GMT Eccentric compensating chuck

GMT Eccentric compensating chuck is used for machining forgings and black bars between centres on copy turning lathes. GMT Eccentric compensating chucks are supplied with special cover at extra cost. This special cover fitted on the chuck in lieu of spring loaded centre to ensure that the chuck works as a self-centering type.

GMT Eccentric compensating chucks are supplied with spring loaded centre. The function of this spring loaded centre is to ensure that the component rests against its face. GMT Eccentric compensating chuck is essentially designed where the component is usually located between two centres. 

 One on the chuck body and one on the tail stock of the machine. Since the line of centres is defined, concentricity is guaranteed, but the function of the jaws is that they are designed to adjust and accommodate the lack of concentricity between the centre line of the component and its outside diameter.

The chuck has floating wedge for compensation and is operated by power - hydraulic or pneumatic rotating cylinder or by an electro mechanical actuator. In this chuck, gripping is achieved through a radially floating wedge. This wedge floats to the required extent in the body of the chuck to compensate the irregularities in the roundness of the component.

The chuck body and wedge are designed to withstand heavy cutting loads. The floating wedge is capable of withstanding high operating forces. The floating wedge with its mechanical advantage, converts the operating force into a high clamping force.

Construction

The body is of forged steel. The guide ways are hardened and ground. The chuck body is suitably recessed to remove large amount of material. The floating wedge and base jaws are made from nickel chrome steel, casehardened and ground on all working surfaces. 

The base jaws are guided in the deep, wide, hardened slots in the body, which provide the ample bearing area necessary to withstand the forces resulting from high gripping forces. Provision has been made for manual lubrication of the sliding surfaces periodically through grease nipples. Serrations are provided on the top face of the base jaws.

GMT Power operated pneumatic chuck

 

Power Operated Pneumatic Front end Chucks are designed to utilise in full, the spindle bore for bar/pipe work. This design avoids rear mounting of the actuating cylinder and necessary draw bar connections. The chuck can be mounted on the lathe spindle with an adaptor flange as needed. The actuating cylinder is built into the chuck. The stationary air distribution system with the ports to supply air to the respective sides of the piston is mounted separately on the chuck.

These chucks are available in various sizes ranging from size 160mm Ø to 1000 mm Ø. The chucks are offered with standard jaw stroke of 4.2mm to 12mm and extended jaw stroke of 19mm to 25.4mm. The extended jaw stroke to hold pipes, casings and tool joints.

For holding long oil pipes, one chuck is mounted on the front end of the spindle, and one chuck at the near end of the spindle. Power Operated Pneumatic Front end Chucks have twin non-return valves, which prevent the clamping air from returning through the port unless air is let in on the other side of the piston. This ensures retention of clamping force even when the air supply is switched off. The maximum operating pressure of the chuck is at 10 bar pressure.

Principle of Operation
Power Operated Pneumatic Front end Chuck has two special rubber seal rings on the distributor assembly. The special seal ring is compressed when the chuck is pneumatically actuated to facilitate opening and closing of chuck jaws. Once the job is clamped due to venting of the air supply, the special seal rings lift to ensure rotation of the chuck. This design eliminates wear on the special seal rings.

Construction
The chuck body is made of forged medium carbon steel. The guideways are flame hardened and ground. The wedge and base jaws are made of nickel chrome steel; case hardened and ground on all working surfaces. Serrations are provided on top face of the ground base jaws. The various radii on the hard jaws in conjunction with serrations are designed to grip a wide range of job diameters.

Electro Pneumatic Control Unit
Each GMT Power Operated Pneumatic Front end Chuck is supplied with an Electro Pneumatic Control Unit. This control unit consists of Lubro Control Unit, Electrical Contactors, and Fuses and in addition, solenoids for interlocking with the main spindle.
Push button or foot operated switch is supplied with the Electro pneumatic Control Unit for actuating the chuck.

