The roll grinder is a metal cutting machine consisting of a bed, a head frame, a tailstock, a bracket, a vertical and horizontal carriage, a grinding head, a measuring frame and an electric numerical control system. The roller grinding machine is divided into 5 subsystems which including a load bearing system, a drive system, a grinding system, a measuring system.

Roll Grinder

The workpiece is supported by the headstock, tailstock and bracket and is driven to rotate by the headstock.

The numerical control system controls the machine tool to make multi-axis composite motion according to the mathematical model of the roll surface busbar, and realizes the grinding of the metal on the roller surface during the movement process.

The on-line measurement system feeds the measurement data back to the grinder control system in real time, and the control system performs closed-loop control on the machine tool to complete the precise machining of the workpiece.

Model

The main types of roll grinders are: MK8440, MK8450, MK8463, MK8480, MK84100, MK84125, MK84160, MK84200, MK84250, MK84300.

Application

  • Multi-roll mill
  • Aluminum foil rolling mill
  • Film industry
  • Printing industry
  • Coating roll
  • Roll manufacturing
  • Special application

Structure Introduction

Bed Frame

The bed body adopts a structure in which the grinding wheel bed is separated from the workpiece bed.

The bed adjustment horn has a short pitch, strong rigidity, and the bed accuracy is not easily changed.

The grinding wheel bed is a wide-body bed with a 1200mm rail spacing. It is equipped with a telescopic stainless steel shield to ensure that it will never rust. The precision ball screw installed in the grinding wheel bed is used to drive the large carriage (Z-axis).

Head Frame

The three-stage V-belt transmission ensures the smoothness and accuracy of the transmission.

Using the AC spindle motor drive enables the headstock to rotate in both forward and reverse directions.

The position control function of the head frame enables automatic positioning of the dial angle, which facilitates the lifting of the rolls and reduces the auxiliary time.

The headstock lubrication system uses a grease pump for automatic timing oiling.

Tailstock

The tailstock movement adopts electric drive mode, and the hydraulic pressure is automatically locked.

The tailstock is equipped with a large stroke (1000mm) hydraulic sleeve.

Wheel Spindle System

The front and rear bearings of the grinding wheel spindle adopt high-precision dynamic and static pressure bearings, and the spindle axial direction adopts high-precision thrust bearings.

In addition, the static pressure effect of the working chamber hydrostatic bearing is enhanced in the rear bearing design to overcome the damage caused by the large belt tension on the bearing bush.

The spindle dynamic and static pressure bearing has the characteristics of high rotation precision, good stability, strong dynamic rigidity and low vibration.

Grinding Frame and Its Feeding Mechanism

The grinding frame adopts a single-layer integral structure and has high rigidity.

The grinding frame rail is a plastic static pressure rail.

The grinding frame feed mechanism consists of a Siemens AC servo motor with a reduction gear and a precisely pre-stretched precision ball screw pair with high feed accuracy and sensitivity.

Carriage Z axis

The carriage adopts a V-flat form of plastic static rail.

The carriage feeding mechanism is composed of a Siemens AC servo motor with a reduction gear and a precision pre-stretched precision ball screw pair. The NC system realizes the closed-loop position control of the carriage through the AC servo motor and the circular grating.

The carriage is driven by a ball screw.

Compared with the traditional rack and pinion transmission adopted by similar grinders at home and abroad, it has the advantages of short mechanical transmission chain, smooth motion, high transmission precision and small clearance.

Servo Motor and Its Control System

All servo motors of the grinding machine adopt Siemens full digital AC servo motor with high precision and high reliability.

Head Frame Control System

The head frame is driven by Siemens 1PH7 AC spindle motor. It is equipped with Siemens Sine/Cos1Vpp and 2048 S/R photoelectric encoder to complete the closed-loop control of the head frame speed and position.

The headstock enables forward and reverse rotation and automatic positioning of the dial angle.

The use of the AC spindle motor greatly reduces the maintenance work of the headstock motor.

For the characteristics of the roll drive, the head frame adopts an AC spindle motor with low rated speed and large starting torque, which saves valuable energy while ensuring the start of heavy-duty rolls.

Wheel Control System

The grinding wheel is driven by Siemens 1PH7 AC spindle motor. It is equipped with Siemens Sine/Cos1Vpp and 2048 S/R photoelectric encoder to complete the closed-loop control of the grinding wheel speed and position.

The grinding wheel enables forward and reverse rotation as well as automatic angular positioning.

In addition, the use of the AC spindle motor greatly facilitates the maintenance of the grinding wheel motor.

