CN116692397A - An automatic separation device and separation method for a cylinder head casting engineering pallet - Google Patents

Abstract

The invention belongs to the technical field of engine cylinder head casting engineering, and discloses an automatic separation device and a separation method for cylinder head casting engineering pallets. The method includes: the pallet positioner obtains in real time whether the workpiece pallet sliding or rolling hard-contacting on the slideway moves to a set position; Extend to the front of the workpiece pallet to prevent the workpiece pallet from moving forward; after the air circuit controller receives the positioning information of the workpiece pallet fed back by the pallet positioner, it further regulates the cylinder of the air circuit system of the cycle operation to continue to push the workpiece and transport it to the next process . In the present invention, the driving force is provided by adding an air cylinder, a slideway is added to the bottom of the workpiece pallet, and a pallet positioning, stop and limit device is provided, so that the workpiece slides and separates from the pallet, thereby eliminating the lifting operation of heavy objects during separation. Among them, the air circuit system of circulating operation is used to improve the safety of the automatic mechanism.

Description

An automatic separation device and separation method for a cylinder head casting engineering pallet

technical field

The invention belongs to the technical field of engine cylinder head casting engineering, and in particular relates to an automatic separation device and method for cylinder head casting engineering pallets.

Background technique

There is a process of separating the casting from the pallet in the casting process of the engine cylinder head. It is necessary to lift and remove the workpiece, return it to the pallet, and re-enter the pouring process. The tray separation process in the prior art generally includes: lifting, moving, putting down, and returning to the tray.

Through the above analysis, the problems and defects of the existing technology are: the existing method needs to lift the workpiece, the TNGA2.5L cylinder head blank (including sand core) weighs about 25 kg, and there is an overweight operation. Although other cylinder heads are lighter, Frequent lifting of heavy objects poses hidden dangers.

Contents of the invention

In order to overcome the problems existing in the related technologies, the disclosed embodiments of the present invention provide an automatic separation device and separation method for cylinder head casting engineering pallets, in particular to a TNGA2.5L cylinder head casting engineering pallet automatic separation device.

The technical solution is as follows: a method for automatically separating cylinder head casting engineering pallets, comprising the following steps:

S1, the pallet positioner obtains in real time whether the workpiece pallet that slides or rolls in hard contact on the slideway moves to the set position;

S2, when the pallet positioner detects that the workpiece pallet moves to the set position, the air path controller controls the stop limit device to extend to the front side of the workpiece pallet, preventing the workpiece pallet from continuing to move forward;

S3. After receiving the workpiece pallet positioning information fed back by the pallet positioner, the air circuit controller further regulates the cylinders of the air circuit system for cyclic operation to continue to push the workpiece and transport it to the next process.

Further, the method for the air path regulator to receive the workpiece pallet positioning information fed back by the pallet positioner to further regulate the gear limit device or the cylinder includes:

Step 1, the pallet positioner collects a large number of real-time running data of the workpiece pallet and the data to be run in the next step and makes it into the input features and labels of the neural network, and trains to obtain a network model that fits the gait characteristics of the workpiece pallet;

Step 2, using the network model fitting the gait characteristics of the workpiece pallet to obtain the velocity increment of the workpiece pallet, and then deriving the motion adjustment trajectory of the workpiece pallet through integral derivation;

Step 3, adding the error parameters to the neural network framework and performing training, predicting the motion transformation and the variance of the motion transformation, and obtaining the motion position indicators of different prediction segments;

Step 4: Correct the motion position of the neural network by combining the uncertainty and the stable operation control method of the cylinder to obtain the positioning adjustment trajectory;

Step 5, adjusting the trajectory according to the positioning, and the gas circuit controller further regulates the movement position of the gear limit device or the cylinder.

In step one, a data-driven workpiece pallet motion state detection model is constructed and trained, and the trained data-driven workpiece pallet motion state detection model is used to determine the relative position and uncertainty based on the data measured by the pallet positioner.

