Crane suspension workpiece positioning system and positioning method

Abstract

The present application relates to a kind of crane suspends workpiece positioning system and positioning method.The system includes crane, lifting appliance, measuring unit, tooling and control unit.Measuring unit is equipped with first measurement component and second measurement component, and the contact terminal of each measurement component is respectively with the first inclined surface and the second inclined surface on tooling along mutually perpendicular first direction and second direction oblique first slope and second slope separable contact.When positioning, each measurement component extends and makes contact terminal contact corresponding slope, and control unit determines the displacement deviation of lifting appliance along two horizontal directions according to the difference between current vertical extension amount and preset reference extension amount and slope inclination;Subsequently, control each electric push rod retraction, make contact terminal and corresponding slope separate, and control crane to adjust the horizontal position of lifting appliance according to the displacement deviation.The present application can complete horizontal positioning before workpiece drops, reduce artificial visual inspection and repeated trial drop, reduce collision, jam and positioning structure damage risk, and structure is simple, not affected by illumination.

Description

Technical Field

[0001] This invention relates to the field of crane technology, and in particular to a crane-suspended workpiece positioning system and positioning method. Background Technology

[0002] Cranes are widely used for lifting and positioning large workpieces, molds, equipment components, and other heavy objects. Bridge cranes typically use a trolley traveling mechanism and a tripod traveling mechanism to move the lifting device along two intersecting horizontal directions, and a hoisting mechanism to raise and lower the device. After the workpiece is lifted by the crane above the target fixture, its horizontal position and vertical orientation usually need to be adjusted to align the positioning holes on the workpiece with the positioning pins on the fixture. Then, the workpiece is lowered to complete its positioning.

[0003] In existing positioning operations, ground personnel typically observe the positional relationship between the workpiece's positioning hole and the tooling's positioning pin, and direct crane operators to jog the trolley, hoisting mechanism, and other components. When there is an angular deviation in the workpiece, manual traction of the workpiece or control of the lifting device's rotation is also required. Operators repeatedly perform trial descents, observe deviations, and adjust the lifting until the positioning pin enters the positioning hole on the workpiece.

[0004] For large workpieces, the locating holes are usually located at the bottom of the workpiece, which are easily obstructed by the workpiece body, lifting fixtures, and tooling structures. Ground personnel cannot simultaneously observe different locating positions and can only estimate them based on the positional relationship between the workpiece's outer contour and the tooling edge. This can easily lead to misjudgments of the workpiece's positional deviation and yaw deviation in two horizontal directions. If the workpiece continues to descend without being fully aligned, the locating pin may first contact the edge of the locating hole, applying a lateral force to the suspended workpiece, causing it to swing and rotate. This necessitates readjusting and relifting the workpiece, and may also damage the locating pin, locating hole, and tooling structure.

[0005] To overcome the shortcomings of manual adjustment, some tooling employs mechanical guiding structures, such as guide cones on locating pins and guide plates around the workpiece. This mechanically guides the workpiece during descent, correcting positional deviations within a certain range. However, when the workpiece exhibits both horizontal and yaw deviations, multiple guide positions may contact each other sequentially, applying forces in different directions to the suspended workpiece. The mechanical guiding structure only functions after the workpiece descends and contacts the guiding structure; the direction and magnitude of the positional deviation cannot be known before descent. When the initial positional deviation exceeds the allowable guide range of the mechanical guiding structure, collisions and jamming may still occur.

[0006] In addition, some solutions use visual inspection to obtain the positional relationship between the workpiece and the tooling. This involves capturing images of the workpiece and tooling with a camera and determining their relative position and orientation based on the captured images. However, in scenarios involving the hoisting of large workpieces, the positioning holes are usually located at the bottom of the workpiece and are easily obstructed by the workpiece itself and the hoisting fixture. Factors such as dust, changes in lighting, and surface reflections in the workshop environment can also affect the stability of visual inspection and limit the camera's installation position and inspection range. Summary of the Invention

[0007] Therefore, the purpose of this invention is to overcome the problems in the prior art where mechanical guiding structures can only passively guide the workpiece after it descends and comes into contact with it, cannot obtain the positional deviation of the workpiece in advance, and are easily affected by the obstruction of the positioning part and the on-site environment during visual inspection.

[0008] To address the aforementioned technical problems, in a first aspect, the present invention provides a crane-suspended workpiece positioning system, wherein the workpiece is fixed to a lifting device connected to a crane, and the positioning system comprises: A measuring unit is mounted on the lifting device and includes a first measuring component and a second measuring component respectively mounted on both sides of the lifting device along a first direction. Each measuring component includes an electric push rod, a contact terminal, and an encoder. The contact terminal is located at the power output end of the electric push rod, which is capable of vertical extension and retraction. The encoder collects the vertical extension and retraction amount of the electric push rod. Two reference blocks are fixed to the fixture for receiving the workpiece and are located below the corresponding measuring components in the measurement state. The two reference blocks are respectively provided with a first inclined surface and a second inclined surface. The first inclined surface is inclined along a first direction, and the second inclined surface is inclined along a second direction. The first direction is perpendicular to the second direction. The contact terminals of the first measuring component and the second measuring component are separably contacted with the first inclined surface and the second inclined surface, respectively, and the current vertical extension and retraction of the electric push rod is collected when they are in contact. The control unit calculates the difference between the current vertical extension and the corresponding preset reference extension to obtain the displacement deviation; and controls the crane according to the displacement deviation to adjust the horizontal position of the lifting device.

