CN115488960B

CN115488960B - Clamp for clamping paper stack and control method

Info

Publication number: CN115488960B
Application number: CN202211090500.XA
Authority: CN
Inventors: 刘长印; 戴志辉; 李铖; 彭晓文
Original assignee: Masterwork Group Co Ltd
Current assignee: Masterwork Group Co Ltd
Priority date: 2022-09-07
Filing date: 2022-09-07
Publication date: 2024-11-15
Anticipated expiration: 2042-09-07
Also published as: CN115488960A

Abstract

The invention provides a clamp for clamping a paper stack and a control method, wherein the clamping method comprises the following steps: s1: initializing a clamp; s2: the control system performs contour scanning on the whole bracket shooting to determine the coordinates of the bracket shooting in a robot coordinate system; s3: performing single-stack measurement, performing data verification and repeated measurement, controlling a robot to move after obtaining single-stack coordinates through measurement, enabling the lower end of a push-pull part of a clamp to cling to the lower edge of a target stack, and completing positioning work before material taking; s4: taking materials, and transferring the clamp to a set position for discharging: and after the discharging is finished, the clamp moves to the initial position of the positioning measurement of the next paper stack, and the actions of material taking, transferring and discharging are circulated. The invention can finish the accurate unstacking operation, and realize no paper scattering, no paper remaining and no paper puncturing; precisely measuring the contour and the position of the bracket shooting; and the position of the paper stack is accurately measured, the grabbing and placing operation of the paper stack is completed, and the paper laying process is reliably removed.

Description

Clamp for clamping paper stack and control method

Technical Field

The invention relates to a paper stack clamp, in particular to a clamp for clamping a paper stack and a control method.

Background

At present, in the post-printing process flows of printing, gilding, die cutting, inspecting products, pasting boxes and the like in the printing and packaging industry, taking a single-paper full waste-removing die cutting machine as an example, feeding the die cutting machine for one piece of paper each time, discharging the material into a plurality of mutually independent box types after removing waste edges and connecting points, and arranging each mutually independent sheet-shaped box type into mutually independent paper stacks by a paper collecting mechanism of the die cutting machine through a plurality of die cutting. In order to prevent the unstable phenomenon caused by the too high height of a single paper stack, when the paper stack reaches a certain height, one paper layer needs to be placed, then the processes of die cutting and placing the paper layer are repeated for a plurality of times, the part between the two paper layers is called a layer, and 1-10 layers are generally collected on a tray according to factors such as layer height. The next procedure of die cutting is to check or paste a box, when checking or pasting the box, a single Zhang Pianzhuang box type is required to be processed, so that a paper stack is required to be taken off from a tray, then the paper stack is placed on a checking machine or a box pasting machine, when one layer of paper stack is taken out, a paper laying operation is required to be carried out on the next layer of paper stack, and the process of taking the paper stack and the paper laying out from the tray and processing is called unstacking. Because the gravity action of the paper stack and the paper stack has certain flexibility, the vertical positioning of different paper stacks on the same paper stack is different, each paper in the single paper stack is independent, the thickness of the single paper is generally less than 1 millimeter, and the lowest paper of the paper stack on the paper stack must be accurately positioned during unstacking, so that the effects of good unstacking, no paper residue and no paper puncture can be achieved. At present, the middle links from the die cutting to the inspected product, the inspected product to the paste box or the die cutting to the paste box are always completed manually, and the unstacking is difficult in an automatic mode.

Disclosure of Invention

The invention provides a clamp for clamping a paper stack and a control method, which are used for solving the problem of unstacking, and can achieve the effect of automatic unstacking by dynamically detecting paper stack parameters and controlling a robot, and achieve the effects of stable and reliable unstacking, beat scanning and positioning, paper stack grabbing and placing and paper laying removal by controlling the movement of the robot, so that paper is not scattered, paper is not left and paper is not punctured. The technical scheme is as follows:

The clamp for clamping the paper stack comprises a clamp body, wherein a quick-change disc is arranged at the top of the clamp body, side plates are arranged at two sides of the clamp, and a bottom plate is arranged at the bottom of the clamp; the front end of the clamp body is provided with a pressing cylinder and a push-pull part, the side surface of the clamp body is provided with a side suction part, the rear surface of the clamp body is provided with a rear suction part, and the side suction part and the rear suction part are both provided with suction nozzles; the bottom plate is provided with a pushing and inserting part and an air tap, and the air tap is arranged at the front end of the bottom plate.

