Coating implements with material supply – Including ball – roller or endless-belt tool – Ball
Reexamination Certificate
2001-04-27
2002-01-29
Walczak, David J. (Department: 3751)
Coating implements with material supply
Including ball, roller or endless-belt tool
Ball
C401S215000, C401S209000
Reexamination Certificate
active
06341914
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a ballpoint pen tip, and also a ball point pen using the same. In detail, the invention relates to a ballpoint pen tip of such a type in which a ball receiving seat is formed by inwardly pressing and deforming a side wall in the vicinity of a front end portion of a metallic pipe body.
In the ballpoint pen tip of this type, conventionally, U.S. Pat. No. 5,899,625 and U.S. Pat. No. 5,904,432 disclosed a ballpoint pen tip in which a ratio (A/T) of an outer diameter A of a ball to a thickness T of a pipe is set to be 5.8 or less, and furthermore, a ratio (D/T) of a depth D of a concave portion to the thickness T of the pipe is set to be 2.0 or less in order to enhance a strength of a ball receiving seat, for example.
Although the conventional ballpoint pen tip having a comparatively small size (for example, 0.3 mm, 0.4 mm or 0.5 mm) is effective in enhancing the strength of the ball receiving seat, the ballpoint pen tip having a large size (for example, 1.0 mm or more) is not preferable in respect of manufacture because the quantity of projection (that is, the quantity of inward pressing and deformation) of an inwardly projecting portion for forming the ball receiving seat is more increased when the outer diameter of the ball is made greater so that a pressing force might be increased during the pressing and deformation and a front end portion of a tool such as a punch for the pressing and deformation might be damaged. On the other hand, even if the thickness of the pipe is simply set to be small in order to easily carry out the pressing and deformation, the thickness of the ball receiving seat itself is reduced so that the strength of the ball receiving seat is lowered.
In the ballpoint pen tip of this type (that is, a ballpoint pen tip of such a type as to form the ball receiving seat through the pressing and deformation), moreover, as the outer diameter of the ball is increased, the size of an ink flowing gap in a central portion of the ball receiving seat tends to be enlarged. Consequently, the capillary force of the ink flowing gap in the central portion is remarkably reduced as compared with that in the ink flowing gap between adjacent inwardly projecting portions. Therefore, it is impossible to rapidly supply ink to the whole ball having a large size so that a blur in handwriting or a break in handwriting might be caused.
In the conventional ballpoint pen tip, furthermore, a spew is easily generated on the outer peripheral edge of a rear end thereof. When the rear end of the ballpoint pen tip is to be pressed and fastened into a fitting hole formed in the front end portion of the penholder or the connecting member, consequently, the outer peripheral edge of the rear end of the ballpoint pen tip (a portion in which the spew is generated easily) bites at the inner face of the fitting hole so that the ballpoint pen tip might be hindered from being pressed and fitted smoothly or pressing and fitting failures might be caused, for example, the inner face of the fitting hole might be damaged. In particular, in the case of the ballpoint pen tip including a ball having a large size, it is necessary to apply a great pressing force depending on a large outer diameter of the pipe. In addition, when the biting at the outer peripheral edge of the rear end is caused, a much greater pressing force is required and the pressing and fitting operations are hard to carry out. Thus, there is a high possibility that the pressing and fitting failures might be caused.
SUMMARY OF THE INVENTION
In order to solve the conventional problems, it is an object of the invention to provide a ballpoint pen tip capable of obtaining a ball receiving seat having easiness of pressing and deformation, a sufficient ink fluidity, a smooth rotation of a ball and a sufficient strength and capable of being smoothly pressed and fitted in a fitting hole even if the ball having a large size is employed.
A ballpoint pen tip, according to the invention, rotatably holds a ball at its front end portion. The ball is held by a plurality of inwardly projecting portions for a ball receiving seat which is formed by inwardly pressing and deforming a neighborhood of a front end portion of a metallic pipe body
2
and a front end edge portion which is formed by inwardly pressing and deforming the front end portion of the pipe body. In the ballpoint pen tip according to the present invention, a relation of A/T>5.8 is satisfied, where A is an outer diameter of the ball and T is a thickness of the pipe body.
The value of the ratio (A/T) of the outer diameter A of the ball to the thickness T of the pipe body
2
is greater than 5.8 (that is, “A/T>5.8”). Therefore, even if the ball
5
having a large size is employed, pressing and deformation for forming the ball receiving seat can be carried out easily. The reason is as follows. Supposing that the value of A/T is equal to or smaller than 5.8 (that is, “A/T≦5.8”), the thickness T of the pipe body
2
is comparatively increased and a great pressing force is required for forming the ball receiving seat even if a strength of the ball receiving seat can be enhanced. Consequently, there is a possibility that the front end portion of a tool (for example, a punch) for pressing and deformation might be damaged and it is hard to carry out manufacture through the pressing and deformation.
Furthermore, it is preferable that the value of A/T according to the present invention is made smaller than 10.0 (that is, “A/T<10.0”). Consequently, it is possible to obtain a ball receiving seat having a sufficient strength. The reason is as follows. If the value of A/T is equal to or greater than 10.0 (that is, “A/T≧10.0”), the thickness T of the pipe body
2
to the outer diameter A of the ball is reduced too much so that the strength of the ball receiving seat is reduced remarkably. Consequently, there is a possibility that a smooth and stable rotation of the ball
5
cannot be obtained for a long period of time.
Accordingly, the ballpoint pen tip
1
according to the invention satisfies a relation of “5.8<A/T<10.0”. Consequently, even if the ball
5
having a large size is employed, it is possible to easily carry out the pressing and deformation for forming the ball receiving seat. In addition, it is possible to set such a proper thickness T that the strength of the ball receiving seat is not reduced.
In the ballpoint pen tip
1
according to the present invention, moreover, it is advantageous that a relation of “D/T>2.0” should be satisfied, where D is a depth of a concave portion
32
which is formed at an outside of the inwardly projecting portions
3
.
The value of the ratio (D/T) of the depth D of the concave portion
32
to the thickness T of the pipe body
2
is greater than 2.0 (that is, “D/T>2.0”). Therefore, even if the ball
5
having a large size is employed, a sufficient ink fluidity can be obtained without causing a blur in handwriting or a break in handwriting. In addition, the ball
5
can be stabilized and supported sufficiently so that a smooth rotation of the ball
5
can be obtained.
The reason is as follows. If the value of D/T is equal to or smaller than 2.0 (that is, “D/T≦2.0”), the depth D of the concave portion
32
to the thickness T of the pipe body
2
is reduced too much (that is, the quantity of projection of the inwardly projecting portion
3
is reduced too much). In particular, if the ball
5
has a large size, the capillary force of an ink discharging gap
31
in the central portion of the ball receiving seat becomes remarkably smaller than the capillary force of the ink discharging gap
31
(a radial groove) between the adjacent inwardly projecting portions
3
. Consequently, the quantity of an ink to be supplied to the ball
5
is lacked so that a blur in handwriting or a break in handwriting is caused. Moreover, if “D/T≦2.0” is obtained, the size of the ball receiving seat itself is reduced so that the ball
5
cannot be supported stably. Thus, there is a possibility that the sm
Abe Hiroyasu
Maki Masahisa
The Pilot Ink Co., Ltd.
Walczak David J.
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