Host machine of ball bar instrument and ball bar instrument

Abstract

The invention provides a main machine of a ball rod instrument and the ball rod instrument. The main machine of the ball rod instrument comprises an inductive probe assembly, a circuit board assembly, a battery assembly, a ball rod instrument main body and a second measuring ball, the inductance measuring head assembly comprises a first measuring ball, a measuring rod, a measuring head body, a guide sleeve, a reset spring and a pin, the first measuring ball is arranged at the first end of the measuring rod, the guide sleeve is arranged on the measuring rod in a sleeving mode, the pin is inserted into the measuring rod and close to the second end of the measuring rod, and the measuring rod, the measuring head body, the guide sleeve and the pin form a precise kinematic pair; the pin moves in the kidney-shaped hole in the measuring head body along with the measuring rod, the pin is tightly matched with the kidney-shaped hole, when the measuring rod is compressed, the reset spring is also compressed, and when the measuring rod is loosened, the reset spring pushes the measuring rod to move outwards till the measuring rod extends outwards to the limit position. According to the invention, the main machine of the ball bar instrument and the ball bar instrument which are simple to operate, high in precision, low in cost and capable of rapidly detecting the precision of the motion axis of the CNC machine tool can be provided.

Description

[0001] This application is a divisional application of a patent application with an application date of June 17, 2020, application number 2020105541593, and invention name "An Inductive Wireless Ballbar". Technical Field

[0002] The invention relates to the field of circular motion trajectory error measurement of numerically controlled machine tools. Background Art

[0003] CNC machine tools play a very important role in modern processing technology. The accuracy of machine tools determines the accuracy of machined parts. If the accuracy of machine tools can be determined to meet the index requirements before processing parts, scrap can be avoided, thereby avoiding large economic losses. Laser interferometers can be used to detect and compensate for the accuracy of machine tool motion axes, but it takes a long time. In actual production, processing workers only need to know whether the accuracy of machine tools meets the requirements, and they do not necessarily need to compensate for the accuracy of machine tools. Therefore, it is necessary to have a device that can quickly detect the accuracy of machine tools. The ballbar is used to comprehensively detect the accuracy of CNC machine tool motion axes.

[0004] At present, some domestic manufacturers and research institutes have made grating ballbars, such as the articulated and retractable ballbar of Xiamen Wanjiu Technology Co., Ltd., the spatial two-link ballbar of Hangzhou Dianzi University, and the double grating ballbar of the Institute of Mechanical Research and Manufacturing Technology of China Academy of Engineering Physics. Although they have their own characteristics, the double grating structure is relatively complex and the cost is relatively high. There are ballbars from API and Renishaw abroad. API's ballbar is also grating type, which is relatively large in size and relatively expensive. Renishaw's is inductive type, which occupies a relatively large market share, but the price is relatively high. For the vast majority of machine tool manufacturers or machining companies, what is needed is a ballbar with high measurement efficiency, convenient maintenance, satisfactory accuracy and relatively low cost.

[0005] Disadvantages of existing technical solutions: The structure of the grating ballbar is complex and the cost is high. The relative position of the magnetic core and the solenoid coil of the foreign inductive ballbar cannot be adjusted, and its zero position needs to be completely guaranteed by the processing accuracy, which has high requirements on the processing accuracy and assembly of parts, and its cost is also relatively high. Summary of the invention

[0006] In order to provide an inductive ballbar with simple operation, high accuracy, low cost and the ability to quickly detect the accuracy of the motion axis of a CNC machine tool, the present invention provides an inductive wireless ballbar, which is mainly composed of a ballbar mainframe, a center support assembly, a center cup assembly and a setting ball assembly.

[0007] The ballbar mainframe comprises an inductive probe assembly, a battery assembly, a circuit board assembly and a ballbar body; further comprises a measuring ball connecting rod movably connected to the battery assembly, and a second measuring ball connected to the measuring ball connecting rod; the inductive probe assembly comprises a first measuring ball, a measuring rod, a probe body, a guide sleeve, a magnetic core sleeve rod, a magnetic core, a coil, a reset spring and a pin; the circuit board assembly comprises a circuit board;

[0008] The first measuring ball is arranged at the first end of the measuring rod, the guide sleeve is sleeved on the measuring rod, the pin is inserted into the measuring rod, and the position of the pin is close to the second end of the measuring rod. The measuring rod, the probe body, the guide sleeve and the pin form a precision motion pair, and the pin moves in the waist-shaped hole on the probe body following the measuring rod, and the pin is tightly matched with the waist-shaped hole;

