• JHC-20 Centerless Grinder
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JHC-20 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

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  • Features
  • Specifications
  • Operation Applications
  • Standard Accessories
  • Optional Accessories
  • Operation Applications

JHC-20 with servo motor for regulating wheel, variable speed.

1. Main Structure of Machines

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.

2. spindle

(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.

3. Regulating wheel drive

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.

4. Spindle oil circulation

(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).

5. Regulator

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

6. Slide Device

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.

7. Wheel Dressing Device

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.

8. Grinding Accuracy

Item Accuracy/ Type/ Capability
Workpiece Ø2 x 20 L
Metal SUJ-2
Hardness HRC-62
Grinding wheel WA 1000#
Machine JHC-18
CUT OFF 0.25 mm
MAG 10000
Ra 0.02μm
RMAx 0.28μm
Rz 0.24μm
RMS 0.02μm
Rt 0.22μm
Rtm 0.20μm

Quality of Our Machines

The performance of all our machines is strictly inspected for roundness, straightness and surface roughness on standard work pieces before delivery.

9. Operation Applications

CNC Coordinate
Measuring Machine

  JHC-20 JHC-20H
Standard work rest (dia.) Ø1 ~ Ø50 mm
Special work rest (dia.) Ø40 ~ Ø100 mm
Grinding wheel size (dia. x width x hole) Ø510 x 205 x Ø254
Regulating wheel size (dia. x width x hole) Ø305 x 205 x Ø127
Grinding wheel speed 1350 R.P.M
Regulating wheel speed 13 - 316 R.P.M (10 steps) 10 - 250 R.P.M variable speed
Grinding wheel motor 20 HP
Regulating wheel motor 3 HP 2.9KW Servo motor
Hydraulic pump motor 1 HP
Coolant pump motor 1/2 HP
Regulating wheel feed on handwheel  3.5 mm (Rev)  0.05 mm (Gra)
Regulating micro feed on handwheel  0.1 mm (Rev) 0.001 mm (Gra)
Table feed on handwheel  9 mm (Rev)  0.05 mm (Gra)
Table micro feed on handwheel  0.2 mm (Rev)  0.001 mm (Gra)
Dressing handwheel  2 mm (Rev)  0.01 mm (Gra)
Regulating wheel tilt angle +5° ~ -3°
Regulating wheel swivel angle ±5°
Floor space (L x W x H) 2400 x 1300 x 1550 mm
Net weight / Gross weight 3200 kgs / 3500 kgs
Size of case (L x W x H) 3200 x 2200 x 1900 mm
* Manufacturer reserves the right to change specification without prior notice.
Grinding Wheel, Grinding Wheel Flange

1. Grinding wheel and grinding wheel flange *1SET

Grinding Wheel, Grinding Wheel Flange

2. Grinding wheel and grinding wheel flange*1SET

Thrufeed Standard Workrest and Blade

3. Thrufeed standard workrest and blade*1SET

Infeed standard workrest and blade

4. Infeed standard workrest and blade*1SET

Tool box and tools

5. Tool box and tools*1SET

Work lamp

6. Work lamp*1SET

Diamond tool

7. Diamond tool*2PCS

Thrufeed safety device

8. Thrufeed safety device*1SET

Flange extractor

9. Flange extractor*1SET

Levelling screw and plate

10. Levelling screw and plate*1SET

Thrufeed process gauge

11. Thrufeed process gauge*1SET

Coolant tank with pump

12. Coolant tank with pump (coolant tank will not be equipped with paper filter and hydrocyclone coolant filtering unit)*1SET

Hydraulic tank with pump

13. Hydraulic tank with pump*1SET

Magnetic separator

1. Magnetic separator

Paper filter coolant

2. Paper filter coolant

Hydrocyclone coolant filtering unit

3. Hydrocyclone coolant filtering unit

Work ejector device

4. Work ejector device

Forming dressing device

5. Forming dressing device

Long V-shaped support

6. Long V-shaped support

Manual parts feeder for infeed grinding

7. Manual parts feeder for infeed grinding

Automatic receiver for thrufeed grinding

8. Automatic recriver for thrufeed grinding

Automatic thrufeed device

9. Automatic thrufeed device

Vibratory parts feeder and straight line feeder

10. Vibratory parts feeder and straight line feeder

Auto thrufeed taper grinding device

11. Auto thrufeed taper grinding device

Auto infeed forming grinding

12. Auto infeed forming grinding

Wheel balancing arbor

13. Wheel balancing arbor

Wheel balancing base

14. Wheel balancing base

Off-line gauging, non-contace O.D. measuring system

15. Off-line gauging, non-contace O.D. measuring system

Grinding wheel automatic balancing system

16. Grinding wheel automatic balancing system

Oil cooler

17. Oil cooler

Rotary type grinding wheel dressing attachment

18. Rotary type grinding wheel dressing attachment

Jib crane & hook for grinding wheel

19. Jib crane & hook for grinding wheel

Grinding blancer for wheels

20. Grinding blancer for wheels

Oil mist / vapour receiver

21. Oil mist / vapour receiver

JHC-18S-NC1 Axis for grinding ejector pin
JHC-12S with small size bar feeder & receiver
JHC-20S with middle-sized bar feeder and non-collide receiver
JHC-18S with 6 meter loading/unloading device
JHC-18 with tandem linkage