JP2007276118A - Manufacturing method of ball-point pen tip - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an uniform holograph with no disturbance by a method wherein the deformation in the crosssectional shape of a ball holding chamber is eliminated by the machining of radial grooves. <P>SOLUTION: In this manufacturing method of a ball-point pen tip, at least a finishing machining to cut the side part of the ball holding chamber 3 is performed after the radial groove parts 6 are formed on an inwardly projecting part 3b. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a ball-point pen tip comprising a ball as a writing member and a ball holder that rotatably holds a part of the ball in a state of protruding from a tip opening.

A ballpoint pen tip that is a pen point member of a ballpoint pen basically includes a ball that is a writing member and a ball holder that rotatably holds a part of the ball in a state of protruding from the tip opening. The ball holder is processed by cutting with a cutter such as a drill or a bite, shearing with a broach cutter, or plastic deformation that reduces the diameter by pressing a roller. The inside of the ball holder holds the ball and is a path for ink, and greatly affects the quality of the ballpoint pen. Therefore, the dimensional accuracy of processing and the finish state of the inner surface are important. Japanese Patent Application Laid-Open No. 11-348484 (Patent Document 1) discloses a solution in which the finishing cost of the ball holding chamber is reduced and the surface is made smooth.
JP 11-348484 A

  However, in the invention described in the above patent document, since the radial groove portion that is the ink circulation hole is processed after the ball holding chamber is processed, the ball holding chamber is affected by the shearing force for forming the radial groove portion. Will be deformed. As a result, the rotation of the ball is affected at the time of writing, and the writing taste is impaired, the difference in the annular gap between the ball and the tip opening is caused, the ink discharge becomes uneven, and the handwriting is disturbed. It was an end.

  Therefore, the present invention forms an inward protruding portion as a seat for restricting the backward movement of the ball as a writing member, and after forming a central hole and a radial groove portion in communication with the inner protruding portion, The gist of the present invention is a method for manufacturing a ballpoint pen tip that performs a finishing process that cuts at least a side portion of a ball holding chamber.

  By forming a center hole and a radial groove in communication with the center hole in the inward projecting part, the finish cutting process is performed, so that the gap between the ball and the ball holder can be kept uniform. Handwriting can be obtained. Further, since the finishing process is also applied to the inward projecting portion except at least the outermost edge portion of the radial groove portion, the radial groove portion as the ink circulation hole is not blocked by the cutting piece (so-called cutting burr), and the ink circulation Is ensured and a stable ink supply to the ball is made, so that a handwriting that is not disturbed can be reliably obtained when writing. Furthermore, the rotation of the ball during writing is smooth and the writing quality is improved.

Hereinafter, an example of the present invention will be described with reference to the drawings. What was shown in FIG. 1 is the longitudinal cross-sectional view which expanded the principal part of the ball-point pen tip processed with the manufacturing method of this invention. As a writing member, a ball 1 made of cemented carbide or ceramics is rotatably held in a ball holder 2 made of a metal or alloy such as stainless steel, brass, or white. The ball holder 2 has a center hole 2 a as a passage for penetrating ink, and a tip portion of the center hole 2 a serves as a ball holding chamber 3 for holding the ball 1. The ball holding chamber 3 has a tip opening portion 3a that is reduced in diameter by plastic deformation (so-called caulking) that is reduced in diameter by pressing a roller, and a range in which the ball 1 can move by the inward protruding portion 3b. have. Further, a ball receiving seat 3c having a curvature similar to that of the ball 1 is formed on the inward projecting portion 3b. The ball receiving seat 3c is configured so that the ball 1 is inwardly projecting from the tip end side of the ballpoint pen tip. It is formed by pressing toward 3b.

Here, in the center hole 2a, a rear hole 4, a middle hole 5 communicating with the rear hole 4, and a plurality of radial grooves 6 communicating with the middle hole 5 and the inward projecting portion 3b are formed in this order from the rear. Has been. Although the radial groove 6 in FIG. 2 does not communicate with the rear hole 4, it may be penetrated to communicate with the rear hole 4. Further, when the ball 1 is in contact with the ball seat 3c at the time of writing, a part of the radial groove portion 6 is blocked, but the outermost edge portion 6a of the radial groove portion which is a non-contact portion with the ball 1 is blocked. As a result, ink is supplied into the ball holding chamber 3.

