Patent Application
20250121401
This disclosure relates generally to a vehicle assembly system for sealing and skiving vehicle seams and, more particularly, to a vehicle assembly system for sealing and skiving vehicle seams, where the assembly system includes an upstream seam sealant station that determines offsets between vehicle reference points and the seams using vision sensors and sends the offsets to a downstream seam skiving station.
Various assemblies require seals. One of those assemblies is vehicles. For example, vehicles often require seals around certain vehicle parts, such as windshields, rear windows, light covers, etc., to prevent moisture and fume intrusion into the vehicle passenger compartment. Current vehicle paint shop sealing processes typically require manual operators to lay down a viscous sealant, such as a liquid polyvinyl chloride (PVC) sealant. The current process requires the manual operator to wipe (skive or squeegee) sealant off the seam and leave a small amount of sealer in the seam, which is a very labor-intensive process and wasteful of the excess sealant, thus costly. This is required for a part fit up on the sealed vehicle body.
During the vehicle manufacturing process, gauge holes provided in the floor pan or subframe of the vehicle are used as a key point of reference to build the vehicle body structure. The sub-assemblies and panels of the vehicle are assembled using the gauge holes as a base line. As the vehicle is being assembled, key body features important to the appearance of the vehicle must be maintained. In order to accomplish the dimensional requirement of the body exterior, seams of the body panels are used to adjust the key body features. This creates seam drift, where the seams constantly move dimensionally to compensate for the key body features. The seams of the vehicle require small beads of sealant to meet the process requirements. Known systems employ vison sensors to measure the seam drift for the process or fixed sensors. This vision process is very time consuming.
The PVC sealant is manufactured in large batch mixers, which creates batch to batch viscosity variations. Additionally, the PVC sealant is pre-catalyzed, and thus it is very sensitive to aging, which also affects the viscosity of the material. This variation in viscosity creates a variation in the application of the sealant onto the seams, which causes variations in the bead seam widths of the sealant applied to the seams. A too narrow sealant bead can cause a water leak into the vehicle causing a warranty claim. A too wide sealant bead can cause an assembly fit up issue where a sub-assembly cannot be assembled onto the vehicle without removing the large bead of the sealant from the interference point causing a need to manually repair the production vehicle. The current correct action for the end user is to manually adjust the pre-pressure of each bead/seam to compensate for the change in material viscosity. This manual adjustment procedure is very time consuming.
Modern vehicle assemblies employ robots to perform a variety of tasks, such as vehicle body welding and painting. The tasks being performed by vehicle assembly robots are becoming more complex and intricate. The dispensing of sealants into intricate vehicle locations is one of those areas where robots are becoming more useful. However, the seams in certain areas of the vehicle, for example, in the tail lamp area, are dimensionally unstable, which makes robotic application of a sealant more difficult.
The following discussion discloses and describes a vehicle assembly system for applying a sealant to seams on a vehicle, where the vehicle includes gauge reference holes. The assembly system includes a first assembly station having at least one vision sensor and at least one robot having a vision sensor and a dispense applicator, where the dispense applicator is configured to apply the sealant to the seams. The at least one vision sensor at the first assembly station provides images of the gauge reference holes on the vehicle, and the vision sensor on the at least one robot at the first assembly station provides images of the seams on the vehicle. The assembly system further includes a second assembly station positioned downstream from the first assembly station and having at least one vision sensor and at least one robot with a vision sensor and a skive, where the skive is configured to remove excess sealant from the seams on the vehicle. The at least one vision sensor at the second assembly station provides images of the gauge reference holes on the vehicle. The assembly system also includes a control system responsive to signals from the vision sensors. The control system uses the signals from the at least one vision sensor at both the first assembly station and the second assembly station to identify the orientation and location of the vehicle in space and uses the signals from the vision sensor on the at least one robot at the first assembly station to provide an offset of the seams relative to the gauge reference holes on the vehicle. The control system provides the offsets from the first assembly station to the second assembly station so that the second assembly station knows the location of the seams relative the gauge reference holes determined at the first assembly station. The control system also uses the signals from the vision sensor on the at least one robot at the first assembly station to measure a size of the sealant that has been dispensed by the dispense applicator, and controls a dispensing pressure of the dispense applicator so as to maintain a certain size of the sealant.
Additional features of the disclosure will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings.
The following discussion of the embodiments of the disclosure directed to a vehicle assembly system for sealing and skiving vehicle seams, where the assembly system includes an upstream seam sealant station that determines offsets between vehicle reference points and the seams using vision sensors and sends the offsets to a downstream seam skiving station is merely exemplary in nature, and is in no way intended to limit the disclosure or its applications or uses.
