MK8220SD×750 CNC Orbiting Crankshaft & Camshaft Grinding Machine
MK8220/SD double wheelhead CNC orbiting crankshaft & camshaft grinder is designed for the automotive and diesel engine industries, mainly used for large batch grinding of crankshafts. It adopts HZC CNC system, with eight CNC axes controlling the rotation of the headstock torque motor (C-axis), wheelhead feed (X-axis, X1-axis), and worktable movement (Z-axis, Z1-axis).
Through the linkage control of the grinding wheel feed axes (X-axis, X1-axis) and the rotation of the headstock (C-axis), high-precision orbiting tangential point grinding of crankshaft
connecting rod journals is achieved. The machine can do automatic cycle of multi-gear cylindrical grinding of crankshaft connecting rod journals and main bearing outer surfaces in one-time clamping.
The machine has automatic clamping of workpieces, automatic axial positioning of workpieces, automatic measurement of the main spindle journal diameter, constant linear speed rotation of the wheel, automatic dressing and compensation of the wheel, automatic jump direction and other functions.
Specifications
| Technical Indicators | Unit | Specification |
| Working range | – | – |
| Max. rotation diameter | mm | Φ200 |
| Max. workpiece length | mm | 750 |
| Center height | mm | 200 |
| Max. workpiece weight | kg | 80 |
| CBN wheel size | mm | Φ600×30 |
| Max. wheel linear speed | m/s | 120 |
| Wheelhead feed (X-axis, X1-axis) | – | – |
| Wheelhead travel | mm | 300 |
| Wheelhead feed speed | mm/min | 0.1～4000 |
| Wheelhead feed resolution | mm | 0.0005 |
| Min. X-axis programming increment | mm | 0.001 |
| Carriage (Z-axis, Z1-axis) | – | – |
| Carriage travel | mm | 1250 |
| Carriage moving speed | mm/min | 1～5000 |
| Carriage moving resolution | mm | 0.001 |
| Min. Z-axis programming increment | mm | 0.001 |
| Headstock (C-axis) | – | – |
| Headstock rotation speed | r/min | 10～100 |
| Headstock spindle taper bore | – | Morse 5 |
| Machine size (about) | – | – |
| Length×Width×Height | mm | 7000×8000×2500 |
Note: Due to the different positions of the electrical cabinet and oil tank, the size of the machine may vary. The size of the machine is for reference only.
Due to the continuous advancement of technology, some parameters may change in the detailed design, and the final machine design parameters shall prevail.
Machine Working Accuracy
Processing according to the drawings confirmed by both parties.
Utility Requirements
| Electrical supply | Three phase five wire system 380V 50Hz |
| Air source pressure | 0.4～0.6Mpa |
| Working environment temperature | 0°C~35°C |
| Working environment humidity | ≤90% |
Machine Structural Characteristics
5.1 Basic Overview
This machine has a carriage moving horizontal bed layout. Behind the bed, there are two
independent wheelhead carriage for grinding the shaft journals. The headstock and tailstock are mounted on the front bed and the workpiece is fixed by centers. The wheel dresser is
located at a diamond roller dresser behind the tailstock. The CNC system adopts the HZC system.
Headstock rotation: C-axis
Forward and backward movement of the right wheelhead: X-axis
Axial movement of the right wheelhead: Z-axis
Wheel rotation of right wheelhead: CS1-axis
Forward and backward movement of the left wheelhead: X2-axis
Axial movement of the right wheelhead: Z2-axis
Wheel rotation of left wheelhead: CS2-axis
Rotation of the diamond roll dresser: SP-axis
5.2 Machine Bed
The bed is of integral structure, with internal rib plates arranged in a box-shaped layout.
It is made of low-alloy high-strength nodular cast iron, offering high overall rigidity, surface wear resistance, and seismic resistance, meets the requirements of efficient and high-precision
equipment for basic components. The wide water channel design ensures smooth return flow of cooling water.
The front bed is used to mount the worktable, The rear bed utilizes closed-type static pressure guideway for mounting the wheelhead.
5.3 Worktable
The worktable is fixed to the front part of the bed, intended for mounting the headstock, tailstock, steady rest, and auxiliary support stand.
5.4 Headstock
The headstock is positioned on the left side of the worktable, mounted on the slider of the linear guideway of the worktable. It can move axially along the linear guideway to ensure that the
headstock spindle and the wheel spindle are parallel to each other.
The torque motor is directly mounted on the headstock spindle. To reduce the temperature of the motor and maintain its efficiency, the torque motor is cooled by introducing cooling fluid into the surrounding pipeline. A circular grating is installed at the rear of the spindle to provide spindle feedback information. This forms a closed-loop control system for precise control of the rotation, speed, and position of the headstock spindle.
Specification of the center: MT.#5.
5.5 Tailstock
The tailstock is mounted on the slider of the linear guideway of the worktable and can move axially along the linear guideway. A hydraulic cylinder is connected to the tailstock body via a piston rod, which drives the tailstock to move forward or backward. The position of the tailstock is controlled by an encoder installed on the front side of the worktable.
The tailstock center is aligned with the headstock center by using two shims on the side and on the bottom. The tailstock center is a “dead” center (it does not rotate during machining), so coolant is required during grinding to lubricate it. Additionally, coolant helps keep the center clean and cool.
The position of the tailstock is monitored by a position magnetic linear encoder. If the position deviates from the programmed setting, an alarm message will be displayed on the operator panel, and the machine cycle will be canceled to prevent the cycle from starting or the machine will shut down.