The lower air cylinder comprises a first lower air cylinder and a second lower air cylinder which are arranged in parallel, and a positioning detection device is arranged at the rear end of the second lower air cylinder and adopts a photoelectric sensor or a visual detection sensor.

A gripping method by a gripper for gripping a stack of sheets, comprising the steps of:

s1: initializing a clamp;

s2: the control system performs contour scanning on the whole bracket shooting to determine the coordinates of the bracket shooting in a robot coordinate system;

S3: performing single-stack measurement, performing data verification and repeated measurement, controlling a robot to move after obtaining single-stack coordinates through measurement, enabling the lower end of a push-pull part of a clamp to cling to the lower edge of a target stack, and completing positioning work before material taking;

S4: taking materials, and transferring the clamp to a set position for discharging: after the discharging is completed, the clamp moves to the initial position of the positioning measurement of the next paper stack, and the actions of material taking, transferring and discharging are circulated;

S5: when a plurality of layers of paper stacks are arranged on the bracket, the paper laying (not limited to the paper laying, and the object playing the role of separating the two layers of paper stacks) is removed after one layer of paper stack is taken.

Further, in step S1, the process of initializing the jig includes the following:

S11: and (3) preliminary self-checking of the clamp: when a control system of the clamp is started, the control system judges whether each cylinder is possibly in a state of clamping a paper stack according to the current state of the clamp, and releases the cylinder for clamping to ensure that no paper exists in the clamp;

s12: the robot returns to the origin: the robot and the clamp return to the set initial positions.

S13: and (3) comprehensive self-checking of the clamp: the control system controls each action mechanism of the clamp to return to the initial state.

S14: and (3) signal reset: the control system resets signals of the respective actuating mechanisms of the robot and the jig.

Further, in step S2, the profile scanning is to detect the distance between the paper stack and the zero point of the ranging sensor by using the ranging sensor on the fixture, and acquire a series of data by controlling the motion path of the robot, so as to obtain the profile parameters of the paper stack.

Further, the contour scanning includes the steps of:

s211: the control system calculates the height of the theoretical paper stack by setting parameters and a coordinate conversion formula, and the clamp is positioned 5-1000mm above the upper surface of the paper stack at the center of the theoretical bracket shooting position;

S212: the control system acquires the value of the ranging sensor at the moment, checks whether the actual value and the theoretical value are within the error range of 0.1-300mm, and if the error is within the range, the height of the clamp is further reduced, and the clamp continues to descend to the position 0.1-290mm away from the height of the paper stack;

S213: the clamp is horizontally moved, and the edge of the paper stack is detected through the instant mutation of the ranging value of the ranging sensor, so that the contour coordinates of the edge of the paper stack in the XY direction are preliminarily obtained;

S214: acquiring a distance measurement sequence of the edge of the paper stack in the XY direction by adopting a triangulation mode, so as to obtain the accurate position of the edge of the paper stack, and further calculating the contour data of the paper stack by establishing a model, wherein the contour data comprises the accurate coordinate position and the rotation angle of the edge of the paper stack in the X Y direction; the rotation angle refers to the rotation angle of the measured stack of sheets to be removed (a bracket beat) relative to the robot coordinate system.

Further, in step S212, if the verification fails, that is, the verification exceeds the range, the method includes the following steps:

S221: the clamp translates the width of the material model by 1/2, a ranging numerical value is obtained, whether the actual value and the theoretical value are in an error range or not is checked, and if the checking is successful, the step S213 is continued; otherwise, continuing to step S222;

S222: the clamp translates the length of the material type by 1/2, the ranging value is obtained, whether the actual value and the theoretical value are in the error range or not is checked, and if the checking is successful, the step S213 is continued; otherwise, the machine is stopped in an alarm mode.

Further, in step S4, the material taking process is as follows:

S41: the first lower pressure cylinder is pressed down until the corresponding pressure detection device detects rated pressure;

S42: the push-pull part is pushed forward, so that the lower part of the push-pull part is contacted with the lower part of the target paper stack and a certain pressure is applied, and the pressure is acquired from the corresponding pressure detection element;

S43: rotating the clamp to increase the pressure between the push-pull part and the target paper stack;

s44: the push-pull part is lifted up to enable the bottom of the target paper pile to tilt;

s45: blowing the air tap to enable all the papers of the target paper stack to leave the paper laying part at one side close to the push-pull part;

s46: the air cylinder of the pushing and inserting part extends out to enable the front fork of the air cylinder to be positioned below the target paper stack and support the paper stack;

s47: the second pressing cylinder presses down until the pressure detection device detects rated pressure;

S48: the first lower pressure cylinder ascends to finish the paper taking action.

