Thursday, May 6, 2010

Team H - Wrap it - Package Wrapper

Main Design Concept

In our project, the main concept is that we use a pair of grippers to rotate the box then wrap four sides and a pair of hinges folds the other two sides to complete the wrapping.  After rotating the box, there will be another gripper like an arm to move the box to the folding subsystem which primarily consists of the hinges. Since we use a relatively simple method for wrapping, the system will focus on the functional efficiency on the premise of the box being completely wrapped.

Figure 1. Grippers to rotate the box
Figure 2. Folder to complete wrapping
Team Members and Responsibilities
Veeren Mandalia: Electronics and Control
Xiaorui Wang: Electronics and Control
Boyuan Li: Mechanical Design and Manufacture
Chen Zhang: Mechanical Design and Manufacture
System Overview
There are six sub-systems in our whole system. Here is the picture of the system.
Figure 3. Automatic Package Wrapper
Overall process of the system
Step 1. Set the box in the initial position which is held by the grippers
Step 2. Adhesive sprayed on the face of the box
Step 3. Stick the paper to the face of the box manually
Step 4. Grippers rotate the box for one loop and wrap the four faces
Step 5. Arm holds the box and grippers move away
Step 6. Arm puts the box on the hinges and hit the box into the folder
Step 7. The movable hinge push the box to the other till the box touch the limit switch
Step 8. Hinges fold extra paper on the box and wrapping completed
Decriptions of sub-systems
Figure 4. Feeder
*  Initially feed the paper
*  Keep feeding paper when the gripper rotating the box
The function of feeder is to feed the paper and make sure it can be move exactly with the box rotating. The wood block on the left side of the feeder is because we did not calculate the length of the sub system accurately.
Figure 5. Gripper
*  Hold the box and finish the initial feeding
*  Rotate and wrap the box in one loop
As is shown in the Figure 5, the pair of grippers is our design of gripper system. First, we designed a sideway along which the slide block can move. Then the gripper system can move horizontally and adjust the distance to hold the box. Since rotating the box needs enough torque to make gripper be able to rotate the box around the shaft, UHU tac was stuck to the surface of the gripper header to hold the box tightly. Also the torque is generated by the friction, so the box can be rotated in several loops. The shaft of the motor was an important part for connecting the header and the motor.
Figure 6. Cutter
*  Hold the paper after wrapping four faces of the box
*  Cut the extra paper
We use a knife linked to a timing belt to realize the cutting function. Since the knife and the wood block is so light that the cutter may be out of the slot, we add several metal on the cutter to make sure it is stable. Before the cutter works, the servo will hold the paper to make it cut easier. When the motor works, the timing belt will move with the pulley, and the cutter starts to work.
Figure 7. Arm
*  Hold the box and place it to the folder
*  Smash the box into the folder
This system consists of two parts: the arm and the hand. The hand can hold the box after wrapping the four sides of the box. The sponge was also added on the finger to create the friction. In addition, the two servos were connected to the finger, so we can set up the speed and the precise position to control the gripper. After moving out the gripper system, the arm then is actuated to place the box on the folding machine. Another important functionality of the arm system is it can be used as a hammer to press the box into the folding machine. For example, since the extra paper prevents the arm moving the box, we control the two servos and make it as a hammer to smash the box in the folding machine.
Figure 8. Sprayer
*  Spray the adhesive on the box to finish the initial feeding
The sprayer is used to spray the adhesive on the box and then stick the paper on it. The principle of this system is a lever mechanism that has mainly three parts. First, we connected one side of the lever to the solenoid so that it can provide the lifting force. Second, the spray adhesive is on the other side and the button can be pressed by the lever. A pipe was connected to the header button in order to extend spray distance and could prevent the adhesive affecting other parts. The position of the support point is very important because it will decide the ratio of the forces on the two sides.
Figure 9. Folder
*  Detect size of the box
*   Fold the extra paper on the top face
When the box is set in the folder, the movable hinge will be controlled by rack and pinion and push the box to the other hinge until the box touch the limit switch. Then the hinges will fold the extra paper on the top face of the box. Since there would be adhesive sprayed on the surface before, the extra paper will stick to the box and the wrapping process is finished.

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