CN116105572A

CN116105572A - Piston molded line detection device

Info

Publication number: CN116105572A
Application number: CN202310120907.0A
Authority: CN
Inventors: 解居麟; 崔积强; 胡林; 成善安; 张成新
Original assignee: Longkou Dachuan Piston Co ltd
Current assignee: Longkou Dachuan Piston Co ltd
Priority date: 2023-02-15
Filing date: 2023-02-15
Publication date: 2023-05-12

Abstract

The invention provides a piston molded line detection device, and mainly relates to the field of size detection. The utility model provides a piston molded lines detection device, includes the support body, support body top surface sets up benchmark revolving stage and inspection revolving stage, set up benchmark molded lines model on the benchmark revolving stage, set up three-dimensional molded lines groove on the benchmark molded lines model, set up the fine setting platform on the inspection revolving stage, the fine setting bench top sets up the anchor clamps subassembly, the support body top sets up the inspection frame, set up parallel expansion bracket on the inspection frame, slide on the vertical sliding frame and set up the sliding seat, the level sets up rigid connecting rod on the sliding seat, the connecting rod is close to benchmark revolving stage one end and sets up the tracking gauge head, the connecting rod other end sets up the molded lines gauge head. The invention has the beneficial effects that: according to the invention, the piston molded line data is converted into the comparison with the standard curve, and the piston skirt molded line data is intuitively displayed in a mode of detecting the error between the piston molded line data and the standard curve, so that the data of the piston molded line can be detected more normally.

Description

Piston molded line detection device

Technical Field

The invention mainly relates to the field of size detection, in particular to a piston molded line detection device.

Background

Pistons are the reciprocating parts in the cylinder block of an automobile engine. The basic structure of the piston can be divided into a top, a head and a skirt. Because the piston runs at high speed in the cylinder body and is accompanied by combustion of gasoline, diesel or natural gas, the temperature of the piston during operation is relatively high. The piston skirt guides the piston to reciprocate in the cylinder and receives side pressure, and when the engine is operated, the piston is bent and deformed by the pressure of gas in the cylinder. After the piston is heated, the expansion amount of the piston pin is larger than that of the piston pin at other positions because the piston pin is more metal. And simultaneously, the piston can generate extrusion deformation under the action of lateral pressure. The combination of the above deformations results in the piston skirt section becoming elliptical with the major axis perpendicular to the direction of the piston pin. Therefore, in order to balance deformation of the piston in operation, the existing piston processing generally processes the outer circle of the skirt part of the piston into an ellipse, so that the piston is closer to a circle after deformation, better contact sealing can be carried out with a cylinder body, abrasion of the piston is reduced, and energy conversion efficiency is improved.

Because the outer circle of the skirt part of the piston is a specially designed ellipse, the necessary detection of the molded line of the skirt part of the piston is needed to ensure the qualified size of the skirt part of the piston when the quality inspection of products is carried out. The existing detection equipment is used for directly detecting specific positions, such as patent number CN202122978035.0, and is a patent document of a piston molded line detection tool, namely, molded lines at different heights of a piston skirt are directly measured, the whole measurement process is complicated, continuous adjustment and trial-and-error are required, and the detection efficiency is low. Meanwhile, the data of all parts obtained by the measuring method cannot be well integrated, and the detected data is difficult to intuitively display.

Disclosure of Invention

In order to solve the defects in the prior art, the invention provides the piston molded line detection device which can convert the piston molded line data into the comparison with a standard curve, and intuitively display the piston skirt portion molded line data in a mode of detecting the error between the piston molded line data and the standard curve, so that the data of the piston molded line can be detected more normally, and the judgment difficulty of whether the molded line detection of the piston is qualified or not is reduced.

