JHC-24H Centerless Grinder

Main Structure of Machines
Hydrostatic Bearings
Semi-Hydraulic Float Bearings
Regulating Wheel Drive
Spindle Oil Circulation
Slide Device
Wheel Dressing Device
Grinding Accuracy

Features
Specifications
Operation Applications
Standard Accessories
Optional Accessories

Lower slide way is equipped with heavy bearing, linear motion system and ball screw.

Strong main structure for JHC-24H

Main Structure of Machines01

They are cast of high grade FC-30 iron, melted by advanced induction furnace, then cast in resin cores. In order to ensure stability and rigidity, they are heat-treated with normalizing procedure prior to machining.

Spindle02

(1) Hydrostatic Bearing

Precision ground hydrostatic bearing: Substantial decrease in heat deformation associated with hydrodynamic bearing. Minimal friction, lateral displacement, and pressure.Extended tool life under heavy cut loads. The grinding wheel spindle runs on hydrostatic bearing with high pressure oil film for added precision under heavy loads. Substantially reduces wear while prolonging spindle trueness. SNCM-210H carbon steel hardened beyond HRC60, Yielding high torsion resistance.

(2) Hydrodynamic Bearing

They are made of SNCM-220H Ni-Cr-Mo alloy steel and case-hardened, carbonize, then computerized sub-zero degree treated, to surface hardness over HRC62 at 1.0mm depth. Core hardness is kept at about HRC25-30 to ensure consistency of high precision grinding operation. Spindle withstand high torsion and have a long and lasting life. They are made of KJ-4 alloy bushing metal with a three point hydraulic cycle system. The semi-hydraulic float spindle is protected by an oil membrane which results in minimal contact friction. This device is specially designed for high speed and heavy load operation.

Regulating Wheel Drive03

A Japanese servo motor provides control of speeds from 10 to 250 RPM., and is used for the regulating wheel which can be adjusted to ideal linear speeds. When the diameter of the regulating wheel changes the same linear speed can still be maintained so as grind the best quality products. The motor is driven by a timing-belt to reduce vibration and noise. Since the motor housing and spindle housing are joined together as an integrated body, when the regulating wheel tilts the motor also follows. This completely overcomes problems caused by unparallelism and torsion of belt pulleys and the belts.

Spindle Oil Circulation04

(1) Hydrodynamic

There is a variable vane type oil pump for the hydraulic dressing and enforced spindle oil circulation. The oil tank is located outside of the machine for easy maintenance. Two layers of filter plus a pressure regulator ensure the cleanliness of spindle oil and the consistency of oil film thickness, thus extending the service life of the wheel spindle and the steadiness of accuracy.

(2) Hydrostatic

Hydraulic pump for grinding wheel head and spindle motor driver with sensing function.When press wheel start button, before oil reach alloy bearing will through pressure detect switch, if pressure is not enough, it cannot push the switch, the spindle will not start. Therefore, when pressure is not enough or oil pipe blocked, pressure switch will stop the wheel spindle automatically. It will protect the wheel spindle and alloy bearing. (Hydraulic pump motor 12model is 2HP, 18, 20 and 24 models are 3HP).

Regulator05

Grinding wheel spindle with high pressure hydrostatic device, apply a regulator on reentrance for adjusting high pressure oil to support radial center. The setting work pressure is 20 kg/cm2

Slide Device06

The lower slide consists of two internally mounted V-shaped slides and cuneiform protector to ensure smooth movement, stable operation and prevent the entering of debris or liquid from the working environment. The swivel slides on a dovetail flute and swivels ±5 degrees. There is a fine tuning hand wheel for precise adjustment. The accuracy per calibration is 0.001mm in diameter for high precision and easy operation.

Wheel Dressing Device07

The device is made of FC-30 cast iron and normalized then precisely ground. It is driven by a hydraulic system with a step-less speed regulator for easy and steady dressing. There is a safety handle for emergency purposes. In order to upgrade the straightness and the surface finish on through-feed grinding of long work pieces, please adjust the angle of the dressing device (swivels ±5 degrees). The regulating wheel should be adjusted to resemble a concave barrel to increase contact length while grinding.

	JHC-2408H	JHC-2410H	JHC-2412H
Standard work rest (dia.)	Ø2 ~ Ø60 mm	Ø2 ~ Ø60 mm	Ø2 ~ Ø60 mm
Special work rest (dia.)	Ø50 ~ Ø150 mm	Ø50 ~ Ø150 mm	Ø50 ~ Ø150 mm
Grinding wheel size (dia. x width x hole)	Ø610 x 205 x Ø304.8	Ø610 x 255 x Ø304.8	Ø610 x 305 x Ø304.8
Regulating wheel size (dia. x width x hole)	Ø305 x 205 x Ø127	Ø305 x 255 x Ø127	Ø305 x 305 x Ø127
Grinding wheel speed	1050 R.P.M
Regulating wheel speed	10 - 250 R.P.M variable speed
Grinding wheel motor	25 HP	30 HP	30 HP
Regulating wheel motor	2.9KW Servo motor	4.4KW Servo motor	4.4KW Servo motor
Hydraulic pump motor	1 HP
Coolant pump motor	1/2 HP
Regulating wheel feed on handwheel	2.5 mm (Rev) 0.01 mm (Gra)
Regulating micro feed on handwheel	0.02 mm (Rev) 0.001 mm (Gra)
Table feed on handwheel	2.5 mm (Rev) 0.01 mm (Gra)
Table micro feed on handwheel	0.02 mm (Rev) 0.001 mm (Gra)
Dressing handwheel	2 mm (Rev) 0.01 mm (Gra)
Regulating wheel tilt angle	+3° ~ -5°
Regulating wheel swivel angle	±1°
Floor space (L x W x H)	2800 x 1500 x 1650 mm
Net weight / Gross weight	6500 kgs / 7000 kgs
Size of case (L x W x H)	3000 x 1800 x 1950 mm (amchine), 2600 x 1400 x 1300 (accessory)
* Manufacturer reserves the right to change specification without prior notice.