KUKA KR12 SCARA Operations Essentials

KUKA KR12 SCARA Operations Essentials

KUKA KR 12 SCARA is a four axis articulated robot designed for small high-speed handling, assembly, inspection, and machining scenarios. This product family includes KR 12 R650 Z400、KR 12 R650 Z340 CR、KR 12 R750 Z400、KR 12 R750 Z340 CR、KR 12 R750 Z600、KR 12 R850 Z400  And models such as KR 12 R850 Z340 CR. They are usually paired with KR C5 micro control cabinets and smartPAD-2 handheld programmers, with a body weight of approximately 49 to 53 kg, a rated load of 6 kg, a maximum load of 12 kg, a maximum arm span covering 650 mm, 750 mm, and 850 mm, and Z-axis travel covering 340 mm, 400 mm, and 600 mm. For on-site engineers, the true factors that affect equipment stability are often not single parameters, but the coordination between installation foundation, load data, stopping distance, safety circuit, cable wiring, ball screw spline lubrication, A1 gearbox oil change, and maintenance cycle. The following summarizes the key technical points of this series from the perspective of operation and troubleshooting.

Mechanical structure and shaft configuration

The KR 12 SCARA adopts a four axis SCARA structure, mainly composed of arms, ball screw splines, connecting rod arms, bases, and electrical equipment. A1 is the rotation of the turntable, A2 is the rotation of the connecting rod arm, A3 is the vertical lifting and lowering, and A4 is the end rotation. The ball screw spline is responsible for the composite transmission of Z-axis linear motion and end rotation, and is one of the most important components to pay attention to in maintenance. The rotation range of A1 and A2 is usually ± 145 °, with some models A2 having a range of ± 135 °; The A3 stroke is divided into -400 mm, -340 mm, or -600 mm according to the model; the A4 rotation range is usually ± 355 °. In terms of speed, A1 is about 400 to 450 °/s, A2 is about 645 to 665 °/s, A3 is about 1.1 to 1.3 m/s, and A4 can reach 2700 °/s. The pose repeatability accuracy is XY ± 0.025 mm, Z ± 0.005 mm, and R ± 0.005 °. The standard model has a protection level of IP20, and the CR model has an IP54, suitable for clean rooms or special environments. The controller is KR C5 micro, with a working temperature of 0 to 42 ° C and a storage and transportation temperature of -25 to 55 ° C. When operating at low temperatures, it is necessary to first reduce the speed and acceleration for preheating to avoid condensation and mechanical shock.

Installation foundation and foundation requirements

KR 12 SCARA must be installed on the ground, with a steel base that is at least 20mm thick, has a flatness of no more than 0.4, and a maximum allowable horizontal deviation of 5 °. The base is not within the scope of robot supply and needs to be prepared by the user themselves. The installation hole diagram must be processed strictly according to the size, fixed with four M12 or M14 screws, and centered with two locating pins. The installation surface must be clean, flat, free of rust and adhesives. The robot must be lowered vertically and slowly to avoid damaging the positioning pin. If the locating pin is damaged, it must be replaced. When tightening screws, gradually apply force in diagonal order. After installation, use M4 hex nuts and tapered spring washers for the grounding wire, with a tightening torque of approximately 2.8 Nm. The equipotential connection must be checked according to VDE 0100 and EN 60204-1. If the base is not installed horizontally or fixed firmly, it will cause abnormal force on the A1 gearbox, changes in stopping distance, and a decrease in repeatability accuracy.

Load, flange and process force

The rated load of KR 12 SCARA is 6 kg, with a maximum load of 12 kg. The maximum additional load on the arm is 2 kg, but the additional load on the arm of KR 12 R750 Z600 is 0 kg. The load center of gravity is based on the A4 flange surface, and KUKA. Load must be used to check the load mass and mass moment of inertia. The load diagram shows curves for 2 kg, 4 kg, 6 kg, 7 kg, 8 kg, 9 kg, 10 kg, 11 kg, 12 kg, etc. The farther the load is from the flange, the smaller the allowable mass. Load data must be input into the control cabinet, otherwise trajectory planning, acceleration, and braking distance will deviate from reality. To reduce vibration, the center of gravity shift of the end load should be minimized as much as possible. In terms of flange load, during operation, the axial force F (a) is about 150 N, the radial force F (r) is about 600 N, the tilting torque M (k) is about 30 Nm, and the torque M (g) is about 25 Nm; during emergency stop, F (a) is about 500 N, F (r) is about 600 N, M (k) is about 30 Nm, and M (g) is about 40 Nm. The tool must be calculated according to the actual load to ensure long-term bearing of these forces and torques. The A3 process force is limited to 100 N, exceeding this limit can cause abnormal wear on the ball screw splines and guide rails.

Stop distance and stop time

The stopping distance is the distance or angle that a robot travels from triggering a stop signal to completely stopping, equal to the reaction distance plus the braking distance, and is part of the danger zone. STOP 0 immediately closes the drive and the brake acts simultaneously; STOP 1 is controlled braking along the trajectory, and after a delay, the drive closes and brakes; STOP 2 means not turning off the drive or applying the brake, and stopping on a regular braking ramp. Taking STOP 0 as an example, the A1 stopping distance of KR 12 R650 Z400 is about 59.57 °, A2 is about 83.63 °, and A3 is about 30.21 mm; the A1 stopping distance of KR 12 R650 Z340 CR is about 60.95 °, A2 is about 84.92 °, and A3 is about 19.98 mm; the A1 stopping distance of KR 12 R750 Z400 is about 46.35 °, A2 is about 40.60 °, and A3 is about 16.16 mm; the A1 stopping distance of KR 12 R750 Z340 CR is about 64.64 °, A2 is about 74.50 °, and A3 is about 20.14 mm; the A1 stopping distance of KR 12 R750 Z600 is about 48.09 °, A2 is about 55.41 °, and A3 is about 46.54 mm; and the A1 stopping distance of KR 12 R850 Z400 is about 51.00 °. A2 is about 44.38 °, A3 is about 16.57 mm; KR 12 R850 Z340 CR has A1 of about 66.81 °, A2 of about 61.58 °, A3 of about 16.24 mm. The stopping time varies with POV, elongation, and load mass. The larger the mass and speed in the STOP 1 curve, the longer the stopping time and distance are usually. The superposition of axial motion will further elongate the stopping distance. Brake wear is related to operating mode, application, and STOP 0 times. It is recommended to check the stopping distance at least once a year. If the stopping distance significantly increases, check the brake, load data, POV, and mechanical transmission.