Jan 30,2019

Automated assembly machine

In automatic assembly operations, a machine is often required to perform one of the simplest actions: grabbing the workpiece at one location and dropping it at another location. In order to achieve this task, engineers have many choices: pneumatic-driven grasping placement manipulator, motor-driven grasping placement manipulator, and cam-driven grasping placement manipulator.

Which way to use depends on the application conditions: which parts need to be assembled? The size of the work-piece? Work-piece weight? Are they in a state of space before being captured? How far do they have to move? What positioning accuracy do you need to put them in another position? Just place the work-piece in place, or must it be pressed into another work-piece? What's the size of the workplace? Requirements for machine capacity and cycle time? How much flexibility does the machine need? What constraints are there in terms of cost, time and manpower?

The pneumatic driving manipulator in the automated assembly machine is very flexible and convenient to install, and the purchase cost is low. However, the acceleration and speed of the pneumatic manipulator are difficult to control accurately, especially when the motion is stiff and the impact vibration is large, so it is only suitable for the occasion where the motion cycle is more than 3 seconds (corresponding working speed is 20 pieces/minute), and the energy utilization efficiency of the cylinder is low (about 16%), so its use cost is high.

Motor-driven manipulator in the automated assembly machine is easy to install, flexible and can stop at many points. If the parts assembly system needs to be changed or redesigned, it can be simply reprogrammed. But the motor-driven manipulator needs to be equipped with complex electrical control system. If this kind of manipulator is used to complete simple repetitive work, it will appear that the cost is high.

The cam manipulator with cam in the automated assembly machine as driving mechanism has the unique advantages of simple structure, stable movement, accurate phase, fast working rhythm, low failure rate, low cost and long service life. Usually, it realizes the combination of direct and direct motion of the manipulator arm through the joint action of two independent cams and the motion conversion of the subsequent linkage mechanism. The composite motion of the manipulator is formed and controlled by the outlines of the cams, and the cam curve is given by the design according to the motion requirements of the manipulator. Especially, it is worth pointing out that because the cam manipulator is a pure mechanical transmission device, as long as its input shaft is connected with the main drive shaft of the main engine through synchronous payment (such as sprocket and gear pair), it can ensure that its action with the main engine is always synchronized in time phase and working rhythm, thus greatly improving the safety of the machine. This is the shortcoming of the non-pure mechanical transmission manipulator.

However, in the application practice of the manipulator, it is also found that the existing direct and direct cam manipulators have obvious defects, that is, the angle between the axis of the power input shaft and the motion plane of the manipulator can not be flexibly selected by the user according to the specific layout needs. This defect seriously restricts its popularization and application.

Circular turret clearance partitioning motion general layout is widely used in automatic assembly machine design. The work-piece is clamped, lifted, moved forward and lowered by a direct cam manipulator and placed in the work-piece seat of the main engine turret. The main engine turret is driven by a cam intermittent mechanism, and the input shaft of the intermittent mechanism is connected with the main drive shaft through a sprocket pair. If the input shafts of all cam manipulators can be connected with the main drive shafts through sprocket pairs, the movement of all cam manipulators in the whole machine can keep synchronization with the movement of the main turret in time phase and working rhythm.

Obviously, the input shafts of a few manipulators are parallel to the main drive shafts, and they are easily connected to the main drive shafts by chain drive. The input shaft and the main drive shaft of the other manipulators are not parallel, and the angle between them is mostly inconsistent. Obviously, it is difficult to transfer power from the main drive shaft to their input shaft. Of course, power can be transmitted through a series of mechanical transformations, but its structure is complex and its cost is high.

So is there a solution that all the input shafts of the cam manipulator and the main drive shafts of the machine can be connected by simple sprocket drive? If there is a way to arrange the motion planes of all cam manipulators according to the path of workpiece transmission, and their input axes can be adjusted to be parallel to the axes of the main drive axes, then the connection will become easy to achieve.

Based on the full analysis of the existing cam-type grasping and placing manipulators at home and abroad, the automatic mechanical team of Billion Reno Company has developed a unique cam manipulator to support the implementation of the above solutions through years of efforts. The angle between the input axis of the manipulator and the motion plane of the manipulator arm can be arbitrarily selected by the user within 0-360 degrees. Users can flexibly orient the direct motion plane of each manipulator when designing the overall layout of the automatic machine, and then adjust the power input axis of each manipulator to a position convenient for connecting with the power output axis of the superior. This simplifies the design, reduces the complexity of the machine, shortens the development cycle of the machine, reduces the overall cost, while maintaining the advantages of pure mechanical transmission, that is, the movement rhythm between the working devices connected by pure mechanical transmission is always coordinated and synchronized. YIHEDA's cam manipulator provides a low-cost grasping-shifting-placing device with compact structure, easy layout and positioning, and flexible selection of the orientation of power input shaft for the development of automatic machines.

Billion Reno-Cam Manipulator is a modular product with various specifications for users to choose on demand. It is equipped with various end-effector (such as grippers and suckers) as upper and lower feeding devices and handling devices. With its unique input shaft flexibility, the existing cam manipulator has broken the limited use of the cable due to its poor flexibility and greatly broadened the cam manipulator in a variety of automatic machinery. And the application prospect of automatic production line.

In summary, Cam Manipulator has the following unique advantages:
1. The orientation of the power input shaft can be flexibly selected, the installation layout is flexible and high, and it is convenient to integrate with the main drive system of the main engine.
2. Modular products, compact structure, a variety of motion trajectories, forms for users to choose.
3. Maintain the advantages of stable movement, accurate phase, fast working rhythm, low failure rate, low cost, high safety and long service life of cam drive.
4. It reduces the responsibility of the overall design of the machine, simplifies the control system of the machine, reduces the design and manufacturing costs of the machine, and shortens the development cycle.