[0009] In one embodiment of the present invention, the inclination angles of the first inclined plane and the second inclined plane relative to the horizontal plane are both α, and α is 25° to 45°.

[0010] In one embodiment of the present invention, the two reference blocks are detachably disposed on both sides of the tooling along the first direction.

[0011] In one embodiment of the present invention, the crane is connected to the lifting device via a cross-shaped balance beam, and the four ends of the cross-shaped balance beam are respectively connected to the four corners of the lifting device via slings; In one embodiment of the present invention, a first positioning post is provided at each end of the same diagonal on the tooling. The upper end of the first positioning post forms a tapered guide portion with a diameter that gradually decreases from bottom to top. The two first positioning posts are respectively used to cooperate with two workpiece positioning holes on the workpiece.

[0012] In a second aspect, the present invention also discloses a crane-suspended workpiece positioning method, using the crane-suspended workpiece positioning system provided in the first aspect, the positioning method comprising: Step S1: Control the crane to move the lifting device carrying the workpiece to the measurement position corresponding to the preset theoretical placement coordinates; Step S2: Control each electric push rod to extend, so that the contact terminal of the first measuring component contacts the first inclined surface and the contact terminal of the second measuring component contacts the second inclined surface, and obtain the current vertical extension amount detected by each encoder; Step S3: Based on the current vertical extension L1 of the first measuring component and the corresponding preset reference extension L... 10 The difference, according to ΔX=(L1-L 10 The displacement deviation in the first direction is determined by tanα. Based on the current vertical extension L2 of the second measuring component and the corresponding preset reference extension L... 20 The difference, according to ΔY=(L2-L 20 The displacement deviation in the second direction is determined by tanα. Wherein, α is the angle of inclination of the inclined plane relative to the horizontal plane, the first inclined plane gradually decreases along the positive direction of the first direction, and the second inclined plane gradually decreases along the positive direction of the second direction. Step S4: Control each electric push rod to retract to the preset retraction position, and according to the displacement deviation in the first direction and / or the second direction, control the crane to adjust the horizontal position of the lifting device in the direction opposite to the direction represented by the corresponding displacement deviation.

[0013] In one embodiment of the present invention, in step S2, during the process of controlling the extension of the power output end of each electric push rod, the drive current of each electric push rod is detected respectively; when the drive current of the corresponding electric push rod reaches a preset current threshold and continues for a preset time, it is determined that the contact terminal corresponding to the electric push rod is in contact with the corresponding inclined surface, and the current vertical extension amount detected by the corresponding encoder is obtained.

[0014] In one embodiment of the present invention, in step S4, when at least one of the first directional displacement deviation and the second directional displacement deviation exceeds the corresponding preset displacement threshold, for any out-of-tolerance direction, the smaller of the absolute value of the displacement deviation in that direction and the corresponding preset maximum single correction amount is determined as the single correction movement amount in that direction; the crane is controlled to move the corresponding single correction movement amount in the direction opposite to the direction represented by the displacement deviation in that direction; after completing the single correction in each out-of-tolerance direction, a preset stabilization time is waited before returning to step S2.

[0015] In one embodiment of the present invention, a calibration step S0 is further included before performing step S1, wherein the calibration step S0 includes: Place the calibration part on the tooling, so that the two first positioning holes on the calibration part respectively mate with the two first positioning pins located at both ends of the same diagonal of the tooling; The counterweight is positioned and connected to the calibration component so that the total weight and center of gravity of the calibration component and the counterweight are matched with the workpiece. The calibration component and the counterweight are lifted to a preset calibration height using a lifting mechanism. The lifting device is connected to the calibration component, the crane is controlled to lift the lifting device to tension the slings, and the jacking mechanism holds the calibration component and the counterweight at the preset calibration height. Obtain the horizontal and lifting coordinates of the crane as the preset theoretical landing coordinates; Control each electric push rod to extend, so that the contact terminals of each measuring component contact the corresponding inclined surface, and obtain the extension amount detected by each encoder, which is used as the preset reference extension amount of the corresponding measuring component.

[0016] In one embodiment of the present invention, a second positioning post is provided at each end of another diagonal line of the tooling, and the calibration component is provided with two second positioning holes that respectively cooperate with the two second positioning posts. The length of the second positioning post is greater than the length of the first positioning post. When the calibration component is placed on the tooling, the two first positioning holes are respectively engaged with the two first positioning pins, and the two second positioning holes are respectively engaged with the two second positioning pins. When the calibration component is lifted, the two first positioning pins first disengage from the corresponding first positioning holes, and the two second positioning pins continue to slide in the vertical direction with the corresponding second positioning holes until the calibration component reaches the preset calibration height.

[0017] In one embodiment of the present invention, when obtaining the preset reference extension amount, each measuring component is controlled to perform multiple contact measurements on the corresponding inclined surface; when the difference between the maximum and minimum values ​​of the extension amounts obtained by the same measuring component in each measurement is not greater than a preset range threshold, the average value of the extension amounts obtained in each measurement is taken as the preset reference extension amount of the measuring component.