Next, a manufacturing method for the above-described ballpoint pen tip will be described with reference to FIG. After the ball holding chamber 3 is formed by cutting with a blade (not shown), the inward protruding portion 3b is sheared with a broach blade (not shown) to form radial grooves 6 as ink circulation holes. Form. Thereafter, as shown in FIG. 3, the side portion 3d which is the side surface of the ball holding chamber 3 deformed at the time of forming the radial groove portion 6 is finished by cutting or the like with a finishing blade (not shown), The deformed portion is removed, and the side 3d of the ball holding chamber 3 is formed in a perfect circle. Next, as shown in FIG. 4, a hammer process of pressing the ball 1 against the inwardly projecting portion 3 b with a hammer tool m is performed, and a ball seat 3 c is formed as a transfer surface of the ball 1 by plastic deformation at that time.

Finally, the ball 1 is disposed so as to contact the seating portion of the ball holding chamber 3, and a caulking process is performed to plastically deform the tip of the ball holder 2 inward (see FIG. 1). By this caulking, the ball 1 is prevented from coming off from the ball holder 2 (ball holding chamber 3). Further, the finishing of the side portion 3d of the ball holding chamber 3 and the processing of forming the inward protruding portion 3b excluding at least the outermost edge portion 6a of the radial groove portion 6 are simultaneously performed. The center axis in the side machining and the center axis in the machining of the inward projecting portion 3b coincide, and in addition, the center of the ball 1 inserted into the ball holding chamber 3 coincides with the machining accuracy. Will improve. In addition, this makes the ball 1 rotate more smoothly during writing, and the writing quality is further improved. This caulking process may be performed before the aforementioned hammer process.

Example 1 in which the inner groove was subjected to side processing after the radial groove was formed, except for the side processing of the inner protrusion after forming the radial groove, and at least the outermost edge of the radial groove A ball-point pen tip manufactured as a second example in which the processing to be formed on the inward projecting portion is performed at the same time as Example 2, and a radial groove portion formed after finishing the inward projecting portion as a comparative example 1, is commercially available. Was assembled into a ballpoint pen sample ("Rolly" manufactured by Pentel Co., Ltd., product code: BP107-A, ink used in the test: the product black ink), and a ballpoint pen sample for writing test was obtained. A ball having a diameter of 0.7 mm was used as the ballpoint pen tip.

<Handwriting visual confirmation test>
Three test ballpoint pen samples were prepared for each, and the writing angle was set to 70 °, the writing load was set to 981 mN, and the writing speed with a spiral writing tester (WRITING TESTER, MODEL TS-4C-10 manufactured by SEIKI KOGYO LAB.). 7 cm / sec, the ballpoint pen sample was rotated under the condition of 1 m / rotation, and a continuous spiral handwriting was written on fine paper from the beginning to 10 m. The handwriting widths of the thick and thin handwritings were measured with a measuring microscope STM manufactured by Olympus Corporation, and the difference between the maximum and minimum handwriting widths in each of the three ballpoint pen samples is shown in Table 1. It was shown to.

<Writing monitor test>
Three test ball-point pen samples were prepared, and three randomly selected monitors were compared with the sample of Comparative Example 1 in terms of writing quality and evaluated on a five-point scale. If it was equivalent to Comparative Example 1, it was 3 points, 4 points if it felt slightly superior, and 5 points if it felt superior. Moreover, if it was felt that the writing taste was slightly inferior to Comparative Example 1, it was evaluated as 2 points, and if it was felt inferior, it was evaluated as 1 point. The results are shown in Table 1.

Longitudinal sectional view of main parts of the ballpoint pen tip of the present invention Principal longitudinal sectional view up to the radial grooving process in Example 1 The principal part longitudinal cross-sectional view to the finishing process of the ball holding chamber in Example 1 The principal part longitudinal cross-sectional view to the hammer processing process in Example 1

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ball 2 Ball holder 2a Center hole 3 Ball holding chamber 3a Tip opening 3b Inner protrusion 3c Ball seat 3d Side 4 Rear hole 5 Middle hole 6 Radial groove 6a Outermost edge M Hammer tool

Claims (2)

An inward protruding portion is formed as a seat for restricting backward movement of the ball as a writing member, and a central hole and a radial groove portion communicating with the inner protruding portion are formed in the inward protruding portion. A method of manufacturing a ballpoint pen tip that performs a finishing process for cutting a side portion. The ballpoint pen tip manufacturing method according to claim 1, wherein the finishing process is also performed on an inward projecting portion excluding at least an outermost edge portion of the radial groove portion.

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