Workpiece size on-line measurement method and device

Abstract

The invention discloses a workpiece size on-line measurement method and device, and belongs to the technical field of measurement devices characterized by the mechanical technology, the device comprises a feeding mechanism and an offset detection mechanism, and the feeding mechanism is used for conveying a crankshaft to a detection position of the offset detection mechanism; a second limiting piece is controlled to descend through a first linear driver, in the descending process, a detection rod of a first displacement sensor is pressed on a long shaft, the second limiting piece is pressed on lugs on the two sides of a crankshaft, positioning of the crankshaft is achieved, and deflection of the crankshaft is avoided; and continuously descending until the first limiting piece presses the short shaft, recording a detection value of the first displacement sensor, comparing the detection value with a standard value of the checking piece, and calculating the surface offset and the eccentricity of the crankshaft.

Description

Technical Field

[0001] The present invention relates to the technical field of measuring devices characterized by mechanical technology, and particularly relates to an on-line measuring method and device for workpiece dimensions. Background Art

[0002] The crankshaft is an important component and can be used in components such as engines. It mainly includes a short shaft and a long shaft, and there is an eccentricity / offset between the short shaft and the long shaft. The traditional method for detecting the eccentricity between the long shaft and the short shaft of the crankshaft is only to simply detect with a caliper or only conduct spot checks, which is very inconvenient, with low detection efficiency; and the detection process requires a large amount of manpower, has low detection accuracy, cannot achieve comprehensive detection, the quality is not completely controllable, and on-line detection cannot be achieved.

[0003] Therefore, it is necessary to design an on-line measuring method for workpiece dimensions that can achieve unmanned and automated detection. Summary of the Invention

[0004] In view of the above technical problems existing in the prior art, the present invention provides an on-line measuring method and device for workpiece dimensions. Through a plurality of positioning mechanisms, the crankshaft is positioned. After positioning, the displacement of the detection piece is detected by a displacement sensor, and the eccentricity is detected based on the displacement.

[0005] The present invention discloses an on-line measuring device for workpiece dimensions, including a loading mechanism and an offset detection mechanism. The loading mechanism includes a loading rack, and a V-shaped groove matching with the crankshaft is arranged on the loading rack. The offset detection mechanism includes a detection rack arranged on the upper side of the loading rack, and a first linear driver is arranged on the detection rack. A first sliding rack is arranged at the output end of the first linear driver, and a first limiting member and a first displacement sensor are arranged on the lower side of the first sliding rack. The detection rod of the first displacement sensor is matched with the long shaft of the crankshaft. The first limiting member is matched with the short shaft of the crankshaft.

[0006] Preferably, a second limiting member is further arranged on the lower side of the first sliding rack, and two spaced second limiting members are matched with the lugs on both sides of the crank arm of the crankshaft. One end of the detection rod of the first displacement sensor is provided with a detection head, and a first spring is arranged on the outer side of the detection rod. In the free state, the distance between the detection head and the long shaft of the detection position crankshaft is less than the distance between the second limiting member and the lug, and less than the distance between the first limiting member and the short shaft. A calibration piece is further included, and the outer diameter of the calibration piece is the same as the diameter of the short shaft.

[0007] Preferably, it further includes a crankshaft lifting mechanism. The crankshaft lifting mechanism includes a first lifting cylinder installed on one side of the loading rack. A positioning block is provided at the output end of the first lifting cylinder, and a positioning groove matching with the short shaft of the crankshaft is provided at the upper end of the positioning block.

[0008] Preferably, it further includes an eccentric hole detection mechanism. The eccentric hole detection mechanism includes a bracket provided on one side of the loading rack. A second linear driver is provided on the bracket. A second carriage is provided at the output end of the second linear driver. A detection slider is slidably installed on the second carriage. A detection needle matching with the eccentric hole at one end of the short shaft is provided at the inner end of the detection slider, and a detection piece is provided at the outer end. A proximity switch matching with the detection piece is provided on the second carriage. A second spring is provided between the detection slider and the second carriage.

[0009] Preferably, it further includes a diameter detection mechanism. The diameter detection mechanism includes a pair of clamping jaws and a second displacement sensor. The clamping jaws match with the short shaft or the long shaft of the crankshaft. The second displacement sensor is provided on one clamping jaw, and the detection end of the second displacement sensor extends towards the limiting block on the side of the other clamping jaw.