The invention aims to achieve the aim, and the aim is achieved by the following technical scheme:

the utility model provides a piston molded line detection device, includes the support body, the support body top sets up the well accuse machine, support body top surface sets up benchmark revolving stage and inspection revolving stage, the support body bottom sets up servo drive, servo drive is used for driving benchmark revolving stage and inspection revolving stage synchronous rotation, can dismantle on the benchmark revolving stage and set up benchmark molded line model, set up three-dimensional molded line groove on the benchmark molded line model, the coaxial fine setting platform on the inspection revolving stage, fine setting platform one side sets up and is used for driving fine setting platform pivoted fine setting servo motor, fine setting platform top sets up the anchor clamps subassembly, the anchor clamps subassembly is used for fixed piston work piece, support body top one side sets up the inspection frame perpendicularly, set up parallel expansion bracket on the inspection frame, parallel expansion bracket front end slip sets up vertical sliding frame, the last slip seat that slides of vertical sliding frame, the level sets up rigid connecting rod on the slip seat, the connecting rod is close to benchmark revolving stage one end and sets up the tracking gauge head, the tracking suits with the molded line groove, the gauge head other end of connecting rod sets up the molded line, the distance between gauge head and the gauge head equals between axis and the inspection revolving stage axis.

The fixture assembly comprises an electric chuck arranged on the top surface of the fine adjustment table and clamping frames arranged on two sides of the electric chuck, a pair of electromagnetic pin shafts are arranged on the top of each clamping frame, the two electromagnetic pin shafts are coaxially arranged, and the electromagnetic pin shafts are matched with the piston pin holes.

The front end of the electromagnetic pin shaft is conical.

The servo driving device is a servo motor and a gear transmission device, the gear transmission device is arranged between the reference turntable and the inspection turntable, and a motor shaft of the servo motor is connected with a rotating shaft of the reference turntable through a coupler.

The fine tuning servo motor is fixedly connected with one side of the inspection turntable, the conductive slip ring is arranged in the rotating shaft of the inspection turntable to supply power for the fine tuning servo motor, fine tuning teeth are arranged on the side wall of the fine tuning table, the fine tuning servo motor is meshed with the fine tuning teeth through a reduction gearbox to drive, and the fine tuning servo motor is used for driving the fine tuning table to rotate relative to the inspection turntable.

The parallel expansion bracket comprises a supporting frame fixedly connected with the inspection bracket, the front end of the supporting frame is provided with a pair of parallel telescopic linear guide rails, the telescopic linear guide rails are provided with vertical installation seats in a sliding mode, the vertical sliding bracket is installed on the vertical installation seats, the middle of the telescopic linear guide rails is provided with a limiting block, and a buffer spring is arranged between the vertical installation seats and the limiting block.

The vertical sliding frame is internally provided with a pair of vertical linear guide rails in parallel in a vertical state, the sliding seat is in sliding connection with the vertical linear guide rails, and an adjusting spring is arranged between the top of the vertical linear guide rails and the sliding seat.

The support frame rear side sets up the magnetism and inhales the seat, perpendicular mount pad end sets up the magnetic chuck, the magnetism is inhaled the seat and is suited with the magnetic chuck.

The connecting rod has the scale in molded lines gauge head one end, molded lines gauge head both sides set up with connecting rod threaded connection's fixation nut, through the adjustable molded lines gauge head's of fixation nut position.

The front end of the tracking measuring head is a ball head.

Compared with the prior art, the invention has the beneficial effects that:

according to the invention, a reference molded line model is set as a standard, and the molded line measuring head is driven to synchronously operate by running along a molded line groove on the reference molded line model through the tracking measuring head. Therefore, the molded line measuring head can move on the piston to be measured in the same track as the molded line groove, and molded line data on the spiral track of the piston are detected. Because the molded line of the molded line groove is a standard line, the data detected by the molded line measuring head is an error with the standard line, and the curve which is displayed on the central control computer and is needed to jump up and down on the reference line is displayed. By setting up and down errors of the datum line, whether the piston molded line is qualified or not can be intuitively judged.

The device converts the molded line data of the piston into error data of the standard line, and can intuitively display the processing error condition of the molded line of the piston through comparison with the standard data, so that whether the molded line of the piston is processed is judged to be qualified or not more simply, and the skirt molded line detection difficulty of the piston is reduced.

Drawings

FIG. 1 is a schematic view of a first perspective view structure of the present invention;

FIG. 2 is a schematic diagram of a second perspective view structure of the present invention;

FIG. 3 is a schematic top view of the present invention;

FIG. 4 is a schematic view of the present invention in partial cross-section from the front view;

FIG. 5 is a schematic view of a portion of the parallel telescoping rack of the present invention;

fig. 6 is a partially enlarged schematic view of the structure of the portion a of fig. 1 according to the present invention.

