Novel robot arm design and implementation for hot forging press automation

Abstract

Manual handling of hot and heavy workpiece in forging press industry increases the process time and causes safety risks to workers. To increase the productivity and optimize the use of manpower, manipulators are needed to be designed for supporting the workers handling the workpiece. Designing robots for such applications is challenging since the robot suffers from a heavy payload at the arm tip, and it operates at a high speed in a large workspace. This research addresses the design and implementation of a novel robot for handling workpiece for a given forging press cell. A novel robotic mechanism is designed with two key features: (i) the addition of parallel links in between serial links, and (ii) the use of hydraulic actuators for driving robot's joints. The addition of parallel links and the use of hydraulic cylinders are to increase the structural rigidity. It is also to reduce the number of joint variables and restrict the end-effector moving parallel to the ground surface so that the robot grips and releases the workpiece in a more efficient and simplified manner. The effectiveness of the designed robot mechanism is demonstrated through functional tests, and experimental results are carried out on the implemented robot.

Kinematic and Dynamic Modelling for a Class of Hybrid Robots Composed of m Local Closed-Loop Linkages Appended to an n-Link Serial Manipulator

“…Class III is a family of the hybrid robots which are composed of some local closed-loop chains appended to a main serial mechanism [25][26][27][28][29][30][31][32][33] (Figure 1c). It is clearly seen that the main architecture of a hybrid robot Class I or II is a parallel mechanism.…”

“…To provide with desirable mechanical advantages for a hybrid robot, some local closed-loop mechanisms are added to the main serial module. For example, when designing manipulators which suffer a heavy payload and operate in a large workspace, parallelograms were added and hydraulic cylinders were used for driving some revolute joints of the manipulators [26,[28][29][30][31]. The addition of parallelograms to the main arm is to increase the rigidity of Class II consists of the hybrid robots which have a basic parallel module combined with a serial manipulator [11][12][13][14][15][16][17][18][19][20][21][22][23][24] (Figure 1b).…”

“…The parallelograms and cylinders and other links of the serial arm naturally compose local closed loops of the entire robot mechanism. Other examples of using local closed-loop linkages to optimize the design and control for a robot can be found in [26][27][28][29][30][31][32][33][34].…”

“…Apart from the aforementioned works, there have been investigations that emphasized on design and development of the hybrid robots Class III [25][26][27][28][29][30][31][32][33]. A valuable comparison of the conventional serial robot architectures and the hybrid robots Class III was presented in [34].…”

“…In the research [25], some theoretical issues related to the kinematic modelling of multi closed-loop mechanisms were addressed. In addition, some closed-form solutions to the kinematics problem of individual hybrid robots Class III were presented in [26][27][28]. These solutions played an important role in validating the design of the robots.…”