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WWW.KITAGAWA.COM. Chucks 101 Agenda Types of Chucks Grip Force Maintenance Jaws Special applications WWW.KITAGAWA.COM.

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Presentation on theme: "WWW.KITAGAWA.COM. Chucks 101 Agenda Types of Chucks Grip Force Maintenance Jaws Special applications WWW.KITAGAWA.COM."— Presentation transcript:

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2 Chucks 101 Agenda Types of Chucks Grip Force Maintenance Jaws Special applications

3 Types of Chucks Thru hole style Closed center Wedge Lever Self Contained Air Pullback

4 Thru Hole style chuck Bar Feed Chucker Work Accurate Durable High Speed High Grip Force Wide Range Of Application Most Common Body Is High Grade Alloy Steal All Wear Surfaces Are Hardened And Ground

5 Closed Center Style Chuck Chucker Work Accurate Durable High Speed High Grip Force Wide Range Of Application Body Is High Grade Alloy Steal All Wear Surfaces Are Hardened And Ground

6 Wedge Style Chuck Interaction between angle on master jaw to angle on wedge plunger. 2 wedge surfaces interacting to give motion and mechanical advantage. Master Jaws Wedge Plunger

7 Lever Style Chuck

8 PW & PWT (BALL LOCK) STYLE PULLBACK CHUCKS STANDARD * PW series (3 Jaw) *PWT series (2 Jaw) COMPENSATING *PW-C series (3 Jaw) *PWT-C series (2 Jaw) ADVANTAGES OD OR ID GRIPPING PULL BACK CHUCK – NO WORKPIECE LIFTING COMPLETELY SEALED CHUCK ON UPTO 20 DEGREE DRAFT ANGLE JAWS EQUALIZE UPTO 5 DEGREES EXCELLENT FOR 1 st OPERATIONS

9 Special Features Of The PW(T) Chuck

10 SPECIAL FEATURES OF THE PU SERIES PULL DOWN FEATURE – IDEAL FOR 2 ND OPERATIONS REQUIRING HIGH PRECISION HIGH GRIPPING FORCE RETENTION HIGH ACCURACY (.0004) HIGH DURABILITY – ALL SLIDING SURFACES ARE HARDENED AND GROUND COMPLETELY SEALED DESIGN

11 Inner Workings Of PU Chuck

12 SPECIAL FEATURES OF THE PUE SERIES PULL DOWN FEATURE – IDEAL FOR 2ND OPERATIONS REQUIRING HIGH PRECISION HIGH GRIPPING FORCE RETENTION HIGH ACCURACY (.0004) HIGH DURABILITY – ALL SLIDING SURFACES ARE HARDENED AND GROUND COMPLETELY SEALED DESIGN

13 PU200 MAIN PARTS BODY MASTER JAW PLUNGER

14 THE PULL-DOWN MECHANISM

15 PU200 PLUNGER ASSEMBLY THE MASTER JAW MOVES IN BOTH THE Y & Z AXES BECAUSE OF THE BODYS ANGLE, WHILE THE PLUNGER JUST MOVES ALONG THE Z AXIS.

16 SPECIAL FEATURES OF THE UVE & UB SERIES UVE750 SELF CONTAINED AIR CHUCK EASY INSTALLATION EXTRA LARGE BORE – NO DRAWTUBE BUILT IN CHECK VALVE HIGH SPEED

17 HOW THE UVE SERIES WORKS AIR FLOWS INTO THE CHUCK AND PUSHES ON THE PISTON. THE PISTON DRAWS THE WEDGE PLUNGER IN OR OUT DEPENDING ON WHICH CAVITY THE AIR FILLS. THE WEDGE PLUNGER MOVES AND CAUSES THE MASTER JAWS TO SLIDE IN OR OUT ALONG THE WEDGE. AS THE MASTER JAWS MOVE ALONG THE WEDGE IN THE WEDGE PLUNGER THE TOP JAWS OPEN AND CLOSE. PISTON WEDGE PLUNGER TOP JAW MASTER JAW AIR FLOWS IN

