JP2001191679A - Ballpoint pen tip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a ballpoint pen tip containing a ball valve mechanism without necessity of a complicated mechanism or an expensive material, to provide a ballpoint pen having general purpose properties so as to improve the pen having high performance at a low cost. SOLUTION: A coiled spring contained in the ballpoint pen is bent at its spring wire material end of the side contacted with a writing ball to the inside and formed in a shape not projected out to the outside from the outer periphery of the spring. Thus, when the spring is inserted into a tip, the spring is not engaged with a step or the like in the tip, but can be easily arrived at the ball.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a ball-point pen having a so-called ball valve mechanism, in which a writing ball is always pressed by an elastic body so as to be in close contact with the inner surface of the tip of the tip.

[0002]

2. Description of the Related Art Conventionally, a ballpoint pen tip having a built-in elastic body and a ball valve mechanism for pressing a writing ball has a structure in which a coiled spring pushes a writing ball through a movable member, or an elastic body has a coiled spring. A structure in which a writing ball is pressed by a rod-shaped part formed of the same body from one end surface of the same, and a structure in which a spring in which the outer diameter of the coil is changed and the writing ball is pressed by the end surface having a smaller outer diameter is used. Etc. are known.

[0003]

The above-mentioned conventional ballpoint pen tip with a built-in ball valve mechanism has problems that the number of parts is large and the productivity is low because the shape of the elastic body is complicated. With a structure in which the writing ball is pressed by the thin end face of the spring whose outer diameter has been changed, burrs and deformation of the end face that occur when cutting the end face in the coil manufacturing process cause the inner part to be inserted when the spring is inserted into the chip. There was a problem that a phenomenon that the writing ball could not be pressed due to being caught on the step occurred.

SUMMARY OF THE INVENTION An object of the present invention is to improve a ballpoint pen tip having a built-in ball valve mechanism for pressing a writing ball by incorporating an elastic body, and to provide a ball valve mechanism that can operate reliably with a reduced number of parts and with good productivity. What you want to do.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a ballpoint pen tip of the present invention is rotatable at its tip so that a ball serving as a writing portion is exposed to the outside, and has a built-in elasticity. The front of the body is designed so that the writing ball is prevented from slipping out by caulking, and the back is loosely fitted so that it cannot be pulled out by the caulking at the rear end of the pen tip or the internal step of the joint part behind the pen tip, and the coil spring contacts the writing ball. The end of the spring wire on the side is bent inward so as not to protrude outside the outer diameter of the spring. In addition, the ink can flow through a gap formed by a plurality of channel grooves provided in appropriate dimensions inside the chip, lateral play in the horizontal direction, and vertical play in the vertical direction. It can be derived on paper.

[0006]

The operation of the above means will be described below. According to the improvement of the present invention, the end of the spring wire rod on the side in contact with the writing ball of the built-in spring is bent inward, so that when the spring is inserted into the chip, the writing ball is not caught by a step inside the chip. It is possible to provide an action that can be easily reached. The spring inserted firmly until it comes into contact with the writing ball is caulked at the rear end face of the chip and is prevented from falling off by the internal step of the joint part holding the chip, so that the writing ball is constantly pressed, and the tip of the tip of the chip This makes it possible to prevent the ink from dripping or dry-up due to close contact with the inside of the caulking. This is effective for any type of ballpoint pen without any restrictions due to the type of ink and the difference in writing ball diameter.

[0007]

1 and 2 show an example of a ball-point pen chip according to an embodiment of the present invention. The details will be described below with reference to the drawings. FIG. 1 is a detailed view of a ballpoint pen tip portion.
A writing ball 2 is secured to the tip of a tip 1 made of a metal such as stainless steel, brass, nickel silver, or plastic, or the like by a caulking 1-1 on a front end side and a receiving seat 1-2 on a rear end side, A writing ball 2, which is a sphere made of ceramic, carbide, stainless steel, or the like, is loosely fitted rotatably with vertical play in front and back. Generally, these caulks 1-1 are processed by plastic deformation or a combination of plastic deformation and cutting. In the chip 1, a flow path from the rear to the tip is formed by the ink holes 1-4.

In the chip 1, the ink hole 1-4 is not closed even when the ball 2 comes into contact with the receiving seat 1-2 in the rear inside at the time of writing.
A plurality of radial grooves, that is, channel grooves 1-3 are provided. A coil spring 3 for constantly pressing the writing ball forward is provided behind the writing ball 2, and the front of the coil spring 3 is secured by the writing ball 2 which is prevented by the caulking 1-1. Due to the internal step of the front and rear joint parts, they were loosely fitted so that they could not be pulled out. Normally, when writing, the coil spring 3 bends and the ball 2 moves rearward inside the pen tip to secure an ink flow path. During non-writing, the ball 2 at the tip acts as a ball valve to close the ink flow path and ink is discharged. In addition to the operation of the backflow prevention mechanism that can prevent backflow, a function of preventing direct current, which causes ink to flow from the pen tip when the pen is turned downward, can be obtained at the same time.

Here, the shape of the coil spring 3 is not particularly limited, and is appropriately set according to the shape inside the chip. However, it is desirable that portions excluding both end surfaces of the coil spring 3 are wound at appropriate intervals so that the ink can flow in the chip without resistance.

FIG. 2 is an enlarged view of an end surface of the coil spring 3 in a cross section taken along the line AA of FIG. 1 and shows a state in which the end 3-1 of the spring wire is bent inward. Since the end 3-1 of the spring wire is always bent inward, it does not protrude outside the outer diameter of the spring. Further, even when the burr 3-2 is formed at the time of cutting the coiling, since the end 3-1 of the spring wire is bent inward, it does not protrude outside the outer diameter of the spring. With this configuration, the coil spring 3 can reach the writing ball 2 without being caught by the step 1-5 in the chip even when the step 1-5 in the chip in FIG. 1 exists, for example.

[0011]

By implementing the present invention, a ballpoint pen tip having a ball valve mechanism for solving problems such as ink leakage and dry-up can be provided with good productivity and at low cost. The spring can easily reach the writing ball without getting caught on the step in the chip in the process of inserting it into the
The defect that the spring does not press the writing ball can be prevented beforehand.

[Brief description of the drawings]

FIG. 1 is a detailed longitudinal sectional view showing a ballpoint pen tip according to an embodiment of the present invention.

FIG. 2 is an enlarged view of an end surface of a coil spring 3 in a cross section taken along line AA of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Chip 1-1 Caulking 1-2 Receiving seat 1-3 Channel groove 1-4 Ink hole 1-5 Step inside chip 2 Writing ball 3 Coil spring 3-1 End of spring wire 2-2 Burr

Claims (1)

[Claims] A writing ball rotatably fitted in a state protruding from a front end thereof is restricted to move forward and backward by a caulking on a front end side by a receiving seat on a rear end side, and a rear end inside. An elastic body that has an ink hole for drawing ink from the side, a channel groove formed by a plurality of grooves communicating the receiving seat and the ink hole, and is further installed so as to constantly press the ball at the tip forward. In the ballpoint pen tip provided, the elastic body is formed of a coil-shaped spring, and the end of the spring wire rod in contact with the writing ball is bent inward.