[0009] The magnetic core sleeve rod is fixedly connected to the second end of the measuring rod and moves with the measuring rod, and the magnetic core is installed in the magnetic core sleeve rod; when the measuring rod is compressed, the reset spring is also compressed; when the measuring rod is released, the reset spring will push the measuring rod to move outward until the measuring rod extends outward to the limit position; the circuit board is fixed on the ballbar body, and the ground end of the circuit board is connected to the ballbar body; the Bluetooth transmitter on the circuit board sends the displacement signal of the inductive probe assembly to the computer; one end of the battery assembly is connected to the circuit board, and the other end of the battery assembly is connected to the ballbar body;

[0010] The center support assembly includes: a measuring ball support block, a magnet, a movable support rod, an elastic claw, a conical limit sleeve, a cam rod, a spring, an adjustment end cover, a handle, a reset spring, an upper pad, a base and a base magnet;

[0011] The measuring ball support block and the magnet are fixedly mounted on the upper end of the movable support rod, and a circle or a plurality of evenly distributed arc bosses are designed on the measuring ball support block;

[0012] The lower end of the movable support rod is a spherical structure, which is placed in the middle of the claw of the elastic claw. When the cam rod is in a loose state, the movable support rod can swing freely in the middle of the claw, or move up and down. When the cam rod is in a locked state, the movable support rod is firmly clamped by the claw and cannot move freely.

[0013] A through hole is provided in the middle of the elastic claw for installing the cam rod, and both ends of the cam rod are in contact with the upper pad, and a spring and an adjusting end cover are arranged in sequence under the upper pad, and the adjusting end cover is connected with the conical limiting sleeve. When the adjusting end cover is screwed inward, the spring is compressed, and the spring elastic force pushes the upper pad to press the cam rod. When the handle is in a vertical state, the cam rod is located at the lowest point of the cam stroke, and the movable support rod moves freely in the middle of the elastic claw. When the handle is pulled to a horizontal state, the cam rod is located at the highest point of the cam stroke, and the elastic claw is squeezed into the conical surface inside the conical limiting sleeve. The claw undergoes elastic deformation and clamps the movable support rod, so that the movable support rod is fixed in a position, and the elastic claw is fixedly connected to the base.

[0014] The center cup assembly includes: a measuring ball support block, a magnet and a center cup support rod;

[0015] The measuring ball support block and the magnet are fixedly installed on one end of the center cup support rod. This end is used to absorb the second measuring ball during measurement and ensure that the center position of the measuring ball does not change during the measurement process. The other end of the center cup support rod is used to clamp on the CNC spindle.

[0016] The setting ball assembly includes: a setting ball and a setting ball handle;

[0017] The setting ball has the same size, specification and accuracy level as the two measuring balls on the ballbar main unit, and the setting ball is fixedly connected to the setting ball handle.

[0018] As a further improvement of the present invention, the battery assembly includes a battery positive electrode guide, a battery, a battery end cover, a spring and a battery negative electrode spring; the battery positive electrode guide is connected to the circuit board through a wire, the battery end cover is connected to the external thread at one end of the ballbar body through an internal thread, and the battery negative electrode spring always maintains reliable contact and electrical conduction with the spring; before the battery end cover is tightened onto the ballbar body, the spring is not in contact with the battery end cover and the ballbar body, and the ballbar is in a power-off state; when the battery end cover is tightened onto the ballbar body, the end of the ballbar body presses against the spring, and at the same time the battery negative electrode spring presses against the battery negative electrode, and presses the battery against the battery positive electrode guide, and the battery is conductive, and the ballbar is in a power-on state.

[0019] As a further improvement of the present invention, the circuit board is fixedly mounted on the ballbar body by screws, the ground terminal of the circuit board is connected to the ballbar body, the power pin of the circuit board is connected to the positive electrode conductor of the battery by a wire, and when the battery is connected, the Bluetooth transmitter on the circuit board sends the displacement signal of the measuring rod to the computer.

[0020] As a further improvement of the present invention, the circuit board assembly also includes a circuit board cover, the ballbar body is made of metal material, the inductive probe assembly and the battery end cover are connected to the ballbar body through threads, and the circuit board cover is connected to the ballbar body through screws.

[0021] As a further improvement of the present invention, three arc bosses are evenly distributed on the measuring ball support block.

[0022] As a further improvement of the present invention, the adjusting end cover is connected to the conical limiting sleeve through a thread.