18 Grip Force Is Affected By: Speed (RPM) Of Chuck – As speed increases grip force decreases. Jaw Height – As the gripping center height increases the grip force decreases. Jaw Mass – As the mass of the top jaw increases the grip force decreases. Chuck Condition - If the chuck has damage or excessive wear grip force can be impacted. Lubrication – Proper chuck lubrication can increase grip force up to 50%. WITH INCREASED HEIGHTWITH INCREASED HEIGHT Grip force and maximum rpm ratings are based on using Kitagawa soft jaws

19 Chuck Specifications You can find this information for all our chucks at 1 1)MECHANICAL ADVANTAGE = MAX GRIP FORCE/MAX DRAWBAR PULL FORCE 5812(Kgf)/2243(Kgf)=2.59(Kgf) MECHANICAL ADVANTAGE 2 2) CYLINDER STROKE MUST EQUAL OR EXCEED CHUCK PLUNGER STROKE 3 3) JAW STROKE IS ON DIAMETER. TO GET STROKE PER JAW DIVIDE BY 2 5.5mm/2 = 2.75mm STROKE PER JAW

20 GRIP FORCE LOSS WITH INCREASED SPEED DECREASED FORCE

21 JAW HEIGHT VS. GRIPPING FORCE WITH INCREASED HEIGHT DECREASED FORCE

22 Jaw Mass Effect On Grip Force AB H H AB A = B Mass (M) = Kg Mass Center Radius (R) = 254 mm M * R * 3 = 7000 B-24 H: H * Grip Force = Grip Force * mm Grip Force / H = New Grip Force 23,861 Kg * 37 mm = 23,861 * 37 = 882,857 Kg/mm 882,857 Kg/mm / 105 mm = Kg New Max Grip Force * R 37 mm

23 Gripping Coefficient Of Friction TS = HOLDING FORCE (Kgf/mm) = (DYNAMIC GRIP FORCE * u (see table above) * GRIPPING DIAMETER)/2000 EXAMPLE: 200mm grip diameter, 3671 Kgf dynamic grip force, serrated fine axial grip with wedge chuck TS = (3671 Kgf *.24 * 200mm)/2000 = Kgf/mm TR = CUTTING TORQUE (Kgf/mm) = CUTTING DIAMETER (mm) * FEED RATE (mm/rev) * DEPTH OF CUT (mm) * MATERIAL CUTTING RESISTANCE (Kg/mm 2) /2000 EXAMPLE: 300mm CUTTING DIAMETER,.100mm/rev FEED RATE, 1.5mm DEPTH OF CUT, MATERIAL IS LOW CARBON STEEL (367.2 Kg/mm 2 ) TR = (300mm *.100mm *1.5 * 367.2) / 2000 = Kgf/mm TS/TR = SAFETY FACTOR88.104/8.262 = SAFETY FACTORYOU WANT AT LEAST 2.5

24 Other Factors That Affect Cutting Torque Workholding 1)Gripping Diameter 2)Friction Coefficient ( u ) 3)Gripping Force Cutting Conditions 1)Cutting Diameter 2)Depth Of Cut 3)Feed Rate 4)Material Cutting Resistance 5)Speed Items In Red Can Be Altered To Suite The Application Other Aspects 1) Gripping Accuracy 2)Toppling Moment Of Part 3)Part Pushback Force From Cut 4)Imbalance Of System (Part & Chuck) - Vibration 5)Rigidity Of System (Chatter)

25 Chuck Maintenance Greasing The Chuck Not Only Lubricates, But Also Helps Remove Contamination From The Chuck Proper Lubrication Can Prevent The Loss Of Up to 50% Of A Chucks Grip Force

26 How CHUCK-EEZ Works

27 Comparison Of Grip Force With CHUCK- EEZ and Lithium Grease With CHUCK-EEZ Grease You have More Grip Force At 5000 RPM Than Lithium Grease Has At 0 RPM

28 Chuck Maintenance – Periodic Disassembly Clean Inspect BENEFITS Increase Chuck Life Decrease Unplanned Downtime Safety Maintain chuck performance and accuracy

29 Jaws Jaw Lift – Sliding jaw chucks will impart a slight lift when they clamp. Forming Soft Jaws – Form soft jaws under clamp load T-Nut Position – There is a maximum front and back position. Potential Problems With Aftermarket Jaws – If the serrations are not made correctly it can cause wear issues and grip force problems.