Further, in step S4, the discharging process is as follows:

S51: the first lower pressure cylinder is pressed down until the corresponding pressure detection device detects rated pressure;

S52: the second pressing cylinder rises until the pressure is lower than the set pressure;

s53: the fork of the pushing and inserting part retreats, and the paper stack falls on the target position;

s54: the first lower pressure cylinder rises, and the discharging action is completed.

Further, in step S5, the paper laying is removed, specifically as follows:

S61: calculating the height coordinate and the paper spreading size of the paper spreading according to the model, positioning a ranging sensor of the clamp right above the center of the paper spreading (the position is not limited to be right above the center, and only the paper spreading can be detected), rotating the side suction part to a horizontal position in the moving process, and determining whether to rotate the rear suction part and extend the rear suction part according to the paper spreading size;

S62: measuring a current ranging value, checking whether the current ranging value is consistent with the model, if so, positioning the air suction nozzle at the central position of the paper laying, descending to a position 1mm-500mm away from the paper laying, otherwise, shifting the clamp, and measuring and checking again;

s63: the air suction nozzle or an additional air blowing device is used for blowing air, so that the phenomenon of paper residue in the paper taking process is prevented;

S64: the clamp is controlled to move downwards, so that the plane of the suction nozzle of the side suction part and/or the rear suction part is reliably contacted with the paper laying;

s65: vacuumizing the suction nozzle to ensure that the paper is firmly adsorbed on the suction nozzle, detecting the vacuum degree, if the vacuum degree reaches the set vacuum degree, carrying out the next step, otherwise, breaking the vacuum, and repeating the paper sucking and paving operation after shifting for a certain distance;

S66: the clamp is controlled to ascend for a small distance, so that the paper laying sucked by the air suction nozzle is separated from the upper surface of the lower paper stack;

S67: moving or rotating the suction nozzle to prevent the lower surface of the paper laying from adhering to the lower paper;

s68: and (5) vertically lifting the paper laying, and controlling the clamp to transfer the paper laying to a proper position.

The clamp for clamping the paper stack and the control method can finish the operation of accurately unstacking, and realize paper scattering, paper residue and paper puncturing; precisely measuring the contour and the position of the bracket shooting; accurately measuring the position of the paper stack and completing the grabbing and placing operation of the paper stack; the paper laying process can be reliably removed.

Drawings

FIG. 1 is a schematic overall execution flow diagram of the control method for stack gripping;

FIG. 2 is a schematic flow chart showing an overall implementation of the control method for stack gripping;

FIG. 3 is a schematic diagram of the contour scanning flow;

FIG. 4 is a schematic illustration of a specific implementation of the contour scan;

FIG. 5 is a schematic diagram of a triangulation scheme;

FIG. 6 is a schematic illustration of a single stack positioning measurement;

Fig. 7 is a schematic view of the structure of the clamp for gripping a stack of sheets.

Detailed Description

As shown in fig. 7, the clamp for clamping the paper stack comprises a clamp body, wherein the top of the clamp body is provided with a quick-change disc 1, two sides of the clamp are provided with side plates 10, and the bottom of the clamp is provided with a bottom plate 11; the front end of the clamp body is provided with a pressing cylinder and a push-pull part 4, the side surface of the clamp body is provided with a side suction part 7, the rear surface of the clamp body is provided with a rear suction part 8, and the side suction part 7 and the rear suction part 8 are both provided with suction nozzles; the bottom plate 11 is provided with a push-insert part 5 and an air tap 6, and the air tap 6 is arranged at the front end of the bottom plate 11. The quick-change disc 1 can be matched with a quick-change disc installed on the manipulator, so that the quick-connection and the disassembly of the clamp are realized, the clamp is convenient to replace, and the quick-change disc can be replaced by a bolt and screw connection mode. The side plates 10 and the bottom plate 11 function to support and fix the clamp body.

The lower pressure cylinder comprises a first lower pressure cylinder 2 and a second lower pressure cylinder 3, and is used for pressing paper stacks. The rear end of the pressing cylinder is provided with a photoelectric sensor 9, the photoelectric sensor 9 is used for positioning the clamp according to the position of the paper stack, and the photoelectric sensor 9 can be replaced by a visual detection sensor. The push-pull part 4 is positioned at the rear lower part of the lower pressing cylinder and is used for pushing and pulling the paper stack.

