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# Two-Piece Hammer

IP.com Disclosure Number: IPCOM000043563D
Original Publication Date: 1984-Sep-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 3 page(s) / 48K

IBM

## Related People

Lee, H: AUTHOR [+2]

## Abstract

Maximizing the conversion of the magnetic energy created by the armature component into print energy results in higher efficiency, tighter packaging and better heat dissipation. Fig. 1 shows the armature 11, with an effective mass of M2, in contact but not connected to the impact mass, M1 . A flexible stem 12, which is physically attached to the armature 11 between M1 and M2, has a spring rate k. The magnetic force applied to the armature 11, reflected to the tip of the stem, is Fo .

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Two-Piece Hammer

Maximizing the conversion of the magnetic energy created by the armature component into print energy results in higher efficiency, tighter packaging and better heat dissipation. Fig. 1 shows the armature 11, with an effective mass of M2, in contact but not connected to the impact mass, M1 . A flexible stem 12, which is physically attached to the armature 11 between M1 and M2, has a spring rate k. The magnetic force applied to the armature 11, reflected to the tip of the stem, is Fo . The velocity of impact of the impact mass V1 is described by equation (1), (assuming constant Fo):

(Image Omitted)

where t = the independent variable, time Wn = the frequency of vibration between the

two masses M1 and M2

Thus at t = 3f = t1, equation (2):

(Image Omitted)

and there is some additional velocity (1/Wn) added. Thus, we now have a series of equations to use to design the two-piece hammer. For example, an impact mass (M1) of 0.4 gram and an impact velocity of 6 meters/sec, with a typical magnetic force of 11 newtons and the effective mass (M2) equal to 0.4 gram, t1 + 1/Wn would have to equal approximately 0.5 millisecond (a feasible pulse width). For the case shown in equation

(Image Omitted)

Therefore, k, the stem stiffness, would then equal 120 lb/in. This is, relatively speaking, an extremely soft stem, but feasible to fabricate. Now, return to equations (1) and (2). If we fabricate an armature 11 as is typically done (Fig. 2) where the stem stiffness is...