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Self Compensating and Low Impact Stress Print Hammer Blade Configuration

IP.com Disclosure Number: IPCOM000049558D
Original Publication Date: 1982-Jun-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Hanna, DW: AUTHOR [+3]

Abstract

A one piece hammer element comprises a flexible beam 10 with a protruding blade 11 consisting of bar 12 connected to the beam 10 by integral side arms 13 and 14 at points A and B. When beam 10 returns to the rest position after impacting paper, the back of beam 10 impacts post 15 of the magnetic stator 16, creating stress at connection points A and B due to the inertial load of the blade 11. This stress is minimized by contouring the blade 11 and side arms 13 and 14 such that the center of gravity 17 of blade 11 is directly in line with the connection points A and B and in line with the direction of the deceleration force. This effectively gives a zero or close to zero moment arm.

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Self Compensating and Low Impact Stress Print Hammer Blade Configuration

A one piece hammer element comprises a flexible beam 10 with a protruding blade 11 consisting of bar 12 connected to the beam 10 by integral side arms 13 and 14 at points A and B. When beam 10 returns to the rest position after impacting paper, the back of beam 10 impacts post 15 of the magnetic stator 16, creating stress at connection points A and B due to the inertial load of the blade
11. This stress is minimized by contouring the blade 11 and side arms 13 and 14 such that the center of gravity 17 of blade 11 is directly in line with the connection points A and B and in line with the direction of the deceleration force. This effectively gives a zero or close to zero moment arm. Thus, the critical bending stress at the connection points A and B is minimized without changing any of the other characteristics of the hammer element. Also, the stiffness of blade 11 is designed to allow some bending to absorb impact energy when printing on one part forms with nearly zero energy absorption when printing on six part forms.

The stiffness of blade 11 is defined as the ratio of an applied force F to the blade displacement d in the direction of the applied force when the beam 10 is held fixed at the blade level. This is shown in Fig. 4. When printing with a one- part form, significantly less print energy is required than when printing with a six- part form. This can be accomplished by controlling the energy input to the hammer element via a pulse width to winding 18 of stator 16. Alte...