[0018] The technical solution of the present invention has the following advantages compared with the prior art: This invention, by setting a first and a second measuring component on the lifting device and a first and a second inclined plane on the tooling, allows the contact terminals of each measuring component to contact the corresponding inclined plane, converting the horizontal displacement of the lifting device relative to the tooling along the first and second directions into changes in the vertical extension of the electric push rod. The control unit compares the current vertical extension of each measuring component with the corresponding preset reference extension, and, in conjunction with the inclination angle of the inclined plane, calculates the displacement deviation of the lifting device along the two horizontal directions. Before the workpiece descends, the control unit actively corrects the deviation based on this deviation, ensuring that the workpiece positioning hole enters the allowable guide range of the corresponding first positioning post on the tooling. This overcomes the shortcomings of traditional methods, such as the difficulty in accurately judging deviations through manual visual inspection and the passive guidance provided by mechanical guide structures only after the workpiece has descended.

[0019] This invention utilizes only two vertically extending measuring components and two mutually perpendicular inclined planes to detect displacement deviations in two horizontal directions. Its structure is simple, requires few detection elements, and is cost-effective. Furthermore, this invention does not rely on visual images, ambient lighting, or workpiece surface features. It is particularly suitable for scenarios where positioning holes are located at the bottom of large workpieces during hoisting and positioning, or where visual inspection is unstable due to dust or changes in lighting conditions. It boasts strong engineering applicability and high reliability. Attached Figure Description

[0020] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0021] Figure 1 This is a schematic diagram of the crane-suspended workpiece positioning system provided by the present invention; Figure 2 This is a top view of the tooling provided by the present invention; Figure 3 This is a top view of the calibration component provided by the present invention; Figure 4 This is a schematic diagram of the first direction displacement deviation measurement principle provided by the present invention; Figure 5 This is a flowchart of the crane-suspended workpiece positioning method provided by the present invention; Figure 6This is a flowchart of the calibration steps provided by the present invention.

[0022] Explanation of reference numerals in the accompanying drawings: 1. Crane; 2. Lifting device; 21. Sling; 22. Cross-shaped balance beam; 31. First measuring component; 32. Second measuring component; 33. Electric push rod; 34. Telescopic rod; 35. Contact terminal; 4. Tooling; 41. First inclined plane; 42. Second inclined plane; 43. First reference block; 44. Second reference block; 45. First positioning post; 46. Second positioning post; 6. Workpiece; 61. Workpiece positioning hole; 7. Calibration component; 71. First positioning hole; 72. Second positioning hole; X, First direction; Y, Second direction; Z, Vertical direction. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0024] See Figures 1 to 4 As shown, this embodiment provides a crane-suspended workpiece positioning system, including a measuring unit, two reference blocks, and a control unit. The measuring unit is mounted on a lifting device 2, and the workpiece 6 is fixed to the lifting device 2. The lifting device 2 is connected to a crane 1, which is used to drive the lifting device 2 to move horizontally and lift vertically. The two reference blocks are respectively fixed to a fixture 4 for receiving the workpiece 6, and the fixture 4 is set in a predetermined positioning area.

[0025] In this embodiment, crane 1 is a bridge crane, and its trolley travel direction, trolley travel direction, and lifting direction are defined as the first direction X, the second direction Y, and the vertical direction Z, respectively. The first direction X and the second direction Y are perpendicular to each other. Tooling 4 is set in a predetermined positioning area, and its first direction X and second direction Y are parallel to the trolley travel direction and the trolley travel direction of crane 1, respectively.

[0026] The lifting device 2 is used to support the workpiece 6. After the two are connected, they remain relatively fixed so that changes in the position of the lifting device 2 can reflect changes in the position of the workpiece 6. The tooling 4 has a first reference block 43 and a second reference block 44 on both sides along the first direction X, both of which are located outside the placement area of ​​the workpiece 6. The first reference block 43 has a first inclined surface 41 that is inclined along the first direction X, and the second reference block 44 has a second inclined surface 42 that is inclined along the second direction Y, so that the two inclined surfaces do not occupy the placement support area of ​​the workpiece 6.

[0027] The measuring unit includes a first measuring component 31 and a second measuring component 32 respectively disposed on both sides of the lifting device 2 along the first direction X. In the measuring state, the crane 1 moves the lifting device 2 to the measuring position corresponding to the preset theoretical landing coordinates, so that the first measuring component 31 and the second measuring component 32 are respectively located above the first inclined plane 41 and the second inclined plane 42, and correspond vertically to the corresponding inclined planes. The two measuring components have identical structures, each including an electric push rod 33, a contact terminal 35 mounted on the lower end of its telescopic rod 34, and an encoder for detecting the vertical extension amount of the telescopic rod 34. The contact terminal 35 is a spherical contact element, rotatably mounted on the lower end of the telescopic rod 34 to reduce friction when in contact with the inclined plane.

[0028] During measurement, crane 1 suspends the lifting device 2 above fixture 4. Each telescopic rod 34 extends downwards, causing the contact terminal 35 to contact the corresponding inclined surface, and the encoder reads the current vertical extension / retraction amount. When the lifting device 2 displaces along the first direction X, the height of the first inclined surface 41 below the contact terminal 35 changes accordingly, causing a corresponding change in the extension amount of the telescopic rod 34; the second measuring component 32 operates on the same principle as the second inclined surface 42. Thus, the two measuring components convert the horizontal displacement of the lifting device 2 into a change in the vertical extension amount of the telescopic rod 34 (e.g., ...). Figure 4 (As shown).