The reference numbers shown in the drawings: 1. a frame body; 2. a central control machine; 3. a reference turntable; 4. checking a rotary table; 5. a servo drive device; 6. a reference profile model; 7. a test rack; 8. a magnetic suction seat; 41. a fine tuning stage; 42. fine tuning a servo motor; 43. a clamp assembly; 44. an electric chuck; 45. a clamping frame; 46. an electromagnetic pin shaft; 47. fine tuning the teeth; 61. a forming wire groove; 71. a parallel expansion bracket; 72. a vertical carriage; 73. a sliding seat; 74. a connecting rod; 75. a tracking probe; 76. a molded line measuring head; 81. a magnetic chuck; 711. a support frame; 712. a telescopic linear guide rail; 713. a limiting block; 714. a vertical mounting base; 715. a buffer spring; 721. a vertical linear guide rail; 722. and (5) adjusting the spring.

Detailed Description

The invention will be further described with reference to the accompanying drawings and specific embodiments. It is to be understood that these examples are illustrative of the present invention and are not intended to limit the scope of the present invention. Further, it will be understood that various changes or modifications may be made by those skilled in the art after reading the teachings of the invention, and such equivalents are intended to fall within the scope of the invention as defined herein.

Examples:

as shown in fig. 1-6, the piston molded line detection device of the invention comprises a frame body 1, wherein the frame body 1 is welded with a bracket through a pipe, and an external welding plate is used as a cover. The bottom of the frame body 1 is provided with adjustable support legs for leveling. The top surface of the frame body 1 is provided with a horizontal plate surface which is used for installing and positioning a reference turntable 3 and a test turntable 4.

The central control machine 2 is arranged at the top of the frame body 1, and the central control machine 2 is used as a control center of each action part of the device and is also used as an input and output and processing unit of monitoring data.

The top surface of the frame body 1 is provided with a reference turntable 3 and an inspection turntable 4, the reference turntable 3 and the inspection turntable 4 are rotatably installed on the horizontal plate surface at the top of the frame body 1 through plane bearings, in this embodiment, the top surface of the horizontal plate surface is provided with two installation counter bores, and the reference turntable 3 and the inspection turntable 4 are respectively installed in the two counter bores. The driving rotating shaft is coaxially arranged at the bottom of the reference rotating table 3, the driven rotating shaft is coaxially arranged at the bottom of the inspection rotating table 4, and the driving rotating shaft, the driven rotating shaft and the frame body 1 are all arranged through bearings. A servo driving device 5 is arranged at the bottom of the frame body 1, and the servo driving device 5 is used for driving the reference turntable 3 and the inspection turntable 4 to synchronously rotate. Specifically, the servo driving device 5 comprises a servo motor and a gear transmission device, wherein the gear transmission device is arranged between the reference turntable 3 and the inspection turntable 4, and the gear transmission device is in three-stage transmission. And a motor shaft of the servo motor is connected with the driving rotating shaft through a coupler. The reference turntable 3 and the inspection turntable 4 can be rotated synchronously by driving the servo motor.

And the reference molded line model 6 is detachably arranged on the reference turntable 3, the reference molded line model 6 is manufactured for simulating the outer circle profile of the piston skirt, and the outer circle profile is the standard outer circle profile of the piston skirt. The reference molded line model 6 is provided with a three-dimensional molded line groove 61, and the bottom surface contour of the molded line groove 61 is the outer circle contour of the reference molded line model 6. The profile groove 61 rises in a spiral shape, and the profile groove 61 covers the deformation area of the reference profile model 6.