Features :

• Power operated pneumatic front end chucks are designed to utilise in full, the spindle bore for bar/pipe work.
• This design avoids rear mounting of the actuating cylinder and necessary draw bar connections.
• The actuating cylinder is built into the chuck.
• The stationary air distribution system is mounted separately on the chuck.
• Power operated pneumatic front end chucks have twin non-return valves.

GMT Standard Power Operated Three Jaw Chuck

Power Operated Three Jaw Chuck with Through Bore(PHNC) : GMT Power Operated Hollow High Speed Chucks are designed to rotate at high speeds on CNC lathes. The compact construction of the PHNC Chucks offer further advantage of less weight and low inertia which have positive influence on the dynamic effect of CNC machine spindle. These chucks have a large through bore and are therefore suitable for bar work. The base jaws and top jaws weight are reduced in these chucks. This not only reduces the mass but also lowers the centre of gravity, which make the centrifugal losses low. 

Chucks on CNC machines need to deliver high initial gripping force. GMT takes care of this in the design by making the chuck operate with a large drawbar pull. Consequently, the wedge is designed to have large contact area with the base jaws. The weight of the body, base jaws and hard jaws are less, without the other essential criteria being sacrificed. The chuck body is recessed to remove a large extent of material to reduce the weight. (from sizes 250 mm to 500 mm). The chuck body is forged steel. The guideways are hardened and ground. 

The wedge, made of nickel chrome steel, is case hardened and ground on all the working surfaces. The base jaws also made of nickel chrome steel, are case hardened and ground to match both the wedge and the body guideways. The base jaws are guided in the deep, wide, hardened slots in the body, which provide the ample bearing area necessary to withstand the forces resulting from high gripping action. Provision has been made for manual lubrication of sliding Serrations are ground on the top face of the base. The serrations on the bottom to match the base jaws. The various radii on the hard jaws in conjunction with the serrations are designed to grip a wide range of diameters. hardened chrome case hardened and ground base jaws and the wedge ensure high load carrying capacity over a very long period. 

Chuck performance detail	2 Jaw and 4 Jaw chucks with through bore can be offered on request
Chuck Size dia 135 165 200 250 315 400 500 Clamping Range External Max 128 165 200 250 315 400 500 Min 10 32 25 28 42 45 74 Internal Max - 165 200 250 315 400 500 Min - 62 70 76 84 105 138 Max Drawbar pull (Kgf) 1780 2000 4000 6000 6000 9000 9000 Max gripping force (Kgf) 3670 5400 8000 12000 13000 20000 21000 RPM max 7000 5000 5000 4000 3200 2500 2000 Weight (without top jaws) Kgs. 6 12.5 18 27.5 36 86 164 Flywheel effect GD2 (KPm2) 0.17 0.2 0.38 0.8 2.6 8.4 24.8 Max top jaws weight (per set) Kgs. 0.7 1.5 1.7 3.5 4 7.5 7.5

GMT universal ball lock chucks

GMT universal ball lock chucks (UBLC) are designed to clamp components and ensure face butting. Ball Lock Chucks have certain distinctive advantages over wedge and lever type chucks. Jaw movement is achieved by sliding and swivel of the base jaws, which are amply proportioned.

This results in less wear, less bearing pressure and less stress concentration in the jaws when compared to same sizes of wedge or lever type chucks. 

Apart from the radial clamping forces, these ball lock chucks provide an axial force to pull the component against the butting face. This is achieved as the jaw movement is along an arc. Wedge, base jaw, spherical aligner, spherical bushes are made of Nickel Chrome Steel, case hardened and precision ground on all working surfaces.

Eccentric compensating type of ball lock chuck is essentially designed where the component is usually located between two centres, one on the chuck body and one on the tailstock of the machine. Since the line of the centres is defined, concentricity is guaranteed and the ball lock chuck design allows adequate freedom for the jaws to adjust and accommodate the irregularities of the job before full clamping force is applied.

Features :

• Positive pull back action against jaw face after clamping due to spherical movement.
• Positive sealing to prevent entry of chips.

GMT UBL chucks are offered in 2 versions:

• Self centering
• Eccentric compensating