JPH10217665A - Ball point pen tip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a ball seat without eccentricity by cutting the end of a metal fine tube to form a ball holding hole and a conical face, and then putting a ball in the ball holding hole, striking the ball and transferring a ball face onto the conical face. SOLUTION: The end of a metal fine tube 1 is cut into the cylindrical shape, and a ball holding hole 2 slightly larger than the diameter of a ball 5 is formed between an inner wall face of the end of the tube and the ball side face. Also a conical face 3 of given angle is formed on a bottom section, and then the end face is turned into the thin wall, and a plurality of ink channels 4 are broached from the conical face 3 is the axial direction. Then the ball 5 is put into the ball holding hole 2, and an end thin wall section 6 is caulked inwardly, and then the ball 5 is struck to transfer the face of the ball 5 onto the conical face 3 and form a ball seat 7. On the other hand, an ink guide refill 9 is inserted from the rear of a tip, and the middle section of the metal fine tube 1 is caulked when the guide is brought into contact with the rear of the ball 5 to fix the guide refill 9, and a part thereof is formed into the ball set, by which the ball sheet without eccentricity can be formed and stabilized writing touch can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a ballpoint pen tip from a thin metal tube.

[0002]

2. Description of the Related Art As a conventional method of manufacturing a ballpoint pen tip from a thin metal tube, a ball receiving seat is formed by pressing and deforming the vicinity of the tip of the thin metal tube inward at a plurality of locations to form an inwardly protruding portion. There is known a method of manufacturing a ball-point pen tip by caulking the edge of the front end inward after mounting.

[0003]

In the above-mentioned conventional processing method, the plurality of inwardly projecting portions serving as ball receiving seats are not regulated from the inside of the thin metal tube, so that their sizes and shapes are difficult to be uniform. It is difficult to align the positions, and when a ball is inserted and the tip edge is crimped inward to make a chip, the ball is seated on the receiving seat with a bias, so that there is a drawback that the ink outflow varies depending on the writing direction of the writing line.

[0004]

In order to achieve the above object, a ballpoint pen tip of the present invention is provided. A ball tip is formed by cutting a tip portion of a thin metal tube to form a ball holding hole and a conical surface. It is necessary to form a stable ball receiving seat without deviation by transferring the ball surface into a conical surface by hitting the ball into the ball holding hole and hitting the ball to form a ball receiving seat.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. First, FIG. 1 is a vertical cross-sectional view of a ballpoint pen tip, and a thin metal tube 1 is SUS304, SUS305, SUS316, S
It is made of a stainless steel thin tube such as US430, and has an inner diameter that secures a sufficient ball receiving seat to receive the pen pressure (in this case, the smaller inner diameter is advantageous), and a smooth flow of the ink in the thin tube (in this case, Considering the range that satisfies both of the above, the ball diameter should be 0.6 to 0.86 times the ball diameter, and the outer diameter should be the bending strength against the pen pressure and the design refinement of the tip unique to a thin tube. Think, 1.3 of the ball diameter
The hardness is preferably 200 to 300 in terms of Vickers hardness in consideration of the ease of cutting (good cut skin, sweeping of chips, holding of tool).

The tip of the metal tube 1 is formed into a cylindrical shape by cutting so that the diameter of the ball 5 is increased by 0.01 to 0.05 mm so that the ink flows smoothly between the inner wall surface and the side surface of the ball. In order to form a stable ball receiving seating surface 7, the bottom surface is formed in a conical surface 3 of 90 to 160 degrees, and then the end surface is conical-turned to reduce the thickness. The ink groove 4 is formed in a suitable length in the axial direction by a plurality of broaching processes. After the ball 5 is inserted into the ball holding hole 2, the tip thin portion 6 is caulked inward, and then the ball 5 is hit to transfer the surface of the ball 5 to the conical surface 3 to form a ball receiving seat 7 and a metal thin tube. The ball 5 can be moved in the axial direction by a distance of 0.02 to 0.06 times the diameter of the ball, so that a gap is formed between the ball 5 and the ball caulking portion 8 so that ink is ejected during writing. The movement amount of the ball may be set to an appropriate value by changing the hit amount of the ball 5 according to the physical properties of ink and the specifications of the writing characteristics.