[0029] The first inclined surface 41 has a certain width along the second direction Y, so that when the lifting device 2 has a certain displacement deviation in the second direction, the contact terminal 35 of the first measuring component 31 can still fall into the effective contact area of ​​the first inclined surface 41. The second inclined surface 42 has a certain width along the first direction X, so that when the lifting device 2 has a certain displacement deviation in the first direction, the contact terminal 35 of the second measuring component 32 can still fall into the effective contact area of ​​the second inclined surface 42.

[0030] The control unit is connected to the crane 1 and two measuring components, and is used to control the extension and retraction of the electric push rod 33, read encoder data, and control the various operating mechanisms of the crane 1. The control unit stores preset reference extension amounts corresponding to the two measuring components, i.e., the extension amount of the telescopic rod 34 required for each contact terminal 35 to contact the corresponding inclined surface when the lifting device 2 and the workpiece 6 are at preset theoretical landing coordinates. The preset theoretical landing coordinates include the horizontal landing position determined by the trolley travel coordinates and the auxiliary trolley travel coordinates, and the measurement height determined by the lifting coordinates.

[0031] The control unit calculates the displacement deviation of the lifting device 2 along the first direction X and the second direction Y based on the difference between the current vertical extension and the corresponding preset reference extension of each measuring component. After the measurement is completed, the control unit controls each telescopic rod 34 to retract, so that the contact terminal 35 is disengaged from the corresponding inclined surface. Then, based on the calculated deviation, the control unit controls the crane 1 to adjust the horizontal position of the lifting device 2, thereby avoiding the telescopic rod 34 from bearing lateral loads during movement and also preventing the contact terminal 35 from being forcibly dragged on the inclined surface.

[0032] In summary, this embodiment utilizes the first inclined plane 41 and the second inclined plane 42 to convert the horizontal displacement of the lifting device 2 in the first direction X and the second direction Y into the change in the vertical extension of the telescopic rod 34, thereby measuring the displacement deviation of the lifting device 2 relative to the tooling 4, which is then used by the control unit for correction control.

[0033] See Figure 1 As shown, the angles between the first inclined plane 41 and the second inclined plane 42 and the horizontal plane are both α, with α ranging from 25° to 45°. The identical inclination angles of the two inclined planes ensure a consistent conversion relationship between the extension changes of the two measuring components and the horizontal displacement.

[0034] If α is less than 25°, the change in the inclined plane height caused by the horizontal displacement is small, the extension of the telescopic rod 34 does not change significantly, and the accuracy of displacement deviation identification is low. If α is greater than 45°, the change in the inclined plane height corresponding to the same horizontal displacement is large, and the requirements for the stroke of the telescopic rod 34, the inclined plane height dimension, and the installation space of the measuring components are higher. Setting α to 25° to 45° can achieve a good balance between measurement sensitivity, stroke utilization, and the structural dimensions of tooling 4.

[0035] In one specific embodiment, α is 30°. The first inclined plane 41 gradually decreases along the first direction X, and the second inclined plane 42 gradually decreases along the second direction Y, with the decreasing direction being consistent with the positive directions of the first direction X and the second direction Y, respectively. When the contact terminal 35 moves along the inclined plane, the height of the inclined plane changes according to a fixed ratio, and the difference between the current vertical extension amount of the telescopic rod 34 and the preset reference extension amount can be converted into a horizontal displacement deviation.

[0036] The first inclined surface 41 and the second inclined surface 42 are formed on the first reference block 43 and the second reference block 44, respectively. The two reference blocks are detachably mounted on the top of the tooling 4. By replacing the reference blocks, the inclination angle, position or size of the inclined surface can be adjusted, and it is also convenient to maintain and replace the inclined surface after it is worn.

[0037] See Figure 1As shown, the hook of the crane 1 is connected to the lifting device 2 via a cross-shaped balance beam 22. The four ends of the cross-shaped balance beam 22 are connected to the four corners of the lifting device 2 via slings 21. The lower end of each sling 21 is offset away from the vertical centerline of the lifting device 2 relative to its upper end, so that the four slings 21 form an outward-opening lifting structure.

[0038] When the spreader 2 swings horizontally or yaws around the vertical direction Z, the tilt angle and stress state of part of the sling 21 change, producing a restoring effect opposite to the swing or yaw direction, thereby suppressing the horizontal swing and yaw of the spreader 2.

[0039] After the yaw angle of the spreader 2 is suppressed within the allowable range, the first measuring component 31 and the second measuring component 32 detect the displacement deviation of the spreader 2 along the first direction X and the second direction Y. The control unit adjusts the horizontal position of the spreader 2 according to the detection results until the displacement deviation in both directions is within the corresponding preset displacement threshold.

[0040] See Figure 2 As shown, the tooling 4 has a first positioning post 45 at each end along the same diagonal, and the workpiece 6 has two workpiece positioning holes 61 corresponding to the two first positioning posts 45. The upper end of the first positioning post 45 forms a tapered guide portion with a diameter that gradually decreases from bottom to top.