[0023] As a further improvement of the present invention, a base magnet is installed at the bottom of the base for adsorbing and fixing the central support assembly on the platform to be measured.

[0024] The beneficial effects of the present invention are:

[0025] A wireless measurement system consisting of a ballbar mainframe (including wireless transmitter), a center support and a center cup assembly, used to comprehensively detect the accuracy of CNC machine tool motion axes;

[0026] Guiding method of the measuring rod of the inductive probe: the precise kinematic pair composed of the measuring rod 2, the guide sleeve 4, the probe body 3 and the pin 19 ensures the running accuracy of the measuring rod. The pin 19 ensures that the measuring rod will not rotate during operation. The guiding of the inductive probe of the ballbar is reliable, the accuracy can meet the use requirements, and the measuring efficiency is high.

[0027] The installation method of the battery 10 is as follows: the positive electrode of the battery is in rigid contact with the positive electrode guide 9 of the battery, and the negative electrode is in elastic contact with the negative electrode spring 15 of the battery, so as to ensure the reliability of the battery installation; the elastic function of the negative electrode spring 15 of the battery is realized by making the metal part into a soft hinge; the battery installation structure is simple, compact, and reliable to install;

[0028] Installation method of the ballbar signal transmitter: The Bluetooth transmitter and circuit board 7 are built into the ballbar body 5, and the circuit board cover is made of non-metallic material to ensure that the Bluetooth signal can be effectively transmitted to the computer;

[0029] The clamping method of the movable support rod 22 of the center support: The structure of the central movable support rod 22 is that the upper end is a straight rod, the top of the straight rod is a magnetic seat device, and the lower end of the support rod has a hemispherical structure, which is equivalent to a ball joint structure. When the cam rod 25 is at the highest position of the stroke, the elastic claw 23 is pushed into the conical surface inside the conical limit sleeve by the elastic force of the spring 26, the hemispherical part of the movable support rod 22 is clamped, and the position of the support rod is fixed; when the cam rod 25 is at the lowest position of the stroke, the elastic claw 23 is pushed out of the conical surface inside the conical limit sleeve by the action of the reset spring 26, the hemispherical part of the movable support rod 22 is released, and the support rod can swing freely or move up and down in the middle of the elastic claw 23. The central support is small in size and easy to carry, and the movable support rod is convenient and reliable to clamp;

[0030] Simple structure, easy to install and maintain; low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 : Set the schematic diagram of the ball component usage;

[0032] Figure 2 : Schematic diagram of ballbar clamping measurement;

[0033] Figure 3 : Stereoscopic image of the ballbar host;

[0034] Figure 4 : Cross-sectional view of the ballbar mainframe;

[0035] Figure 5 : Figure 4 The enlarged image on the right is a schematic diagram of the battery assembly;

[0036] Figure 6 : Exploded view of the ballbar mainframe;

[0037] Figure 7 : Stereoscopic diagram of the center support assembly;

[0038] Figure 8 : Cross-sectional view of the center support assembly;

[0039] Fig. 9 : Exploded view of the center support assembly;

[0040] Fig.10 : Enlarged view of the movable support rod and the measuring ball support block;

[0041] Fig.11 : Schematic diagram of the center cup assembly;

[0042] Fig.12 : Set the ball component diagram.

[0043] The names of the components in the figure are as follows:

[0044] Ballbar mainframe 100, center support assembly 200, center cup assembly 300, setting ball assembly 400, CNC spindle 500, first measuring ball 1, measuring rod 2, probe body 3, guide sleeve 4, ballbar body 5, circuit board cover 6, circuit board 7, magnetic core sleeve rod 8, battery positive electrode guide sheet 9, battery 10, battery end cover 11, second measuring ball 12, measuring ball connecting rod 13, spring piece 14, battery negative electrode spring piece 15, magnetic core 16, coil 17, reset spring 18, pin 19, measuring ball support block 20, magnet 21, movable support rod 22, elastic claw 23, conical limit sleeve 24, cam rod 25, spring 26, adjustment end cover 27, handle 28, reset spring 29, upper pad 30, base 31, base magnet 32, center cup support rod 33, setting ball 34, setting ball handle 35. DETAILED DESCRIPTION

[0045] The present invention will be further described below in conjunction with the accompanying drawings.

[0046] like Figure 1 and Figure 2 As shown, an inductive wireless ballbar is mainly composed of four parts: a ballbar host 100, a center support assembly 200, a center cup assembly 300 and a setting ball assembly 400.