[0010] Preferably, the loading mechanism further includes a second lifting cylinder, a third linear driver, and a lifting rack movably installed inside the loading rack. The second lifting cylinder is installed on the lower side of the loading rack, and a slider is provided at the output end of the second lifting cylinder. A slide rail is provided on the lower side of the lifting rack, and the slider matches with the slide rail. The third linear driver is installed on the lower side of the lifting rack, and the output end of the third linear driver is connected to the slider.

[0011] Preferably, a lifting block is provided at the output end of the second lifting cylinder, and the slider is fixed on the lifting block. The output end of the third linear driver is connected to the lifting block. A third displacement sensor is provided on the second lifting cylinder, and the outer end of the detection rod of the third displacement sensor is installed on the lifting block or the slider.

[0012] Preferably, a loading positioning mechanism is provided upstream of the loading mechanism. The loading positioning mechanism includes a fourth cylinder and a fifth cylinder respectively provided on both sides of the loading rack. A push block is provided at the output end of the fourth cylinder, and the push block extends towards the V-shaped groove of the loading rack; A U-shaped positioning block is provided at the output end of the fifth cylinder, and the convex platforms on both sides of the U-shaped positioning block are matched with the lugs of the crankshaft arm.

[0013] The present invention also discloses a measurement method using the above measurement device, including the following steps: Transport the crankshaft to the detection position through the loading mechanism; Control the second limiting member and the first displacement sensor to descend through the first linear driver; During the descending process, the detection rod of the first displacement sensor presses on the long shaft; Continue to descend until the first limiting member presses on the short shaft, and record the detection value of the first displacement sensor; Obtain the standard value of the first displacement sensor detecting the calibration part, wherein the diameter of the calibration part is the same as that of the short shaft; Obtain the surface offset and eccentricity through the difference between the detection value and the standard value.

[0014] Preferably, the calculation method of the eccentricity is: (1); (2); Wherein, L1 represents the detection value of the crankshaft, L0 represents the standard value of the calibration part, represents the surface offset, b represents the diameter of the long shaft, and a represents the diameter of the short shaft.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The loading mechanism is used to transport the crankshaft to the detection position of the offset detection mechanism; the second limiting member is controlled to descend through the first linear driver. During the descending process, the detection rod of the first displacement sensor presses on the long shaft, and the second limiting member presses on the lugs on both sides of the crankshaft to realize the positioning of the crankshaft and avoid the deflection of the crankshaft; continue to descend until the first limiting member presses on the short shaft, record the detection value of the first displacement sensor, compare the detection value with the standard value of the calibration part, and calculate the surface offset and eccentricity of the crankshaft. Description of the Drawings

[0016] Figure 1 is a schematic structural diagram of the on-line workpiece size measurement device of the present invention; Figure 2 is a schematic structural diagram of the crankshaft; Figure 3 is a schematic diagram of the positioning of the crankshaft; Figure 4 is a schematic diagram of the installation of the detection head of the eccentricity detection mechanism; Figure 5It is a schematic structural diagram of the feeding mechanism; Figure 6 It is a schematic structural diagram of the feeding positioning mechanism; Figure 7 It is a marking diagram of the surface offset, major axis diameter, and minor axis diameter.

[0017] Markings in the figure: 1 frame, 2 feeding mechanism, 21 feeding rack, 22 V-shaped groove, 25 lifting rack, 26 slide rail, 27 third linear actuator, 31 second lifting cylinder, 32 third displacement sensor, 33 lifting block, 35 slider, 4 crankshaft, 41 short axis, 42 crankshaft arm, 43 lug, 44 long axis, 45 eccentric hole, 5 offset detection mechanism, 51 detection rack, 52 first linear actuator, 521 first carriage, 53 first limit member, 55 second limit member, 56 first displacement sensor, 57 first spring, 58 detection head, 6 crankshaft lifting mechanism, 61 first lifting cylinder, 62 positioning groove, 63 positioning block, 7 diameter detection mechanism, 71 jaw, 73 second displacement sensor, 74 limit block, 8 eccentric hole detection mechanism, 81 bracket, 82 second linear actuator, 83 second carriage, 85 detection needle, 86 proximity switch, 87 detection slider, 88 detection member, 89 second spring; 9 feeding positioning mechanism, 91 fourth cylinder, 92 pushing block, 95 fifth cylinder, 96 U-shaped positioning block. Detailed implementation mode

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0019] Overview: As Figure 2 , the crankshaft 4 includes a long axis 44 and a short axis 41 connected to both sides of the crankshaft arm 42. When the lug 43 is horizontal, there is an eccentricity between the long axis 44 and the short axis 41 in the longitudinal direction, and there is an offset on the outer surfaces of the long axis 44 and the short axis 41. One end of the short axis 41 is provided with a hole, and one end of the long axis 44 is provided with an eccentric hole 45.