[0041] When the displacement deviations in both directions are within the corresponding preset displacement thresholds, the two workpiece positioning holes 61 on the workpiece 6 enter the allowable guide range of the corresponding first positioning post 45, and the control unit controls the workpiece 6 to move downward. When the workpiece 6 descends, the tapered guide part first enters the workpiece positioning hole 61, and the outer peripheral surface of the tapered guide part generates a horizontal guiding effect on the opening of the workpiece positioning hole 61, guiding the workpiece 6 to move towards the predetermined landing position, completing the final positioning.

[0042] Therefore, the outward-stretched arrangement of the cross-shaped balance beam 22 and the four slings 21 is used to suppress the swaying and yaw of the lifting device 2, enabling the measuring unit to perform detection while the lifting device 2 is in a stable state; the measuring unit reduces the displacement deviation to within the allowable range of the first positioning post 45; the first positioning post 45 completes the final positioning during the descent of the workpiece 6. The three work together to reduce the risk of the first positioning post 45 bearing excessive lateral load or jamming, and improve the reliability of the positioning.

[0043] See Figure 5 As shown, this embodiment also provides a positioning method based on the above-mentioned crane-suspended workpiece positioning system, including the following steps: S1. Control the crane 1 to move the lifting device 2 carrying the workpiece 6 to the measurement position corresponding to the preset theoretical landing coordinates. The coordinates include the preset horizontal landing position and the preset measurement height, wherein the horizontal landing position is determined by the trolley travel coordinates and the gantry travel coordinates, and the measurement height is determined by the lifting coordinates.

[0044] S2. The telescopic rods 34 of the first measuring component 31 and the second measuring component 32 are extended downward, so that the contact terminals 35 contact the first inclined surface 41 and the second inclined surface 42 respectively, and the current vertical extension amount detected by the two encoders is read.

[0045] S3. Based on the difference between the current vertical extension and retraction of each measuring component and the corresponding preset reference extension, determine the displacement deviation of the lifting device 2 along the first direction X and the second direction Y respectively.

[0046] Specifically, the angles between the first inclined plane 41 and the second inclined plane 42 and the horizontal plane are both α. The first inclined plane 41 gradually decreases along the positive direction of the first direction X, and the second inclined plane 42 gradually decreases along the positive direction of the second direction Y. When the lifting device 2 shifts along the positive direction of the first direction X, the height of the first inclined plane 41 below the contact terminal 35 decreases, and the required extension amount of the telescopic rod 34 increases, L1-L 10 The value is positive. When the contact terminal moves along the inclined plane, the horizontal displacement and the change in vertical height satisfy the geometric relationship Δh = ΔX·tanα. Therefore, the horizontal displacement deviation is equal to the change in vertical extension divided by tanα. Let the current vertical extension of the first measuring component 31 be L1, and the preset reference extension be L. 10 The current vertical extension / retraction of the second measuring component 32 is L2, and the preset reference extension / retraction is L. 20 The displacement deviations in the two directions are as follows: ΔX = (L1 - L 10 ) / tanα; ΔY = (L2- L 20 ) / tanα; In the formula, the signs of ΔX and ΔY correspond to the positive directions of the first direction X and the second direction Y, respectively. Taking the first direction X as an example, when the lifting device 2 shifts along the positive X direction, the height of the first inclined plane 41 decreases, the extension of the telescopic rod 34 increases, and L1-L 10 Since ΔX is a positive value, it represents a positive offset in the positive direction. ΔY is determined in the same way.

[0047] S4. Control the two telescopic rods 34 to retract, causing the contact terminal 35 to disengage from the corresponding inclined surface. When the displacement deviation in any direction exceeds the corresponding preset displacement threshold, control the crane 1 to adjust the horizontal position of the lifting device 2 according to the deviation in that direction.

[0048] The first directional displacement deviation corresponds to the control mechanism of the trolley traveling, and the second directional displacement deviation corresponds to the control mechanism of the gantry traveling. Crane 1 moves in the opposite direction to the deviation direction to reduce the positional deviation in the corresponding direction.

[0049] S5. After completing the horizontal position adjustment, repeat steps S2 to S4 until the displacement deviation in both directions is within the corresponding preset displacement threshold, and then control the workpiece 6 to move downward.

[0050] This embodiment achieves positioning by repeatedly performing a cyclical process of measurement, retraction, adjustment, and re-measurement. Each telescopic rod 34 retracts before the lifting device 2 moves horizontally, separating the contact terminal 35 from the corresponding inclined surface to prevent the telescopic rod 34 from bearing lateral loads during movement. Through repeated measurement and adjustment, the displacement deviation of the lifting device 2 in both directions gradually decreases, eventually entering the allowable guide range of the first positioning post 45.

[0051] Furthermore, each electric actuator 33 is connected to a current detection module, which is electrically connected to the control unit, and is used to detect the drive current of the corresponding electric actuator 33.

[0052] In step S2, the control unit controls the telescopic rod 34 to extend downwards, while continuously monitoring the drive current of each electric push rod 33 through the current detection module. When the contact terminal 35 is not in contact with the inclined plane, the electric push rod 33 is in an unloaded state, and the drive current remains within the unloaded current range; after the contact terminal 35 contacts the inclined plane, the resistance to the extension of the telescopic rod 34 increases, and the drive current rises accordingly.

