Workholding solutions for more productive machining

February 17, 2014 7:05 am

 The continuing advances in production methods in manufacturing industries such as the automotive, pumps and valves have created a need, not only for precision workholding devices but also for custom-manufactured special workholding products. The applications for these special workholding products typically are hard-to-hold and non-cylindrical components. A special team of designers, experienced machinists and manufacturing engineers work closely with customers to provide workholding solutions.
Here are five case studies at random where you’ll see solutions to problems you may relate to, such as components with extruded stock, non-cylindrical parts, eccentric, off-centre and non-traditional applications.
Case study 1: turbine housingAfter detailed study of the component, the research team at Guindy arrived at a workholding solution with Universal Ball Lock Chuck including a special balancing arrangement.
Universal Ball Lock Chucks (UBLC) are designed to clamp components and ensure face butting. These power-operated 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. As 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.
Case study 2: tripodThe production and machining of components with intersecting axes has for a long time involved high processing expenditure. These components were either processed on special machines, transfer lines or on conventional lathes in several chucking operations. Guindy Machine Tools (GMT) has developed indexing power chucks to meet the persistent problems in machining components with intersecting axes in a CNC lathe.
Indexing chucks of different sizes are designed for machining typical parts like Universal joints, tripods, spider and valve bodies etc. Power operated power indexing chucks are offered with index position:4 x 90 degree3 x 120 degree2 x 180 degree.
Clamping, de-clamping, indexing and locking of index drum are performed by integral hydraulic cylinders. The oil fed to the different cylinders through a pipe bundle running through the spindle bore. The component is clamped by moving the lower jaw through an integral cylinder. The upper jaw is stationary.
These automatic indexing chucks are hydraulically controlled through two, four-way solenoid valves. In addition the electrical circuit includes an adjustable time delay relay to incorporate short time lag between indexing and locking cycles. The indexing is done when the main spindle is running.
Case study 3: crankshaftGuindy has in its workholding range a complex chuck that is designed for pin milling of crank shaft journal.
This chuck is tailor made to suit the machine. Crankshaft is held between centres of RH and LH chuck. For example, crankshaft blanks for truck engines are very unbalanced at the start of the operation. The flange and stub end are clamped by right hand and left hand chuck for further operations. Aligning jaw of the chuck facilitates job clamping. Chucks are actuated by hydrauliccylinders.
Case study 4: motor flange GMT has developed specialised power chucks for second operations where radial clamping is not possible. A suitable locator is used to locate the component centre. The fingers located in a rod, which has a helical groove ensure that the component is flat against the chuck. This enables loading yet ensures accurate location.
GMT-make hydraulic rotating cylinder is used to move the chuck fingers swings in and clamps the component in a single motion. Actuator pin is located on helical groove for actuating the finger. Fingers during de-clamping lift and swings out for component unloading and loading. The chuck firmly clamps the component without any distortion or surface damage.
Features• Chuck has a locator for locating the component• Power operated twist finger chucks cannot perform without locating the component• Fingers are located in a rod, which has a helical groove• Actuator pin located on helical groove for actuating the finger. Fingers during clamping and de-clamping lift, swings in and out, for component loading and unloading.
ApplicationAutomotive, wheel turning, aerospace, aircraft, commercial vehicles, energy, heavy duty machines, defence production, oil and wind generators.
Case study 5: engine pistonThis chuck is ideal for the finishing operation. The radial pull back function of the chuck ensures that there is a positive resting of the component after clamping. It also has a high-gripping force, repeatability and is ideal for auto components.