The fine adjustment table 41 is coaxially installed on the inspection turntable 4, the fine adjustment table 41 can rotate relative to the inspection turntable 4, and through adjustment of the fine adjustment table 41, the initial position of the detection cut of the piston to be detected can be adjusted, so that the initial position of the molded line measuring head 76 on the piston to be detected is consistent with the initial position of the tracking measuring head 75 on the molded line groove 61, the molded line detection track of the piston to be detected is consistent with the molded line groove 61 track, and accurate molded line data of the piston are obtained. When the piston molded line is detected, the servo driving device 5 drives the reference turntable 3 and the inspection turntable 4 to synchronously rotate, the tracking probe 75 moves along the molded line groove 61 on the outer wall of the reference molded line model 6 and passes through a spiral track, the molded line probe 76 passes through the same track on the outer wall of the piston along with the track of the tracking probe 75, the molded line probe 76 transmits detected data into the central control computer 2, and the data obtained by the central control computer 2 are errors of the piston and the standard molded line. The error curve can be drawn by the central control computer, and the error curve is a curve which floats up and down on a reference straight line. The maximum error lines above and below the basic alignment line can clearly and intuitively reflect whether the molded line of the piston exceeds a standard area, so that whether the outer contour of the piston is qualified in processing is intuitively judged.

A fine tuning servo motor 42 for driving the fine tuning table 41 to rotate is installed on one side of the fine tuning table 41. Specifically, the fine tuning servo motor 42 is fixedly installed on one side of the inspection turntable 4, and the conductive slip ring is installed in the rotating shaft of the inspection turntable 4 to supply power for the fine tuning servo motor 42. The side wall of the fine adjustment table 41 is provided with fine adjustment teeth 47, the fine adjustment servo motor 42 is meshed with the fine adjustment teeth 47 through a reduction gearbox, and the fine adjustment servo motor 42 is used for driving the fine adjustment table 41 to rotate relative to the inspection turntable 4. The fine adjustment table 41 can be precisely adjusted by the fine adjustment servo motor 42, so that the cutting angle of the piston to be measured during detection can be precisely adjusted.

The fine adjustment table 41 is provided with a clamp assembly 43 at the top, and the clamp assembly 43 is used for fixing a piston workpiece. The clamp assembly 43 includes an electric chuck 44 for holding the piston and a positioning and clamping mechanism on both sides. The top surface of the fine tuning table 41 is coaxial with an electric chuck 44, and the electric chuck 44 is used for fixing a piston. The center of the electric chuck 44 is provided with a supporting table, and the supporting table positions the end face of the head of the piston, so that the initial height of the detection of the molded line of the piston is consistent with the starting height of the molded line groove 61. The clamping frames 45 are arranged on the horizontal plate surfaces on two sides of the inspection turntable 4, a pair of electromagnetic pin shafts 46 are arranged at the top of the clamping frames 45, the two electromagnetic pin shafts 46 are coaxially arranged, and the electromagnetic pin shafts 46 are matched with piston pin holes. When the piston needs to be fixed, the piston is firstly placed at the center of the electric chuck 44, then the two electromagnetic pin shafts 46 are controlled to extend through the central control computer 2, and the two electromagnetic pin shafts 46 are respectively inserted into the two pin holes of the piston. The electromagnetic pin 46 limits the piston, then the central control machine 2 controls the electric chuck 44 to clamp the piston, and then the electromagnetic pin 46 contracts to loosen the fixing of the piston. At this time, the positioning of the initial detection position of the piston is completed.

More specifically, the front end of the electromagnetic pin shaft 46 is tapered, and the rear end of the electromagnetic pin shaft 46 is consistent with the size of the pin hole of the piston. Through the arrangement of the conical electromagnetic pin shafts 46, the insertion of the electromagnetic pin shafts 46 into the pin holes can be guided, and the electromagnetic pin shafts 46 can be accurately inserted into the pin holes. The fixture assembly firstly limits the piston through the electromagnetic pin shaft 46 and determines the clamping angle of the piston, so that the cutting-in position of the molded line measuring head 76 for molded line detection of the piston is ensured, and then the fixing of the piston is completed through clamping and positioning of the electric chuck 44, so that the piston can be well positioned, the piston is ensured not to move during molded line detection, and the accuracy of molded line detection of the piston is ensured.

The inspection rack 7 is vertically installed on one side of the top of the rack body 1, and the inspection rack 7 is an installation rack of the detection device. In this embodiment, the inspection rack 7 and some column structures mounted thereon are all mounted by using a material with good rigidity, so as to reduce deformation in the inspection process and influence the inspection result.

