Cycle time optimized production system universal joint star
High-precision and coolant-free production of universal joint stars – with simultaneous machining of the workpiece on both sides
The machine concept:
Precision, speed, reliability
During a machining cycle, two raw parts are machined simultaneously.
All sides of the workpiece are machined in one system to save time.
Further information about workpieces
- Universal Joint Stars
- Threaded and offset fittings
- 3- and 4-way valves
- Roughing the ends and tenons
- Finishing the cones
- Complete cutting process in one machine
- Very short processing times
- Coolant-free machining process significantly increases tool life (factor 2) compared to coolant-based processes
- 2 horizontal swivel axes (A1, A2) one above the other
- 4 facing heads (Z1-Z4, X1-X4)
- Tool holder on facing head: T-Max® P cutting head for turning
- Torque: 16 Nm
- Power: 8,9 kW
- Measuring station for 100% measurement. The component length and the journal diameter is measured.
- Robot for loading and unloading the measuring station
- Step conveyor, conveyor belt and loading portal to the
- Loading the machine
- Loading portal with three servo axes (U, V, W axis)
- Chip conveyor
- Machine tool: 4800 x 2000 mm
- Machine tool incl. periphery: 6500 x 3800 mm
Significantly improved tool life through dry machining.
100 % measurement with temperature compensation and automatic measured value feedback for autocorrection.
The machine has a minimum footprint including all peripheral components.
Two universal joint stars in 29.2 seconds each!
This results in a cycle time of 14.6 seconds per gimbal star!
Depending on the processing effort, the machine is able to achieve a cycle time of only 11.5 seconds when processing universal joint stars.
Experience the production line Universal Joint Star in action
Effizientes Be- und Entladen des Bearbeitungsraums
The raw parts arrive at the machine in larger quantities as bulk material. A lift and tilt device is used to load a step conveyor which places the blanks on a conveyor belt. During the infeed section on the conveyor belt, the blanks are aligned and separated at the end of the belt by two anti-cyclically operating pneumatic guide units so that they can be picked up by the robot within easy reach.
Through the infeed section on the conveyor belt, the surplus workpieces are pushed onto a chain belt and guided back into the step conveyor.
Capacity: The step feeder
The conveyor belt – separation and alignment
Agile and fast:
The robot arm
A robot now takes over the workpiece and places it in the loading portal.
In the system shown in the picture, a robot from ABB was used at the customer’s request: here the IRB 1200 model. This robot arm is predestined for the task with its small size and extreme maneuverability. The high speed also speaks for this model.
Optionally, robots of all known manufacturers can be integrated.
Ready to be taken over by the robot
Teamwork: robot and loading portal
No waiting times:
The loading portal
The loading and unloading process of the processing machine in combination with the measuring process of the finished workpieces is not performed by the robot alone. Only in combination with the loading gantry does efficient loading and unloading of the processing unit become possible: The loading gantry, which can be moved in the X, Y and Z directions, is equipped with four grippers; two parallel grippers each serve for unloading and two centric grippers for loading the machine. After the centric grippers have been loaded with the blanks, the portal moves into the machine room, where it first removes the two finished workpieces before inserting the blanks into the clamping devices arranged one above the other.
A firm grip: centric gripper for raw parts
Quality with 100 % testing
Double sided double pack:
The 2 x 2 processing
The machining process starts while the loading gantry with the two finished parts travels to the measuring station and transfers the parts there directly. The robot then loads the loading portal with two new blanks.
HK-CON relies on “interrupted” machining to compensate for any minimal shifts in the zero point that may occur due to the large machining forces during roughing: First, the face and diameter of pins 1 and 3 are simultaneously roughed. Then the star is rotated by 90° to rough the face and diameter of pins 2 and 4 and then finish directly. Finally, the star is rotated by 90° once again – cones 1 and 3 are now finished.
Facing slide with tool
Finishing the rough-machined tenons
The finished workpieces:
Removal and measuring station
The robot removes the finished workpieces from the measuring device – while the next unmachined parts to be processed go into machining – and places them on the parts chute. The measuring device is an in-house development.
In combination with a measuring computer (Marposs, Promess or other manufacturer), the two last machined journal diameters and the total length of the finished part are measured 100 percent.
Since the universal joint stars are machined dry, the finished parts have an increased temperature during measurement. This is recorded by a thermocouple integrated in the measuring station in order to calculate the exact measured value via temperature compensation. In addition to the output “ok” and “n.ok”, the
the measuring computer returns the data to the machine, which automatically makes the necessary tool corrections.
The values on which the correction is based are regularly compared with the reference values of a setting master.
Checking the dimensional accuracy
Tested and found to be good:
The robot unloads all “OK” finished parts according to the PLC command on the parts chute to a turntable.
All “not OK” parts are collected separately.
Parts chute and turntable
Sophisticated: Details make the difference!
High contact pressure
The two workpiece clamping devices are arranged vertically above each other and consist of two parts: The fixed die and the moving punch.
In order to clamp the workpiece during machining, the punch closes and presses the blank against the die. The contact pressure is maintained by a proportional pressure control valve.
Since all four journals of the star must be machined, each of the two clamping devices has an A axis so that the workpieces can be rotated through 360° during the machining cycle.
Firmly clamped between die and punch
The two opposite journals are machined simultaneously; the pressing unit is thus located in the center of the machine, so that the tools can approach the universal joint stars from the right and left simultaneously.
The tool design is identical on the right and left side and consists of two facing slides arranged vertically one above the other, which can be moved in Z direction.
In this machine, facing slides with only one tool holder are installed, which means that the dry machining takes place with only one tool plate. However, it is also possible to use cross slides with two tool holders.
In principle, the cross slides are designed with unbalance correction.
Since the front face of the trunnions is also machined, the tool holder is designed so that it can be precisely positioned via a U-axis. le four trunnions of the star are to be machined, each of the two clamping devices has an A-axis so that the workpieces can be rotated through 360° during the machining cycle.
Symmetry on two workpieces
Long tool life – coolant-free machining
HK-CON uses no coolant during the entire machining process. Thus, the tool life of the tool plates could be significantly improved by a factor of 2 compared to conventional processes using cooling lubricants.
Quantities – high output
The machining area: The heart of the system with the two two-part clamping devices arranged horizontally one above the other
Loading and unloading portal