[0053] The control unit compares the drive current of each electric actuator 33 with a preset current threshold. When the drive current reaches the preset current threshold and remains there for a preset time, the control unit determines that the contact terminal 35 has made contact with the corresponding inclined surface, then stops the extension of the electric actuator 33, and reads the current vertical extension amount detected by the corresponding encoder.

[0054] Each electric push rod 33 extends simultaneously, and the contact state of the two measuring components is determined independently. When one of the contact terminals 35 contacts the inclined plane first, the control unit controls that electric push rod 33 to stop extending, while the other electric push rod 33 continues to extend until its contact terminal 35 also completes contact and the extension amount is read.

[0055] The preset current threshold is predetermined based on the no-load current, rated current, extension speed of the electric push rod 33, and the load change after the contact terminal 35 contacts the inclined surface. The preset time is used to filter out misjudgments caused by starting impact, mechanical vibration, or instantaneous current fluctuations. In one embodiment, the preset time is 0.2 to 0.5 seconds.

[0056] The contact status is determined by detecting the drive current, eliminating the need for additional contact switches on the contact terminal 35 or the inclined surface. This simplifies the structure and allows the two measuring components to independently determine the contact status and read the extension amount.

[0057] Furthermore, in step S4, when at least one of the first directional displacement deviation and the second directional displacement deviation exceeds the corresponding preset displacement threshold, the control unit determines the corresponding single correction movement amount for each deviation direction.

[0058] For any out-of-tolerance direction, the control unit compares the absolute value of the displacement deviation in that direction with the corresponding preset maximum single correction amount. If the absolute value of the deviation is not greater than the maximum single correction amount, then the absolute value of the deviation is used as the correction movement amount for this time; if the absolute value of the deviation is greater than the maximum single correction amount, then the maximum single correction amount is used as the correction movement amount for this time.

[0059] After determining the corrective movement amount, the control unit controls crane 1 to move in the opposite direction to the deviation direction. When the displacement deviation in the first direction is positive, the trolley traveling mechanism is controlled to move in the negative direction of the first direction X; when it is negative, it moves in the positive direction of the first direction X. The corrective method for the second direction Y is the same.

[0060] By setting a preset maximum single correction amount, the movement distance of the lifting device 2 for each correction can be limited, thus avoiding excessive single movement distance that could cause large swings between the lifting device 2 and the workpiece 6.

[0061] After completing a single correction in each out-of-tolerance direction, the control unit controls the crane 1 to stop horizontal movement and waits for a preset stabilization time to allow the swing of the lifting device 2 and workpiece 6 to decay to within the allowable range before returning to step S2 for the next round of measurement. The preset stabilization time is determined through on-site debugging based on the load state of the lifting device 2 and workpiece 6, the length of the sling 21, the operating speed of the crane 1, and its deceleration characteristics.

[0062] By limiting the amount of movement in a single correction and waiting for the spreader 2 to stabilize after correction, the impact of swaying on the next round of extension detection can be reduced, allowing the spreader 2 to gradually approach the preset horizontal positioning position.

[0063] Further, see Figure 6 As shown, calibration step S0 is performed before step S1 to obtain the preset theoretical positioning coordinates and the preset reference extension L corresponding to the first measuring component 31. 10 The preset reference extension L corresponding to the second measuring component 32 20 The details are as follows: S01. Place the calibration part 7 on the fixture 4. The calibration part 7 is provided with two first positioning holes 71 and two second positioning holes 72 (e.g., ...). Figure 3As shown), the tooling 4 is provided with two first positioning posts 45 located at both ends of the same diagonal, and two second positioning posts 46 located at both ends of the other diagonal (as shown). Figure 2 (As shown). When the calibration part 7 is placed on the tooling 4, the two first positioning holes 71 respectively engage with the two first positioning pins 45, and the two second positioning holes 72 respectively engage with the two second positioning pins 46 to determine the initial position of the calibration part 7 relative to the tooling 4.

[0064] The lengths of the two second positioning posts 46 are both greater than the lengths of the two first positioning posts 45, and the second positioning posts 46 have an oblong cross-section. The second positioning hole 72 is an oblong hole adapted to the second positioning posts 46, forming a sliding fit between them in the vertical direction. The oblong fit can restrict the rotation of the calibration part 7 about the vertical direction Z, while allowing the calibration part 7 to slide in the vertical direction Z, so that the calibration part 7 maintains a constant angular position during the lifting process.

[0065] At least one counterweight is positioned and connected to the calibration component 7 so that the total weight and combined center of gravity of the calibration component 7 and the counterweight are matched with the weight and center of gravity of the workpiece 6 to be placed, so as to simulate the load state of the workpiece 6 on the lifting device 2 and each sling 21 during the formal placement process.

[0066] S02. The calibrator 7 and the counterweight are lifted to the preset calibration height by the lifting mechanism. In the initial stage of lifting, the two first positioning pins 45 and the corresponding first positioning holes 71, and the two second positioning pins 46 and the corresponding second positioning holes 72 together maintain the initial horizontal and angular positions of the calibrator 7. As the calibrator 7 continues to rise, the two first positioning pins 45 first disengage from the corresponding first positioning holes 71, and the two second positioning pins 46 continue to maintain a sliding fit with the corresponding second positioning holes 72 until the calibrator 7 reaches the preset calibration height. Thus, while allowing the calibrator 7 to rise in the vertical direction, its movement in the first direction X and the second direction Y and its rotation around the vertical direction Z are restricted.