Further, the construction and training of a data-driven workpiece pallet motion state detection model includes:

(1) Obtain the relevant data collected by the pallet locator, and use the gradient method to calculate the attitude quaternion based on the acquired data, and use the attitude quaternion to convert the acceleration and angular velocity from the pallet locator coordinate system to the local positioning detection coordinate system ;

(2) Transform the quaternion into Euler angles in the order of motion position angle, pitch angle, and roll angle, and take the difference between the motion position angle of the Euler angle and the attitude angle to convert the motion adjustment trajectory from the local positioning detection coordinate system to the global coordinate system;

(3) Build a data-driven workpiece pallet motion state detection model, use standard data sets and self-collected data sets as training sets and test sets, train the data-driven workpiece pallet motion state detection model, and randomly Rotate features and labels for each window based on the data-driven workpiece pallet motion detection model.

Further, using the attitude quaternion to convert the acceleration and angular velocity from the pallet positioner coordinate system to the local positioning detection coordinate system includes:

Use the following formula to convert the vector a _IMU in the pallet positioner coordinate system to a _INS in the local positioning detection coordinate system:

in, Represents the conjugate conjugate of a quaternion.

In the second step, the error parameters are added to the data-driven workpiece pallet motion state detection model and trained to predict the motion transformation and its variance, and calculate the uncertainty of the prediction results; at the same time, the predicted motion position index is obtained.

In step 4, the digital-analog fusion positioning model is constructed to obtain the positioning result by expanding the Kalman filter to tightly couple the audio distance measurement and the high-frequency velocity vector output by the data-driven workpiece pallet motion state detection model.

In step four, the uncertainties include:

σ _data = mean(v _i )

σ _total = σ _data + σ _model

Among them, _σtotal represents the total uncertainty of prediction; _σdata represents data uncertainty; _σmodel represents model uncertainty;

Motion position correction for neural networks involves:

First, use the following formula to calculate the correction angle of the straight line sequence

in, Represents the average stability of the production scene, c _i represents the correlation between the production scene information and the direction of the equipment, represented by the difference between the average motion position angle of each straight line sequence and the average neural network PDR direction; c _a represents the anchor point, the anchor point It is the correlation quantity on the stable production scene environment and low-uncertainty straight-line sequence;

Secondly, the adjustment trajectory predicted based on the data-driven workpiece pallet motion state detection model is rotated Adaptive correction of the adjustment trajectory is performed.

Another object of the present invention is to provide an automatic separation device for cylinder head casting engineering pallets to implement the automatic separation method for cylinder head casting engineering pallets. The device includes:

The air circuit system for circulating operation is used to push the workpiece pallet through the cylinder;

The workpiece tray is used to hold the workpiece;

The lower part of the workpiece pallet slides or rolls in hard contact with a slideway;

A pallet positioner for detecting the moving position of the workpiece pallet is installed on the end side of the slideway;

A stop limit device for limiting the forward movement of the workpiece pallet is also installed on the end side of the slideway;

After the pallet positioner detects that the workpiece pallet moves to the set position, the air circuit regulator controls the stop limit device to extend to the front of the workpiece pallet to prevent the workpiece pallet from moving forward; The air circuit system regulates the recovery of the cylinder through the air circuit controller, returns to the origin, and pushes the next workpiece.

Further, the height of the stop and limit device is lower than the height of the workpiece pallet, and the stop and limit device adopts a hidden structure. After the pallet positioner detects that the workpiece pallet moves to the set position, the extension of the stop and limit device is controlled by the air circuit regulator. Go to the front of the workpiece pallet and stop the workpiece pallet from moving forward.

Combining all the above-mentioned technical solutions, the advantages and positive effects of the present invention are: by increasing the driving force provided by the cylinder, a slideway is added to the bottom of the workpiece pallet, and a pallet positioning, stop and limit device is set to separate the workpiece from the pallet, thereby Eliminate heavy lifting during separation. Among them, the air circuit system of circulating operation is used to improve the safety of the automatic mechanism.

Description of drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the disclosure and together with the description serve to explain the principles of the disclosure;

Fig. 1 is a flow chart of the automatic separation method for the cylinder head casting engineering pallet provided by the embodiment of the present invention;

Fig. 2 is a flow chart of the method for further regulating the gear-limiting device or the cylinder by the gas path regulator receiving the workpiece pallet positioning information fed back by the pallet positioner provided by the embodiment of the present invention;

Fig. 3 is a schematic diagram of an automatic separation device for a cylinder head casting engineering pallet provided by an embodiment of the present invention;

In the figure: 1. Pneumatic circuit system for cyclic operation; 2. Cylinder; 3. Workpiece pallet; 4. Workpiece; 5. Slideway; 6. Pallet positioner; .

