The arm adopts single piston rod hydraulic cylinder to realize the reciprocating motion of the straight line.

The electric control system is operated by SIEMENS PLC control system [6]

Flow control of robot hand movement.

manipulator end effector

The manipulator end effector (gripper) is the key component of the workpiece for loading and unloading operations. [7]. According to the requirements of CNC machine tools, consider the implementation of gripper grip size of 30 kg and the implementation of reliability, this paper uses rack and pinion type gripper. Gear drive has the advantages of high drive accuracy, stability and reliability and high transmission torque. Because the shape of the workpiece is round

Steel type, the quality of the workpiece is 30 kg, therefore, the design of the horizontal working stroke of 40 mm, so that it can capture 80 mm diameter round steel workpiece. The gripper structure is shown in figure 3. The driving force of the piston rod is provided by the hydraulic system. The piston rod drives the middle rack, and the middle rack drives the sector gear to rotate to control the stretching of the fingers. When the piston rod

When moving to the left, the fingers are in a clamping state; when the piston rod moves to the right, the finger is released, and the gripper is put down the workpiece.

hydraulic system design

According to the requirements of the processing line, the manipulator needs 3

The movement function of an executive body, that is, the vertical arm rising and falling,

The single piston rod hydraulic cylinder controls the stretching and retraction of the wrist part, as well as

Perform clamping and opening of the gripper [8-9]. Table 1 is the master of the manipulator

Performance parameters.

In Figure 4, the M is a hydraulic pump. Three phase alternating current motor is adopted in motor. V1 and V2 are overflow valves, and V1 is responsible for regulating the total pressure of the hydraulic system. V2 regulates the discharge and pressure of the balance circuit and balances the load. V3, V4, V5 and V6 are system throttle valves, respectively, control the system inlet and outlet oil flow. 1DT~6DT is the quick shut-off valve of the system, the quick shut-off valve adopts 24 V control signal, and the on-off control can make the hydraulic system respond quickly. The specific control process is as follows.

1) when the 1DT coil is energized, the hydraulic system is put into operation; when the 1DT coil is out of power, the hydraulic system stops working.

2) when the 5DT coil is energized, the hydraulic oil into the hydraulic cylinder piston rod by V5, paw gently to perform; and when the 6DT coil is energized, the hydraulic oil quickly return oil, execute the gripper release, perform gripper speed regulation by V5 and V6.

3) when the displacement sensor signal, 4DT coil power, hydraulic oil through the V4 into the horizontal telescopic cylinder, the wrist was gently extended; when the hydraulic servo valve is energized, the wrist to perform retraction movements, protrusive movement speed regulated by V4.

4) 2DT and 3DT control the rise and fall of the manipulator, respectively, and the speed of ascension is adjusted by V3.

5) control valve and fast shut-off valve control by the PLC system to control the completion of the manipulator, rising, falling and retractable parts are equipped with travel switches, to prevent excessive travel during the abnormal action.

PLC control system design

Considering the stability and reliability of the manipulator and the flexibility and convenience of the connection of various control components, the manipulator PLC control system selects the SIEMENS S7-200 PLC which is used more in china. PLC control system using CPU224 processor, with the characteristic of 24 digital I/O and 8 analog I/O; use RS485 communication / programming port with the PPI communication protocol, MPI communication protocol and free communication ability. The main I/O assignments for the PLC control system are shown in table 2. The input point of the system is mainly the command of the manipulator, the control of the panel and the control of the stepper motor, and the output point is the hydraulic system to cut off the control of the solenoid valve and the flow control valve.