The stop station 14 includes two robots 18 and 20 slidable on a rail 22 and two vision sensors 24 and 26 positioned at one side of the vehicle 12 and two robots 28 and 30 slidable on a rail 32 and two vision sensors 34 and 36 positioned at the other side of the vehicle 12. Likewise, the stop station 16 includes two robots 40 and 42 slidable on a rail 44 and two vision sensors 46 and 48 positioned at one side of the vehicle 12 and two robots 50 and 52 slidable on a rail 54 and two vision sensors 56 and 58 positioned at the other side of the vehicle 12. The number of robots at the stop stations 14 and 16 are shown by example in that any reasonable number of robots can be employed for a particular operation. Each of the robots 18, 20, 28 and 30 includes a robot mounted vision sensor 60 that locates individual seams on the vehicle 12. A vision controller 62 represents all of the vision control devices necessary to control the vision sensors 60 on the robots 18, 20, 28, 30, 40, 42, 50 and 52, and the vision sensors 24, 26, 34, 36, 46, 48, 56 and 58 consistent with the discussion herein, where multiple controllers and devices would be required.
The vehicles 12 are equipped with gauge holes (not shown) on each quadrant on the body of the vehicle 12 that provide reference locations on the vehicle 12. The gauge holes are imaged by the vision sensors 24, 26, 34 and 36, and the vision controller 62 uses those images to identify the orientation and location of the vehicle 12 in space. Once the gauge holes are imaged and the location of the vehicle 12 is mathematically identified by the vision controller 62 when stopped at the stop station 14, the vision sensors 60 on the robots 18, 20, 28 and 30 provide images to the vision controller 62 that identifies the location or offset of the seams on the vehicle 12 relative to the gauge holes to which the robots 18, 20, 28 and 30 are going to apply the sealant. Particularly, the vision sensors 60 on the robots 18, 20, 28 and 30 provide seam drift location measurements and variations. The robot path is modified for the seam drift variations and the robots 18, 20, 28 and 30 apply a sealant using a suitable sealant applicator to the various seams on the vehicle 12 stopped at the station 14. As will be discussed below, the seam drift offsets from the station 14 are sent to the station 16 to be used by the robots 40, 42, 50 and 52 to perform a skiving operation to remove excess sealant on the vehicle 12 stopped at the station 16.
Traditionally, this process of identifying the offset of the seams, or some other feature on the vehicle 12, was performed at each stop station 14 and 16. This disclosure proposes determining the mathematical offsets between the seams and the gauge holes, or other features, at a first stop station, here the stop station 14, and transfer or send those offsets to downstream stop stations, such as the stop station 16, so that the offsets at the downstream stop stations do not need to be recalculated, which reduces cycle time. Further, if the offsets do not need to be recalculated at the downstream stop stations, then the robots at those stop stations may not need the vision sensors 60, which reduces hardware. The vision systems at those downstream stop stations would still need to identify the location of the gauge holes on the vehicle 12. Once the location of the gauge holes are identified, then the offsets that have been received from an upstream stop station are used to identify the location of the seams. In other embodiments, it may be desirable to have a first stop station that only determines the offsets between the gauge holes and the features on the vehicle that are then sent to downstream stop stations.
Typically, a positive displacement metering system is used to maintain a constant flow rate of sealant to the sealant applicator on the robot. As generally discussed above, as the viscosity of the material changes, the amount of pre-pressure used at the start of dispensing the sealant bead is constant and causes the start of the bead to change as the viscosity of the sealant changes. As the material viscosity decreases, the bead size will initially increase on the initial opening of the sealant applicator, which creates a larger bead than desired. As the material viscosity increases on the initial opening of the sealant applicator, a smaller sealant bead is created than desired.
This disclosure proposes using a vision system and control algorithm, for example, the vision sensors 24, 26, 34 and 36, the vision sensors 60, the vision controller 62 and the sealant dispense controller, to adjust the dispense system pre-pressure of the sealant applicator on, for example, the robots 18, 20, 28 and 30 to compensate for viscosity changes in the sealant as it is being dispensed. The vision system measures a key area of the seam, typically the start of the bead width on each vehicle 12. The vision controller 62 provides the bead width data back to the sealant dispense controller associated with each robot 18, 20, 28 and 30. The vision system also measures multiple points on the seam to provide individual seam width data and very accurate sheet metal seam location, such as less than 0.5 mm seam location accuracy. With the control algorithm, the dispense controller adjusts the pre-pressure up or down to compensate for the changing viscosity of the sealant.