Detailed ways

In order to make the above objects, features and advantages of the present invention more comprehensible, specific implementations of the present invention will be described in detail below in conjunction with the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, the present invention can be implemented in many other ways different from those described here, and those skilled in the art can make similar improvements without departing from the connotation of the present invention, so the present invention is not limited by the specific implementation disclosed below.

Embodiment 1, as shown in Figure 1, the method for automatically separating the cylinder head casting engineering pallet provided by the embodiment of the present invention includes:

S1, the pallet positioner 6 obtains in real time whether the workpiece pallet 3 sliding or rolling hard-contacting on the slideway 5 moves to a set position;

S2, when it is detected that the workpiece pallet 3 moves to the set position, the stopper device 7 is controlled to extend to the front side of the workpiece pallet 3 through the air circuit regulator 8, preventing the workpiece pallet 3 from continuing to move forward;

S3, after receiving the positioning information of the workpiece pallet 3 fed back by the pallet positioner 6, the gas circuit controller 8 further regulates the cylinder 2 of the gas circuit system 1 in the cycle operation to continue to push the workpiece 4 and transport it to the next process.

The invention utilizes the action of the cylinder to provide power, and realizes the pallet separation by pushing and sliding instead of lifting; and ensures the safety during the operation by using the two-hand operation circuit.

The present invention simplifies the work by designing a new-style pallet separation device, reduces the work of lifting heavy objects, and improves the operability of the process.

As shown in Fig. 2, in step S2-step S3, the method for further regulating the gear limit device 7 or the cylinder 2 by the gas path controller 8 receiving the positioning information of the workpiece pallet 3 fed back by the pallet positioner 6 includes:

S201, the pallet locator 6 acquires a large number of real-time running data of the workpiece pallet 3 and data to be run in the next step and makes them into input features and labels of the neural network, and trains to obtain a network model that fits the gait characteristics of the workpiece pallet 3;

S202, using the network model fitting the gait characteristics of the workpiece pallet 3 to obtain the velocity increment of the workpiece pallet 3, and then deriving the movement adjustment trajectory of the workpiece pallet 3 through integral derivation;

S203, adding error parameters to the neural network framework and performing training, predicting motion transformation and motion transformation variance, and obtaining motion position indicators of different prediction segments;

S204, by combining the uncertainty and the stable operation control method of the cylinder, correcting the motion position of the neural network to obtain a positioning adjustment trajectory;

S205, adjusting the track according to the positioning, the gas circuit controller 8 further regulates the movement position of the gear limit device 7 or the cylinder 2 .

In the embodiment of the present invention, in step S201, a data-driven workpiece pallet 3 motion state detection model is constructed and trained, and the data-driven workpiece pallet 3 motion state detection model based on the training is based on the data measured by the pallet positioner 6. Data determine relative position and uncertainty.

The construction and training based on the data-driven workpiece pallet 3 motion state detection model includes:

(1) Obtain the relevant data collected by the pallet positioner 6, and calculate the attitude quaternion based on the acquired data using the gradient method, and use the attitude quaternion to convert the acceleration and angular velocity from the pallet positioner 6 coordinate system to the local positioning detection coordinates Department;

(2) Transform the quaternion into Euler angles in the order of motion position angle, pitch angle, and roll angle, and take the difference between the motion position angle of the Euler angle and the attitude angle to convert the motion adjustment trajectory from the local positioning detection coordinate system to the global coordinate system;

(3) Build a data-driven workpiece pallet 3 motion state detection model, use standard data sets and self-collected data sets as training sets and test sets, train the data-driven workpiece pallet 3 motion state detection model, and train The process randomly rotates the features and labels of each window based on the data-driven workpiece pallet 3 motion state detection model.

Using the attitude quaternion to convert the acceleration and angular velocity from the pallet positioner 6 coordinate system to the local positioning detection coordinate system includes:

Use the following formula to transform the vector a _IMU in the 6-coordinate system of the pallet positioner into a _INS in the local positioning detection coordinate system:

in, Represents the conjugate conjugate of a quaternion.