The push plate and the pull plate of the push-pull part 4, the fork of the push-and-insert part 5, the suction nozzle fixing plate of the side suction part 7 and the suction nozzle fixing plate of the rear suction part 8 are all driven by an air cylinder, the suction nozzle of the side suction part 7 is arranged on the suction nozzle fixing plate of the side suction part 7, and the suction nozzle of the rear suction part 8 is arranged on the suction nozzle fixing plate of the rear suction part 8.

The invention also provides a control method for clamping the paper stack, which is shown in fig. 1 and 2 and comprises the following steps:

s1: the fixture is initialized, and the specific operation is as follows:

s11: and (3) preliminary self-checking of the clamp: when the control system of the clamp is started, the control system judges whether each cylinder is likely to be in a state of clamping the paper stack according to the current state of the clamp, if the cylinder is likely to be in the state of clamping the paper stack, the cylinder for clamping is firstly loosened to enable the paper to fall off, but the phenomenon that the cylinder in the state of clamping the paper is loosened at the original point (which can be defined at the initial position of the clamp and is the highest position of the clamp generally) of the clamp, so that the paper stack falls off from the clamp and the paper stack collapses and breaks off is avoided.

S12: the robot returns to the origin: after the clamp performs preliminary self-inspection, the robot and the clamp return to the set initial positions under the condition that the clamp does not clamp paper.

S2: the control system performs contour scanning on the whole bracket shooting, and the specific operation is as follows:

S21: judging whether the whole bracket shooting is subjected to contour scanning or not, if the whole bracket shooting is not subjected to contour scanning, starting to perform contour scanning so as to determine the coordinates of the bracket shooting in a robot coordinate system, and determining target coordinate values (namely the coordinate values of the bracket shooting in the robot coordinate system), wherein the contour scanning comprises bracket shooting contour rough measurement and bracket shooting contour accurate measurement as shown in fig. 3; at this time, "bracket shooting" in the bracket shooting outline rough measurement and the bracket shooting outline accurate measurement refers to bracket shooting and unstacked paper carried by the bracket shooting outline rough measurement and the bracket shooting outline accurate measurement are relative values, and the difference is that the numerical value of the accurate measurement is more accurate.

S22: if the profile is scanned, calculating an accurate position required to start measurement according to the stored target coordinate value, wherein the accurate position is used as a measurement starting position from the robot to the first stack.

Further, in step S21, the profile scanning is to detect the distance between the paper stack and the zero point of the ranging sensor by using the ranging sensor on the fixture, and acquire a series of data by controlling the motion path of the robot, so as to obtain the profile parameters of the paper stack. As shown in fig. 4, the specific description is as follows:

s211: the control system calculates the theoretical paper stack height by setting parameters and a coordinate conversion formula, and the clamp descends to the position 5mm-1000mm away from the paper stack height;

If the error between the actual value and the theoretical value is greater than half of the height of the paper stack, the clamp is sequentially shifted to the X Y direction and checked in consideration of the possibility that the light does not fall on the uppermost paper stack, if the check is passed, the next step is continued, otherwise, the alarm is stopped.

Wherein, anchor clamps are towards X Y orientation skew in proper order and check-up, include the following step:

S221: the clamp translates the width of the material model by 1/2, a ranging numerical value is obtained, whether the actual value and the theoretical value are in an error range or not is checked, and if the checking is successful, the step S213 is continued; otherwise, continuing to step S222; the material type refers to shape information data such as length, width, folding angle and the like of the material of the sheet Zhang Chengpin, and the width of one side of the sheet is generally taken. The purpose of the translation is to check errors in the setup data and the actual data, ensuring that the ranging position is in the upper surface of the stack to be disassembled rather than in the gap between the stacks (one stack of sheets is listed on one bracket, each time the clamp grips a stack of sheets).

Further, the order of translation 1/2 width and 1/2 length in S221 and S222 may be interchanged.