This disclosure also proposes a robot sealant applicator that includes robotic vision and precision applicator tips to precisely place the sealant on the seam to eliminate or reduce the labor-intensive manual skiving process. In one embodiment, a small 3 mm to 12 mm bead width of sealant is dispensed onto the seam in the precise location to eliminate or reduce the need for manual or robotic skiving. The precision sealer applicator is designed to fit into tight areas such as tail lamp areas of the vehicle.
This disclosure also includes a discussion of a robotic process where a robot or robots utilize a precision tool to both dispense a sealant onto and skive the sealant off of a seam or seams of a vehicle. The robot applicator includes a precision applicator tip or tips to precisely place the sealant on the seam to facilitate robotic skiving, thus eliminating the labor-intensive manual skiving process. A small bead of sealant is dispensed onto the seam in the precise location, and then a skive or skives located on the tool skive off excess material to leave a very flat sealed seam, where parts such as window glass, or other sub-assemblies, can be assembled over the sealed joint and not to interfere with the glass to body seal.
In this example, the manufacturing assembly 100 includes a vehicle part 130, specifically a rear window frame of a truck, that receives the sealant. The robot arm 102 is controlled so that the nozzle 106 is positioned at the proper location near the part 130. The robot arm 102 moves the nozzle 106 along the part 130 so that as the sealant is being dispensed from the nozzle 106 the sealant is deposited as a sealant bead 132 on the part 130. Once the sealant bead 132 is deposited on the part 130, the robot arm 102 is controlled to place one of the skives 114, 116 or 118 on the sealant and move the selected skive 114, 116 or 118 along the bead 132 to remove excess sealant. The part 130 is then placed in an oven 134 to heat and cure the sealant to provide the desired seal.
The tool 154 is positioned, for example, relative to the part 130 so that the nozzle 166 is at the proper location to place the bead 132 of sealant. The controller 176 controls the dispense system 174 to pump sealant down the applicator 170 to be dispensed by the nozzle 166 as a continuous sealant stream 178 or in a pulsed manner. The controller 176 moves the tool 154 so that the nozzle 166 dispenses the sealant stream 178 to form the bead 132 and at the same time the skive 160 removes excess sealant as it is being laid down on the part 130.
As mentioned above, the skives 114, 116 and 118 need to be periodically cleaned to remove the collected sealant therefrom.
Eventually a hard film will develop on the skives 114, 116 and 118 that can't be cleaned by the skive cleaner 180, but needs to be removed.
The solvent cleaner 210 can also have a number of features. For example, the brushes can be configured to clean the front and the back of the skives at the same time, and can be configured to be removed and replaced without the use of tools. The tank 214 can have a fluid level sensor to indicate the level of the solvent therein, and can have a simple drain and replacement feature. The solvent cleaner 210 can have a closed design to minimize vapors and solvent evaporation and a closed recirculating system to maintain the solvent level. The opening 216 can be covered with a lid that automatically opens and closes. A filter reservoir can be provided to clean and maintain the solvent level.
A cleaner can also be provided to clean the applicator 72 including the nozzles 82, 84 and 86. This cleaner could have an air nozzle for sealant blow off, a design that manages airflow to eliminate overspray on vision equipment and an independent air nozzle control to optimize cleaning.
The various sealant dispensing and skiving devices and systems discussed herein can offer a number of advantages and features many of which are discussed above. For example, as discussed above, the bead size of the dispensed sealant can be measured by a vision system to adjust the dispensing pressure to dynamically adjust the bead size. Further, component gap sizes can be measured, robot speeds can be changed and/or dispense parameters can be adjusted to increase or decrease the sealant bead size. The sealant dispensing nozzles can be accurately positioned and the amount of the sealant being dispensed can be minimized to reduce the sealant waste volume, where too much sealant results in high waste, sealing defects and the need to provide additional skiving. Vision systems can be employed to locate each seam being sealed independently to adjust for sheet metal body build variations. The skives can be keyed to facilitate the accurate location of each skive. The skive assembly provides the ability to accurately install replacement skives. A position sensor can be employed to identify the extend/retract position of the skive and a vision system can be employed to provide seam offsets for accurate placement of the skive.
The foregoing discussion discloses and describes merely exemplary embodiments of the present disclosure. One skilled in the art will readily recognize from such discussion and from the accompanying drawings and claims that various changes, modifications and variations can be made therein without departing from the spirit and scope of the disclosure as defined in the following claims.
This application claims the benefit of the filing date of U.S. Provisional Application No. 63/589,730, titled, Robotic Sealer Dispense and Skive Applicator and Process, filed Oct. 12, 2023.
| Number | Date | Country | |
|---|---|---|---|
| 63589730 | Oct 2023 | US |