In step S202, the error parameters are added to the data-driven workpiece pallet 3 motion state detection model and trained to predict the motion transformation and its variance, and calculate the uncertainty of the prediction result; at the same time, obtain the predicted motion position index.

In step S204, a digital-analog fusion positioning model is constructed to obtain a positioning result by tightly coupling the audio ranging observations with the extended Kalman filter and the high-frequency velocity vector output by the data-driven workpiece pallet 3 motion state detection model.

In step S204, the uncertainty includes:

σ _data = mean(v _i )

σ _total = σ _data + σ _model

Among them, _σtotal represents the total uncertainty of prediction; _σdata represents data uncertainty; _σmodel represents model uncertainty;

Motion position correction for neural networks involves:

First, use the following formula to calculate the correction angle of the straight line sequence

in, Represents the average stability of the production scene, c _i represents the correlation between the production scene information and the direction of the equipment, represented by the difference between the average motion position angle of each straight line sequence and the average neural network PDR direction; c _a represents the anchor point, the anchor point It is the correlation quantity on the stable production scene environment and low-uncertainty straight-line sequence;

Secondly, the adjustment trajectory predicted based on the data-driven workpiece pallet 3 motion state detection model is rotated Adaptive correction of the adjustment trajectory is performed.

Embodiment 2, Fig. 3 is the cylinder head casting engineering tray automatic separation device provided by the embodiment of the present invention, including:

The air circuit system 1 for circulating operation is used to push the workpiece pallet 3 through the cylinder 2;

The workpiece tray 3 is used to hold the workpiece 4;

The lower part of the workpiece pallet 3 slides or rolls in hard contact with a slideway 5;

A pallet positioner 6 for detecting the movement position of the workpiece pallet 3 is installed on one side of the end of the slideway 5;

A stop limit device 7 for limiting the workpiece pallet 3 to move forward is also installed on the end side of the slideway 5;

When the pallet positioner 6 detects that the workpiece pallet 3 moves to the set position, the stopper device 7 stops the workpiece pallet 3 from moving forward, and the workpiece 4 is pushed out from the workpiece pallet 3 by the cylinder 2 and sent into the slideway 5 Enter the next process; the height of the stop limit device 7 is lower than the height of the workpiece pallet 3, so as to avoid hindering the separation of the workpiece 4 from the workpiece pallet 3; the stop limit device 7 adopts a hidden structure, and the workpiece pallet 3 is detected by the pallet positioner 6 After moving to the set position, the stop limit device 7 is controlled by the air circuit regulator 8 to extend to the front side of the workpiece pallet 3 to prevent the workpiece pallet 3 from moving forward; 1. Regulate the recovery of the cylinder 2 through the air circuit regulator 8, return to the original point, and push the next workpiece 4. Such reciprocating operation solves the problems existing in the manual tray separation process in the prior art, saves labor and realizes safe production.

In the above-mentioned embodiments, the descriptions of each embodiment have their own emphases, and for parts that are not detailed or recorded in a certain embodiment, refer to the relevant descriptions of other embodiments.

The information interaction and execution process between the above-mentioned devices/units are based on the same idea as the method embodiment of the present invention, and its specific functions and technical effects can be found in the method embodiment section, and will not be repeated here.

Those skilled in the art can clearly understand that for the convenience and brevity of description, only the division of the above-mentioned functional units and modules is used for illustration. In practical applications, the above-mentioned functions can be assigned to different functional units, Completion of modules means that the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiment may be integrated into one processing unit, or each unit may exist separately physically, or two or more units may be integrated into one unit, and the above-mentioned integrated units may adopt hardware It can also be implemented in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the protection scope of the present invention. For the specific working process of the units and modules in the above system, reference may be made to the corresponding process in the foregoing method embodiments.

Based on the technical solutions described in the above-mentioned embodiments of the present invention, the following application examples can be further proposed.

According to an embodiment of the present application, the present invention also provides a computer device, which includes: at least one processor, a memory, and a computer program stored in the memory and operable on the at least one processor, When the processor executes the computer program, the steps in any of the foregoing method embodiments are implemented.

An embodiment of the present invention also provides a computer-readable storage medium, where a computer program is stored in the computer-readable storage medium, and when the computer program is executed by a processor, the steps in the foregoing method embodiments can be implemented.