Wherein, the profile coordinates of the edge of the paper stack in the XY direction are preliminarily obtained, the method comprises the following processing steps:

S2131: the robot moves to the extreme position of the in-tray photographing and placing X direction, the jump of the ranging sensor is detected in the moving process, if the jump exceeds the set layer height of 1/4-1, the X edge is found, the Y direction is shifted by 1/10-1/2 of the width/length, the robot is moved into the range of the in-tray photographing paper stack, the jump is detected, if the jump exceeds the set layer height of 1/4-1 and the jump is within the range of 0.1-300mm with the theoretical error, the X edge is found for the second time. (single or multiple X edge coordinates can be found in a pass method)

S2132: the robot moves to the Y-shaped similar limit position of the support shooting placement, the jump of the ranging sensor is detected in the moving process, if the jump exceeds 1/4-1 set layer height, the Y edge is found, the X direction is offset by 1/10-1/2 material width/length, the robot moves into the range of the support shooting paper stack, the jump is detected, if the jump exceeds 1/4-1 set layer height and the jump is within the range of 0.1-300mm with theoretical error, the Y edge is found for the second time. (one or more Y-edge coordinates can be found in a pass method)

S2133: and taking a larger or smaller value of the XY coordinates according to the layout relation of the actual bracket shooting and the robot, wherein the principal principle of the selection of the XY coordinates refers to the coordinate value of the nearest position to the robot.

S214: based on the preliminary measurement result in step S213, the reference point of the accurate measurement position is determined based on the preliminary measurement result, as shown in fig. 5, by adopting a triangulation method, the ranging sequence of the edge of the paper stack in the XY direction is obtained, so as to obtain the accurate position of the edge of the paper stack, and further, the contour data of the paper stack, including the accurate coordinate position, rotation angle, etc. of the edge of the paper stack in the X Y direction, is calculated by establishing a model. The rotation angle refers to the rotation angle of the measured stack of sheets to be removed (a bracket beat) relative to the robot coordinate system.

Furthermore, before operation, the system needs to acquire material type data to be unstacked, namely, data of the length, width, layer number, layer height, length direction gap, width direction gap and bracket shooting height of the small paper stack. The bracket beats need to be placed in a specific area. And setting parameters, a bracket shooting placement area and a robot base height by combining the touch screen to build a model.

S3: and (3) single-stack measurement is carried out, data verification and repeated measurement are carried out, the robot is controlled to move after the single-stack coordinates are obtained through measurement, the lower end of the push-pull part 4 of the clamp is clung to the lower edge of the target paper stack, and positioning work before material taking is completed.

In order to prevent displacement of the stack during gripping or falling apart of the stack, a positioning measurement is performed for each small stack (single stack) during destacking. The coordinates of the first stack of sheets are calculated from the sheet stack profile data, the robot is controlled to a position where the measurement starts, as shown in fig. 6, and then the coordinates of the edges of the individual stacks are measured according to the principle of triangulation. The moving direction of the clamp is the length direction of the paper to be unstacked, the laser irradiation position is the center position of the paper in the width direction, the edge of the paper stack is detected when the value is suddenly changed according to the value change of the distance measuring sensor obtained in real time, and the bottom coordinates of the paper stack are calculated through a trigonometric function relation.

S4: the material is taken, and the process is as follows:

s41: the first hold-down cylinder 2 is pressed down until the corresponding pressure detecting means detects the rated pressure.

S42: the push-pull portion 4 is pushed forward so that the lower portion of the push-pull portion 4 contacts the lower portion of the target sheet bundle and applies a certain pressure, which is acquired from the corresponding pressure detecting element.

S43: the clamp is rotated 0.01-10 degrees depending on the actual situation, thereby increasing the pressure between the push-pull 4 and the target stack. The rotation angle is required to be specifically tested according to the related information such as the clamp assembly process, the shape of the paper stack to be disassembled, the position of the paper stack to be disassembled in the whole paper stack and the like.

S44: the push-pull part 4 is lifted up to lift the bottom of the target paper pile.

S45: the air tap 6 blows to enable all the papers of the target paper stack to leave the paper laying at the side close to the push-pull part 4.

S46: the cylinder of the push-insert part 5 extends out to enable the front end fork of the cylinder to be positioned below the target paper stack and support the paper stack.

S47: the second depressing cylinder 3 is depressed until the pressure detecting means detects the rated pressure.

S48: the first pressing cylinder 2 is lifted up to finish the paper taking action.

The clamp lifts up the paper stack, transfers and places the paper stack to a target position, and the push-pull part 4 retreats and descends to finish the reset operation in the lifting process.

S5: discharging, wherein the process is as follows:

s51: the first hold-down cylinder 2 is pressed down until the corresponding pressure detecting means detects the rated pressure.

S52: the second hold-down cylinder 3 is raised until the pressure is lower than the set pressure.

S53: the fork of the push-in part 5 retreats and the stack of sheets falls to the target position.