[0020] The following further describes the present invention in detail with reference to the accompanying drawings: The first aspect of the present invention provides an on-line workpiece size measuring device, asFigures 1 - 6 It includes a feeding mechanism 2 and an offset detection mechanism 5 arranged on a frame 1. The feeding mechanism 2 includes a feeding rack 21, and a V-shaped groove 22 matching with a crankshaft 4 is arranged on the feeding rack 21; the offset detection mechanism 5 includes a detection rack 51 arranged on the upper side of the feeding rack, a first linear driver 52 is arranged on the detection rack 51, a first sliding carriage 521 is arranged at the output end of the first linear driver 52, and a second limiting member 55 and a first displacement sensor 56 are arranged on the lower side of the first sliding carriage 521; two spaced second limiting members 55 cooperate with lugs 43 on both sides of a crank arm 42 of the crankshaft 4 to position the crankshaft and prevent the crankshaft from deflecting. The detection rod of the first displacement sensor 56 cooperates with a long shaft 44 of the crankshaft 4; a first limiting member 53 matching with a short shaft 41 of the crankshaft 4 is further arranged on the lower side of the first sliding carriage 521 for positioning the short shaft 41.

[0021] The feeding mechanism is used to convey the crankshaft 4 to the detection position of the offset detection mechanism; the second limiting member 55 is controlled to descend by the first linear driver 52. During the descending process, the detection rod of the first displacement sensor 56 presses on the long shaft 44, and the second limiting member presses on the lugs on both sides of the crankshaft to position the crankshaft and prevent the crankshaft from deflecting; continue to descend, as Figure 3 shown, the first limiting member 53 presses on the short shaft 41, the detection value of the first displacement sensor 56 is recorded, the detection value is compared with the standard value of a calibration piece, and the surface offset and eccentricity of the crankshaft are calculated.

[0022] Wherein, a detection head 58 is arranged at one end of the detection rod of the first displacement sensor 56, and a first spring 57 is arranged on the outer side of the detection rod. A third spring is arranged between the second limiting member 55 and the first sliding carriage 521 for positioning the crankshaft and preventing deflection.

[0023] As Figure 4 shown, in the free state / lifting state, the distance between the detection head 58 and the long shaft 44 of the crankshaft 4 at the detection position is less than the distance between the second limiting member 55 and the lug 43, and is less than the distance between the first limiting member 53 and the short shaft 41.

[0024] Figure 1 and Figure 4 A crankshaft lifting mechanism 6 and an eccentric hole detection mechanism 8 are also shown. The crankshaft lifting mechanism 6 includes a first lifting cylinder 61 installed on one side of the feeding rack 21. A positioning block 63 is arranged at the output end of the first lifting cylinder 61, and a positioning groove 62 matching with the short shaft 41 of the crankshaft 4 is arranged at the upper end of the positioning block 63. The positioning groove 62 cooperates with the short shaft 41 to adjust the height on the short shaft side and cooperate with the V-shaped groove on the long shaft side to ensure that the crankshaft is in a horizontal position and avoid detection errors caused by the V-shaped groove 22. Figure 3 The crankshaft lifting mechanism 6 is removed.

[0025] The eccentric hole detection mechanism 8 includes a bracket 81 arranged on one side of the loading rack 21, a second linear driver 82 is arranged on the bracket 81, a second slide 83 is arranged at the output end of the second linear driver 82, and a detection slider 87 is slidably mounted on the second slide 83; the inner end of the detection slider 87 is provided with a detection needle 85 that matches the eccentric hole 45 at one end of the short shaft 41, and the outer end is provided with a detection member 88; the second slide 83 is provided with a proximity switch 86 that matches the detection member 88; a second spring 89 is arranged between the detection slider 87 and the second slide 83, until the buffering and resetting functions. The detection needle 85 is extended into the eccentric hole by the second linear driver 82, and when it reaches a certain depth, the detection member 88 approaches the proximity switch 86, and generates detection information, and it is considered that the detection result of the eccentric hole is qualified. In the case that the eccentric hole 45 has a deviation, the detection needle 85 cannot enter the eccentric hole, and the electrical signal of the proximity switch 86 cannot be detected, and the product is judged to be unqualified at this time.