The embodiment of the present invention also provides an information data processing terminal. When the information data processing terminal is implemented on an electronic device, it provides a device input interface to implement the steps in the above-mentioned method embodiments. The information data Processing terminals are not limited to mobile phones, computers, and switches.

The embodiment of the present invention also provides a regulator, which is used to provide a device input interface to implement the steps in the above method embodiments when implemented on an electronic device.

The embodiment of the present invention also provides a computer program product, which, when the computer program product is run on the electronic device, enables the electronic device to implement the steps in the foregoing method embodiments.

If the integrated unit is realized in the form of a software function unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the procedures in the method of the above-mentioned embodiments in the present application can be completed by instructing related hardware through a computer program. The computer program can be stored in a computer-readable storage medium. The computer program When executed by a processor, the steps in the above-mentioned various method embodiments can be realized. Wherein, the computer program includes computer program code, and the computer program code may be in the form of source code, object code, executable file or some intermediate form. The computer-readable medium may at least include: any entity or device capable of carrying computer program codes to a photographing device/terminal device, a recording medium, a computer memory, a read-only memory (Read-Only Memory, ROM), a random access memory (Random Access Memory, RAM), electrical carrier signals, telecommunication signals, and software distribution media. Such as U disk, mobile hard disk, magnetic disk or optical disk, etc.

The above is only a preferred specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any person familiar with the technical field is within the technical scope disclosed in the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles shall fall within the protection scope of the present invention.

Claims (10)

1. The automatic separation method for the tray of the cylinder cover casting engineering is characterized by comprising the following steps of:

s1, a tray positioner (6) acquires whether a workpiece tray (3) sliding or rolling on a slideway (5) moves to a set position in real time;

s2, when the tray positioner (6) detects that the workpiece tray (3) moves to a set position, the gas path regulator (8) controls the stop limiting device (7) to extend to the front side of the workpiece tray (3) so as to prevent the workpiece tray (3) from continuing to move forwards;

s3, after the gas path regulator (8) receives the workpiece tray (3) positioning information fed back by the tray positioner (6), the gas cylinder (2) of the gas path system (1) regulating and controlling the circulation operation continuously pushes the workpiece (4) and conveys the workpiece to the next working procedure.

2. The automatic separation method of the tray for the cylinder cover casting engineering according to claim 1, wherein the method for controlling the stop limiting device (7) to extend to the front side of the workpiece tray (3) comprises the following steps:

step one, a tray positioner (6) acquires real-time operation data and next data to be operated of a workpiece tray (3) to manufacture input features and labels of a neural network, and trains to obtain a network model fitting gait features of the workpiece tray (3);

step two, obtaining the speed increment of the workpiece tray (3) by utilizing a network model fitting gait characteristics of the workpiece tray (3), and obtaining a motion adjustment track of the workpiece tray (3) through integral deduction;

step three, adding error parameters to a neural network frame, training, predicting motion transformation and motion transformation variance, and obtaining motion position indexes of different prediction sections;

step four, correcting the movement position of the neural network by combining uncertainty and a cylinder steady operation regulation method to obtain a positioning adjustment track;

fifthly, according to the positioning and adjusting track, the air path regulator (8) further regulates and controls the movement position of the stop limiting device (7) or the air cylinder (2).

3. The automatic separation method of the tray for the cylinder cover casting engineering according to claim 2, wherein in the step one, training to obtain a network model fitting the gait characteristics of the workpiece tray (3) comprises: and constructing and training a data-driven workpiece tray (3) motion state detection model, and determining the relative position and uncertainty based on the data measured by the tray positioner (6) by utilizing the trained data-driven workpiece tray (3) motion state detection model.