[0047] like Figures 3 to 6 As shown, the ballbar main unit 100 includes: a first measuring ball 1, a measuring rod 2, a probe body 3, a guide sleeve 4, a ballbar body 5, a circuit board cover 6, a circuit board 7, a magnetic core sleeve rod 8, a battery positive electrode guide 9, a battery 10, a battery end cover 11, a second measuring ball 12, a measuring ball connecting rod 13, a spring 14, a battery negative electrode spring 15, a magnetic core 16, a coil 17, a reset spring 18, and a pin 19.

[0048] like Figures 7 to 10 As shown, the center support assembly 200 includes: a measuring ball support block 20, a magnet 21, a movable support rod 22, an elastic claw 23, a conical limit sleeve 24, a cam rod 25, a spring 26, an adjustment end cover 27, a handle 28, a reset spring 29, an upper pad 30, a base 31, and a base magnet 32.

[0049] like Fig.11 As shown, the center cup assembly 300 includes: a measuring ball support block 20 , a magnet 21 , and a center cup support rod 33 .

[0050] like Fig.12 As shown, the setting ball assembly 400 includes: a setting ball 34 and a setting ball handle 35 .

[0051] The technical solution of the present invention is described in detail as follows:

[0052] 1) Ballbar main unit 100

[0053] The ballbar mainframe comprises an inductive probe assembly, a battery assembly, a circuit board assembly and a ballbar body.

[0054] The inductive probe assembly comprises a first measuring ball 1 , a measuring rod 2 , a probe body 3 , a guide sleeve 4 , a magnetic core sleeve rod 8 , a magnetic core 16 , a coil 17 , a reset spring 18 , and a pin 19 .

[0055] The inductive probe assembly is characterized in that the measuring rod 2, the measuring head body 3, the guide sleeve 4, and the pin 19 form a precision motion pair, which is reliable in guiding and ensures the accuracy of the measuring rod movement. The pin 19 moves in the waist-shaped hole on the measuring head body 3 following the measuring rod 2, and the matching clearance with the waist-shaped hole is very small, that is, it is tightly matched, thereby limiting the effective stroke of the measuring rod and ensuring that the measuring rod will not rotate during operation.

[0056] The magnetic core sleeve rod 8 is fixedly connected to the measuring rod 2 and moves with the measuring rod. The magnetic core 16 is installed inside the magnetic core sleeve rod 8.

[0057] When the measuring rod 2 is compressed, the reset spring 18 is also compressed; when the measuring rod 2 is released, the reset spring 18 will push the measuring rod 2 to move outward until the measuring rod reaches the limit position of extending outward.

[0058] The battery assembly comprises a battery positive electrode conductor 9 , a battery 10 , a battery end cover 11 , a spring 14 , and a battery negative electrode spring 15 .

[0059] The battery assembly is characterized in that the battery positive electrode guide 9 is connected to the circuit board through a wire, the battery end cover 11 is connected to the external thread at one end of the ballbar body 5 through an internal thread, and the battery negative electrode spring 15 and the spring 14 always maintain reliable contact and electrical conduction.

[0060] The circuit board is fixed on the ballbar body 5, and the ground terminal of the circuit board is connected to the ballbar body 5. The Bluetooth transmitter on the circuit board sends the displacement signal of the inductive probe to the computer for the computer software to analyze the measurement data.

[0061] Before the battery end cap 11 is screwed onto the ballbar body 5, the spring sheet 14 is not in contact with the battery end cap 11 and the ballbar body 5, and the ballbar is in a power-off state. When the battery end cap 11 is screwed onto the ballbar body 5, the end of the ballbar body 5 presses against the spring sheet 14, and at the same time, the negative electrode spring sheet 15 of the battery presses against the negative electrode of the battery, and presses the battery against the positive electrode guide sheet 9 of the battery, and the battery is now conductive, and the ballbar is in a power-on state.

[0062] The measuring ball connecting rod 13 is threadedly connected to the battery end cover 11. The second measuring ball 12 is fixedly connected to the measuring ball connecting rod 13. After the second measuring ball 12 and the measuring ball connecting rod 13 are screwed off, different extended measuring rods can be installed to measure circles (or arcs) with different radii.

[0063] The circuit board assembly includes a circuit board 7 and a circuit board cover 6 .

