Ball point pen tip and production method thereof

Details Ball point pen tip and production method thereof Ball point pen tip and production method thereof

1996-03-22

1998-06-09

Stoll, William E.

Coating implements with material supply

Including ball, roller or endless-belt tool

Ball

B43K 108

Patent

active

057624348

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

This invention relates to a ball point pen tip having the structure wherein a reduced diameter portion is formed by caulking inward a distal butt end portion of a taper surface whose diameter progressively decreases towards a distal end, and a ball as a writing member is allowed to partly protrude from an opening while being held by a ball holding portion as a part of an ink passage, and to a production method of such a ball point pen tip.


BACKGROUND INFORMATION

Ball point pens have been designed conventionally so that writing can be made mainly at a writing angle within the range of 90.degree. to 50.degree.. However, there is the case where writing is made at a smaller writing angle than the ordinary writing angle when Arabic characters or alphabets are written, and ball point pens capable of providing clear written characters even at such a small writing angle have been desired.
To attain writing at the small writing angle, the distal butt end portion of a ball point pen tip must not catch the surface of a to-be-written object such as a sheet of paper. This requirement can be satisfied by preventing the distal end portion of the ball point pen tip other than the ball from coming into contact with a written surface even when writing is made at a small writing angle. To prevent the contact of the distal end portion of the ball point pen tip with the written surface, it may be possible to set a caulking angle of a reduced diameter portion, which prevents fall-out of the ball, to a small angle, or to reduce the thickness of the distal end portion of the ball point pen tip. However, when the thickness of the distal end portion is reduced or the caulking angle of the distal butt end portion is set to a small caulking angle, machining with a large deformation quantity must be carried out in comparison with the case where machining is made at a large caulking angle, in order to obtain a diameter reduction quantity necessary for holding the ball. In this case, adverse influences are exerted on the inner surface of the reduced diameter portion as a portion corresponding to the caulked portion of an ink passage and the shape of the distal butt end is likely to become non-uniform. In consequence, uniform supply of ink to the written surface or uniform rotation of the ball is impeded and a non-uniform density occurs in written characters. When the distal end shapes of the butt end are not uniform, a portion which is unnecessarily elongated than required is formed towards the distal end side, and the ball is likely to come into contact with the written surface at a small writing angle.
From the aspect of production methods, a production method of a ball point pen tip is known which comprises forming interior components of a ball point pen tip such as a center hole, a ball chamber, etc, so as to hold a ball of the metallic ball point pen tip made of a metal such as brass, german silver, stainless steel, copper alloy and aluminum alloy, loading then the ball into the ball chamber and caulking inward a distal butt end portion so as to hold the ball. The caulked portion formed at the distal butt end portion for holding the ball greatly affects writing quality of the ball point pen such as a hand writing condition and catch with a sheet surface.
This caulking working of the ball point pen tip is effected by bringing a pressure contact member into pressure contact with the ball point pen tip, and ball point pen tips having various required quality have been worked by adjusting the angle at which the pressure contact surface of the pressure contact member comes into contact with the ball point pen tip (caulking angle).
When the caulking angle of the ball point pen tip and its caulking strength can be variously adjusted, variance of the angle and size of the caulked portion occurs in the product, and in order to keep required writing quality, strict check of defective products and strict control of the caulking angle must be made. In either case, job becomes more complicated.
Particularly in th

REFERENCES:
patent: 4726845 (1988-02-01), Thompson et al.

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