Next, an ink guide core 9 is mounted in the chip. The ink guide core 9 has a weak capillary force at the inner diameter of the metal thin tube 1, and it is difficult to transfer ink from the rear end of the metal thin tube 1 to the ball 5. This is to prevent the ink from running out of ink inside the thin metal tube 1 when left upward. The ink guide core 9 is formed by extruding a resin such as polyacetal, and has a groove 10 for forming a capillary on its outer surface.
Are formed in a large number in the axial direction. The ink guide core 9 as described above is inserted from the rear part of the chip, abuts against the rear surface of the ball 5, further presses the ball 5, and when the ball 5 comes into contact with the inside of the caulking part 8, the middle of the thin metal tube 1 is punched and caulked. 11 and fix the ink guide core 9. By doing so, there is no gap between the ball and the ball caulking portion 8 and no ink comes out, but at the time of writing, the ball 5 is pressed, and further, the ball 5 presses the ink guide core 9 and the ink guide core 9 is elastically deformed and the ball caulking portion 8 and A gap is formed in the ball 5 and the ink comes out, and the leading end surface of the ink guide core 9 also partially plays a role of a ball receiving seat, which contributes to the improvement of writing quality. By the way, a punch caulking 1 for fixing the ink guide core 9
1 is a columnar shape or a conical shape whose root is thicker so that the outer diameter is 0.2 to 0.4 times the inner diameter of the thin metal tube 1 and the depth is 0.25 to 0.45 times the inner diameter of the thin metal tube 1. The pin is pressed to form a depression. If the size of the punch caulking 11 exceeds this range, the fixing of the ink guide core 9 becomes unstable or the flow of ink is hindered.

The positioning of the ink guide core 1 in the thin metal tube is performed by bringing the tip of the ink guide core 9 into contact with the lower surface of the ball while the ball 5 is in contact with the inside of the ball caulking portion 8. With the ball 5 in contact with the ball receiving seat 7, the tip of the ink guide core 9 may be in contact with the lower surface of the ball 5 for positioning, and the thin metal tube 1 may be punched and fixed.

[0009]

As described above, according to the present invention, a conical surface is formed at the bottom of a ball holding hole by cutting a thin metal tube, and the ball surface is transferred by hitting the ball onto the conical surface. It can be a ball receiving surface. For this reason, there is no deviation in the sitting of the ball, and there is no change in the ink flow rate depending on the writing direction, so that a stable writing quality can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a chip of the present invention.

FIG. 2 is an enlarged vertical sectional view of a peripheral portion of the ball in FIG. 1;

FIG. 3 is a longitudinal sectional view of the ink guide core of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal thin tube 2 Ball holding hole 3 Conical part 4 Ink groove 5 Ball 6 Thin part 7 Ball receiving seat 8 Ball caulking part 9 Ink guide core 10 Groove 11 Punching

Claims (7)

[Claims] 1. A conical surface which forms a ball holding hole and a ball receiving seat by forming a ball holding hole and a ball receiving seat by expanding the inside of a thin metal tube by cutting.
After that, a plurality of ink grooves are formed by broaching, and the outer periphery of the tip is conically turned to make the end thinner. After the ball is inserted, the thinned end is caulked inward to hold the ball. Hold the ball and tap the ball to transfer the ball surface to the conical surface to form a ball seat, and then insert the ink guide core from the rear of the metal thin tube, punch and caulk the middle of the metal thin tube, and fix the ink guide core from the metal thin tube. Ballpoint pen tip to manufacture. 2. The ball-point pen tip according to claim 1, wherein said ball-point pen tip has a ball holding hole having a ball diameter of 0.01 to 0.05 mm larger and a conical surface angle of 90 to 160 degrees. 3. The ball-point pen according to claim 1, wherein the ball-point pen tip has an outer diameter of the metal thin tube of 1.3 to 1.6 times the ball diameter and an inner diameter of 0.6 to 0.86 times the ball diameter. Chips. 4. The ball-point pen tip according to claim 1, 2 or 3, wherein the ball-tip tip hits the ball and the amount of axial movement of the thin metal tube after forming the ball receiving seat is 0.02 to 0.06 times the ball diameter. Ballpoint pen tip. 5. The tip of the ink guide core is brought into contact with the lower end surface of the ball in a state where the ball is in contact with the inner surface of the ball caulking portion at the tip of the metal tube, and the side surface of the metal tube is punched. Is 0.2 to 0.4 times the diameter of the metal tube and the depth is 0.25 to 0.4 times the inner diameter of the metal tube.
5. The ballpoint pen tip according to claim 1, wherein the ink guide core is fixed to a metal tube by forming a five-fold concave part and forming a convex part inside. 6. The ball-point pen tip is configured such that a tip end surface of an ink guide core is brought into contact with a ball lower end surface in a state where a ball is in contact with a ball receiving seat, and a side surface of a metal thin tube is punched to have a diameter outside the metal thin tube. 2. The ink guide core is fixed to the metal tube by forming a concave portion having a diameter of 0.2 to 0.4 times and a depth of 0.25 to 0.45 times the inner diameter of the metal tube, forming a convex portion on the inner side. The ballpoint pen tip according to 2, 3, or 4. 7. The ball-point pen tip has an ink guide core formed by extrusion molding of plastic such as polyacetal, and has a plurality of grooves formed in its outer surface extending in the axial direction, and has a circumscribed circle diameter of 0.75 to 0 of a thin metal tube. 7. The ballpoint pen tip according to claim 1, 2, 3, 4, 5, or 6.