30 THE SLIDING JAW STYLE POWER CHUCKS OPEN AND CLOSE WHEN THE MASTER JAWS SLIDES ALONG THE WEDGE PLUNGERS FITTED SLOTS. THE FIGURE ABOVE SHOWS A CASE OF OD CLAMPING. THE MASTER JAWS MOVE UNTIL THE TOP JAWS TOUCH THE WORK PIECE. HOWEVER, THERE IS A GAP BETWEEN THE MASTER JAW TABS AND THE WEDGE PLUNGERS SLOTS. SO IN ORDER FOR THE MASTER JAWS TO MAKE CONTACT WITH THE WEDGE PLUNGER THE JAWS WILL TILT WHEN THE WORK PIECE IS GRIPPED. THE INNER TOP AND OUTER BOTTOM OF THE MASTER JAWS TAB WILL CONTACT THE DOVETAIL GROOVES (SLOT) IN THE WEDGE PLUNGER.. THE AMOUNT OF LIFT UP IS INCREASED BY THE FOLLOWING CONDITIONS: HIGH GRIPPING FORCE TALLER JAWS (HIGH GRIPPING CENTER HEIGHT) SMALL GRIPPING DIAMETER Jaw Lift In Sliding Jaw Chucks

31 Step 1 Step 2 Step 3 Step 4 Step 5 Forming Soft Jaws For A Sliding Jaw Chuck

32 EVEN IF YOU RE-MOUNT THE TOP JAWS THAT WERE MADE ON THE CHUCK AT THE SAME POSITION, THE GRIPPING ACCURACY WILL MOST LIKELY BE WORSE THAN BEFORE THE REMOVAL OCCURED. IF YOU NEED THE ACCURACY TO REMAIN THE SAME AS BEFORE, YOU WILL NEED TO RE-CUT THESE JAWS ON THE CHUCK. THE FIGURE SHOWS THE WORST CASE SCENARIO. TOP JAWS WERE FINISHED TOUCHING THE RIGHT-AND SIDE OF T-NUTS (AS SHOWN ON THE LEFT SIDE OF THE FIGURE). THEN, THEY WERE DETACHED AND RE-INSTALLED TOUCHING THE LEFT-HAND SIDE OF THE T-NUTS. IN THIS CASE, SINCE THERE IS A GAP BETWEEN THE T-NUT AND THE TOP JAWS, THE POSITION OF THE TOP JAWS IS NOT COMPLETELY THE SAME. THIS IS THE CAUSE FOR THE DETERIORATION OF ACCURACY. Why You Need To Reform Soft Jaws After Removal

33 T-Nut Positioning

34 IMPROPER CHAMFERING IMPROPER PITCH COMMERCIAL SOFT JAW ISSUES Serrations Need To Properly Mate Up Between The Master Jaw And Top Jaw

35 COMMERCIAL VS. PRECISION SOFT JAWS COMMERCIALPRECISION

36 COMMERCIAL VS. PRECISION SOFT JAWS ON CHUCK SURFACE

37 Special Applications Some Parts Will Not Run Productively Or Accurately On Standard Chucks and Workholding. In These Instances We Would Utilize PW, PU Or Other Types Of Pullback Chucks. Some Parts May Also Be More Suited To An Indexing Chuck. Advantages Of Specialized Workholding Achieve Higher Output Improve Accuracy To Meet Statistical Process Controls Lower Maintenance Suitable For Automated Loading Engineered To Meet The Needs Of A Specific Part And Process


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