[0064] The circuit board assembly is characterized in that the circuit board 7 is fixedly mounted on the ballbar body 5 by screws, and the ground terminal of the circuit board is connected to the ballbar body 5. The power pin of the circuit board is connected to the positive electrode conductor 9 of the battery by a wire. When the battery is connected, the Bluetooth transmitter on the circuit board can send the displacement signal of the measuring rod to the computer.

[0065] The ballbar body 5 is made of metal material. The inductive probe assembly and the battery end cover are connected to the ballbar body through threads. The circuit board cover is connected to the ballbar body 5 through screws.

[0066] 2) Center support assembly 200

[0067] The central support assembly is characterized in that the measuring ball support block 20 and the magnet 21 are fixedly mounted on the upper end of the movable support rod 22, and a circle of or a plurality of evenly distributed arc bosses are designed on the measuring ball support block 20. Preferably, three evenly distributed arc bosses are designed on the measuring ball support block 20. During measurement, under the action of the magnetic suction force, the first measuring ball 1 can reliably contact the three arc bosses, ensuring that the center position of the measuring ball will not change when the measuring ball rotates in all directions.

[0068] The lower end of the movable support rod 22 is a spherical structure, which is placed in the middle of the claws of the elastic claws 23. When the cam rod 25 is in a loose state, the movable support rod 22 can swing freely in the middle of the claws, or move up and down. When the cam rod 25 is in a locked state, the movable support rod 22 is firmly clamped by the claws and cannot move freely.

[0069] There is a through hole in the middle of the elastic claw 23 for installing the cam rod 25. The two ends of the cam rod 25 are in contact with the upper pad 30, and the spring 26 and the adjustment end cover 27 are installed in sequence below the upper pad 30. The adjustment end cover 27 is connected to the conical limit sleeve 24 through a thread. When the adjustment end cover 27 is tightened inward, the spring 26 will be compressed, and the spring elastic force pushes the upper pad 30 to press the cam rod 25. When the handle 28 is in a vertical state, the cam rod 25 is located at the lowest point of the cam stroke, and the movable support rod 22 can move freely in the middle of the elastic claw 23. When the handle 28 is pulled to a horizontal state, the cam rod 25 is located at the highest point of the cam stroke. At this time, the elastic claw 23 is squeezed into the conical surface inside the conical limit sleeve 24, the claw undergoes elastic deformation, and clamps the movable support rod 22, so that the movable support rod is fixed in a position. The elastic claw 23 is fixedly connected to the base 31.

[0070] The bottom of the base 31 is provided with a base magnet 32 ​​for adsorbing and fixing the central support assembly on the platform to be measured.

[0071] 3) Center cup assembly 300

[0072] The center cup assembly is characterized in that the measuring ball support block 20 and the magnet 21 are fixedly mounted on one end of the center cup support rod 33. During measurement, this end is used to attract the second measuring ball 12 and ensure that the center position of the measuring ball does not change during the measurement process. The other end of the center cup support rod 33 is used to clamp on the CNC spindle. When measuring a circle on the XY plane, the center cup assembly 300 and the CNC spindle 500 remain stationary, and the center support assembly 200 follows the XY motion platform of the CNC to make a circular motion around the center cup assembly with a set radius of the ballbar mainframe 100. When measuring the YZ and XZ sections, the center support assembly 200 follows the XY motion platform, and the center cup assembly 300 follows the CNC spindle 500 to move up and down. During measurement, the ballbar records the difference between the motion trajectory and the standard circle (arc). The motion accuracy of the CNC machine tool is calculated through software analysis.

[0073] 4) Setting ball assembly 400

[0074] The characteristic of the setting ball device is that the setting ball 34 has the same size, specification and accuracy level as the two measuring balls on the ballbar main unit. The setting ball 34 is fixedly connected to the setting ball handle 35. The setting ball device is used to set the coordinate origin at the beginning of the measurement. The method of using the setting ball device is as follows: firstly, the setting ball is adsorbed on the movable support rod 22 of the center support, and the setting ball can swing freely or move up and down with the movable support rod; the CNC spindle with the center cup assembly clamped is controlled to move toward the center support assembly, and when the center cup support rod 33 moves to about 2 mm above the setting ball 34, the movable support rod 22 of the center support and the setting ball device will be adsorbed on the center cup support rod 33 under the action of magnetic force, and the center position of the setting ball is the coordinate origin of the measurement. By turning the handle 28 to the locking position (the handle is in a horizontal state), the position of the movable support rod 22 can be fixed, that is, the coordinate origin of the measurement can be fixed. Then the CNC spindle is moved upward for a certain distance, the setting ball device is taken out, and the measurement can be carried out downward.