The inspection rack 7 is provided with a parallel telescopic rack 71 in the vertical direction, and the parallel telescopic rack 71 is perpendicular to the inspection rack 7. Specifically, the parallel telescopic frame 71 includes a support frame 711 detachably and fixedly connected to the test frame 7, and the middle part of the support frame 711 is fixed to the test frame 7 by bolts. The front end of the supporting frame 711 is provided with a pair of telescopic linear guide rails 712 which are installed in parallel, a vertical installation seat 714 is installed on the telescopic linear guide rails 712 in a sliding manner, and the vertical sliding frame 72 is fixedly installed on the vertical installation seat 714 through bolts. The middle part of the telescopic linear guide 712 is provided with a limiting block 713, and a buffer spring 715 is arranged between the vertical mounting seat 714 and the limiting block 713. The buffer spring 715 is compressed so as to push the tracking probe 75 into close contact with the profile groove 61.

More specifically, the sliding component of the vertical mounting seat 714 and the telescopic linear guide 712 is a sleeve, and the sleeve and the telescopic linear guide 712 form a telescopic rod, so that the telescopic linear guide 712 does not exceed the vertical mounting seat 714 and is exposed outside the vertical mounting seat 714, and thus does not interfere with the vertical sliding frame 72 mounted on the vertical mounting seat 714.

The magnetic attraction seat 8 is arranged on the rear side of the supporting frame 711, and the on-off of the magnetic attraction seat 8 is controlled by the central control computer 2. The end of the vertical mounting seat 714 is provided with a magnetic chuck 81, the magnetic chuck 8 is matched with the magnetic chuck 81, and after the magnetic chuck 8 is electrified, the magnetic chuck 81 can be adsorbed by the magnetic chuck 8, so that the vertical mounting seat 714 slides towards the direction of the magnetic chuck 8, and the separation of the tracking probe 75 and the molded line groove 61 is realized.

A pair of vertical linear guides 721 are disposed in parallel in a vertical state in the vertical sliding frame 72, and the sliding seat 73 is slidably connected to the vertical linear guides 721. When the tracking probe 75 runs along the linear groove 61, the sliding seat 73 moves linearly along the track of the sliding seat under the limit of the vertical linear guide 721.

Further, an adjusting spring 722 is installed between the top of the vertical linear guide 721 and the sliding seat 73. The setting of the adjusting spring 722 enables the sliding seat 73 to be supported on the vertical linear guide 721 to a certain extent, so that friction between the tracking probe 75 and the side wall of the molded line groove 61 can be reduced when the sliding seat 73 performs linear reciprocating rectilinear motion, and the tracking probe 75 runs smoothly along the molded line groove 61, so that the detection result of the molded line probe 76 on the piston is more accurate. More specifically, the middle part of the vertical linear guide 721 is provided with a locating plate. When the tracking probe 75 is released from contact with the molded line groove 61, the adjusting spring 722 will press the sliding seat 721 to move the sliding seat 721 to the limit position of the positioning plate, and the molded line probe 76 is at the initial position of the piston molded line detection.

The rigid connecting rod 74 is horizontally installed on the sliding seat 73, the connecting rod 74 is made of alloy materials with higher rigidity, and when external force is applied to the connecting rod 74, the deformation of the connecting rod 74 is smaller, so that the data detection error of a piston molded line is smaller.

The tracking probe 75 is installed at one end of the connecting rod 74, which is close to the reference turntable 3, and the front end of the tracking probe 75 is a ball head. The friction force between the tracking probe 75 and the molded line groove 61 is smaller due to the arrangement of the ball head, so that the vibration of the tracking probe 75 can be reduced, and the error of the molded line probe 76 on the molded line detection of the piston is reduced. The other end of the connecting rod 74 is provided with a molded line measuring head 76, and the distance between the molded line measuring head 76 and the tracking measuring head 75 is equal to the distance between the axis of the reference turntable 3 and the axis of the inspection turntable 4. More specifically, the connecting rod 74 has a scale at one end of the molded line measuring head 76, and fixing nuts screwed on two sides of the molded line measuring head 76 are screwed on the connecting rod 74, and the positions of the molded line measuring head 76 can be adjusted by the fixing nuts, so that the distance between the molded line measuring head 76 and the tracking measuring head 75 is equal to the distance between the axis of the reference turntable 3 and the axis of the inspection turntable 4.

In this embodiment, the servo driving device 5, the fine adjustment servo motor 42, the electric chuck 44, the electromagnetic pin 46, the molded line measuring head 76 and the magnetic attraction seat 8 are all electrically connected with the central control unit 2.

More specifically, taking the structure in the embodiment as an example, the control process of the device according to the time sequence is as follows: when the piston is placed in the center of the electric chuck 44, the central control computer 2 controls the electromagnetic pin shaft 46 to extend, the electromagnetic pin shaft 46 is inserted into a pin hole of the piston to complete positioning of the piston, then the central control computer 2 controls the electric chuck 44 to clamp the head of the piston, and meanwhile the electromagnetic pin shaft 46 is retracted to loosen clamping of the piston. Then, the central control computer 2 controls the magnetic suction seat 8 to loosen the adsorption to the magnetic suction disc 81, so that the vertical installation seat 714 moves towards the reference molded line model 6 under the pushing of the elastic force of the buffer spring 715, the tracking probe 75 is abutted against the initial position of the molded line groove 61 of the reference molded line model 6, and the molded line probe 76 is correspondingly abutted against the outer wall of the piston. The central control machine 2 then controls the servo driving device 5 to drive the reference turntable 3 and the inspection turntable 4 to synchronously rotate, the reference molded line model 6 on the reference turntable 3 rotates along with the reference turntable, the spiral molded line groove 61 drives the tracking probe 75 to pass through a spiral track on the reference molded line model 6, and correspondingly, the molded line probe 76 passes through the spiral track on the piston skirt. At this time, the slide block 73 slides upward along the vertical linear guide 721 as the shaped wire groove 61 guides the tracking probe 75. At the same time, the vertical mounting base 714 also slides along the telescopic linear rail 712 along with the movement of the tracking probe 75 in the irregular circular surface in the linear groove 61. After the molded line measuring head 76 finishes the molded line detection of the piston, the central control computer 2 controls the servo driving device 5 to drive reversely, so that the tracking measuring head 75 is reset on the reference molded line model 6, then the central control computer 2 controls the magnetic suction seat 8 to be electrified to adsorb the magnetic suction disc 81, the collision of the tracking measuring head 75 on the reference molded line model 6 is loosened, and then the electric chuck 44 releases the clamping of the piston to take down the piston.

When the piston profile is detected, the profile measuring head 76 passes through the pin hole position on the piston, and at the moment, the profile measuring head 76 is separated from the outer side surface of the skirt of the piston and is not contacted with the piston, the part of data is not the data to be detected, and the central control machine 2 ignores the part of data.

Specifically, after the reference profile model 6 is installed, a certain error difference exists in the installation of the reference profile model 6, and a certain virtual position error exists in the driving of the servo driving device 5, so that a certain offset exists between the starting point of the profile of the tracking probe 75 on the reference profile model 6 and the initial position of the piston profile detection. When the detected data error is found to be large during the line detection, the fine adjustment table 41 can be driven to rotate clockwise and anticlockwise by the fine adjustment servo motor 42 for a plurality of angles, the line detection is performed once after each rotation, the fine adjustment table 41 is adjusted by taking the angle closest to the standard data as the reference angle after the plurality of times of detection, and at this time, the contact position of the line measuring head 76 on the piston is closest to the starting point position of the tracking measuring head 75 on the reference line model 6.

Claims

1. The utility model provides a piston molded line detection device, includes support body (1), accuse machine (2), its characterized in that in support body (1) top setting: the utility model is characterized in that a reference turntable (3) and a test turntable (4) are arranged on the top surface of the frame body (1), a servo driving device (5) is arranged at the bottom of the frame body (1), the servo driving device (5) is used for driving the reference turntable (3) to synchronously rotate with the test turntable (4), a reference molded line model (6) is detachably arranged on the reference turntable (3), a three-dimensional molded line groove (61) is arranged on the reference molded line model (6), a fine tuning table (41) is coaxially arranged on the test turntable (4), a fine tuning servo motor (42) for driving the fine tuning table (41) to rotate is arranged on one side of the fine tuning table (41), a clamp assembly (43) is arranged at the top of the fine tuning table (41), a piston workpiece is fixed by the clamp assembly (43), a test frame (7) is vertically arranged on one side of the top of the frame body (1), a parallel telescopic frame (71) is arranged on the test frame (7), a vertical sliding frame (72) is arranged at the front end of the parallel telescopic frame (71), a sliding seat (73) is arranged on the vertical sliding frame (72), a sliding seat (73) is arranged on the sliding seat (73), a connecting rod (74) and is close to one end of the measuring head (75) of the connecting rod) which is arranged on the measuring head (75), the other end of the connecting rod (74) is provided with a molded line measuring head (76), and the distance between the molded line measuring head (76) and the tracking measuring head (75) is equal to the distance between the axis of the reference turntable (3) and the axis of the inspection turntable (4).

2. A piston-type line inspection apparatus as claimed in claim 1, wherein: the fixture assembly (43) comprises an electric chuck (44) arranged on the top surface of the fine adjustment table (41) and clamping frames (45) arranged on two sides, a pair of electromagnetic pin shafts (46) are arranged on the top of each clamping frame (45), the two electromagnetic pin shafts (46) are coaxially arranged, and the electromagnetic pin shafts (46) are matched with piston pin holes.

3. A piston-type line inspection apparatus as claimed in claim 2, wherein: the front end of the electromagnetic pin shaft (46) is conical.

4. A piston-type line inspection apparatus as claimed in claim 1, wherein: the servo driving device (5) is a servo motor and a gear transmission device, the gear transmission device is arranged between the reference turntable (3) and the inspection turntable (4), and a motor shaft of the servo motor is connected with a rotating shaft of the reference turntable (3) through a coupler.

5. A piston-type line inspection apparatus as claimed in claim 1, wherein: the fine adjustment servo motor (42) is fixedly connected with one side of the inspection turntable (4), the conductive slip ring is arranged in the rotating shaft of the inspection turntable (4) to supply power for the fine adjustment servo motor (42), fine adjustment teeth (47) are arranged on the side wall of the fine adjustment table (41), the fine adjustment servo motor (42) is meshed with the fine adjustment teeth (47) through a reduction gearbox to drive, and the fine adjustment servo motor (42) is used for driving the fine adjustment table (41) to rotate relative to the inspection turntable (4).

6. A piston-type line inspection apparatus as claimed in claim 1, wherein: the parallel telescopic rack (71) comprises a supporting frame (711) fixedly connected with the inspection rack (7), a pair of telescopic linear guide rails (712) which are arranged in parallel are arranged at the front end of the supporting frame (711), vertical installation bases (714) are arranged on the telescopic linear guide rails (712) in a sliding mode, the vertical sliding rack (72) is installed on the vertical installation bases (714), limiting blocks (713) are arranged in the middle of the telescopic linear guide rails (712), and buffer springs (715) are arranged between the vertical installation bases (714) and the limiting blocks (713).

7. The piston-type line inspection apparatus of claim 6, wherein: a pair of vertical linear guide rails (721) are arranged in parallel in a vertical state in the vertical sliding frame (72), the sliding seat (73) is connected with the vertical linear guide rails (721) in a sliding mode, and an adjusting spring (722) is arranged between the top of the vertical linear guide rails (721) and the sliding seat (73).

8. The piston-type line inspection apparatus of claim 6, wherein: the magnetic suction seat (8) is arranged on the rear side of the supporting frame (711), the magnetic suction disc (81) is arranged at the tail end of the vertical installation seat (714), and the magnetic suction seat (8) is adaptive to the magnetic suction disc (81).

9. A piston-type line inspection apparatus as claimed in claim 1, wherein: the connecting rod (74) is provided with scales at one end of the molded line measuring head (76), fixing nuts in threaded connection with the connecting rod (74) are arranged at two sides of the molded line measuring head (76), and the positions of the molded line measuring head (76) can be adjusted through the fixing nuts.

10. A piston-type line inspection apparatus according to any one of claims 1-8, wherein: the front end of the tracking measuring head (75) is a ball head.