[0026] Figure 1 , Figure 2 and Figure 3 The diameter detection mechanism 7 is shown, and the diameter detection mechanism 7 includes a pair of jaws 71 and a second displacement sensor 73; the jaws 71 are matched with the short axis 41 or the long axis 44 of the crankshaft 4; the second displacement sensor 73 is arranged on one jaw 71, and the detection end of the second displacement sensor 73 extends to the limit block 74 on one side of the other jaw 71. By comparing the detection value of the second displacement sensor with the standard value, it can be detected whether the diameter is qualified. Figure 2 The diameter detection mechanism 7 is arranged on the short axis side, but can also be arranged on the long axis side. The structures and functions of the two installation methods are the same or similar, and the present invention will not repeat them.

[0027] Figure 5 The second lifting cylinder 31, the third linear drive 27 and the lifting frame 25 movably installed on the inner side of the loading frame 21 of the feeding mechanism 2 are shown. The second lifting cylinder 31 is installed on the lower side of the loading frame 21, and a slider 35 is provided at the output end of the second lifting cylinder 31; a slide rail 26 is provided on the lower side of the lifting frame 25, and the slider 35 cooperates with the slide rail; the third linear drive 27 is installed on the lower side of the lifting frame 25, and the output end of the third linear drive 27 is connected to the slider 35.

[0028] Lift the lifting frame 25 and the crankshaft by the second lifting cylinder 31 to disengage the crankshaft 4 from the V-shaped groove of the loading rack 21; after pushing the lifting frame 25 to the next station by the third linear actuator 27, control the lifting frame 25 to descend by the second lifting cylinder, and the crankshaft 4 enters the V-shaped groove 22 of the corresponding station, realizing the movement and sequential detection of the crankshaft. After descending, the lifting frame 25 is restored to its original position by the third linear actuator 27. By repeating the above steps, the automatic loading and detection of the crankshaft 4 are realized.

[0029] More specifically, a lifting block 33 is provided at the output end of the second lifting cylinder 31, and the slider 35 is fixed on the lifting block 33; the output end of the third linear actuator 27 is connected to the lifting block 33; a third displacement sensor 32 is provided on the second lifting cylinder 31, and the outer end of the detection rod of the third displacement sensor 32 is installed on the lifting block 33 or the slider 35 to achieve stable translation and monitor the lifting height.

[0030] As Figure 6 Fig. shows a loading positioning mechanism 9 provided upstream of the loading mechanism 2. The loading positioning mechanism 9 includes a fourth cylinder 91 and a fifth cylinder 95 respectively arranged on both sides of the loading rack 21. A pushing block 92 is provided at the output end of the fourth cylinder 91, and the pushing block 92 extends towards the V-shaped groove 22 of the loading rack for pushing the crankshaft arm towards one side of the loading rack; a U-shaped positioning block 96 is provided at the output end of the fifth cylinder 95, and the convex platforms on both sides of the U-shaped positioning block 96 cooperate with the lugs 43 of the crankshaft arm 42 to adjust the position of the lugs and the flipping position of the crankshaft.

[0031] The second aspect of the present invention provides a detection method through an on-line workpiece size measuring device, including the following steps: Step S1: Transport the crankshaft to the detection position by the loading mechanism 2.

[0032] Step S2: Control the second limiting member 55 and the first displacement sensor 56 to descend by the first linear actuator 52.

[0033] During the descending process, the detection rod of the first displacement sensor 56 presses on the long shaft 44.

[0034] During the descending process, the first limiting member 53 presses on the corresponding lug 43 for coaxial positioning, and the third spring on the first limiting member 53 provides buffering and floating. After the detection rod presses on the long shaft 44, a relative displacement is generated between the detection rod and the first displacement sensor 56, and the first displacement sensor generates an electrical signal and a detection value according to the displacement.

[0035] Step S4: Continue to lower until the first limit member 53 presses against the short shaft 41, then stop lowering and record the detected value L1 of the first displacement sensor 56.

[0036] Step S5: Obtain the standard value L0 of the first displacement sensor 56 for detecting the calibration member.

[0037] Wherein, the outer diameter of the calibration member is the same as that of the short shaft 41, and it is a columnar or tubular member. Replacing the crankshaft with the calibration member can obtain the standard value. The shape of the calibration member is a columnar or tubular member, that is, a standard member with equal long shaft and short shaft diameters and a center distance of 0.

[0038] Step S6: Obtain the surface offset by the difference between the detected value and the standard value.