5.6 Steady Rest
The steady rest utilizes a hydraulic self-centering steady rest to support the workpiece. The steady rest is installed on the worktable, positioned between the headstock and the
tailstock. During the grinding, the steady rest supports the workpiece and positions it on the machining axis using steady rest shims. Even if there are variations in the size of the shaft, the positioning of the workpiece remains constant. The steady rest is hydraulically driven, providing comprehensive support to the workpiece.
There are auxiliary supports on the worktable for assisting with loading and unloading of the workpiece.
5.7 Carriage and Wheelhead Feed Mechanism (Z-axis, Z1-axis, X-axis, X1- axis)
Two cross carrriage are located at the rear of the bed, with the Z-axis utilizing hydrostatic guideway and driven by a linear motor. The X-axis guideway of the wheelhead also employ
hydrostatic guideway and are driven by a linear motor. Both wheelheads are equipped with orbiting gauge for online measurement, with the right wheelhead additionally equipping angular and axial positioning device.
The machine can simultaneously grind the main journal and crankpin of the crankshaft.
Depending on the structure and size of the workpiece, it can even grind adjacent main journals and crankpins simultaneously, with the main journals still supported by the hydraulic steady rest. The orbiting gauge allows for measurement while grinding.
5.8 Wheel Spindle System
The wheel spindle system adopts a built-in motor electric spindle structure.
It is supplied with oil from an independent lubrication oil tank. The hydrostatic lubrication system features fine filtering, oil temperature maintenance, oil temperature alarm, and pressure protection functions, ensuring the high precision, high rigidity, high load-bearing capacity, and high reliability requirements of the spindle system.
5.9 Automatic Measuring System
The machine adopts the Fenar-L automatic measuring mechanism to realize automatic measurement of workpiece dimensions.
The measuring action is controlled by the computer and interlocked with the machine movements. Measurement data can be displayed on the control panel screen in both graphical and numerical forms. It is equipped with a calibration device for the measuring mechanism.
The automatic measuring device measurement range: determined according to the selection of user workpiece.
The axial positioning device uses the T25 axial tool alignment gauge for positioning.
5.10 Diamond Roller Dresser
The diamond roll dresser is located on the right side of the worktable and is installed on the worktable.
The rotation of the diamond roll is driven by the electric spindle.
At the beginning of the grinding wheel dressing cycle, the diamond roller starts to rotate, and
the coolant is also activated. The grinding wheel, through the carriage and the wheelhead body, moves to squeeze the diamond roll to dress the profile of the grinding wheel and improve the grinding surface of the grinding wheel.
5.11 Coolant System
The cooling water tank is equipped with a magnetic separator and a paper tape filter, with a filtration precision of ≤20μm, which fully meets the continuous needs of efficient grinding production, further ensuring the quality of grinding.
The water tank adopts an independent cooling water tank with a volume of ≥500L. Workpiece cooling: flow rate 50L/Min, lift 18m.
Flushing: flow rate 50L/Min, lift 5m.The water tank is equipped with a water chiller.
5.12 Guard
The machine is equipped with full guard to prevent splashing of coolant, along with a mist suction device to ensure a clean environment and the health of the operators.
5.13 CNC System and Electrical System
The CNC machine adopts the HZC CNC system.
The CNC system features a pendant-style manual pulse generator, built-in PLC, and an LED color display.
The machine is equipped with an independent electrical cabinet, internally equipped with lighting fixtures and a dehumidifying cooling device.
The machine is equipped with a three-color alarm lamp.
The main electrical components are sourced from reputable brands.
A pendant-style control panel is provided, adopting a centralized operation control panel where all operating components and CNC systems are concentrated. The panel includes working
status indicator lights, display gauges, and necessary operation buttons and selection switches. The machine is equipped with an automatic wheel balancing device.
5.14 Hydraulic, Lubrication, Pneumatic Systems
The coolant system adopts a high flow rate and high-pressure cooling method. The coolant
tank is placed on the side of the machine, and the cooling fluid back to the magnetic separator of the coolant system from the reflux groove. It then flows into the cooling fluid pool through a paper filtration device. After secondary filtration, the sand particles and chips in the cooling fluid are filtered to ensure grinding quality. The flow rate of the coolant system is 200L/min.
Additionally, there is a separate cooling water line used for flushing sediment in the return tank. The coolant system utilizes water chiller for cooling.
5.15 Machine Paint
The color of the machine paint is determined by the user-provided color chart. In the absence of specific user requirements, the standard color of the manufacturer will be applied.
Main Purchased Parts
| Name | Manufacturer |
| CNC system | Huazhong CNC |
| Servo motor | Huazhong CNC |
| Main journal outer diameter measuring device | Italy Marposs Fenar-L |
| Axial positioning instrument | Italy Marposs T25 |
| Dynamic balancing device | Italy Marposs |
| Ball screw | Nanjing Technology and Equipment or equivalent brand |
| Ball screw supporting bearing | Luoyang Bearing Research Institute or equivalent brand |
| Coolant tank with magnetic and paper tape filtration | Shanghai Tianbo or equivalent brand |
| Main hydraulic components | Taiwan HP or equivalent brand |
| Main pneumatic components | Taiwan CHELIC or equivalent brand |
| Electric cabinet dehumidification and refrigeration device | Tongfei or equivalent brand |
| Inverter | Huichuan or equivalent brand |
| Diamond roll | Zhengzhou Abrasive GrindingResearch Institute or equivalent brand |
Machine Technical Documents
Machine user manual 1 set
(including electrical instructions, hydraulic diagrams, lubrication diagrams,lubrication instructions)
System operation manual 1 set
Frequency converter user manual 1 set
Coolant system user manual 1 set