the second contact support 400. During one rotation of the contact component, the second dial indicator 530 detects the relevant data of the surface being tested along one rotation. When the probe of the second dial indicator 530 initially touches the surface being tested, the second dial indicator 530 is zeroed. If the upper and lower surfaces of the contact component are perfectly parallel, the reading of the second dial indicator 530 should not change during this reading process. However, if the upper and lower surfaces are not perfectly parallel, the reading of the second dial indicator 530 will change. By reading the change in the relevant reading, it can be determined whether the degree of change is within the allowable deviation range (whether the difference between the maximum and minimum readings of the dial indicator is within the allowable deviation range). This will determine whether the parallelism of the upper and lower surfaces of the contact component meets the accuracy requirements.

[0048] In one embodiment, when testing the coaxiality of the assembled contact components to ensure assembly accuracy, a first dial indicator 520 and a second dial indicator 530 are used in conjunction to test the coaxiality between the first contact support 200 and the second contact support 400. Specifically, during one rotation of the contact component, the first dial indicator 520 measures the data around the outer edge of the corresponding part of the first contact support 200, and is zeroed when its probe touches the outer edge. The second dial indicator 530 measures the data around the outer edge of the corresponding part of the second contact support 200, and is zeroed when its probe touches the outer edge. When the first contact support 200 and the second contact support 400 are perfectly coaxial, the readings of both dial indicators will remain constant during the rotation of the contact component. If the first contact support 200 and the second contact support 400 are not perfectly coaxial, the readings of the two dial indicators will change accordingly during the rotation of the contact component. By judging whether the relevant difference is within the allowable deviation range (for each detected position during the rotation process, the coaxiality error is the difference between the readings of the two dial indicators; and the final coaxiality error between the two contact supports can be the largest of the aforementioned differences), it can be determined whether the coaxiality between the first contact support 200 and the second contact support 400 in the contact component can meet the accuracy requirements.

[0049] The above are merely preferred embodiments of this disclosure. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this disclosure, and these improvements and modifications should also be considered within the scope of protection of this disclosure.

Claims

1. A fixture for assembling and testing contact components of a gas-insulated switch, the contact components comprising a first contact support (200), a contact insulating cylinder (300), and a second contact support (400) connected axially in sequence, characterized in that, The assembly and testing fixture includes an assembly section (100) arranged along a vertical axis and a testing section (500) located on one side of the assembly section (100). The assembly unit (100) includes: A bottom positioning assembly (110) includes a bottom base (112), a positioning disk (111), and a bearing unit (120), wherein the bearing unit (120) connects the bottom base (112) and the positioning disk (111), and the bearing unit (120) includes a tapered roller bearing (122); the positioning disk (111) has a positioning surface for radially positioning the first contact support (200); The main frame (130) extends upward from the bottom base (112), and the bottom end (131) of the main frame (130) is connected to the positioning disk (111); and The top positioning assembly (140), located at the top (132) of the main frame (130), includes a linear centering unit (143) for radially positioning the second contact support (400).

2. The assembly and testing fixture for contact components of gas-insulated switches according to claim 1, Its features are, The bearing unit (120) includes a first planar bearing (121) and a second planar bearing (123), and the first planar bearing (121), the tapered roller bearing (122), and the second planar bearing (123) are connected sequentially along the vertical axis.

3. The assembly and testing fixture for contact components of gas-insulated switches according to claim 1, Its features are, The positioning plate (111) is provided with a positioning countersink to form the positioning surface, and a connecting hole is provided; The vertically extending connector (113) passes through an opening on the first contact support (200) and enters the connection hole.

4. The assembly and testing fixture for contact components of gas-insulated switches according to claim 3, Its features are, The bottom base (112) is provided with a locking hole; The locking pin (114) extending vertically can pass through the opening on the positioning plate (111) and enter the locking hole.

5. The assembly and testing fixture for contact components of gas-insulated switches according to claim 1, Its features are, The top positioning assembly (140) includes a steel top base (141) and a steel positioning connector (142) disposed below the steel top base (141). The steel top base (141) can be coaxially connected to the second contact support (400), and the steel positioning connector (142) is coaxially connected to the main frame (130). The steel top base (141) and the steel positioning connector (142) are connected by the linear centering unit (143).

6. The assembly and testing fixture for contact components of gas-insulated switches according to claim 5, Its features are, The linear centering unit (143) is at least one linear sliding bearing disposed on the top surface of the steel positioning connector (142).

7. The assembly and testing fixture for contact components of a gas-insulated switch according to claim 6, Its features are, The linear sliding bearings are in the form of three and are arranged circumferentially.

8. The assembly and testing fixture for contact components of a gas-insulated switch according to claim 6, Its features are, The top end (132) of the main frame (130) is provided with a positioning connection groove, and the steel positioning connector (142) is located in the positioning connection groove.

9. The assembly and testing fixture for contact components of gas-insulated switches according to claim 1, Its features are, The detection unit (500) is located on the bottom base (112).

10. The assembly and testing fixture for contact components of a gas-insulated switch according to claim 9, Its features are, The detection unit (500) includes a support rod (510) and a first detection dial indicator (520) and a second detection dial indicator (530) disposed on the support rod (510). The first detection dial indicator (520) and the second detection dial indicator (530) are respectively disposed at positions corresponding to the first contact support seat (200) and the second contact support seat (400).

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