The grinding wheel adopts an AC spindle motor of up to 100KW, which ensures the grinding machine has strong grinding ability and meets the requirements of the user’s rapid and large load processing.

Electrical Control Cabinets

In order to ensure the overall reliability of the electrical system of the grinding machine, the electrical control cabinet casing, the power distribution system in the cabinet, the protection components, switching components and control components all adopt imported international famous brand products (Siemens, Rittal).

U1 Axis

The U1 shaft drive system is driven by a Siemens AC servo motor with a right angle reducer to drive an eccentric drive.

Drive the center frame upper slide through the connecting rod.

The tailstock end center frame is set to two layers, the lower layer base can be moved longitudinally along the bed rail, and the upper layer slide plate can be horizontally and horizontally adjusted (adjustment amount 1.5) under the U1 axis drive to achieve the correction of the roll installation accuracy.

The special structure design of the center frame slide can easily replace the center frame seat mounted on the skateboard, which greatly shortens the auxiliary time for replacing the tile seat, and is especially suitable for the support of multi-size rolls.

CNC System

The CNC host adopts Siemens’ new generation all-digital control system 840D, integrated S7-300 programmable controller.

The I/O contacts outside the machine are transferred to the central control system via the PROFIBUS industrial fieldbus.

The human interface function is completed by the new high performance SINUMERIK PCU50 module.

Compared with the industrial computer-specific system developed by the grinding machine factory used by similar grinding machines in foreign countries, the 840D system is more powerful, more reliable and easier to maintain. (Because the 840D system has been verified by thousands of users and Siemens has been continuously improved for many years. ).

Due to the versatility of the 840D system, the maintenance of the grinding machine is extremely convenient, and all electrical components can be purchased on the market.

The grinder electrical system does not have the black box problem common to imported grinders.

Human Machine Interface

The display adopts Siemens 15-inch LCD monitor OP15, Chinese/English display, and the operating system adopts MS-WINDOWS XP.

The system has complete alarm and diagnostic functions, and is equipped with a wealth of help and operation tips.

The well-designed screens and operating menus are easily and quickly mastered by operators and maintenance personnel.

Measuring Frame System

The measuring arm guide rail adopts the imported linear guide of STAR.

The transmission system is driven by a Siemens AC servo motor with a speed reducer through a keyless connection to a precise pre-stretched precision ball screw. The CNC system realizes the closed loop position control of the measuring frame through the AC servo motor and linear encoder.

The measuring frame adopts linear guide rail and ball screw drive. Compared with the rack and pinion transmission adopted by similar grinders at home and abroad, it has the advantages of smooth motion, high transmission precision, good sensitivity and accurate positioning, which greatly improves the accuracy of the measuring system.

High-precision CNC Curve Grinding Device (U-axis)

The device adopts static pressure eccentric sleeve structure (with spindle dynamic and static bearing).

The transmission system is driven by a Siemens AC servo motor with a speed reducer through a keyless connection to drive the precision ball screw. The linear guide rail is positioned to move the ball nut up and down to drive the high-precision static pressure biasing for small angle swing. The grinding wheel spindle in the static pressure eccentric sleeve makes a slight gap-free incision (or withdrawal) movement with respect to the roller surface.

This movement is combined with the movement of the carriage (Z-axis) to grind the desired curve on the surface of the roll.

The specially designed transmission structure ensures that the drive system is always in a gap-free state, resulting in high curve grinding accuracy.

Roll Grinding

(1) Grinding wheel speed, fine grinding steel roll 25~35m/s

Rough and finely ground chilled cast iron rolls 20~25m/s

Super fine grinding, mirror grinding 15~20m/s

(2) When the workpiece (roller) speed is coarsely ground, 30~50m/min

15~30m/min during fine grinding

10~15m/min for precision polishing

When grinding slender rolls, low speeds should be used, especially when the calender rolls with small roll size are ground, the speed of the workpiece rolls is less than 10 m/min.

(3) The longitudinal feed rate of the carriage is 240~600m/min when rough grinding; or the longitudinal feed of the carriage per workpiece is about 2/3~3/4 of the width of the grinding wheel.

80~200m/min during fine grinding; or the longitudinal feed of the workpiece per revolution of the workpiece is about 1/4~1/2 of the width of the grinding wheel.

(4) The cross feed amount of the pallet shall be determined according to the hardness of the roller and the diameter of the grinding roller surface for each reciprocating stroke. The transverse feed amount shall be 0.03~0.05mm/reciprocating stroke.

For rolls with a hard material and a large roll neck, the cross feed should be reduced.

0.005~0.01mm/reciprocating stroke during fine grinding. 0.002~0.005mm/reciprocating stroke for precision polishing.