[0067] The preset calibration height is the measurement height of the workpiece 6 simulated by the calibration component 7 during formal operation.

[0068] S03. Connect the lifting device 2 to the calibration component 7, and control the crane 1 to lift the lifting device 2 to tension each sling 21. At the same time, the jacking mechanism holds the calibration component 7 and the counterweight at the preset calibration height. At this time, the calibration component 7 and the counterweight simulate the workpiece 6 in the formal measurement state, and the position of the lifting device 2 and the stress state of each sling 21 correspond to the reference state during the formal measurement.

[0069] The crane 1's trolley travel coordinates, gantry travel coordinates, and hoisting coordinates are read and combined to determine the preset theoretical landing coordinates, which are then stored in the control unit. The trolley travel coordinates and gantry travel coordinates are used to determine the preset horizontal landing position, while the hoisting coordinates are used to determine the preset measurement height.

[0070] S04. After the lifting device 2, the calibration component 7 and the counterweight are kept in the calibration state, the telescopic rods 34 of the first measuring component 31 and the second measuring component 32 are controlled to extend downward, so that the contact terminals 35 contact the first inclined surface 41 and the second inclined surface 42 respectively.

[0071] When the contact terminal 35 of the first measuring component 31 is in stable contact with the first inclined surface 41, the extension amount detected by the encoder is read and determined as the preset reference extension amount L corresponding to the first measuring component 31. 10 When the contact terminal 35 of the second measuring component 32 is in stable contact with the second inclined surface 42, the extension amount detected by the encoder is read and determined as the preset reference extension amount L corresponding to the second measuring component 32. 20 The control unit will L 10 L 20 It is stored in association with the corresponding preset theoretical landing coordinates.

[0072] L 10 L 20 These represent the reference extension amount required for the contact terminals 35 of the two measuring components to contact the corresponding inclined surface when the lifting device 2 is in the preset horizontal position and the preset measuring height, respectively.

[0073] S05. Control the retraction of the two telescopic rods 34 to separate the contact terminal 35 from the corresponding inclined surface. Maintain the support of the lifting mechanism for the calibration component 7 and the counterweight, control the lifting mechanism of the crane 1 to descend, so that each sling 21 changes from a tensioned state to a slack state, and transfers the load of the calibration component 7 and the counterweight to the lifting mechanism.

[0074] After confirming that the calibration component 7 and the counterweight are stably supported by the lifting mechanism, disconnect the lifting device 2 from the calibration component 7, and control the crane 1 to move the lifting device 2 upward until it is separated from the calibration component 7.

[0075] Subsequently, the lifting mechanism is controlled to lower the calibration component 7 and the counterweight. During the descent, the second positioning pin 46 continues to maintain a sliding fit with the second positioning hole 72 until the calibration component 7 is supported again on the tooling 4.

[0076] After the calibration component 7 and the counterweight are stably supported on the fixture 4, remove the counterweight and move the counterweight and calibration component 7 out of the fixture 4. Then, remove the second positioning post 46, which is detachably mounted on the fixture 4, to avoid interfering with the normal positioning of the workpiece 6. At this point, the calibration process is complete.

[0077] Furthermore, when acquiring the preset reference extension amount, each measuring component is controlled to perform multiple contact measurements on the corresponding inclined plane. When the difference between the maximum and minimum values ​​of the extension amounts obtained from each measurement by the same measuring component is not greater than a preset range threshold, the average value of each measurement is taken as the preset reference extension amount of that measuring component; if the difference between the maximum and minimum values ​​is greater than the preset range threshold, multiple contact measurements are performed again until the above conditions are met.

[0078] The preset range threshold is determined based on the encoder resolution and the mechanical repeatability of the measuring components, and its value ranges from 0.1 mm to 0.5 mm. By taking the average value after multiple contact measurements, the influence of vibration, contact state differences, and repeatability errors of the measuring components on the calibration results can be reduced, thereby improving the reliability and calibration accuracy of the preset reference extension.

[0079] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A crane-suspended workpiece positioning system, wherein the workpiece is fixed to a lifting device, the lifting device being connected to the crane, characterized in that: The positioning system includes: A measuring unit is mounted on the lifting device and includes a first measuring component and a second measuring component respectively mounted on both sides of the lifting device along a first direction. Each measuring component includes an electric push rod, a contact terminal, and an encoder. The contact terminal is located at the power output end of the electric push rod, which is capable of vertical extension and retraction. The encoder collects the vertical extension and retraction amount of the electric push rod. Two reference blocks are fixed to the fixture for receiving the workpiece and are located below the corresponding measuring components in the measurement state. The two reference blocks are respectively provided with a first inclined surface and a second inclined surface. The first inclined surface is inclined along a first direction, and the second inclined surface is inclined along a second direction. The first direction is perpendicular to the second direction. The contact terminals of the first measuring component and the second measuring component are separably contacted with the first inclined surface and the second inclined surface, respectively, and the current vertical extension and retraction of the electric push rod is collected when they are in contact. The control unit calculates the difference between the current vertical extension and the corresponding preset reference extension to obtain the displacement deviation; and controls the crane according to the displacement deviation to adjust the horizontal position of the lifting device.

