No.000162 Grip and Rotate Feed Mechanism

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35

Application Overview

Purpose

• Purpose
  • Feeding the workpiece after rotating 90°.
• Operation
  • On the output side of the cylinder, the clamped workpiece is unclamped at the first return stroke after the swing arm tumbles hitting the stopper surface and comes to a halt. At the cylinder return side, the arm rises up in an unclamped condition, hits the stopper surface and comes to a halt. When the cylinder moves again toward the output side, the workpiece is clamped at the beginning of the stroke.

Target workpiece

• Shape: Small-size battery case
• Size: W 22 x L 45 x H 10 mm
• Weight: 0.03 kg

Design Specifications

Operating Conditions or Design Requirements

• Grips the workpiece after receiving it.
• Rotation: 90°
• Work head drop: 100 mm

Required Performance

• Locating accuracy: ± 1 mm

Selection Criteria for Main Components

• Cylinder
  • Small-size, double-acting
• Tension spring
  • Auxiliary part for initially performing the clamp motion/Retaining workpieces during revolution motion .
    Spring constant k = 0.22 N/mm
    Spring tensile length l = 11.7 mm
    Workpiece retaining force = k x l = 2.57 N

Design Evaluation

Verification of main components

• Verify the cylinder thrust and spring load from the load moment.
• Check the force to operate the arm.
  • Conditional values: Workpiece mass m = 0.03 kg
    Gravitational acceleration = 9.8 m/s²
    Cylinder diameter = 16 mm
    Supply pressure = 0.5 Mpa
    Mechanical efficiency = 80%
    
    Distance between the tension spring shaft and the rotary shaft at the chuck release: L1 = 10.5 mm
    Distance between the tension spring shaft and the rotary shaft after the workpiece is moved: L2 = 28.3 mm
    Distance between the tension spring shaft and the rotary shaft at the chuck release: L3 = 38.4 mm
    Distance between the cylinder shaft and the rotary shaft after the workpiece is moved: L4 = 17.3 mm
    
    Tension spring natural length L = 80 mm
    Initial tension of the tension spring: F1 = 3.73 N
    Length of the tension spring at the chuck release: L5 = 114 mm
    Length of the tension spring after revolution of the workpiece: L6 = 99 mm
    Spring constant k = 0.22 N/mm
    Tension of the tension spring at the chuck release: F2 ＝ F1+ k x (L5-L) ＝ 3.73 + 0.22 x (114 - 80) ＝ 11.2 N
    Tension of the tension spring at the chuck release: F3 ＝ F1+ k x (L6-L) ＝ 3.73 + 0.22 x (99 - 80) ＝ 7.9 N
    Cylinder thrust F4 = 101 N
    Cylinder thrust F5 = 75 N
    
    Moment ratio.
    In chuck operation/arm revolution.
    Moment generated by the cylinder thrust. From M1 = F4 x L3, M1 = 101x 38.4 ＝ 3879 N・mm
    Moment generated by the spring. From M2 = F2 x L1, M2 ＝ 11.2 x 10.5 ＝ 117.6 N・mm
    
    When the arm is pulled up after revolution of the workpiece.
    Moment generated by the cylinder thrust. From M3＝F5×L4, M3 ＝ 75 x 17.3 ＝ 1297.5 N・mm
    Moment generated by the spring. From M4 ＝ F3 x L2, M4 ＝ 7.9 x 28.3 ＝ 223.6 N・mm
    
    From calculations shown above, we obtain M1≫M2 and M3≫M4, which shows that the arm drive operates without delay.

Other Design Consideration

• Shape of the shoulder pad for locating the main revolution arm.
• Link shape at the chuck part that fixes the grip release angle and grip close angle.