[0075] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention. The inductive probe using this design can also be used for inductive probes for length measurement.

Claims

1. A ballbar mainframe, characterized in that: The invention comprises an inductive probe assembly, a circuit board assembly, a battery assembly, a ballbar body connected to the inductive probe assembly, and a second measuring ball; the inductive probe assembly comprises a first measuring ball, a measuring rod, a measuring head body, a guide sleeve, a reset spring, and a pin, wherein the first measuring ball is arranged at the first end of the measuring rod, the guide sleeve is sleeved on the measuring rod, the pin is inserted into the measuring rod and is located close to the second end of the measuring rod, the measuring rod, the measuring head body, the guide sleeve, and the pin form a precision motion pair, the pin moves in a waist-shaped hole on the measuring head body following the measuring rod, the pin is tightly matched with the waist-shaped hole, when the measuring rod is compressed, the reset spring is also compressed, when the measuring rod is released, the reset spring will push the measuring rod to move outward until the measuring rod reaches the extreme position of extending outward.

2. The main unit of the ballbar according to claim 1, characterized in that: It also includes a measuring ball connecting rod movably connected to the battery assembly, the measuring ball connecting rod is connected to the second measuring ball, one end of the battery assembly is connected to the circuit board of the circuit board assembly, and the other end of the battery assembly is connected to the ballbar instrument body.

3. The main unit of the ballbar according to claim 1, characterized in that: It also includes a magnetic core sleeve rod, a magnetic core and a coil. The magnetic core sleeve rod is fixedly connected to the second end of the measuring rod and moves with the measuring rod. The magnetic core is installed in the magnetic core sleeve rod.

4. The main unit of the ballbar according to claim 1, characterized in that: The Bluetooth transmitter on the circuit board of the circuit board assembly sends the displacement signal of the inductive probe assembly to the computer, and the circuit board cover of the circuit board assembly is made of non-metallic material.

5. The main unit of the ballbar according to claim 1, characterized in that: The circuit board of the circuit board assembly is fixed on the ballbar body, and the grounding terminal of the circuit board is electrically connected to the ballbar body.

6. The main unit of the ballbar according to claim 1, characterized in that: The battery assembly includes a battery positive electrode conductor, a battery, a battery end cover, a spring and a battery negative electrode spring. The battery positive electrode conductor is connected to the circuit board of the circuit board assembly through a wire, and the battery end cover is connected to the external thread at one end of the ballbar body through an internal thread. The battery negative electrode spring always maintains reliable contact and electrical conduction with the spring.

7. The main unit of the ballbar according to claim 6, characterized in that: Before the battery end cover is screwed onto the ballbar body, the spring sheets are not in contact with the battery end cover and the ballbar body, and the ballbar is in a power-off state. When the battery end cover is screwed onto the ballbar body, the end of the ballbar body presses against the spring sheet, and at the same time, the negative electrode spring sheet of the battery presses against the negative electrode of the battery and presses the battery against the positive electrode guide sheet of the battery. At this time, the battery is conductive and the ballbar is in a power-on state.

8. The main unit of the ballbar according to claim 6, characterized in that: It also includes a measuring ball connecting rod, which is threadedly connected to the battery end cover.

9. A ballbar, characterized in that: The ballbar comprises a main unit of the ballbar according to any one of claims 1 to 8, a center support assembly, a center cup assembly and a setting ball assembly; both ends of the main unit of the ballbar are respectively connected to the center support assembly and the center cup assembly; the setting ball assembly is used for setting the coordinate origin at the beginning of measurement.

10. The ballbar according to claim 9, characterized in that The center support assembly includes a measuring ball support block, a magnet, a movable support rod, an elastic claw, a conical limit sleeve, a cam rod, a spring, an adjusting end cover, a reset spring of the center support assembly, an upper pad, a base and a base magnet, wherein the measuring ball support block and the magnet are fixedly mounted on the upper end of the movable support rod, the lower end of the movable support rod is placed in the middle of the claw of the elastic claw, a through hole for mounting the cam rod is provided in the middle of the elastic claw, the elastic claw is fixedly connected to the base and is configured to be squeezed into the conical surface inside the conical limit sleeve when the cam rod is at the highest point of the cam stroke, the two ends of the cam rod are in contact with the upper pad, the spring and the adjusting end cover are sequentially mounted under the upper pad, and the adjusting end cover is connected to the conical limit sleeve.

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