# Mold Components

HYDRAULIC UNSCREWING DEVICE Calculations/Specifications

HYDRAULIC UNSCREWING DEVICE Calculations/Specifications

B. Control Cam Calculation

Thread Lead = 1/(Threads per inch) = 1/Pitch = Inches/Thread Thread Length = Length of threads to be removed from the cap A. Stroke (Inches) NOTE: Limit switches should be used if possible to limit full cylinder travel. This will extend the seal life inside the hydraulic cylinder.

+ Safety (.5 revolutions minimum)

Thread Lead b) 1. Required stroke – Inches = Gear Pitch Diameter x π x Required Revolutions If required stroke is too long, a cogwheel transmission should be used. 2. Length of Rack b 2 = x + y + b 1 c) Stripper stroke (Inches) = Cylinder Stroke – Required Rack Stroke

FULL OPEN POSITION ANTI-ROTATIONAL STRIPPER PLATE "OR BUMP" MOVES UP AT A FASTER

OPEN

RATE DUE TO ANGLE BETA AND SEPARATES FROM THE MAIN STRIPPER PLATE MOVING AT RATE DUE TO ANGLE ALPHA

CLOSED POSITION BOTH STRIPPER PLATES MOVE UP TOGETHER AT THE SAME RATE DUE TO ANGLE ALPHA

CLOSED

ANTI-ROTATIONAL STRIPPER PLATE MAIN STRIPPER PLATE STRIPPER PLATES

BUMP LIFT

ANTI-ROTATIONAL STRIPPER PLATE

ß BETA

ALPHA

PUSHED UP BY CAM ANGLES THREADS GET ROTATED

CAM

MAIN STRIPPER PLATE

ATTACHED TO MOLD

CAM

MOVING HYDRAULIC CYLINDER PUSHES CAM AND RACK

STATIONARY HYDRAULIC CYLINDER

SPUR GEAR

MOVES MAIN STRIPPER PLATE

B

BUMP

PITCH DIA.

STATIONARY HYDRAULIC CYLINDER BODY

RACK

A

MOVING RACK

STROKE

C. Unscrewing Force These figures should only be used as a guideline, as many other factors will affect the calculation (material, variation of dimensions, material shrinkage, core surface area, temperature, lubricants, friction, etc.). f) Residual Pressure (PSI) = 1/100 of maximum injection pressure g) Effective core surface area (Square Inches or in 2 , Outer Core Cylinder Shell) Flat end of threaded core neglected, x 2 value for 45° triangle thread shape = major thread dia. of the core x π x thread height x 2 h) Unscrewing torque (in-lb f ) = Residual Pressure x Effective core surface area x major thread radius of core i) Unscrewing force rack (lb f ) Unscrewing Torque X number of cavities = Gear pitch radius k) Hydraulic force (lb f ) NOTE: x 1.5 is 50% Safety Factor, if x 1.0 there would be no safety factor. = Unscrewing Force x 1.5

BACK VIEW, THREADED CORES EXTEND FROM OTHER SIDE OF THE SPUR GEAR

PITCH CIRCLE – PITCH DIA. x PI SPUR GEAR

Y = MAXIMUM PRODUCT SPACING (MULTIPLE CAVITIES CAN BE LOCATED BETWEEN)

> PITCH DIA. PERIMETER x REVOLUTIONS b 1

X

REQUIRED STROKE TO UNSCREW CAPS

UNUSABLE SPACE

b 2

84

85

U.S. 800-626-6653 ■ Canada 800-387-6600 ■ dme@milacron.com ■ www.dme.net ■ store.dme.net

U.S. 800-626-6653 ■ Canada 800-387-6600 ■ www.dme.net ■ store.dme.net

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