2. The crane-suspended workpiece positioning system according to claim 1, characterized in that: The first inclined plane and the second inclined plane are both inclined at an angle of α relative to the horizontal plane, and α is 25° to 45°.

3. The crane-suspended workpiece positioning system according to claim 1, characterized in that: The two reference blocks are detachably disposed on both sides of the tooling along the first direction.

4. The crane-suspended workpiece positioning system according to claim 1, characterized in that: The crane is connected to the lifting device via a cross-shaped balance beam, and the four ends of the cross-shaped balance beam are respectively connected to the four corners of the lifting device via slings; And / or, a first positioning post is provided at each end of the same diagonal on the tooling, and the upper end of the first positioning post forms a tapered guide portion with a diameter that gradually decreases from bottom to top. The two first positioning posts are respectively used to cooperate with two workpiece positioning holes on the workpiece.

5. A method for suspending and positioning a workpiece using a crane, characterized in that: Using the crane suspension workpiece positioning system according to any one of claims 1 to 4, comprising: Step S1: Control the crane to move the lifting device carrying the workpiece to the measurement position corresponding to the preset theoretical placement coordinates; Step S2: Control each electric push rod to extend, so that the contact terminal of the first measuring component contacts the first inclined surface and the contact terminal of the second measuring component contacts the second inclined surface, and obtain the current vertical extension amount detected by each encoder; Step S3: Based on the current vertical extension L1 of the first measuring component and the corresponding preset reference extension L... 10 The difference, according to ΔX=(L1-L 10 The displacement deviation in the first direction is determined by tanα. Based on the current vertical extension L2 of the second measuring component and the corresponding preset reference extension L... 20 The difference, according to ΔY=(L2-L 20 The displacement deviation in the second direction is determined by tanα. Wherein, α is the angle of inclination of the inclined plane relative to the horizontal plane, the first inclined plane gradually decreases along the positive direction of the first direction, and the second inclined plane gradually decreases along the positive direction of the second direction. Step S4: Control each electric push rod to retract to the preset retraction position, and according to the displacement deviation in the first direction and / or the second direction, control the crane to adjust the horizontal position of the lifting device in the direction opposite to the direction represented by the corresponding displacement deviation.

6. The crane-suspended workpiece positioning method according to claim 5, characterized in that: In step S2, during the process of controlling the extension of the power output end of each electric push rod, the drive current of each electric push rod is detected respectively; when the drive current of the corresponding electric push rod reaches the preset current threshold and continues for a preset time, it is determined that the contact terminal corresponding to the electric push rod is in contact with the corresponding inclined surface, and the current vertical extension amount detected by the corresponding encoder is obtained.

7. The crane-suspended workpiece positioning method according to claim 5, characterized in that: In step S4, when at least one of the first directional displacement deviation and the second directional displacement deviation exceeds the corresponding preset displacement threshold, for any out-of-tolerance direction, the smaller of the absolute value of the displacement deviation in that direction and the corresponding preset maximum single correction amount is determined as the single correction movement amount in that direction; the crane is controlled to move the corresponding single correction movement amount in the direction opposite to the direction represented by the displacement deviation in that direction; after completing the single correction in each out-of-tolerance direction, a preset stabilization time is waited before returning to step S2.

8. The crane-suspended workpiece positioning method according to claim 5, characterized in that: Before performing step S1, a calibration step S0 is also included, which includes: Place the calibration part on the tooling, so that the two first positioning holes on the calibration part respectively mate with the two first positioning pins located at both ends of the same diagonal of the tooling; The counterweight is positioned and connected to the calibration component so that the total weight and center of gravity of the calibration component and the counterweight are matched with the workpiece. The calibration component and the counterweight are lifted to a preset calibration height using a lifting mechanism. The lifting device is connected to the calibration component, the crane is controlled to lift the lifting device to tension the slings, and the jacking mechanism holds the calibration component and the counterweight at the preset calibration height. Obtain the horizontal and lifting coordinates of the crane as the preset theoretical landing coordinates; Control each electric push rod to extend, so that the contact terminals of each measuring component contact the corresponding inclined surface, and obtain the extension amount detected by each encoder, which is used as the preset reference extension amount of the corresponding measuring component.

9. The crane-suspended workpiece positioning method according to claim 8, characterized in that: The tooling has a second positioning post at each end of the other diagonal line, and the calibration part has two second positioning holes that mate with the two second positioning posts respectively. The length of the second positioning post is greater than the length of the first positioning post. When the calibration component is placed on the tooling, the two first positioning holes are respectively engaged with the two first positioning pins, and the two second positioning holes are respectively engaged with the two second positioning pins. When the calibration component is lifted, the two first positioning pins first disengage from the corresponding first positioning holes, and the two second positioning pins continue to slide in the vertical direction with the corresponding second positioning holes until the calibration component reaches the preset calibration height.

10. The crane-suspended workpiece positioning method according to claim 8, characterized in that: When obtaining the preset reference extension amount, each measuring component is controlled to perform multiple contact measurements on the corresponding inclined surface; when the difference between the maximum and minimum values ​​of the extension amounts obtained by the same measuring component in each measurement is not greater than the preset range threshold, the average value of the extension amounts obtained in each measurement is taken as the preset reference extension amount of the measuring component.

Images