S54: the first pressing cylinder 2 ascends, and the discharging action is completed.

And after the discharging is finished, controlling the robot to move to the initial position of the positioning measurement of the next paper stack, and circularly taking, transferring and discharging.

S6: when a plurality of layers of paper stacks are arranged on the bracket, the laying paper needs to be removed after one layer of paper stack is taken out, and the concrete steps are as follows:

S61: the height coordinates and the paper laying size of the paper laying are calculated according to the model, a distance measuring sensor of the clamp is positioned right above the center of the paper laying (the position is not limited to be right above the center, and only the paper laying can be detected), the side suction part 7 is rotated to a horizontal position in the moving process, and whether the rear suction part 8 is rotated or not and whether the rear suction part 8 is extended or not are determined according to the paper laying size.

S62: and measuring the current ranging value, checking whether the current ranging value is consistent with the model, if so, positioning the air suction nozzle at the central position of the paper laying, descending to the position 1-500 mm away from the paper laying, otherwise, shifting the clamp, and measuring and checking again.

S63: the air suction nozzle or the additional air blowing device can blow air to prevent the phenomenon of paper residue in the paper taking process.

S64: the clamp is controlled to move downwards so that the suction nozzle plane of the side suction part 7 and/or the rear suction part 8 reliably contacts the paper laying.

S65: the vacuum suction nozzle is vacuumized, the paper is firmly adsorbed on the suction nozzle, the vacuum degree is detected, if the vacuum degree reaches the set vacuum degree, the next step is carried out, otherwise, the vacuum is broken (the vacuum state is destroyed), and the paper sucking and paving operation is repeated after a certain distance is deviated.

S66: the clamp is controlled to rise for a short distance to enable the laying paper sucked by the air suction nozzle to be separated from the upper surface of the lower layer paper stack.

S67: the suction nozzle is moved or rotated to prevent the lower surface of the paper from sticking to the lower paper.

Although the invention has been described hereinabove with reference to embodiments, various modifications thereof may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In particular, the features of the disclosed embodiments may be combined with each other in any manner as long as there is no structural conflict, and the exhaustive description of these combinations is not given in this specification merely for the sake of omitting the descriptions and saving resources. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. The clamping method of the clamp for clamping the paper stack comprises the steps that the clamp comprises a clamp body, wherein a quick-change disc is arranged at the top of the clamp body, and a bottom plate is arranged at the bottom of the clamp body; the front end of the clamp body is provided with a pressing cylinder and a push-pull part; the bottom plate is provided with a push-insert part and an air tap, the air tap is arranged at the front end of the bottom plate, the lower air cylinder comprises a first lower air cylinder and a second lower air cylinder which are arranged in parallel, the rear end of the second lower air cylinder is provided with a positioning detection device, and the positioning detection device adopts a photoelectric sensor or a visual detection sensor;

the clamping method comprises the following steps:

s1: initializing a clamp;

The process of taking the material is as follows:

S48: the first lower pressure cylinder ascends to finish the paper taking action;

After the step S4, when a plurality of layers of paper stacks are arranged on the bracket shooting, laying paper is arranged between the two layers of paper stacks, and the laying paper is removed after one layer of paper stack is taken out, the concrete steps are as follows:

S61: calculating the height coordinate and the paper spreading size of the paper spreading according to the model, positioning a ranging sensor of the clamp right above the center of the paper spreading, swinging down the side suction part to a horizontal position in the moving process, and determining whether to swing down the rear suction part and extend the rear suction part according to the paper spreading size;

2. The method for stack gripping according to claim 1, characterized in that: in step S1, the process of initializing the jig includes the following:

S11: and (3) preliminary self-checking of the clamp: when a control system of the clamp is started, the control system judges whether each cylinder is possibly in a state of clamping a paper stack according to the current state of the clamp, and releases the cylinders for clamping;

3. The method for stack gripping according to claim 1, characterized in that: in step S2, the profile scanning is to detect the distance between the paper stack and the zero point of the distance measuring sensor by using the distance measuring sensor on the clamp, and acquire data by controlling the motion path of the robot, so as to obtain the profile parameters of the paper stack.

4. A method for stack gripping according to claim 3, characterized in that: the contour scan includes the steps of:

5. The method for stack gripping according to claim 4, characterized in that: in step S212, if the verification fails, i.e. the range is exceeded, the steps of:

6. The method for stack gripping according to claim 1, characterized in that: in step S4, the discharging process is as follows: