Self-adaptive edge rolling method based on EHA closed-loop main power control robot

Abstract

The invention relates to a self-adaptive edge rolling method based on an EHA closed-loop main power control robot, which is completed by using floating edge rolling equipment with EHA control, and comprises the following steps: S1, selecting a proper rolling assembly according to the shape of a plate and process requirements, and mounting the rolling assembly on the floating edge rolling equipment; s2, according to the forming angle of the plate, the rolling flanging angle and the edge rolling pass of each time are determined, a rolling assembly is driven by floating edge rolling equipment to conduct multi-pass bending with the determined angle, and the plate is bent and formed; and S3, the binding pressure output by the floating binding equipment is set, a rolling assembly is driven by the floating binding equipment to conduct constant-force rolling on the bent and formed plate, and the formed part is pressed and fixed. According to the self-adaptive edge rolling method based on the EHA closed-loop main power control robot, pre-edge rolling treatment for determining the edge turning angle and final edge rolling treatment for determining the edge rolling force are conducted respectively, and the edge rolling quality is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of hemming control methods, and in particular to an adaptive hemming method based on an EHA closed-loop active force control robot. Background Art

[0002] Robotic hemming, a specialized form of hemming, is performed using a hemming tool mounted on the end of a robot arm. It is typically performed on pre-flange panels. An industrial robot controls the hemming tool, rolling it repeatedly along the edge of the panel, wrapping the outer panel around the inner panel and joining them. Different hemming tools are equipped with different roller types to handle different panel types. A single hemming robot can hem multiple panels, or multiple robots can collaborate to hem the same panel. A variety of roller types are available, suited for different panel profiles. Hemming technology is highly adaptable to new products. Compared to traditional hemming processes, robotic hemming offers the following advantages: 1. Reliable and easy maintenance; 2. Small footprint and clean environment; 3. High degree of automation and product flexibility; 4. Fast production cycle and low equipment cost.

[0003] For example: The Chinese invention patent with the publication (announcement) number CN102513430A discloses a hemming robot and a hemming method thereof, wherein the hemming robot includes: a robot body, a rolling head device, a PLC control device, a hemming fixture table, and a robot control device, wherein the robot control device is connected to the hemming fixture table and the robot body; the rolling head device is connected to the robot body and the hemming fixture table, and the PLC control device is connected to the robot control device and the hemming fixture table. The hemming robot and the hemming method provided by the present invention can automatically complete the hemming process, and the hemming pressing of key automotive components can be completed by a single robot. At the same time, compared with the traditional hemming process, the degree of automation of the hemming process and the quality of the product are effectively improved, the labor intensity of the operator is reduced, the cost of the hemming equipment is reduced, and flexible production is achieved.

[0004] However, the existing technical solutions have the following main shortcomings in practical applications:

[0005] 1. There is no built-in pressure sensor, and the pressure value cannot be fed back at all times, resulting in uneven force on the panel during the robot hemming process, which can easily cause quality defects in the panel;

[0006] 2. There is no active force control, and the rolling pressure cannot be set;

[0007] 3. The existing hemming methods all adopt a one-time hemming forming method. When the hemming angle is too large, the quality of the hemming cannot be controlled. Summary of the Invention

[0008] To this end, the technical problem to be solved by the present invention is to overcome the problem that the existing rolling equipment and rolling methods are unable to control the rolling quality due to defects, and to provide an adaptive rolling method based on the EHA closed-loop active force control robot, which performs pre-rolling processing to determine the flanging angle and final rolling processing to determine the rolling force, thereby improving the rolling quality.

[0009] To solve the above technical problems, the present invention provides an adaptive hemming method based on an EHA closed-loop active force control robot, which is completed using a floating hemming device with EHA control, and includes the following steps:

[0010] S1. Select the appropriate rolling assembly according to the shape of the plate and the process requirements, and install the rolling assembly on the floating hemming equipment;

[0011] S2. Determine the flanging angle and number of rolling passes for each rolling process based on the forming angle of the plate, and use the floating rolling device to drive the rolling assembly to perform multiple bending passes at the determined angle to bend the plate into shape;

[0012] S3. Set the rolling pressure output by the floating rolling device, and use the floating rolling device to drive the rolling assembly to perform constant force rolling on the bent and formed plate to press and fix the formed part.

[0013] In one embodiment of the present invention, the floating hemming device comprises: an EHA electro-hydraulic linear drive device, the rolling assembly is mounted on the EHA electro-hydraulic linear drive device, and the EHA electro-hydraulic linear drive device has two control modes: position control mode and force control mode;

[0014] In step S2, the EHA electro-hydraulic linear drive device is adjusted to a position control mode to perform rolling at a determined angle;

[0015] In step S3, the EHA electro-hydraulic linear drive device is adjusted to a force control mode to perform rolling with a determined force.

[0016] In one embodiment of the present invention, the floating hemming device further includes: a driving device, which drives the EHA electro-hydraulic linear driving device to move freely in multiple directions and angles in space.

[0017] In one embodiment of the present invention, in step S1, the rolling assembly is provided with a plurality of rolling wheels with different structures, and the rolling wheels with different structures are used in different rolling scenarios.

[0018] In one embodiment of the present invention, in step S1, the rolling assembly is provided with a plurality of rolling wheels of different sizes, and the rolling wheels of different sizes are used in different rolling scenarios.

[0019] In one embodiment of the present invention, in step S2, the flanging angle of each rolling is determined to be 30-45°.

[0020] In one embodiment of the present invention, in step S2, when performing multiple roll edge treatments, the contact position of the rolling assembly with the plate is set to be the same during each roll edge treatment.

[0021] In one embodiment of the present invention, in step S2, the floating hemming device is capable of detecting changes in hemming pressure in real time.

[0022] In one embodiment of the present invention, the method further includes step S4, wherein a mathematical relationship between the rolling pressure and the rolling flanging angle is determined based on the rolling pressure detected in real time in step S2, and an offline simulation model is established.

[0023] In one embodiment of the present invention, in step S3, the rolling force of the constant force rolling is set to 1000-3000N.

[0024] The above technical solution of the present invention has the following advantages over the prior art:

[0025] The present invention discloses an adaptive hemming method based on an EHA closed-loop active force control robot, which adopts two hemming forming technologies: pre-hemming processing and final hemming processing. Two different hemming schemes are respectively adopted during the two hemming forming processes; when performing the pre-hemming processing, the pre-hemming processing is divided into a multi-pass hemming forming process for determining the flanging angle according to the hemming forming angle. Compared with one-time hemming forming, it is easier to control the quality of the hemming forming. A floating hemming device with EHA control is adopted to limit the angle of each hemming to meet the process requirements; when performing the final hemming processing, a stable hemming pressure is set, and a closed-loop control of the pressure is achieved by using a floating hemming device with EHA control to ensure that the force on the plate is stable during the hemming process, thereby achieving consistency in the hemming quality of different hemming positions. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0027] Figure 1 It is a flowchart of the steps of the adaptive hemming method based on the EHA closed-loop active force control robot of the present invention;

[0028] Figure 2 This is a flow chart of a hemming process using the adaptive hemming method based on the EHA closed-loop active force control robot of the present invention;

[0029] Figure 3It is a structural schematic diagram of the floating hemming device of the present invention;

[0030] Figure 4 It is a structural schematic diagram of the piping assembly of the present invention.

[0031] Description of the accompanying drawings: 1. rolling assembly; 11. bevel hemming wheel; 12. convex hemming wheel; 13. flat hemming wheel; 2. EHA electro-hydraulic linear drive device; 3. drive device; DETAILED DESCRIPTION

[0032] 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 the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0033] Reference Figure 1 As shown, the present invention discloses an adaptive hemming method based on an EHA closed-loop active force control robot, which is completed using a floating hemming device with EHA control, including the following steps:

[0034] S1. Select the appropriate rolling assembly according to the shape of the plate and the process requirements, and install the rolling assembly on the floating hemming equipment;

[0035] Using two-time rolling forming technology:

[0036] S2. Pre-rolling: Based on the forming angle of the plate, the angle of each rolling and the number of rolling passes are determined. The floating rolling device drives the rolling assembly to perform multiple bending passes at a determined angle to bend the plate into shape. During the pre-rolling process, the pre-rolling process is divided into a multi-pass rolling forming process with a determined flanging angle according to the rolling forming angle. Compared with a single-pass rolling forming process, it is easier to control the quality of the rolling forming. The floating rolling device with EHA control can limit the angle of each rolling to meet the process requirements.

[0037] S3. Final rolling processing: Set the rolling pressure output by the floating rolling equipment, and use the floating rolling equipment to drive the rolling assembly to perform constant force rolling on the bent and formed sheet, and press and fix the formed part; when performing the final rolling processing, set a stable rolling pressure, and use the floating rolling equipment with EHA control to achieve closed-loop control of the pressure to ensure that the sheet is subjected to stable force during the rolling process, thereby achieving consistency in the rolling quality of different rolling positions.

[0038] Reference Figure 2 As shown, in this embodiment, the above-mentioned hemming method is further disclosed by taking the example of rolling the outer panel of the automobile door cover to cover the inner panel:

[0039] Reference Figure 2As shown in (a), before the roll hemming process, the outer panel of the automobile door cover is bent by a stamping die to form a state in which one side is attached to the inner panel and the other side is bent relative to the inner panel. The folding angle mostly varies due to the different opening angles of the stamping die. The opening angle of the car door is mostly 90°. For some parts to be rolled with special requirements, such as the engine hood and front door, where the curvature changes greatly, the folding angle will be different, but it is designed to be around 90° as much as possible to ensure the folding quality.

[0040] Reference Figure 2 (b) and Figure 2 As shown in (c), the outer panel of the automobile door cover is pre-rolled. As mentioned above, according to the actual process control requirements, in the pre-rolling process, the smaller the flanging angle is, the easier it is to control the rolling quality. However, at the same time, the smaller the flanging angle is, the more pre-rolling passes will be, and the rolling time of the entire workstation will be extended accordingly. Therefore, it is necessary to ensure the quality of rolling while reducing the number of rolling passes as much as possible. In order to meet this requirement, after multiple tests, it was determined that when the flanging angle is 30 to 45 degrees each time, the rolling quality can meet the process requirements. In this embodiment, when a 90° bend needs to be completed, the bending angle can be set to 30 degrees for three bends, or the bending angle can be set to 45 degrees for two bends.

[0041] Reference Figure 2 As shown in (d), the outer panel of the automobile door cover is subjected to final rolling processing. A constant pressure value is set, and the part to be bent of the outer panel of the automobile door cover is completely pressed to 0° so that the outer panel of the automobile door cover completely covers the inner panel. As the last process of rolling forming, it often determines the final forming quality of the panel. Therefore, only by using a constant rolling pressure can the consistency of the rolling quality at different rolling positions be guaranteed.

[0042] Reference Figure 3 As shown, in this embodiment, a floating rolling device is used to drive the rolling assembly 1 to implement the above method. Specifically, the floating rolling device includes: an EHA electro-hydraulic linear drive device 2 and a drive device 3, wherein: the EHA electro-hydraulic linear drive device 32 provides control force for the rolling assembly 1, and the drive device 3 drives the rolling assembly 1 to achieve spatial movement.

[0043] Specifically, the rolling component 1 is installed on the EHA electro-hydraulic linear drive device 2, which is an electro-hydraulic actuator developed by our company. Among them, EHA (Electro-Hydrostatic Actuators) is a standard power unit formed by integrating a motor, pump, oil tank, hydraulic cylinder and control valve group into one device. The hydraulic cylinder includes a piston rod that can be extended and retracted along the cylinder body. The EHA electro-hydraulic linear drive device 2 drives the rolling component 1 to perform the rolling process by controlling the extension and retraction of the piston rod. The EHA electro-hydraulic linear drive device 2 has two control modes: position control mode and force control mode, that is, it can adjust the magnitude of the applied force by controlling the position (outputting a constant displacement), and can also adjust the displacement by controlling the magnitude of the force (outputting a constant force ), these two control modes can respectively complete the rolling process requirements of step S2 and step S3. In step S2, the EHA electro-hydraulic linear drive device 2 is adjusted to the position control mode to perform rolling at a determined angle, which can ensure that the flanging angle is 30-45° each time, thereby ensuring the quality of the flanging; in step S3, the EHA electro-hydraulic linear drive device 2 is adjusted to the force control mode to perform rolling with a determined force, which can enable the rolling component 1 to give equal (or close) rolling pressure to the surface of the plate when rolling the plane of the plate or suddenly turning to roll a pit of a certain depth, thereby ensuring the rolling quality.

[0044] Specifically, the hemming method using the EHA electro-hydraulic linear drive device 2 has the following advantages over traditional spring, pneumatic, and six-dimensional force methods:

[0045] 1. The EHA electro-hydraulic linear drive device 2 can achieve high-precision closed-loop constant force control, and the pressure can be actively adjusted according to different working conditions;

[0046] 2. The EHA electro-hydraulic linear actuator 2 has built-in force sensors and displacement sensors, which can provide real-time feedback of pressure and displacement information, achieving data closed loop and transparency;

[0047] 3. Compared with traditional debugging methods, the EHA electro-hydraulic linear drive device 2 can reduce debugging difficulty and improve debugging efficiency, and the debugging time is half of the traditional method;

[0048] 4. Compared with the six-dimensional force rolling device, the EHA electro-hydraulic linear drive device 2 is simple to debug and has low cost.

[0049] The following table 1 compares the EHA electro-hydraulic linear drive device 2 with the traditional method:

[0050] Table 1

[0051]

[0052] In this embodiment, the driving device 3 is a multi-axis robot arm. In other embodiments, the driving mechanism can also be set as a multi-axis transfer platform, as long as it can drive the EHA electro-hydraulic linear driving device 2 to move freely in multiple directions and angles in space, so that the rolling component 1 can complete the rolling process at multiple angles and multiple positions.

[0053] In the actual production process, taking the rolling hemming process of the four doors and two lids of a car as an example, it includes: a variety of rolling hemming forms applied to different parts, such as: ordinary rolling hemming, sunroof rolling hemming, water drop rolling hemming and half hemming. Different rolling components 1 need to be used for different rolling hemming processes. Even if the same rolling hemming process is used, the size of the panel must be considered and rolling components 1 of different sizes must be selected.

[0054] Reference Figure 4 As shown, the rolling assembly 1 is provided with a variety of rolling wheels of different structures and sizes, and the rolling wheels of different structures and sizes are used in different rolling scenarios. Specifically, the rolling wheels include: a bevel rolling wheel 11, a convex rolling wheel 12 and a flat rolling wheel 13. Different rolling wheels can be used in different scenarios. The bevel rolling wheel 11, the convex rolling wheel 12 and the flat rolling wheel 13 are respectively arranged on different sides; and, in this embodiment, different rolling wheels are integrated on the same rolling assembly. With the help of the rotation function of the driving device 3, it is possible to realize the rapid switching of different rolling wheels on the rolling assembly, and use different rolling wheels to perform rolling processing on the edge parts of the plate.

[0055] Specifically, the structure of the EHA electro-hydraulic linear drive device 2 and the structure of the rolling assembly 1 have been disclosed in other patents applied for by our company. Since the invention of this application lies in the adaptive rolling method, the structure of the EHA electro-hydraulic linear drive device 2 and the structure of the rolling assembly 1 will not be described here one by one.

[0056] Specifically, in step S2, when performing multiple rolling processes, the rolling component 1 is set to have the same contact position with the plate during each rolling process, and the rolling force is applied at the same position, which can ensure the flatness of the bent part when the plate is bent, and prevent the plate from being deformed in a step-like manner due to multiple pressures at different positions. In addition, applying pressure at the same position can also ensure that the force arm is the same each time the pressure is applied, thereby ensuring that the pressure value detected each time the pressure is applied is accurate.

[0057] As mentioned above, a pressure sensor is provided in the EHA electro-hydraulic linear drive device 2, and the floating rolling device can detect the change of the rolling pressure in real time through the pressure sensor. Therefore, in a specific embodiment, step S4 is also included: according to the rolling pressure detected in real time in step S2, the mathematical relationship between the rolling pressure and the rolling flanging angle is determined, and an offline simulation model is established; after the offline simulation model is established, it is trained with a large amount of data sets to realize artificial intelligence rolling processing.

[0058] Specifically, in step S3, the rolling force of the constant force rolling is set to 1000~3000N, and the actual rolling force value is determined according to the actual rolling demand of the plate; and in step S3, the rolling component 1 is set to use a constant rolling force value to move back and forth on the plate to achieve rolling processing. During the overpressure process of reciprocating movement, the rolling distance between two adjacent rollings is less than the width of the rolling wheel in the rolling component 1, that is, there is a position where the rolling overlaps between two adjacent rollings, which can ensure the flatness of the entire plate during rolling.

[0059] In the actual production process, a floating rolling device can be used to complete the rolling of multiple sets of plates. The plates are placed on the assembly line, and a floating rolling device is set up to perform rolling processing on the same position of multiple sets of plates. In this way, multiple floating rolling devices are set up at different positions along the assembly line to complete the rolling processing of the entire plate; floating rolling devices can also be used to work together to complete the rolling processing of the same set of plates, that is, the position of the plate is fixed, and multiple floating rolling devices are set up around the outer periphery of the plate to complete the rolling process of a plate at the same time.

[0060] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. An adaptive hemming method based on an EHA closed-loop active force control robot, using a floating hemming device with EHA control, characterized in that: The following steps are involved: S1. Select the appropriate rolling assembly according to the shape of the plate and the process requirements, and install the rolling assembly on the floating hemming equipment; S2. Determine the flanging angle and number of rolling passes for each rolling process based on the forming angle of the plate, and use the floating rolling device to drive the rolling assembly to perform multiple bending passes at the determined angle to bend the plate into shape; S3. Set the rolling pressure output by the floating rolling device, and use the floating rolling device to drive the rolling assembly to perform constant force rolling on the bent and formed plate to press and fix the formed part.

2. The adaptive hemming method based on the EHA closed-loop active force control robot according to claim 1, characterized in that: The floating hemming device includes: an EHA electro-hydraulic linear drive device, the rolling assembly is installed on the EHA electro-hydraulic linear drive device, and the EHA electro-hydraulic linear drive device has two control modes: position control mode and force control mode; In step S2, the EHA electro-hydraulic linear drive device is adjusted to a position control mode to perform rolling at a determined angle; In step S3, the EHA electro-hydraulic linear drive device is adjusted to a force control mode to perform rolling with a determined force.

3. The adaptive hemming method based on the EHA closed-loop active force control robot according to claim 1, characterized in that: The floating hemming device further comprises a driving device, which drives the EHA electro-hydraulic linear driving device to move freely in multiple directions and angles in space.

4. The adaptive hemming method based on the EHA closed-loop active force control robot according to claim 1, characterized in that: In step S1, the rolling assembly is provided with a plurality of rolling wheels with different structures, and the rolling wheels with different structures are used in different rolling scenarios.

5. The adaptive hemming method based on the EHA closed-loop active force control robot according to claim 1, characterized in that: In step S1, the rolling assembly is provided with a plurality of rolling wheels of different sizes, and the rolling wheels of different sizes are used in different rolling scenarios.

6. The adaptive hemming method based on the EHA closed-loop active force control robot according to claim 1, characterized in that: In step S2, the flanging angle of each rolling is determined to be 30-45°.

7. The adaptive hemming method based on the EHA closed-loop active force control robot according to claim 1, characterized in that: In step S2, when performing multiple roll edge treatments, the contact position of the rolling assembly with the plate is set to be the same during each roll edge treatment.

8. The adaptive hemming method based on the EHA closed-loop active force control robot according to claim 1, characterized in that: In step S2, the floating hemming device can detect the change of hemming pressure in real time.

9. The adaptive hemming method based on the EHA closed-loop active force control robot according to claim 8, characterized in that: The method further includes step S4, determining the mathematical relationship between the rolling pressure and the rolling flanging angle according to the rolling pressure detected in real time in step S2, and establishing an offline simulation model.

10. The adaptive hemming method based on the EHA closed-loop active force control robot according to claim 1, characterized in that: In step S3, the rolling force of the constant force rolling is set to 1000-3000N.

Images