[0039] Step S7: Calculate the eccentricity of the crankshaft based on the surface offset, the long shaft diameter, and the short shaft diameter.

[0040] Such as Figure 7 , the calculation method of the eccentricity is: (1); (2); Wherein, L1 represents the detected value of the crankshaft, the reading of the first displacement sensor during the actual detection of the workpiece / crankshaft to be measured, L0 represents the standard value of the calibration member, which is the reading of the first displacement sensor when calibrating with the calibration member, represents the surface offset, b represents the long shaft diameter, a represents the short shaft diameter, D represents the eccentricity, represents the center axis spacing between the short shaft and the long shaft. Usually, the DL value is saved as a fixed parameter and will only change when re-calibration is required.

[0041] The specific solution method is as follows: Taking the upper end face of the short shaft 41 as the reference M, then the longitudinal distance between the central axis of the short shaft and the reference is: M - a / 2, and the longitudinal distance between the central axis of the long shaft and the reference is: , subtracting the two distances can obtain the eccentricity D.

[0042] Step S8: Determine whether the absolute value of the difference between the eccentricity and the standard value exceeds the first threshold.

[0043] If yes, execute Step S9: The crankshaft is unqualified and an alarm message is generated.

[0044] If not, execute Step S10: The crankshaft is qualified, control the second limit member 55 and the first displacement sensor 56 to rise through the first linear actuator 52, and execute Step S1 until all crankshafts are detected.

[0045] Through the offset detection mechanism, the present invention detects the surface displacement of the upper end surface of the crankshaft (the surface where the short shaft abuts against the first limiting member), and calculates the eccentricity through the surface displacement, the diameters of the short shaft and the long shaft, which can realize automatic detection and feeding, improve the detection efficiency, and can realize full-quantity detection and on-line detection.

[0046] It can prevent unqualified products from flowing into the next process, and can also provide data for the next process to improve the accuracy; it can detect other types and specifications of crankshafts in the mixed materials, and can quickly identify the workpieces during mixed production (measure the standard-size workpieces, obtain the values and match them with the system to quickly determine which type of workpiece this is), so as to select the corresponding formula.

[0047] In some processes described in the specification, claims and the above-mentioned drawings of the present application, a plurality of operations appear in a specific order, but it should be clearly understood that these operations can be executed not in the order in which they appear in this article or in parallel. The serial numbers of the operations, such as 101, 102, etc., are only used to distinguish different operations, and the serial numbers themselves do not represent any execution order. In addition, these processes may include more or fewer operations, and these operations can be executed in sequence or in parallel. It should be noted that the descriptions such as "first" and "second" in this article are used to distinguish different messages, devices, modules, etc., do not represent the sequence, and do not limit that "first" and "second" are of different types.

[0048] It should be understood that terms such as "including" or "having" are intended to indicate the existence of the features, numbers, steps, actions, components, parts or combinations thereof disclosed in this specification, and do not exclude the possibility of the existence or addition of one or more other features, numbers, steps, actions, components, parts or combinations thereof.

[0049] In addition, it should be noted that, without conflict, the embodiments in the present disclosure and the features in the embodiments can be combined with each other.

[0050] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An on-line workpiece size measuring device, characterized in that It includes a feeding mechanism (2) and an offset detection mechanism (5). The feeding mechanism (2) includes a feeding rack (21), and a V-shaped groove (22) matching with the crankshaft (4) is arranged on the feeding rack (21). The offset detection mechanism (5) includes a detection rack (51) arranged on the upper side of the feeding rack, and a first linear driver (52) is arranged on the detection rack (51). A first carriage (521) is arranged at the output end of the first linear driver (52), and a first limiting member (53) and a first displacement sensor (56) are arranged on the lower side of the first carriage (521). The detection rod of the first displacement sensor (56) matches with the long axis (44) of the crankshaft (4). The first limiting member (53) matches with the short axis (41) of the crankshaft (4).

2. The on-line workpiece size measuring device according to claim 1, characterized in that, A second limiting member (55) is further arranged on the lower side of the first carriage (521), and the two spaced second limiting members (55) match with the lugs (43) on both sides of the crankshaft arm (42) of the crankshaft (4). A detection head (58) is arranged at one end of the detection rod of the first displacement sensor (56), and a first spring (57) is arranged on the outer side of the detection rod. In the free state, the distance between the detection head (58) and the long axis (44) of the detection position crankshaft (4) is less than the distance between the second limiting member (55) and the lug (43), and less than the distance between the first limiting member (53) and the short axis (41). It further includes a calibration part, and the outer diameter of the calibration part is the same as the diameter of the short axis (41); the calibration part is a columnar or tubular part.