4. A method for automatically separating a tray for cylinder head casting engineering according to claim 3, wherein the construction and training of a data-driven workpiece tray (3) motion state detection model comprises:

(1) Acquiring related data acquired by the tray positioner (6), calculating to obtain a posture quaternion by using a gradient method based on the acquired data, and converting acceleration and angular speed from a coordinate system of the tray positioner (6) to a local positioning detection coordinate system by using the posture quaternion;

(2) Converting quaternion into Euler angles according to the sequence of the motion position angles, pitch angles and roll angles, and converting the motion adjustment track from a local positioning detection coordinate system to a global coordinate system by taking the motion position angle difference value of the Euler angles and the attitude angles;

(3) And constructing a data-driven workpiece tray (3) motion state detection model, training the data-driven workpiece tray (3) motion state detection model by using a standard data set and a self-collected data set as a training set and a testing set, and randomly rotating the characteristics and labels of each window of the data-driven workpiece tray (3) motion state detection model in the training process.

5. The automatic separation method of a tray for cylinder head casting engineering according to claim 4, wherein converting acceleration and angular velocity from a tray positioner (6) coordinate system to a local positioning detection coordinate system by using attitude quaternion comprises:

vector a in the coordinate system of the pallet positioner (6) is determined by _IMU Conversion to a under a local positioning detection coordinate system _INS ：

wherein ,representing the conjugate of the quaternion.

6. The automatic separation method of a tray for cylinder head casting works according to claim 2, wherein in the second step, adding error parameters to the neural network frame and training comprises: adding error parameters to a motion state detection model of a workpiece tray (3) based on data driving, training, predicting motion transformation and variance thereof, and calculating uncertainty of a prediction result; and simultaneously obtaining the predicted movement position index.

7. The automatic separation method of a tray for cylinder head casting works according to claim 2, wherein in the fourth step, performing the motion position correction on the neural network includes: and constructing a digital-analog fusion positioning model, and tightly coupling an audio ranging observed quantity with a high-frequency speed vector output by a workpiece tray (3) motion state detection model based on data driving through extended Kalman filtering to obtain a positioning result.

8. The method of automatic separation of a casting pallet for cylinder heads according to claim 2, wherein in step four, the uncertainty includes:

σ _data ＝mean(v _i )

σ _tota1 ＝σ _data +σ _model

wherein ,σ_total Representing the total uncertainty of the prediction; sigma (sigma) _data Representing data uncertainty; sigma (sigma) _model Representing model uncertainty;

performing kinematic location correction on a neural network includes:

first, benefitCalculating correction angle of straight-line sequence by

wherein ,representing the average stability of the production scenario, c _i Representing the association quantity of the production scene information and the equipment direction, wherein the association quantity is represented by the difference value of the average motion position angle and the average neural network PDR direction of each straight-line sequence; c _a Representing an anchor point, the anchor point being a stable production scenario environment and an associated quantity on a straight-through sequence of low uncertainty;

then, the adjustment track predicted by the motion state detection model of the workpiece tray (3) based on data driving is rotatedAnd performing adaptive correction of the adjustment track.

9. An automatic separation device for a tray in cylinder head casting engineering, characterized in that the automatic separation method for the tray in cylinder head casting engineering according to any one of claims 1 to 8 is implemented, and the device comprises:

the gas path system (1) is used for pushing the workpiece tray (3) through the gas cylinder (2);

a workpiece tray (3) for holding a workpiece (4);

the lower part of the workpiece tray (3) is in sliding or rolling hard contact with a slideway (5);

a tray positioner (6) for detecting the movement position of the workpiece tray (3) is arranged at one side of the tail end of the slideway (5);

a stop limiting device (7) for limiting the workpiece tray (3) to continuously move forwards is further arranged on one side of the tail end of the slideway (5);

after the tray positioner (6) detects that the workpiece tray (3) moves to a set position, the gas circuit regulator (8) controls the stop limiting device (7) to extend to the front side of the workpiece tray (3) so as to prevent the workpiece tray (3) from continuing to move forwards; when the workpiece (4) is pushed to a proper position, the gas path system (1) for circulating operation regulates and controls the recovery of the cylinder (2) through the gas path regulator (8), and returns to the original point to push the next workpiece (4).

10. The automatic separation device for the cylinder cover casting engineering trays according to claim 9, wherein the height of the blocking limiting device (7) is lower than that of the workpiece tray (3), the blocking limiting device (7) adopts a hidden structure, and after the tray positioner (6) detects that the workpiece tray (3) moves to a set position, the blocking limiting device (7) is controlled to extend to the front side of the workpiece tray (3) through the air channel regulator (8) so as to prevent the workpiece tray (3) from continuing to move forwards.