3. The on-line workpiece size measuring device according to claim 1, characterized in that, It further includes a crankshaft lifting mechanism (6). The crankshaft lifting mechanism (6) includes a first lifting cylinder (61) installed on one side of the feeding rack (21), a positioning block (63) is arranged at the output end of the first lifting cylinder (61), and a positioning groove (62) matching with the short axis (41) of the crankshaft (4) is arranged at the upper end of the positioning block (63).

4. The on-line workpiece size measuring device according to claim 1, characterized in that, It further includes an eccentric hole detection mechanism (8). The eccentric hole detection mechanism (8) includes a bracket (81) arranged on one side of the feeding rack (21). A second linear driver (82) is arranged on the bracket (81), a second carriage (83) is arranged at the output end of the second linear driver (82), and a detection slider (87) is slidably installed on the second carriage (83). A detection needle (85) matching with the eccentric hole (45) at one end of the short axis (41) is arranged at the inner end of the detection slider (87), and a detection part (88) is arranged at the outer end. A proximity switch (86) matching with the detection part (88) is arranged on the second carriage (83). A second spring (89) is arranged between the detection slider (87) and the second carriage (83).

5. The on-line workpiece size measuring device according to claim 1, characterized in that, It further includes a diameter detection mechanism (7). The diameter detection mechanism (7) includes a pair of clamping jaws (71) and a second displacement sensor (73). The clamping jaws (71) match with the short axis (41) or the long axis (44) of the crankshaft (4). The second displacement sensor (73) is arranged on one clamping jaw (71), and the detection end of the second displacement sensor (73) extends towards the limit block (74) on the side of the other clamping jaw (71).

6. The on-line workpiece size measuring device according to claim 1, characterized in that, The loading mechanism (2) further includes a second lifting cylinder (31), a third linear actuator (27), and a lifting frame (25) movably installed inside the loading rack (21). The second lifting cylinder (31) is installed on the lower side of the loading rack (21), and a slider (35) is arranged at the output end of the second lifting cylinder (31). A slide rail (26) is arranged on the lower side of the lifting frame (25), and the slider (35) is matched with the slide rail. The third linear actuator (27) is installed on the lower side of the lifting frame (25), and the output end of the third linear actuator (27) is connected to the slider (35).

7. The on-line workpiece size measuring device according to claim 6, characterized in that, A lifting block (33) is arranged at the output end of the second lifting cylinder (31), and the slider (35) is fixed on the lifting block (33). The output end of the third linear actuator (27) is connected to the lifting block (33). A third displacement sensor (32) is arranged on the second lifting cylinder (31), and the outer end of the detection rod of the third displacement sensor (32) is installed on the lifting block (33) or the slider (35).

8. The on-line workpiece size measuring device according to claim 7, characterized in that, A loading positioning mechanism (9) is arranged upstream of the loading mechanism (2). The loading positioning mechanism (9) includes a fourth cylinder (91) and a fifth cylinder (95) respectively arranged on both sides of the loading rack (21). A pushing block (92) is arranged at the output end of the fourth cylinder (91), and the pushing block (92) extends towards the V-shaped groove (22) of the loading rack. A U-shaped positioning block (96) is arranged at the output end of the fifth cylinder (95), and the convex platforms on both sides of the U-shaped positioning block (96) are matched with the lugs (43) of the crankshaft arm (42).

9. An on-line workpiece size measurement method using the on-line workpiece size measurement device according to any one of claims 1-8, characterized in that, Including the following steps: Transport the crankshaft to the detection position through the loading mechanism. Control the second limiting member and the first displacement sensor to descend through the first linear actuator. During the descending process, the detection rod of the first displacement sensor presses on the long shaft. Continue to descend until the first limiting member presses on the short shaft, and record the detection value of the first displacement sensor. Obtain the standard value of the first displacement sensor for detecting the calibration part, wherein the outer diameter of the calibration part is the same as that of the short shaft. Obtain the surface offset and eccentricity through the difference between the detection value and the standard value.

10. The on-line measurement method of workpiece size according to claim 9, characterized in that, The calculation method of the eccentricity D is as follows: （1）； （2）； Among them, L1 represents the measured value of the crankshaft, and L0 represents the standard value of the calibration piece. It represents the surface offset, b represents the major axis diameter, and a represents the minor axis diameter.

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